1. The document investigates the effect of ammonia concentration on the electrical, optical, and structural properties of cadmium sulfide (CdS) thin films deposited via chemical bath deposition (CBD).
2. When the ammonia concentration was varied from 0.1M to 3.0M, films were obtained between 0.25M and 2.5M ammonia, with the best results at 2.0M.
3. Electrical measurements showed the films have n-type conductivity. Carrier concentration decreased from 1.831x106 cm-3 to 1.026x106 cm-3 as ammonia increased from 0.5M to 2.5M due to changes in sulfur
Characterization Studies of CdS Nanocrystalline Film Deposited on Teflon Subs...IJLT EMAS
In this article, different substrates for deposition of
CdS material have been discussed. Till date glass, mica, quartz,
ceramic, etc. are commonly employed substrates in thin film
growth. In the present work, CdS is deposited on Teflon
substrate by chemical bath deposition (CBD) method. Also the
films were deposited on different substrates like glass, copper
and zinc and compared with those prepared on Teflon substrate.
The films prepared on Teflon substrate were uniform, stable and
also showed good radiating property. These films were further
characterized by UV-VIS absorption spectral studies, SEM and
EDS studies.
Aluminum doped cadmium selenide tin films of different compositions, (0.1-1.0 mol %) deposited by dip
coating method on cleaned glass substrates at room temperature. All the films are polycrystalline nature
having hexagonal structure. For all the films the preferred orientation is (100). Some other orientations like
(101), (110), (112) (202) (203) are also observed in the films. The values of interplanar distance, dislocation
density, microstrain, lattice parameters, volume of unit cell, number of crystallites per unit area and particle
size of the aluminum doped thin films were calculated and their variation with dopant concentration was
studied. Interplanar distance, intensity, lattice parameters, volume of unit cell and particle size increases up
to 0.25mol % of aluminum. Microstrain, dislocation density and number of crystallite per unit area decreases
up to 0.25mol % aluminum concentration
Influence of Field Assisted Chemical Spray Pyrolysis Deposition Technique on the Structural and Optical Properties of CdS Thin Films
Original Research Article
Journal of Chemistry and Materials Research Vol. 1 (2), 2014, 23–27
U.U. Iwok*, J.A. Bwamba, N.O. Alu, K.K. Adama, Z. Abdullahi, A.C. Egba, A.A. Oberafo, B.O. Akogwu
Characterization Studies of CdS Nanocrystalline Film Deposited on Teflon Subs...IJLT EMAS
In this article, different substrates for deposition of
CdS material have been discussed. Till date glass, mica, quartz,
ceramic, etc. are commonly employed substrates in thin film
growth. In the present work, CdS is deposited on Teflon
substrate by chemical bath deposition (CBD) method. Also the
films were deposited on different substrates like glass, copper
and zinc and compared with those prepared on Teflon substrate.
The films prepared on Teflon substrate were uniform, stable and
also showed good radiating property. These films were further
characterized by UV-VIS absorption spectral studies, SEM and
EDS studies.
Aluminum doped cadmium selenide tin films of different compositions, (0.1-1.0 mol %) deposited by dip
coating method on cleaned glass substrates at room temperature. All the films are polycrystalline nature
having hexagonal structure. For all the films the preferred orientation is (100). Some other orientations like
(101), (110), (112) (202) (203) are also observed in the films. The values of interplanar distance, dislocation
density, microstrain, lattice parameters, volume of unit cell, number of crystallites per unit area and particle
size of the aluminum doped thin films were calculated and their variation with dopant concentration was
studied. Interplanar distance, intensity, lattice parameters, volume of unit cell and particle size increases up
to 0.25mol % of aluminum. Microstrain, dislocation density and number of crystallite per unit area decreases
up to 0.25mol % aluminum concentration
Influence of Field Assisted Chemical Spray Pyrolysis Deposition Technique on the Structural and Optical Properties of CdS Thin Films
Original Research Article
Journal of Chemistry and Materials Research Vol. 1 (2), 2014, 23–27
U.U. Iwok*, J.A. Bwamba, N.O. Alu, K.K. Adama, Z. Abdullahi, A.C. Egba, A.A. Oberafo, B.O. Akogwu
We report research on electrodeposition of indium sulfide films, with In2S3 a less hazardous alternative to CdS buffer layers in solar cells. Numerous organic and aqueous/organic electrolytes of InCl3, NaCl, and elemental sulfur were investigated, including several glycols and amides. Temperatures ranged from 80-170°C, and deposition voltages from -0.6 to -1.2 V (Ag/AgCl with organic filling solution). Substrates included indium tin oxide-on-glass, molybdenum, and titanium, with indium or graphite anodes. Rapid stirring was used. Deposition was sluggish in all baths. Uniformity and adherence were only moderate, with irregular coverage and cracking-and-flaking sometimes evident. The best baths were ethylene glycol or 1, 2-propanediol-based, with golden-yellow films, nominally In2S3-xOx, depositing typically heavier around the substrate edges. With low temperatures and/or large currents, brown films more rich in indium sometimes formed. Cyclic voltammetry elucidated onset potentials, secondary reactions, and photoactivity, with the greatest anodic photocurrents arising from In2S3's n-type conductivity occurring with mixed ethylene glycol/propionic acid/water baths. Scanning electron microscope photographs indicated a compact small grain microstructure for yellow films. Energy dispersive X-ray analysis and photoelectron spectroscopy data indicate up to 15% oxygen content.
Swelling properties of pulp treated with deep eutectic solventsMichal Jablonsky
The reaction of cellulose with water produces swelling and structural changes of the fibres, both effects being of crucial importance for the understanding of paper formation. It was investigated how the treatment of pulp with deep eutectic
solvents affects the swelling kinetics of the fibres. Unbleached kraft pulp was treated with three deep eutectic solvents containing choline chloride (ChCl) – ChCl:lactic acid (1:9), ChCl:oxalic acid (1:1) and ChCl:malic acid (1:1) – and with the system alanine:lactic acid (1:9). The rate and maximum swelling of the
pulp in water were determined using a modified monitoring unit for measuring swelling ability. Since paper swells extremely rapidly in water even at 23°C, this apparatus made it possible for the first time to obtain accurate rate data on the swelling of DES-delignified pulp in water.
Influence of reaction medium on morphology and crystallite size of zinc oxidejournal ijrtem
ABSTRACT : Zinc oxide nanoparticles were prepared by reacting zinc chloride and sodium hydroxide in different mediums such as chitosan, poly vinyl alcohol, ethanol and starch. The materials were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) studies, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Elemental analysis was done by energy dispersive X-ray Analysis (EDAX).
KEY WORDS : Nano zinc oxide, morphology, crystallite size
The presentation assesses the use of simultaneous neutron and x-ray tomography as a method to characterize damage induced in concrete by delayed ettringite formation (DEF). The presentation also analysis the effect of potassium content in the damage mechanism of concrete due to delayed ettringite formation (DEF)
Synthesis Characterization and Properties of Silica-Nickel Nanocomposites thr...IJERA Editor
There has been an increasing demand for high performance Nanocomposites which can withstand several conditions such as low and high temperature, pressure and atmosphere in various applications. In order to meet these demands, SiO2-Nickel Nanocomposites can be explored for important applications in various industries. Metals having sizes of the order of a few nanometers dispersed in silica matrix and their sintering mechanism have been discussed in this work. A Niihara approach is chosen to measure the micro-fracture toughness of silica-nickel Nanocomposites for both type of cracks found in this work.
Congestion Control in Manets Using Hybrid Routing ProtocolIOSR Journals
Abstract : As the network size increases the probability of congestion occurrence at nodes increases. This is because of the event driven nature of ad hoc networks that leads to unpredictable network load. As a result congestion may occur at the nodes which receive more data than that can be forwarded and cause packet losses. In this paper we propose a hybrid scheme that attempts to avoid packet loss due to congestion as well as reduce end to end delay in delivering data packets by combining two protocols- Destination sequenced distance vector routing (DSDV), which is a table driven or proactive protocol and Improved Ad-hoc on demand vector routing (IAODV) which is an on-demand or reactive protocol that reduces packet loss due to congestion. The strategy adopted is use DSDV for path selection and if congestion occurs than switch over to IAODV. The routing performance of this model is then compared with IAODV and DSDV in terms of end to end delay, throughput and packet delivery fraction. Keywords- DSDV, Hybrid protocol, AODV, IAODV, MANET
The Protective Role Of High Dietary Protein On Arsenic Induced Hepatotoxicity...IOSR Journals
The objective of the present investigation was to study the protective role of High dietary protein on arsenic induced hepatotoxicity model in adult male albino rats. Hepatotoxicity in rats was caused by arsenic tri oxide at a dose of 3mg- /ml/kg body weight. Hepamerz, a drug used as standard hepatoprotective agent, was administered orally as standard hepatoprotective agent for 14 consecutive days prior to arsenic treatment at a dose of 10mg- /ml/kg body weight. This drug has many side effects. These side effects have prompted the scientific world for the search of alternative natural remedies of liver damage. The High dietary protein was administered orally to rats along with arsenic. The biochemical parameters were investigated. The results indicated that biochemical changes produced by arsenic were restored to almost normal by High protein diet. The High protein diet produced hepatoprotective effect through the modulation of antioxidant - mediated mechanism by altering serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), alkaline phosphatase (ALP), superoxide dismutase (SOD) and catalase (CAT) activities and reduced glutathione (GSH) and lipid peroxidation (LPO) levels - against arsenic induced hepatotoxicity model in rats.
We report research on electrodeposition of indium sulfide films, with In2S3 a less hazardous alternative to CdS buffer layers in solar cells. Numerous organic and aqueous/organic electrolytes of InCl3, NaCl, and elemental sulfur were investigated, including several glycols and amides. Temperatures ranged from 80-170°C, and deposition voltages from -0.6 to -1.2 V (Ag/AgCl with organic filling solution). Substrates included indium tin oxide-on-glass, molybdenum, and titanium, with indium or graphite anodes. Rapid stirring was used. Deposition was sluggish in all baths. Uniformity and adherence were only moderate, with irregular coverage and cracking-and-flaking sometimes evident. The best baths were ethylene glycol or 1, 2-propanediol-based, with golden-yellow films, nominally In2S3-xOx, depositing typically heavier around the substrate edges. With low temperatures and/or large currents, brown films more rich in indium sometimes formed. Cyclic voltammetry elucidated onset potentials, secondary reactions, and photoactivity, with the greatest anodic photocurrents arising from In2S3's n-type conductivity occurring with mixed ethylene glycol/propionic acid/water baths. Scanning electron microscope photographs indicated a compact small grain microstructure for yellow films. Energy dispersive X-ray analysis and photoelectron spectroscopy data indicate up to 15% oxygen content.
Swelling properties of pulp treated with deep eutectic solventsMichal Jablonsky
The reaction of cellulose with water produces swelling and structural changes of the fibres, both effects being of crucial importance for the understanding of paper formation. It was investigated how the treatment of pulp with deep eutectic
solvents affects the swelling kinetics of the fibres. Unbleached kraft pulp was treated with three deep eutectic solvents containing choline chloride (ChCl) – ChCl:lactic acid (1:9), ChCl:oxalic acid (1:1) and ChCl:malic acid (1:1) – and with the system alanine:lactic acid (1:9). The rate and maximum swelling of the
pulp in water were determined using a modified monitoring unit for measuring swelling ability. Since paper swells extremely rapidly in water even at 23°C, this apparatus made it possible for the first time to obtain accurate rate data on the swelling of DES-delignified pulp in water.
Influence of reaction medium on morphology and crystallite size of zinc oxidejournal ijrtem
ABSTRACT : Zinc oxide nanoparticles were prepared by reacting zinc chloride and sodium hydroxide in different mediums such as chitosan, poly vinyl alcohol, ethanol and starch. The materials were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) studies, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Elemental analysis was done by energy dispersive X-ray Analysis (EDAX).
KEY WORDS : Nano zinc oxide, morphology, crystallite size
The presentation assesses the use of simultaneous neutron and x-ray tomography as a method to characterize damage induced in concrete by delayed ettringite formation (DEF). The presentation also analysis the effect of potassium content in the damage mechanism of concrete due to delayed ettringite formation (DEF)
Synthesis Characterization and Properties of Silica-Nickel Nanocomposites thr...IJERA Editor
There has been an increasing demand for high performance Nanocomposites which can withstand several conditions such as low and high temperature, pressure and atmosphere in various applications. In order to meet these demands, SiO2-Nickel Nanocomposites can be explored for important applications in various industries. Metals having sizes of the order of a few nanometers dispersed in silica matrix and their sintering mechanism have been discussed in this work. A Niihara approach is chosen to measure the micro-fracture toughness of silica-nickel Nanocomposites for both type of cracks found in this work.
Congestion Control in Manets Using Hybrid Routing ProtocolIOSR Journals
Abstract : As the network size increases the probability of congestion occurrence at nodes increases. This is because of the event driven nature of ad hoc networks that leads to unpredictable network load. As a result congestion may occur at the nodes which receive more data than that can be forwarded and cause packet losses. In this paper we propose a hybrid scheme that attempts to avoid packet loss due to congestion as well as reduce end to end delay in delivering data packets by combining two protocols- Destination sequenced distance vector routing (DSDV), which is a table driven or proactive protocol and Improved Ad-hoc on demand vector routing (IAODV) which is an on-demand or reactive protocol that reduces packet loss due to congestion. The strategy adopted is use DSDV for path selection and if congestion occurs than switch over to IAODV. The routing performance of this model is then compared with IAODV and DSDV in terms of end to end delay, throughput and packet delivery fraction. Keywords- DSDV, Hybrid protocol, AODV, IAODV, MANET
The Protective Role Of High Dietary Protein On Arsenic Induced Hepatotoxicity...IOSR Journals
The objective of the present investigation was to study the protective role of High dietary protein on arsenic induced hepatotoxicity model in adult male albino rats. Hepatotoxicity in rats was caused by arsenic tri oxide at a dose of 3mg- /ml/kg body weight. Hepamerz, a drug used as standard hepatoprotective agent, was administered orally as standard hepatoprotective agent for 14 consecutive days prior to arsenic treatment at a dose of 10mg- /ml/kg body weight. This drug has many side effects. These side effects have prompted the scientific world for the search of alternative natural remedies of liver damage. The High dietary protein was administered orally to rats along with arsenic. The biochemical parameters were investigated. The results indicated that biochemical changes produced by arsenic were restored to almost normal by High protein diet. The High protein diet produced hepatoprotective effect through the modulation of antioxidant - mediated mechanism by altering serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), alkaline phosphatase (ALP), superoxide dismutase (SOD) and catalase (CAT) activities and reduced glutathione (GSH) and lipid peroxidation (LPO) levels - against arsenic induced hepatotoxicity model in rats.
Fluorescence technique involves the optical detection and spectral analysis of light emitted by a substance undergoing a transition from an excited electronic state to a lower electronic state. The aim of this study is to assess the -amino levulinic acid (-ALA) uptake. Based on image processing technique, Matlab was used to analyze the fluorescence images resulted from activation of (-ALA) and follow its uptake along one week. Analyzing the RGB colours pixel profile from obtained results showed different profiles for malignant tissues, normal tissues, treated just after PDT and finally at one week post PDT. The treated tissues fluorescence profile showed changes from closer to malignant tissue profile till been closed to normal one.
Perishable Inventory Model Having Weibull Lifetime and Time Dependent DemandIOSR Journals
In this paper we develop and analyse an inventory model for deteriorating items with Weibull rate of decay and time dependent demand. Using the differential equations, the instantaneous state of inventory at time‘t’, the amount of deterioration etc. are derived. With suitable cost considerations the total cost function and profit rate function are also obtained by maximizing the profit rate function, the optimal ordering and pricing policies of the model are derived. The sensitivity of the model with respect to the parameters is discussed through numerical illustration. It is observed that the deteriorating parameters have a tremendous influence on the optimal selling price and ordering quantity.
Mathematical Modelling: A Comparatively Mathematical Study Model Base between...IOSR Journals
In this paper, we have studied on the topic of „Corruption‟. Also, I will try to find or study the effect of corruption on the Development of the country or any country of the world. Therefore, how find the solution of the problem of corruption will be destroyed completely from the society. We have observed that the Development of the country depends upon Corruption. That is, when the Corruption increases, Development decreases automatically of any country of the world. Therefore, I will try to find the formula on the problem of „Relation between the Corruption and Development of any field or any country of the world‟. Also, I have to highlight the concept of „Application of Mathematical modeling in the interesting problem “corruption” in every field of our country or world .Also, Applied Mathematics focuses on the formulation and study of Mathematical Models .Thus the activity of Applied Mathematics is vitally connected with Research in Pure Mathematics. So I will try to study on it and find, what is corruption and quantity of corruption and also find the growth of corruption and how it will decay? Now we convert this areal world problem to mathematics problem and find some formulae on it such as Mathematical Corruption Growth formula, Mathematical Constant corruption level formula and Mathematical decay of corruption formula.
Design and Implementation of Encoder for (15, k) Binary BCH Code Using VHDL a...IOSR Journals
Abstract: In this paper we have designed and implemented(15, k) a BCH Encoder on FPGA using VHDL for reliable data transfers in AWGN channel with multiple error correction control. The digital logic implementation of binary encoding of multiple error correcting BCH code (15, k) of length n=15 over GF (24) with irreducible primitive polynomial x4+x+1 is organized into shift register circuits. Using the cyclic codes, the reminder b(x) can be obtained in a linear (15-k) stage shift register with feedback connections corresponding to the coefficients of the generated polynomial. Three encoder are designed using VHDL to encode the single, double and triple error correcting BCH code (15, k) corresponding to the coefficient of generated polynomial. Information bit is transmitted in unchanged form up to k clock cycles and during this period parity bits are calculated in the LFSR then the parity bits are transmitted from k+1 to 15 clock cycles. Total 15-k numbers of parity bits with k information bits are transmitted in 15 code word. Here we have implemented (15, 5, 3), (15, 7, 2) and (15, 11, 1) BCH code encoder on Xilinx Spartan 3 FPGA using VHDL and the simulation & synthesis are done using Xilinx ISE 13.3. BCH encoders are conventionally implemented by linear feedback shift register architecture. Encoders of long BCH codes may suffer from the effect of large fan out, which may reduce the achievable clock speed. The data rate requirement of optical applications require parallel implementations of the BCH encoders. Also a comparative performance based on synthesis & simulation on FPGA is presented. Keywords: BCH, BCH Encoder, FPGA, VHDL, Error Correction, AWGN, LFSR cyclic redundancy checking, fan out .
An Overview of Intrusion Detection and Prevention Systems (IDPS) and Security...IOSR Journals
Technical solutions, introduced by policies and implantations are essential requirements of an
information security program. Advanced technologies such as intrusion detection and prevention system (IDPS)
and analysis tools have become prominent in the network environment while they involve with organizations to
enhance the security of their information assets. Scanning and analyzing tools to pinpoint vulnerabilities, holes
in security components, unsecured aspects of the network and deploying of IDPS technology are highlighted.
A Study on the Relationship between Nutrition Status and Physical Fitness of ...IOSR Journals
Abstract: Nutritional status during school age is a major determinant of nutritional and health status in adult
life. Many studies showed that under nutrition and anaemia had an adverse impact on performance and
consequently led to reduction in wages for persons employed in manual labour.
The past three decades have witnessed the emergence of over nutrition as a problem in school-age children in
developed countries and in affluent urban segments in developing countries. The main determinants of
performance are physical fitness and skill. Longitudinal studies have shown that the lifestyle and physical
fitness during childhood and adolescence were major determinants of lifestyle, physical fitness and freedom
from non-communicable diseases in adult life.
“Prevalent Clinical Entities Of Hilly Regions, Aetio-Pathogenesis Factors, An...IOSR Journals
Certain Surgical Clinical Conditions Manifests To Variable Extents With High
Prevalence In Hilly Regions. The Discrete Analysis Of Different Aetio-Pathogenesis Factors & Resultant Patho-
Physiological Changes Exhibit Comparative Co-Relation To Clinical Manifestations, ManageMent GuideLines &
OverAll Result OutCome ParaMetres.
Optimized Traffic Signal Control System at Traffic Intersections Using VanetIOSR Journals
Abstract: Traditional Automated traffic signal control systems normally schedule the vehicles at intersection in
a pre timed slot manner. This pre-timed controller approach fails to minimize the waiting time of vehicles at the
traffic intersection as it doesn’t consider the arrival time of vehicles. To overcome this problem an adaptive and
intelligent traffic control system is proposed in such a way that a traffic signal controller with wireless radio
installed at the intersection and it is considered as an infrastructure. All the vehicles are equipped with onboard
location, speed sensors and a wireless radio to communicate with the infrastructure thereby VANET is formed.
Once the vehicles enter into the boundary of traffic area, they broadcast their positional information as data
packet with their encapsulated ID in it. The controller at the intersection receives the transmitted packets from
all the legs of intersection and then stores it in a temporary log file. Now the controller runs Platooning
algorithm to group the vehicles approximately in equal size of platoons. The platoons are formed on the basis of
data disseminated by the vehicles. Then the controller runs Oldest Job First algorithm which treats platoons as
jobs. The algorithm schedules jobs in conflict free manner and ensures all the jobs utilize equal processing time
i.e the vehicles of each platoons cross the intersection at equal delays. The proposed approach is evaluated
under various traffic volumes and the performance is analyzed.
Keywords Conflict graphs, online job scheduling, traffic signal control, vehicular ad hoc network (VANET)
simulation, vehicle-actuated traffic signal control, Webster’s algorithm.
Wireless Network Security Architecture with Blowfish Encryption ModelIOSR Journals
Abstract: In this research paper ,we developed a model for a large network, wireless nodes are interconnected and each can be considered as a node processor that offer services to other node processors connected to a specific network. A very high proportion of the nodes that offer services need to carry out an authentication process so as to make an access request to the node offering the service. In this context, an integrated reconfigurable network security architecture moved to the application layer has become the need of the day for secure wireless data sharing. The security schemes of the seven layer OSI architecture need to be placed intrinsically in the wireless node itself and should be capable of supporting the MAC layer, IP address based layer and the routing protocols of the network layer. This work focuses on the use of emulator and embedded hardware architectures for wireless network security. In this work, the individual nodes can have a unique security signature pattern maintained by respective wireless nodes using an encryption algorithm and this is made dynamic. The metrics includes latency, throughput, Scalability, Effects of data transfer operation on node processor and application data located in the processor Keywords:Wireless Network security, Embedded hardware, Reconfigurable architecture, blowfish algorithm
Refining Measure of Central Tendency and DispersionIOSR Journals
A unified approach is attempted to bring the descriptive statistics in to a more refined frame work. Different measure of central tendencies such as arithmetic mean, median, mode, geometric mean and harmonic mean are derived from a generalized notion of a measure of central tendency developed through an optimality criteria. This generalized notion is extended to introduce the concept of an interval of central tendency. Retaining the spirit of this notion, measure of central tendency may be called point of central tendency. The same notion is further extended to obtain confidence interval for population mean in a finite population model and confidence interval for probability of success in Bernoulli population.
Calcium Chloride Applications to Improve Fruit Quality on Bruised and Disease...IOSR Journals
The problems faced by producer canned of pineapple are the high of bruised which caused by the mechanical damage such as pressure, vibration during harvest, transport to the fruit processing and pathological damage caused by fruit diseases. The objective of research was to obtain the treatment time of CaCl2 applications and dosage of CaCl2 to improve the fruit quality of pineapple. This research used Split Plot Design and each treatment replicated 3 times. The main plot is time of CaCl2 applications that consists of three levels, thats are : 90 day after forcing (daf) (W90), 120 daf (W120) and twice time of CaCl2 applications on 90 and 120 daf (W90+120). The sub plot is dosage of CaCl2 that consists of three levels, thats are : 50 kg ha-1 (C50), 75 kg ha-1 (C75) and 100 kg ha-1 (C100). The results of research showed that the combined treatment twice time of CaCl2 applications on 90 and 120 day after forcing and dosage of CaCl2 100 kg ha-1 produces the calcium content on fruit is higher than the other combined treatments and produce the fruit texture, percentage of fruit diseases and percentage of bruised are lower than the other combined treatments
Influence of Synthesizing Temperatures on the Crystallinity, Morphology and B...AI Publications
CdSe thin films were deposited using Chemical Bath Deposition (CBD) by maintaining the bath at 20 °C, 40 °C, 60 °C and 80 °C temperatures. The thin films were deposited on ordinary glass substrates then characterized for their crystallinity, morphological and optical properties. From the X-ray Diffraction (XRD) analysis; it was revealed that there was a significant difference in crystallinity and the UV-vis spectroscopy enhanced the study of the energy band gaps which showed a drastic shifting. The study performed on the surface morphologies of the CdSe thin films exhibited a double layer of deposition; but did not show considerable difference from each other for different temperatures. The EDS pattern helped in determining the stoichiometric ratio.
Structural, Optical and Electrical Studies on Spray Deposited Mercury Doped C...ijrap
Thin films of cadmium sulphide have been prepared using home built spray pyrolysis unit on glass substrate at 400 C. Aqueous solutions of cadmium chloride and thiourea were used for the cadmium
sulphide (CdS) films and different proportions by weight/volume of mercury II chloride was used for doping Hg onto cadmium sulphide (Cd1-xHgxS) films. The films obtained are having continuous, smooth surface with good transmittance. The thickness of all films is of the order of 320 nm. Determination of the crystalline nature has been done using XRD pattern. The effect of Hg on the surface morphology of CdS film has been studied by Scanning Electron Microscopy. The optical band gap has been calculated using the data from transmission spectra. Resistance before and after doping with Hg is also presented in the paper.
STRUCTURAL, OPTICAL AND ELECTRICAL STUDIES ON SPRAY DEPOSITED MERCURY DOPED C...ijrap
Thin films of cadmium sulphide have been prepared using home built spray pyrolysis unit on glass
substrate at 400 C. Aqueous solutions of cadmium chloride and thiourea were used for the cadmium
sulphide (CdS) films and different proportions by weight/volume of mercury II chloride was used for
doping Hg onto cadmium sulphide (Cd1-xHgxS) films. The films obtained are having continuous, smooth
surface with good transmittance. The thickness of all films is of the order of 320 nm. Determination of the
crystalline nature has been done using XRD pattern. The effect of Hg on the surface morphology of CdS
film has been studied by Scanning Electron Microscopy. The optical band gap has been calculated using
the data from transmission spectra. Resistance before and after doping with Hg is also presented in the
paper.
Thin films of cadmium sulphide have been
successfully deposited by chemical bath deposition (CBD)
technique using a mixed aqueous solution of cadmium
sulphate, thiourea, and triethylamine. The films were
characterized using a variety of techniques. Powder X-ray
diffraction analysis shows that the as-deposited thin film has
the hexagonal (wurtzite) structure. Scanning electron
microscope (SEM) micrographs show the film surface consists
of clusters with a globular surface morphology. Energy
dispersive X-ray diffraction (EDAX) analysis confirmed the
film to be consistent with the formation of cadmium sulphide
on silica glass slide. The band gap, determined from optical
absorption spectroscopy, was 2.42 eV which is consistent with
other published results.
5 ijaems jun-2015-19-x-ray diffraction of multilayer cd s-polyaniline thin filmsINFOGAIN PUBLICATION
In the present investigation, the films of Cadmium Sulphide and Polyaniline have been prepared by vacuum Evaporation Technique. The growth and characterization of single layer and multilayer films have been done. In this paper, the study of X-Ray diffraction of multilayer CdS/Polyaniline thin films has been done.
Synthesis and application of natural dye sensitizd cds thin films as photoano...eSAT Journals
Abstract
Natural dyes obtained from plants, vegetables and fruits are widely studied and tested as low cost sensitizer for dye sensitized solar cell ( DSSC) in order to replace the rare and expensive inorganic and organic sensitizers. Although, many works have been done using TiO2, ZrO2, ZnO etc. as the nanoporous semiconductor, little importance was given to the use of CdS thin film as a cost effective alternative. In the present study CdS thin films were synthesized by chemical bath deposition (CBD) technique and its optical, structural and morphological properties were investigated by XRD, SEM and UV-Vis absorption spectroscopy. The as synthesized films were found to be nanoporous in nature and are favorable for adsorbing the dyes on to its surface. Two natural dyes extracted from locally available plant leaves namely lawsonia inermis linn and caesalpinia pulcherrima were then adsorbed on the as synthesized CdS thin films for the formation of the working electrode for application in DSSC. The interaction between the nanoporous CdS thin films and the natural dyes were investigated through UV-Vis absorption spectroscopy with an aim to fabricate working electrode for application in DSSC.
Keywords: DSSC, thin film, CdS, natural dyes
Optical and Morphological Characterization of BaSeThinFilms Synthesized via C...IOSR Journals
Barium selinide (BaSe) thin films were deposited onto glass substrate via chemical bath deposition (CBD) method. The effect of deposition time on the thin film formation mechanism has been studied to understand the optimum conditions for synthesis process. The phase identification and surface morphology of thin coated films were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively while the optical characterizations were conducted by means of ultraviolet visible (UV- Vis) spectroscopy. XRD study confirms the polycrystalline hexagonal structure of the thin films. The XRD peaks at 2θ =23.84° and 2θ = 23.86o showed the preferential orientation along the (021) and (201)plane with deposition time 20 hours and 22 hours respectively, whereas the major peak at (111) was obtained with a deposition time of 24 hours. With the increase in deposition time up to 24 hours, the film gradually grew thicker along with the fine increase in the grain size. The direct optical band gap of the films was measured to be varied from 1.33 to 3.37 eV.
Morphological and Optical Study of Sol-Gel SpinCoated Nanostructured CdSThin ...iosrjce
Nanostructured CdS thin films of different thicknesses were deposited on a cleaned glass substrate
using sol-gel spin coating technique. CdS thin films were prepared using cadmium acetate as cadmium source
and thiourea as sulfur source. The Morphological, chemical composition, and optical properties of the spin- coated
CdS thin film were studied using field emission- scanning electron microscopy (FE-SEM), Energy dispersive X –ray
(EDX) spectroscopy, and a UV-Vis-NIR spectrophotometer.The morphological results revealed that the films consist
of agglomerated spherical CdS nanoparticles with diameter < 20 nm, which distributed uniformly on the substrate
surface.The films show high transmittance > 90% and very strong absorption edge at 295 nm.The absorption edge
shifts towards longer wavelength as the film thickness increased.
An Investigation of SILAR Grown Cobalt Selenide Thin Films IIJSRJournal
Nowadays, several deposition techniques have been used to produce thin film materials. The obtained films were characterized by using different tools. These semiconductor materials could be employed in solar cell, laser devices and opto-electronic devices. The main objective of this work is to produce cobalt selenide thin films through successive ionic layer adsorption and reaction method. Advantages of this method include simple procedures, inexpensive equipment, it does not need expensive vacuum system and high quality substrate. During the deposition process, the films were deposited onto soda lime glass under various anionic bath immersion times. The properties of the films were studied for the first time via field emission scanning electron microscopy (FESEM) and UV-visible spectrophotometer. Based on the FESEM analysis, uniform morphology could be observed for the sample produced for 30 seconds (anionic immersion time). The band gap was about 2.6 eV and the optical transmission increased in the visible region could be detected for these samples.
Radial Nano-Heterojunctions Consisting of CdS Nanorods Wrapped by 2D CN:PDI P...Pawan Kumar
Solar energy harvesting using semiconductor photocatalysis offers an enticing solution to two of the biggest societal challenges, energy scarcity and environmental pollution. After decades of effort, no photocatalyst exists which can simultaneously meet the demand for excellent absorption, high quantum efficiency and photochemical resilience/durability. While CdS is an excellent photocatalyst for hydrogen evolution, pollutant degradation and organic synthesis, photocorrosion of CdS leads to the deactivation of the catalyst. Surface passivation of CdS with 2D graphitic carbon nitrides (CN) such as g-C3N4 and C3N5 has been shown to mitigate the photocorrosion problem but the poor oxidizing power of photogenerated holes in CN limits the utility of this approach for photooxidation reactions. We report the synthesis of exfoliated 2D nanosheets of a modified carbon nitride constituted of tris-s-triazine (C6N7) linked pyromellitic dianhydride polydiimide (CN:PDI) with a deep oxidative highest occupied molecular orbital (HOMO) position, which ensures sufficient oxidizing power for photogenerated holes in CN. The heterojunction formed by the wrapping of mono-/few layered CN:PDI on CdS nanorods (CdS/CN:PDI) was determined to be an excellent photocatalyst for oxidation reactions including photoelectrochemical water splitting, dye decolorization and the photocatalytic conversion of benzyl alcohol to benzaldehyde. Extensive structural characterization using HR-TEM, Raman, XPS, etc., confirmed wrapping of few-layered CN:PDI on CdS nanorods. The increased photoactivity in CdS/CN:PDI catalyst was ascribed to facile electron transfer from CdS to CN:PDI in comparison to CdS/g-C3N4, leading to an increased electron density on the surface of the photocatalyst to drive chemical reactions.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Properties of CdS Chemically Deposited thin films on the Effect of Ammonia Concentration
1. IOSR Journal of Applied Physics (IOSR-JAP)
e-ISSN: 2278-4861.Volume 4, Issue 4 (Sep. - Oct. 2013), PP 01-07
www.iosrjournals.org
www.iosrjournals.org 1 | Page
Properties of CdS Chemically Deposited thin films on the Effect
of Ammonia Concentration
Munikrishna Reddy Y and Nagendra Vara Prasad M
Department of Physics, S S B N Degree & PG College, Anantapuram – 515001, A.P
Abstract : The effect of ammonia concentration on electrical properties, optical properties and structural
properties of chemical bath deposited (CBD) Cadmium sulphide (CdS) thin films has been revealed. The films
were prepared by using cadmium acetate as cadmium ion (Cd2+
) source, thiourea as sulphur ion (S2-
) source
and ammonia as the complexing agent. Ammonia concentration was changed from 0.1 M – 3.0 M. Ammonia
concentration at 2.0 M uniform, dense and continuously coated films were obtained. Not only typical cadmium-
pure but also unusual sulphur deficiency phenomena were observed for CBD CdS thin films. In the present
investigation, the carrier concentration varied form 1.831X106
cm-3
to 1.026X106
cm-3
when ammonia
concentration is changed from 0.5M to 2.5 M. The direct band gap energy at 0.5M is 1.92eV while at 2.5M is
2.65eV. The surface morphology of as deposited thin films is almost smooth and no grains were observed
clearly at low molar concentration and predominant grains at the concentration of ammonia is 2.0M. By
estimated Cd:S ratio value is found to be 1.04 by using EDAX. The thin film deposited at 2.0M concentration
shows the highest degree crystallinity. The formation mechanism of the films with various ammonia
concentrations is discussed.
Keywords: Ammonia effect, CBD-CdS thin films, Optical studies, SEM, XRD
I. Introduction
A number of physical and chemical methods were employed for the fabrication of hetero-junction
semiconductor thin films [1]. A wide variety of microstructures and consequently properties can be obtained by
simply varying the deposition conditions during the growth of the thin film. Also, the thin film properties are
strongly dependent on the method of deposition, the substrate materials, temperature, rate of deposition and
the background pressure. The application and properties of the given material determine the most suitable
technique for the preparation of thin films of the material. The different materials for the window layer, active
layer and transparent conducting electrodes for solar cells were prepared and characterised. Various deposition
techniques were employed for the deposition of these materials in thin film form and the structural and optical
properties of these films were studied using different characterisation tools [2]. Among them chemical bath
deposited (CBD) thin films have been reported in1960’s – 1990’s. Recent attention in chemical solution
deposition of CdS nanocrystals, nanotubes etc [3]. In this deposition, high quality thin films of CdS were
prepared effectively. CdS is a direct band gap of 2.42 eV II – IV semiconductor compound at room temperature
and it has been studied for many years for various optoelectronic applications. Some applications of CdS thin
films including photo detectors, piezoelectric transducers, bolo meters, solar cells, etc. [4]. CdS is one of the
most investigated thin films for photovoltaic application in the last five decades. Literature gives that CdS exist
in two crystalline forms [5] namely hexagonal phase and cubic phase . It is possible to grow CdS thin films in
both these phases. Extensive researches have been done on the deposition and characterization of CdS
semiconducting thin films due to their potential applications [6]. Direct band gap CdS thin films have been the
subject of intensive research because of its intermediate band gap, high absorption coefficient, electron affinity,
low resistivity, easy ohmic contact and finally the structure.
Deposition of CdS is based on the slow release of Cd2+
ions and S2-
ions in an aqueous alkaline bath
and the subsequent condensation of these ions on substrate suitably mounted in the bath. The slow release of
Cd2+
is achieved by adding a complexing agent to the Cd salt. The S2-
ions are supplied by the decomposition of
thiourea. It is observed that under a critical concentration ratio of species in solution, nanocrystalline CdS can be
deposited [7]. Over the years, different cadmium sources have been used in this process, such as cadmium
sulphate, cadmium acetate, cadmium iodide/nitrate, and cadmium chloride [6, 7]. The effect of Cd source on the
film properties has drawn attention for some times. Kitaev et al. found that when CdCl2 was used as a Cd source
the CdS film thickness was moderate and higher than CdSO4 or Cd(NO3)2 were used [8]. Similar results were
obtained when Ortega-Borges and Lincot [9] studied the CdS growth rate dependence. Actually, CdTe is one of
the most important semi conductors because of the direct band gap energy (1.45 eV), and the high conversion
efficiency of solar light in electricity. This is normally prepared by sublimation, by heating CdTe powder of
high purity at 700°C and deposited on a substrate at 500°C [10]. However, CdTe does not grow
stoichiometrically, having slight Cd vacancies deficiency, consequently growing as p-doped [11]. Thus, a
2. Properties of CdS Chemically Deposited thin films on the Effect of Ammonia Concentration
www.iosrjournals.org 2 | Page
natural n-doped material is required as a partner to achieve a good junction with high efficiency in solar
conversion. CdS thin films grown as n-type semiconductor due to the donor centres formed during deposition.
CdS is normally prepared by a low cost and low temperature technique: the Chemical Bath Deposition (CBD).
CdS polycrystalline films possess a direct band gap of 2.42-2.45 eV at room temperature. Hani et al
studied the effect of cadmium sources on film optical/electrical properties as well as film thickness, composition
and crystal structure [12]. The literature also revealed that the influence of thiourea concentration and found that
the growth rate was faster when the quantity of thiourea is much greater than cadmium chloride concentration in
the solution. Moreover, the literature also reported the influence of ammonia concentration on CdS thin film
thickness [13]. Several reports mentioned a modified CBD process for fabrication of large sized ZnS or CdS
thin films [14]. Application of substrate vibration reduced the formation and residence gas bubbles on the glass
substrates during CBD of ZnS or CdS, resulting in the growth of smooth, uniform and compact thin films with a
quality high enough for use in large sized solar cells. In our work with Chemical Bath Deposition (CBD) of
CdS, it was observed that the ammonia concentration in the CBD solution also played an important role in the
characterization of CdS thin films. In this work, we investigated the influence of ammonia concentration on the
electrical, optical and structural properties of CdS thin films. We present the results of the CdS thin films using
UV-Vis absorption, X-ray diffraction, Scanning Electron Microscope (SEM), and Energy Dispersive X-ray
Spectroscopy (EDAX). The detailed study on the effect of ammonia concentration on the physical properties of
CBD-CdS thin films is mentioned.
II. Experimental Details
In the present work, the experimental setup for the fabrication of CdS thin films by CBD consists of
magnetic stirrer and an aqueous solution used for preparation of Cd and S ions. The thin films were growing on
25.4 mm X 76.2 mm X 1.5 mm microscope glass slides. Before the deposition, the glass substrates were cleaned
in an ultrasonic cleaner using acetone and alcohol and they were soaked in a chromic acid cleaning solution for
20 min. Further, they were cleaned ultrasonically in an isopropyl alcohol. Finally, they were washed in
deionised water and dried by flowing with dry nitrogen for 30 min. The initial pH was adjusted with pH meter
until to obtain the pH=10.0 value. For this present work, cadmium acetate is the cadmium source and
ammonium acetate serves as a buffer. Ammonia is the complexing agent and thiourea is the source of sulphur.
The temperature of the mixer was maintained at constant temperature, 70°C and also all these
processes were carried out at this temperature only. The growth of CdS film occurs either by ion-by-ion
condensation of Cd and S ions on the substrate surface or by the adsorption of colloidal particles of CdS [15].
The glass substrates were cleaned thoroughly and inserted in the deposition cell containing the required amount
of de-ionized water. As-grown CdS layers are hard and look yellowish, shiny and have a smooth surface. The
last steps were washing in deionised water and air drying. The glass slides are taken out from the solution after
end of the film deposition. The prepared slides were rinsed with 10% ammonia solution, ultrasonically cleaned
with deionised water for a few minutes to remove the white and adherent precipitates during deposition and
blown dry nitrogen gas. The prepared thin films were examined and characterised by means of UV-Vis
absorption spectrophotometer, SEM and XRD.
III. Results And Discussion
Chemical Bath Deposition (CBD) of high quality CdS thin films are based on the chemical
precipitation of CdS in bath. The precipitation control can be achieved by controlling the free cadmium metal
ions concentration; generally ammonia is used as a complexing agent. The cadmium salt produces free cadmium
ions (Cd2+
) through a dissociation reaction. The cadmium ions then complexing with ammonia form the
dominant tetra-amino-cadmium complex ion Cd(NH3)4
2+
. On the surface, the Cd(NH3)4
2+
ions react with
hydroxide ions to form the absorbed dihydroxo-diamino-cadmium complex. This complex then reacts with
thiourea to form the absorbed metastable complex [Cd(OH)2(NH3)2SC(NH2)2]. Finally, CdS is formed and a
new surface site is generated through decomposition of the absorbed metastable complex [16]. The reaction of
this process is given below:
Cd(NH3)4
2+
+ SC(NH2)2 + 2OH-
→ CdS + CH2N2 + 2H2O + 4 NH3 (1)
3. Properties of CdS Chemically Deposited thin films on the Effect of Ammonia Concentration
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Table 1: Concentration and volumes of reactants in the CBD deposition bath
Exp.
No.
Cd(CH3COO)2 2H2O
30 ml (M)
(NH4)2(CH3COO)2 2H2O
30 ml (M)
SC(NH2)2
20 ml (M)
NH3 H2O
26 ml (M)
1. 0.004 0.04 0.05 0.1
2. 0.004 0.04 0.05 0.25
3. 0.004 0.04 0.05 0.5
4. 0.004 0.04 0.05 1.0
5. 0.004 0.04 0.05 1.25
6. 0.004 0.04 0.05 1.5
7. 0.004 0.04 0.05 2.0
8. 0.004 0.04 0.05 2.5
9. 0.004 0.04 0.05 3.0
The Table 1 gives the concentration of ammonia and volumes of reactants to form the CdS thin films in
the CBD bath. In the table, experiments 1 and 9 did not have any deposition. In the experiments 2-8, the film
growth rate shows behaviour of super saturation. The observation made in the first 20 min was that the fastest
growth obtained in experiment 4 with ammonia concentration 1.0 M. It is observed that the growth decreases
with the increase of the concentration of ammonia from 1.0 M. In the experiment 8, the deposition is quite slow
when compared to experiment 3. Exp. 3-8 show the growth rates of depositions which gives the thickness, super
saturation of film deposition surface, uniformity of film colour and grain geometry among all the tests. During
CBD deposition, the temperature is kept constant at 70° C and it was observed that the growth increases with the
increase of the concentration of ammonia and decrease of the concentration of thiourea [16]. Unlike other
deposition methods, the growth rate in the CBD technique cannot be kept constant during film deposition. Fig. 1
shows the growth rate decay with the increase of the ammonia concentration and this is one of the parameters
that influence the characterization of polycrystalline thin films.
The result shown in Fig.1 is consistent with that reported by Q Q Liu et al [17]. They studied the
dependence of film growth rate as a function of ammonia concentration from 0.5 M to 1.0 M and found that the
film growth rate was peaked at 1.5 M of concentration of ammonia. Their work also showed that the ammonia
concentration of 0.6 M was sufficient to bind Cd2+
into cadmium tetra amine complex ions Cd(NH3)4
2+
needed
for slow growth rate as described in Eq. (1). On the other hand, when ammonia concentration is sufficiently low,
the product of [Cd2+
] and [OH-
] was greater than the solubility product of Cd(OH)2 (1.2 X 10-14
) given in the
Eq.(2):
Cd2+
+ OH-
↔ Cd (OH)2 (2)
The ammonia concentration varied from 0.1 to 3.0 M. When 0.1 M of ammonia was added to the
solution for the first experiment as shown in Table 1, no film was formed on the substrate even after a
deposition time of over 3 hrs. In experiments 2-9, the ammonia concentration was increased from 0.25 to 3.0 M,
and films were obtained on the glass substrate and the colour of the film changed from light yellow to deep
yellow (Fig.2a). However, when the ammonia concentration was equal to or exceeds 2.5 M, nothing was
deposited on the substrates except much yellow powder was produced in the bath after CBD deposition.
4. Properties of CdS Chemically Deposited thin films on the Effect of Ammonia Concentration
www.iosrjournals.org 4 | Page
Type of conductivity of the thin films, mobility and carrier concentration of the as-doped films is
determined by using Hall Effect experiment. The Hall coefficient was calculated for all the investigated
samples. The sign is negative and charge carriers are due to electrons. Therefore, the results showed that the
prepared thin films of CdS had negative (n-type) conductivity. From the observations, it is observed that the
Hall coefficient is found to be increased from 340.8 cm3
/Coulomb to 608.4 cm3
/Coulomb as the ammonia
concentration is increased from 0.5 to 2.0 M and constant at 2.5 M. The mobility of the CdS thin films is
calculated from the Hall coefficient [18]. It is found to be increased from 1.363 cm2
/V-S to 4.58 cm2
/V-S as the
concentration is increased from 0.5 to 2.0 M, and at 2.5 M concentration the mobility is also same i.e., 4.58
cm2
/V-S. It is observed that the carrier concentration decreases with the increase of ammonia concentration. The
carrier concentration at 0.5 M is 1.8316X1016
cm-3
and at 2.5 M is 1.026 X1016
cm-3
. This is because the S: Cd
ratio increases in the same order. The excess content of Cd means that either interstitial Cd ions or S vacancies
exist in the film, act as donor and results in decrease in the carrier concentration of the films [19].
The optical band gap energy and absorption coefficient (α) of the chalcogenides thin films was
determined using UV-VIS spectrophotometer in the wavelength range of 350 to 850 nm at room temperature. In
the present work, the photons of selected wavelength are directed at the sample, and the relative transmission of
various photons observed.
Fig. 3 shows the optical transmission spectra of CdS thin films at different ammonia concentrations in
the wavelength range of 350 to 850 nm. All the films have a high transmission in the wavelength range of above
550 nm. The percentage of transmittance was about 70% at near IR region.
5. Properties of CdS Chemically Deposited thin films on the Effect of Ammonia Concentration
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The optical band gap energy (Eg) of the CdS thin films have been determined by extrapolating the
linear portion of the curves of (αhν)2
Vs (hν) as shown in Fig. 4. From the figure, it is observed that all the films
have direct band gap values of 1.92 eV to 2.65 eV for the films of ammonia concentration in the range of 0.5 M
to 2.5 M. These values are found to be smaller than the values reported previously which were in the range of
2.42 eV to 2.62 eV [20]. The deviation of the energy gap values from the standard bulk value of 2.42 eV is due
to the use of greatly wide range of ammonia concentration in the present CBD process [21,23]. Hence, the CdS
thin films can be considered to be good for use as visible transmitting thin films since the range of band gap for
visible transmitting film is 1.5 to 3.0 eV.
Fig. 5 shows the XRD patterns for CdS thin film with the bath temperature 70°C and 90°C. The
observation was that at bath temperature 70°C consists of a primitive lattice structure with the orthorhombic
phases and this is matched with the JCPDS reference No. 47-1179 [22]. From the fig. 5, a peak from
orthorhombic structure, wurtzite, was observed at 26.81° corresponding to the (3 1 3) reflection and 27.42°
corresponding to the (4 2 0) reflection. When temperature is changed from 70°C to 90°C, the angle of
reflections shifted and orthorhombic phases have changed into cubic phases. The observed major reflection for
the film with bath temperature 90°C is identified as per the standard JCPDS card No. 89-0440 (cubic-C). 2
values of diffraction peaks observed are 26.56°, 30.59° and 43.73° which corresponding to reflections from (1 1
1), (2 0 0) and (2 2 0) planes of cubic (zincblende) CdS, respectively. The sudden change in phase from
orthorhombic to cubic is due to the reduction of sulphur content in high temperature.
Fig. 6 displays SEM images of CdS thin films recorded at different concentrations of ammonia. It is
observed that the surface morphology of as-deposited films is almost smooth and no grains are observed clearly
at low molar concentration (Fig.6.a). The size of the grain in the deposited films has been observed with the
increase in the concentration of ammonia. Thus, the change in the surface features and the improvement in the
6. Properties of CdS Chemically Deposited thin films on the Effect of Ammonia Concentration
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Grain growth are clearly noticed from the SEM images of the film deposited at a higher concentration.
The films deposited at 2.0 M concentration of ammonia are having predominant grains (Fig. 6. c). The
developments of uniformly distributed roughly spherical grains grown perpendicular to the surface of the
substances are observed for the films at 2.0 M. It is noticed that the film surface is pin-hole free texture without
any micro cracks [24]. The estimated average grain size is observed to be increasing with the increase of the
concentration of ammonia. The estimated mean size of the grain at molar concentration is about 0.4 μm .
In the present work, the compositional analysis of the films were carried out by Energy dispersive
analysis of X-ray (EDAX) spectroscopy using Oxford Inca Penta FeTX3 EDS instrument attached to Carl Zeiss
EVO MA 15 Scanning Electron Microscope. The EDAX spectra of CdS thin films doped at different ammonia
concentration are shown in Fig. 7.
The EDAX spectrum displays the characteristic peaks corresponding to the binding energy state of Cd
and Oxygen ions. No other impurity peaks are detected in the spectrum which is an indication of the chemical
purity of the sample. The estimated Cd to S ratio value is found to be 1.04 (Cd:S = 50.04:49.96). No, detectable
change in the computational changes are observed during the increase of ammonia concentration. Since the
films are deposited on Silicon substrate, a predominant peak corresponding to silicon is observed in the spectra.
For our calculation, we have not uniformly considered these Si peaks [24].
IV. Conclusion
The energy gap of as-doped CdS thin films in the present study shows that the energy gap is decreased
from 2.7497 eV to 2.2122 eV when concentration is increased from 0.5M to 2.0M and becomes constant above
2.0M. The deviation of these values from the standard bulk value of 2.37 eV is explained on the basis of the
small grain size. The difference between Eg values of our samples and the earlier reports can be attributed to
various grain sizes of thin film due to the use of the greatly wide range of ammonia concentration in our CBD
process. The Hall coefficient is a characteristic of the material from which the conductor is made. Also, the Hall
coefficient depends on the type of the charge carriers that constitute the current. The Hall coefficient was
calculated for investigating all samples. The sign is negative and charge carriers are due to electrons. Therefore,
the results showed that the prepared thin films of CdS had negative (n-type) conductivity. It is observed that all
the films have direct band gap values of 1.92 eV to 2.65 eV for the films with ammonia concentration in the
range of 0.5 M to 2.5 M. These values are found to be smaller than the values reported previously which were in
7. Properties of CdS Chemically Deposited thin films on the Effect of Ammonia Concentration
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the range of 2.42 eV to 2.62 eV. The deviation of the energy gap values from the standard bulk value of 2.42 eV
is due to the use of greatly wide range of ammonia concentration in the present CBD process. Hence the CdS
thin films can be considered to be good for use as visible transmitting thin films since the range of band gap for
visible transmitting film is 1.5 to 3.0 eV. It is observed that the surface morphology of as deposited films is
almost smooth and no grains are observed clearly at low molar concentration. The size of the grain in the
deposited films has been observed in the increase of concentration of ammonia. Also, the films deposited at 2.0
M concentration of ammonia are having predominant grains. The EDAX spectrum displays the characteristic
peaks corresponding to the binding energy state of Cd and Oxygen ions. No other impurity peaks are detected in
the spectrum which is an indication of the chemical purity of the sample. The estimated Cd to S ratio value is
found to be 1.04 (Cd:S = 50.04:49.96). No, detectable change in the computational changes were observed
during the increase of ammonia concentration.
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