Abstract: Zinc Oxide (ZnO) thin films were prepared on corning (7059) glass substrates at a thickness of 75.5 and 130.5nm by RF sputtering technique. The deposition was carried out at room temperature after which the samples were annealed in open air at 1500C. The electrical and structural properties of these films were studied. The electrical properties of the films were monitored by four-point probe method while the structural properties were studied by X-ray diffraction (XRD). It was found that the electrical resistance of the films decreases with increase in the thickness of the films. The XRD analysis of the films showed that the films have a peak located at 〖34.31^0-34.35〗^0with hkl (002). Other parameters calculated include the stress ( ) and the grain size (D).
This is a power point presentation of project work on preparing Zinc oxide thin films by using SILAR technique and CBD technique and studying its characteristics.
Sebastiani - Nano-mechanical and microstructural characterization of MS-PVD N...thinfilmsworkshop
http://www.surfacetreatments.it/thinfilms
Nano-mechanical and microstructural characterization of MS-PVD Nb thin films (Marco Sebastiani - 30')
Speaker: Marco Sebastiani - Roma 3 University | Duration: 30 min.
Abstract
E. Bemporad1, M. Sebastiani1, F. Carassiti1
1Mechanical and Industrial Engineering Department, University of Rome ‘Roma Tre’, Via della Vasca Navale 79-00146 Rome, Italy
The main objective of the present study was to identify the influence of the applied bias voltage on the microstructural and mechanical properties of magnetron sputtering physical vapour deposition (MS-PVD) niobium thin films for use in superconducting resonant cavities for particle accelerators.
The microstructure and mechanical properties evolution as a function of the applied bias voltage and nature of the substrate (copper or quartz) were investigated by means of micro-hardness and nanoindentation testing, FIB/SEM, AFM and TEM techniques.
The superconducting properties (critical temperature Tc and residual resistivity) were determined by a calibrated four-contact probe and a cryogenic apparatus and then correlated to the mechanical properties.
Significant difference in terms of microstructure, surface roughness and mechanical properties were observed for biased coatings grown on different substrates. The observed differences are likely connected to the low conductivity of quartz that induces a re-sputtering effect and a consequent modification of the superconducting performances.
Rosa alejandra lukaszew a review of the thin film techniques potentially ap...thinfilmsworkshop
SRF is a surface phenomenon where only ~10 penetration depths are needed (l=40 nm for niobium), thus it has been recognized for some time now that it would be economically convenient to use thin film coated cavities. But problems arise with defects within 1 or 2 l of the surface or on the surface, and insufficient attention has been paid to this topic, including trapping of impurities like oxygen in defects as well as surface roughness enabling magnetic field pinning sites. Earlier attempts at CERN applied standard sputter PVD methods, but the grain size for the CERN Nb/Cu films was 100 nm, which is 10,000 times smaller than for conventional SRF cavities with the ensuing problems that appear at grain boundaries. Thus, these prior attempts showed higher surface resistance and worst Q-slope than bulk. I will review more modern approaches using higher energetic PVD methods for thin film deposition which offer promise to achieve thin films with improved superconducting performance.
This is a power point presentation of project work on preparing Zinc oxide thin films by using SILAR technique and CBD technique and studying its characteristics.
Sebastiani - Nano-mechanical and microstructural characterization of MS-PVD N...thinfilmsworkshop
http://www.surfacetreatments.it/thinfilms
Nano-mechanical and microstructural characterization of MS-PVD Nb thin films (Marco Sebastiani - 30')
Speaker: Marco Sebastiani - Roma 3 University | Duration: 30 min.
Abstract
E. Bemporad1, M. Sebastiani1, F. Carassiti1
1Mechanical and Industrial Engineering Department, University of Rome ‘Roma Tre’, Via della Vasca Navale 79-00146 Rome, Italy
The main objective of the present study was to identify the influence of the applied bias voltage on the microstructural and mechanical properties of magnetron sputtering physical vapour deposition (MS-PVD) niobium thin films for use in superconducting resonant cavities for particle accelerators.
The microstructure and mechanical properties evolution as a function of the applied bias voltage and nature of the substrate (copper or quartz) were investigated by means of micro-hardness and nanoindentation testing, FIB/SEM, AFM and TEM techniques.
The superconducting properties (critical temperature Tc and residual resistivity) were determined by a calibrated four-contact probe and a cryogenic apparatus and then correlated to the mechanical properties.
Significant difference in terms of microstructure, surface roughness and mechanical properties were observed for biased coatings grown on different substrates. The observed differences are likely connected to the low conductivity of quartz that induces a re-sputtering effect and a consequent modification of the superconducting performances.
Rosa alejandra lukaszew a review of the thin film techniques potentially ap...thinfilmsworkshop
SRF is a surface phenomenon where only ~10 penetration depths are needed (l=40 nm for niobium), thus it has been recognized for some time now that it would be economically convenient to use thin film coated cavities. But problems arise with defects within 1 or 2 l of the surface or on the surface, and insufficient attention has been paid to this topic, including trapping of impurities like oxygen in defects as well as surface roughness enabling magnetic field pinning sites. Earlier attempts at CERN applied standard sputter PVD methods, but the grain size for the CERN Nb/Cu films was 100 nm, which is 10,000 times smaller than for conventional SRF cavities with the ensuing problems that appear at grain boundaries. Thus, these prior attempts showed higher surface resistance and worst Q-slope than bulk. I will review more modern approaches using higher energetic PVD methods for thin film deposition which offer promise to achieve thin films with improved superconducting performance.
Novel effects can occur in materials when structures are formed with sizes comparable to any one of many possible length scales, such as the de Broglie wavelength of electrons, or the optical wavelengths of high energy photons. In these cases quantum mechanical effects can dominate material properties. One example is quantum confinement where the electronic properties of solids are altered with great reductions in particle size. The optical properties of nanoparticles, e.g. fluorescence, also become a function of the particle diameter. This effect does not come into play by going from macrosocopic to micrometer dimensions, but becomes pronounced when the nanometer scale is reached.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Effect of Exchangeable Cations on Bentonite Swelling Characteristics of Geosy...drboon
Geosynthetic clay liners (GCLs) are thin hydraulic barriers which contain the bentonite sandwiched between geotextiles or geomembrane. Bentonite swelling is a very common phenomenon observed in GCLs. It is one of the major causes for permeability reduction in hydraulic barriers. The aim of this study is to characterize the swelling behavior of bentonite in GCLs by exchangeable cations. X-ray diffraction test and scanning electron microscopy were used to quantify the swelling characteristics of this bentonite under contact with salt solutions, as in the hydraulic barriers. The results from X-ray diffraction test showed that the presence of clay minerals was swelling montmorillonite. The swell volume of bentonite decreases with increasing valence of cations. In the case of the same valence the free swell volume of bentonite increased with decreasing concentration of permeant liquids. From another test, the scanning electron microscopy, it can be seen that the bentonite appears as corn flake like crystals for air-dried bentonite. However, specimen permeated with salt solutions, the clay has become more porous and fluffy and porous size seemed to be diminished.
Preparation and Properties of Nanocrystalline Zinc Oxide Thin Filmsijtsrd
Metal oxide is highly important material which possesses many unique optical and electrical properties for applications in many areas such as Solar cells, Gas sensors and so on. With the development of research and applications of Metal oxide thin films, research results are verified that the morphology of Metal oxide thin films are plays an important role in applications of these films. Variety of morphologies, complex structure has been developed by physical or chemical methods. However the work on controlled growth of these films is still in developing state. Therefore in present work we deposited ZnS and ZnO metal oxides thin films on different substrates by Chemical Bath Deposition Technique. Structural, Surface Morphology and Optical properties of as deposited films were investigated by XRD, SEM, and UV VIS Spectrophotometer. The band gap is also calculated from the equation relating absorption co efficient to wavelength. The band gap indicates the film is transmitting within the visible range and the band gaps changes because of the grain size of the films. We also observed that, the change in preparative parameters affects the deposition rate of thin films. From the observation, it is clear that the growth rate increases as the deposition temperature, increases. S. S. Kawar "Preparation and Properties of Nanocrystalline Zinc Oxide Thin Films" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-4 , June 2020, URL: https://www.ijtsrd.com/papers/ijtsrd31623.pdf Paper Url :https://www.ijtsrd.com/physics/nanotechnology/31623/preparation-and-properties-of-nanocrystalline-zinc-oxide-thin-films/s-s-kawar
Synthesis, Characterization of ZnS nanoparticles by Coprecipitation method us...IOSR Journals
ZnS nanoparticles are prepared by coprecipitation method using various capping agents like PVP (polyvinylpyrrolidone), PVA (polyvinylalcohol) and PEG-4000 (polyethyleneglycol). These are characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, Fourier Transform Infra-red spectra (FTIR) and Transmission electron microscopy (TEM). UV-Visible absorption spectra are used to find the optical band gap and the values obtained have been found to be in the range of 3.80-4.00eV. The particle size of nanoparticles calculated from XRD pattern has been in the range of 2-4 nm. It is also observed that the particle size of nanoparticle is affected by the nature of capping agent. Photo catalytic degradation of xylenol orange (XO) by the nanoparticles shows that these act as photo catalysts under sunlight irradiation. The XO dye was degraded more than 87.24, 83.42 and 73.05% in the presence of PEG-4000, PVA and PVP capped ZnS nanoparticles in 120, 150 and 180 min. respectively. The kinetics of catalyzed by synthesized ZnS nanoparticles with XO dye follows pseudo-first order kinetics with reasonable apparent rate constants.
Transparent and Conducting TiO2 : Nb Thin Films Prepared by Spray Pyrolysis T...arj_online
To date, only sputtering and pulsed laser deposition (PLD) techniques have been employed
successfully to fabricate highly conducting and transparent TiO2:Nb (TNO) films. In this article, we demonstrate
that transparent and conducting
TiO2
: Nb
films can be made by the spray pyrolysis technique. The films were
deposited on Corning 7059 glass substrates at 500
15˚C using an alcoholic precursor solution consisting of
titanium (iv) isopropoxide and
NbCl5
. The influence of increasing
Nb
concentration on the electrical, optical
and structural properties was investigated. The minimum resistivity, 3.36
-3 10
Ω cm, for
Ti1-xNbxO2
film (x
= 0.15) was obtained after 1 hour post deposition annealing in hydrogen atmosphere at 500˚C. The x-ray
diffraction of hydrogen annealed films showed a polycrystalline anatase (004)-oriented phase without any second
phases. The optical band gap for undoped and doped films lay in the range 3.38 – 3.47 eV. Using dispersion
analysis, optical constants were determined from spectro-photometric measurements for films on glass.
Novel effects can occur in materials when structures are formed with sizes comparable to any one of many possible length scales, such as the de Broglie wavelength of electrons, or the optical wavelengths of high energy photons. In these cases quantum mechanical effects can dominate material properties. One example is quantum confinement where the electronic properties of solids are altered with great reductions in particle size. The optical properties of nanoparticles, e.g. fluorescence, also become a function of the particle diameter. This effect does not come into play by going from macrosocopic to micrometer dimensions, but becomes pronounced when the nanometer scale is reached.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Effect of Exchangeable Cations on Bentonite Swelling Characteristics of Geosy...drboon
Geosynthetic clay liners (GCLs) are thin hydraulic barriers which contain the bentonite sandwiched between geotextiles or geomembrane. Bentonite swelling is a very common phenomenon observed in GCLs. It is one of the major causes for permeability reduction in hydraulic barriers. The aim of this study is to characterize the swelling behavior of bentonite in GCLs by exchangeable cations. X-ray diffraction test and scanning electron microscopy were used to quantify the swelling characteristics of this bentonite under contact with salt solutions, as in the hydraulic barriers. The results from X-ray diffraction test showed that the presence of clay minerals was swelling montmorillonite. The swell volume of bentonite decreases with increasing valence of cations. In the case of the same valence the free swell volume of bentonite increased with decreasing concentration of permeant liquids. From another test, the scanning electron microscopy, it can be seen that the bentonite appears as corn flake like crystals for air-dried bentonite. However, specimen permeated with salt solutions, the clay has become more porous and fluffy and porous size seemed to be diminished.
Preparation and Properties of Nanocrystalline Zinc Oxide Thin Filmsijtsrd
Metal oxide is highly important material which possesses many unique optical and electrical properties for applications in many areas such as Solar cells, Gas sensors and so on. With the development of research and applications of Metal oxide thin films, research results are verified that the morphology of Metal oxide thin films are plays an important role in applications of these films. Variety of morphologies, complex structure has been developed by physical or chemical methods. However the work on controlled growth of these films is still in developing state. Therefore in present work we deposited ZnS and ZnO metal oxides thin films on different substrates by Chemical Bath Deposition Technique. Structural, Surface Morphology and Optical properties of as deposited films were investigated by XRD, SEM, and UV VIS Spectrophotometer. The band gap is also calculated from the equation relating absorption co efficient to wavelength. The band gap indicates the film is transmitting within the visible range and the band gaps changes because of the grain size of the films. We also observed that, the change in preparative parameters affects the deposition rate of thin films. From the observation, it is clear that the growth rate increases as the deposition temperature, increases. S. S. Kawar "Preparation and Properties of Nanocrystalline Zinc Oxide Thin Films" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-4 , June 2020, URL: https://www.ijtsrd.com/papers/ijtsrd31623.pdf Paper Url :https://www.ijtsrd.com/physics/nanotechnology/31623/preparation-and-properties-of-nanocrystalline-zinc-oxide-thin-films/s-s-kawar
Synthesis, Characterization of ZnS nanoparticles by Coprecipitation method us...IOSR Journals
ZnS nanoparticles are prepared by coprecipitation method using various capping agents like PVP (polyvinylpyrrolidone), PVA (polyvinylalcohol) and PEG-4000 (polyethyleneglycol). These are characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, Fourier Transform Infra-red spectra (FTIR) and Transmission electron microscopy (TEM). UV-Visible absorption spectra are used to find the optical band gap and the values obtained have been found to be in the range of 3.80-4.00eV. The particle size of nanoparticles calculated from XRD pattern has been in the range of 2-4 nm. It is also observed that the particle size of nanoparticle is affected by the nature of capping agent. Photo catalytic degradation of xylenol orange (XO) by the nanoparticles shows that these act as photo catalysts under sunlight irradiation. The XO dye was degraded more than 87.24, 83.42 and 73.05% in the presence of PEG-4000, PVA and PVP capped ZnS nanoparticles in 120, 150 and 180 min. respectively. The kinetics of catalyzed by synthesized ZnS nanoparticles with XO dye follows pseudo-first order kinetics with reasonable apparent rate constants.
Transparent and Conducting TiO2 : Nb Thin Films Prepared by Spray Pyrolysis T...arj_online
To date, only sputtering and pulsed laser deposition (PLD) techniques have been employed
successfully to fabricate highly conducting and transparent TiO2:Nb (TNO) films. In this article, we demonstrate
that transparent and conducting
TiO2
: Nb
films can be made by the spray pyrolysis technique. The films were
deposited on Corning 7059 glass substrates at 500
15˚C using an alcoholic precursor solution consisting of
titanium (iv) isopropoxide and
NbCl5
. The influence of increasing
Nb
concentration on the electrical, optical
and structural properties was investigated. The minimum resistivity, 3.36
-3 10
Ω cm, for
Ti1-xNbxO2
film (x
= 0.15) was obtained after 1 hour post deposition annealing in hydrogen atmosphere at 500˚C. The x-ray
diffraction of hydrogen annealed films showed a polycrystalline anatase (004)-oriented phase without any second
phases. The optical band gap for undoped and doped films lay in the range 3.38 – 3.47 eV. Using dispersion
analysis, optical constants were determined from spectro-photometric measurements for films on glass.
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Dye Sensitized Solar Cells Incorporated with Tio2 -ZnO NanoparticlesScientific Review SR
We demonstrated an improvement in efficiency of Dye sensitized solar cells (DSSCs) decorated with
zinc oxide (ZnO) nanoparticles (NPs) through successive ionic layer adsorption and reaction (SILAR). A series of
ZnO with different SILAR cycles were synthesized on TiO
2 that has been pre-grown on fluorine tin oxide (FTO)
glass slides. The performance of DSSCs containing ZnO NPs was significantly affected. The photovoltaic (PV)
performance decreased with increasing number of SILAR cycles from two SILAR cycles to four SILAR cycles,
the best performance was achieved using the anodes prepared with two SILAR cycles. The best cell shows a
conversion efficiency (η) of 0.0064 %. The cell exhibits ~ 2.13 improvement over the performance (0.0030 %) of
bare FTO-based device. The related PV performance enhancement mechanism is discussed
Surface Morphological and Electrical Properties of Sputtered Tio2 Thin FilmsIOSR Journals
Titanium dioxide films were formed on quartz and crystalline p-Si (100) substrates by DC reactive magnetron sputtering method. Pure titanium target was sputtered at a constant oxygen partial pressure of 5x10-2 Pa, and at different sputtering powers in the range 80 – 200 W. The as-deposited films were annealed in air for 1 hour at 1023 K. The deposited films were characterized by studying the surface morphology by atomic force microscopy (AFM), electrical and dielectric properties from current-voltage and capacitance-voltage measurements. Atomic force micrographs of the films showed that the Rrms and Ra increased with the increase of sputter power from 80 to 200 W. The leakage current density was increased by increasing the sputtering power.
Structural, Dielectric and Optical properties of Sputtered TiO2 nano-filmsIOSR Journals
Thin films of TiO2 were deposited on quartz and p-Si (100) substrates held at room temperature by sputtering of titanium target at various sputter powers in the range 80 - 200 W. The as-deposited films were annealed in air for an hour at 1023 K. The annealed films were characterized by using Fourier transform infra red spectroscopy, X-ray diffraction, Surface morphology, dielectric and optical properties. The deposition rate of the films increased from 1.26 to 6.66 nm/min. with increase of sputter power from 80 to 200 W. TiO2 films formed at sputter power of 80 W and annealed at 1023 K were polycrystalline in nature with anatase phase crystallite size of 40 nm, dielectric constant of 10, optical band gap of 3.65 eV and refractive index 2.35.
Un doped and doped with Al ZnS thin Films have been fabricated by vacuum evaporation
technique under the vacuum of 10-5 Torr on glass substrate at room temperature and with different
ratio of Al concentration of thickness (0.8µm). The optical properties were revealed by UV-Visible
transmittance spectra and the band gap energy was determined. Transmission spectra indicate a high
transmission coefficient (¨95%). The results showed that films have direct optical transition, and the
values of energy gap were found to decrease with doping concentrations. Also the optical constants
such as absorption coefficient, refractive index, extinction coefficient and dielectric constant have
been calculated. The effect of doping concentration on the electrical properties has been studied
Detecting of NH3, CO2 polluted gases by using ZnO- In2O3 thin filmsijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Detecting of NH3, CO2 polluted gases by using ZnO- In2O3 thin filmsijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
Studies on in-Doped Zno Transparent Conducting thin FilmsIJRESJOURNAL
ABSTRACT: In this manuscript we have investigated the influences of indium dopants on zinc oxide (ZnO) thin films regarding physico-chemical properties for application in modern conducting devices. As a starting material, Indium (III) chloride, and Zn(CH3COO)2⋅2H2O were used. The complex TSDC spectrum was obtained by submitting the sample to a constant electrical field Ep = 10M V/m during 2 min at a varing polarization temperature of Tmax = 1500C. A minimal sheet resistance with electrical resistivity as low in the range of 10-3 Ω·cm was found for this thin film.
Annealing and Microstructural Characterization of Tin-Oxide Based Thick Film ...Anis Rahman
Abstract. The sheet resistance of tin oxide based thick-film resistors exhibits two regions of temperature dependence,
described by hopping (23°C-200°C) and diffusion mechanisms (200°C-350°C), respectively.
Annealing these samples causes the sheet resistance to increase in both regions. In the post-annealed samples,
the hopping conduction range is extended by 50°C (23°C-250°C) while the hopping parameter, To, is decreased by
more than 50%. The activation energy of diffusion (0.60 eV) is the same for both pre- and post annealed samples, but
the magnitude of resistance in the diffusion controlled region is increased significantly as a result of annealing. These
changes are explained in terms of a net decrease in the concentration of tin ions in the glass matrix. From a careful
microstructural study it was found that a conduction path composed of tin-oxide grains or their clusters in contact
with each other does not exist in the present system. HREM micrographs showed the presence of nanocrystalline
tin-oxide particles in the glass phase separating the tin-oxide grain clusters. Estimated average separation between
the nanocrystals in 4 nm, consistent with a variable-range hopping conduction via the dissolved tin ions in the glass
matrix.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
Influence of Thickness on Electrical and Structural Properties of Zinc Oxide (ZnO) Thin Films Prepared by RF Sputtering Technique
1. ISSN 2350-1030
International Journal of Recent Research in Physics and Chemical Sciences (IJRRPCS)
Vol. 2, Issue 1, pp: (38-43), Month: April 2015 – September 2015, Available at: www.paperpublications.org
Page | 38
Paper Publications
Influence of Thickness on Electrical and
Structural Properties of Zinc Oxide (ZnO) Thin
Films Prepared by RF Sputtering Technique
1
M.Momoh, 2
S.Abdullahi, 3
A.U Moreh
1, 2, 3
Department of Physics, Usmanu Danfodiyo University, Sokoto, Sokoto, Nigeria
Abstract: Zinc Oxide (ZnO) thin films were prepared on corning (7059) glass substrates at a thickness of 75.5 and
130.5nm by RF sputtering technique. The deposition was carried out at room temperature after which the samples
were annealed in open air at 1500
C. The electrical and structural properties of these films were studied. The
electrical properties of the films were monitored by four-point probe method while the structural properties were
studied by X-ray diffraction (XRD). It was found that the electrical resistance of the films decreases with increase
in the thickness of the films. The XRD analysis of the films showed that the films have a peak located at
- with hkl (002). Other parameters calculated include the stress (s ) and the grain size (D).
Keywords: Electrical Properties, Film thickness, Structural properties, Zinc oxide.
I. INTRODUCTION
Transparent conducting oxides (TCOs) have a range of highly useful applications as transparent electrodes in
optoelectronic devices such as solar cells and flat panel displays. TCO coatings are essential for solar cell applications
since they constitute a fundamental part in the emerging new generations of photovoltaic devices. The properties of TCO
films include large band gap (>3 eV), low resistivity (103
- 10-4
Ω cm) and a very good optical transmittance (80 - 90%)
in the visible range [1]. Though indium tin oxide (ITO) film is extensively applied to photovoltaic devices and flat panel
display because of its good electrical and optical properties, it has some problems such as high cost, low stability to H2
plasma and toxicity. Recently, Zinc Oxide (ZnO) thin films have attracted much attention as a transparent and conductive
film material because it exhibits a wide band gap, high transparency and low resistivity. As a wide and direct band gap
semiconductor material, ZnO has a band gap of 3.37 eV at room temperature, which makes it have potential in blue and
ultraviolet (UV) photoelectric applications, such as transparent high power electronics, UV detectors, and short
wavelength devices. Its large excitons binding energy of about 60 MeV makes it a good choice for fabrication of excitons-
related devices, such as short-wave light emitters. Zinc oxide has some advantages over GaN such as higher radiation
hardness, simplified processing due to amenability to conventional chemical wet etching and the availability of large area
substrates at relatively low material costs, non-toxicity and relatively low deposition temperature [2]. Zinc oxide thin
films have been prepared by various deposition methods such as thermal oxidation [3], Spin coating [4] vacuum
evaporation [5], electron beam evaporation [6], sputtering [7] - [10] Spray pyrolysis [11] - [14] and chemical bath
deposition [15].
In this paper, we report the influence of film thickness on electrical and structural properties of Zinc Oxide thin film
grown by RF sputtering technique. This technique is chosen because it provides a higher degree of ionization/dissociation
that leads to greater oxidation rate at the substrate surface [16]. In general, the advantages of sputtering are the simple
apparatus, high deposition rate, low substrate temperature, good surface flatness, transparency and dense layer formation
[17].
2. ISSN 2350-1030
International Journal of Recent Research in Physics and Chemical Sciences (IJRRPCS)
Vol. 2, Issue 1, pp: (38-43), Month: April 2015 – September 2015, Available at: www.paperpublications.org
Page | 39
Paper Publications
II. EXPERIMENTAL
A. Substrate preparation:
Before the deposition, the substrates were kept in a dilute chemical detergent (a detergent solution used in the laboratory
to solubilise biological macromolecules such as proteins) solution at 100°C in ultrasonic bath for 10 minutes to remove
oils and protein molecules and rinsed with double distilled water to remove possible left detergent contaminants. To
remove organic contaminants, the substrates were boiled in dilute hydrogen peroxide- (H2O2) solution for 15 minutes. The
substrates were extracted from the bath and rinsed with distilled water and later dried with nitrogen gas before being
introduced into the sputtering chamber. Throughout the period of substrate preparation, film deposition and film
characterization, the laboratory staff wore protective clothing so as not to contaminate the samples.
B. Thin film deposition:
Zinc Oxide thin films were deposited onto corning glass (7059) substrate using an RF power of 60W. A Zinc Oxide target
with 4N purity and 4cm in diameter was located on the cathode, which was about 7cm from the substrate mounting plate.
The deposition was carried out at room temperature. Prior to deposition, the chamber was evacuated to 4.6×10-3
mbar.For
plasma formation, research grade argon with 4N purity was used at a pressure range of 10-2
-10-1
mbar, oxygen was also
added to facilitate the formation of ZnO on the substrate. Other deposition parameters that were kept constant include the
deposition temperature, oxygen/argon flow rate and the sputtering RF power. The details of the deposition parameters are
shown on table1. In this study, the deposition rate is nearly constant as the sputtering time ranges from 60 to 103.5
minutes. A deposition rate of 1.26nm/minute was therefore obtained.
TABLE I: DEPOSITION PARAMETERS USED IN THE STUDY
S/No Parameters Deposition details
1 Substrate Corning Glass 7059
2 Target/Target diameter ZnO Ceramic target 4N/4cm
3 Substrate/Target Distance 7 cm
4 Annealing Environment Nitrogen/Air
5 Annealing set points 150o
C, 300o
C and 450o
C
6 Annealing Ramp rate 10o
C/min.
7 Annealing period 60 minutes
8 Film Thickness 130.5nm
9 Deposition pressure 4.6 x10-3
mbar
10 Argon/Oxygen flow rate 1 sccm at 1:1 ratio
11 Substrate temp Room Temp.
12 Rf power 60 W.
13 Deposition time/period 1 Hour
The grown films were subjected to electrical characterization by the use of a 4-point probe. Four-point probe method is an
electrical resistance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to
make more accurate measurements than traditional two-terminal (2T) sensing. A probe head with tungsten carbide tips
with a point radius of 0.002", a probe spacing of 0.05" and a probe pressure of 70 to 180 grams was used for all
measurements. Current was supplied by a Crytronics model 120 current source with a range of applied currents between
1μA to 100 mA. Voltages were measured by a Keithley model 181-nanovolt electrometer with an input impedance of
greater than 1 GΩ. Sheet resistance (Rs in units of Ω/sq.) and resistivity (ρ in units of Ω cm) were determined from;
r = 2ps
v
I
(1)
Where S is the spacing between the probes The crystal structure of the films on the other hand was inspected using
PANALYTICAL XPERT PRO diffractometer performed in 2 at a voltage of 45KV and a current of 40mA.The
sweeping angle was 20 to 80 degrees, the scan speed 0.8 degrees/minute at a scan step of 0.02 and employing a
radiation. The surface morphology of the films was
studied by the use of Veeco Dektak 150 profilemeter while the microstructure was determined by EV®MA-10 scanning
electron microscope at an accelerating potential of 18kv.The chamber is pumped down to a vacuum range of 10-5
to 10-6
torr. Lattice parameters were then calculated from;
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dhkl =
1
4
3
h+ hk + k
a2
+
l2
c2 (2)
Where h, k and l are the Miller indices, a and c are lattice parameters
III. RESULTS AND DISCUSSION
A. Electrical properties:
Table II shows the resistivity and sheet resistance of the films annealed in open air .It can be seen that the resistivity for
the 75.5nm thick film is greater than that of the 130.5nm film. It is known that ZnO thin films generally exhibit n type
conductivity, its value depending on the deposition parameters. This conductivity has been attributed to intrinsic donor
defects such as donor vacancies and Zn interstitials. More recent reports have proposed that the conductivity is due to
hydrogen, since hydrogen impurities can interact with oxygen vacancies resulting in complexes that can act as shallow
donors. In any case, experimental conditions such as substrate temperature and deposition time (directly related to the film
thickness) can influence the intrinsic defect concentration, thus affecting the conductivity of the films. The observed
increase in the conductivity can be correlated with the decreased concentration of grain boundaries in thicker films due to
the presence of bigger grains and improved crystallinity, which can reduce scattering processes and increase the
conductivity. In addition, the increasing of the thickness can lead to higher concentration of intrinsic defects and thus to
an increased conductivity [18]. According to [19] the decrease seen for the sample was as a result of increase in carrier
concentration and mobility. Furthermore, the increase in carrier concentration could be attributed to crystallization of the
grains into a dense structure in the film [13]. There are two reasons for the increase in carrier concentration. First, many
free electrons are caught by large numbers of traps formed by defects. Second, when a semiconductor is abruptly
terminated at the surface, the disruption of potential function would create discrete energy states within the band gap
which were called surface states and could trap free carriers. [20], further explained that the increase of conductivity in the
130nm thin film may be due to the increase in inter metallic island distance with the increase of film thickness.
In a research, [1], concluded that with increase in the thickness of the thin films, carrier mobility and concentration is also
improved which is attributed to the improved crystallinity and increased crystallite sizes that weakens inter-crystallite
boundary scattering and increases carrier lifetime. The observed increase in sheet resistance for the 75.5nm film is
probably due to the discontinuous nature of the film. The observed dependence of sheet resistance on thickness is in good
agreement with Fuchs-Sondheimer theory [21].
TABLE II: ELECTRICAL PARAMETERS OF ZnO THIN FILMS
Thickness (nm) Resistivity (Ω cm) Sheet Resistance (Rs) Ω
75.5 6.0×10-4
2.27×10-3
130.5 1.8×10-4
0.816×10-3
B. Structural Properties:
Fig. 2, shows the X-ray diffraction profiles of ZnO films in the thickness of 75.5nm and 130.5nm respectively. From the
XRD profile, the film deposited at a thickness of 75.5nm exhibited the (002) orientation at 2 =34.310
and 130nm thick
34.350
. The predomination of (002) peak in the pattern proved that the ZnO films have Wurtzite crystalline structure with
a preferential orientation along the c-axis and without formation of any secondary phases. The shift of the (002) peak
towards higher angles also implies relaxation of the residual strain introduced in the films during the deposition process.
The indication that the grains are strongly oriented along the c-axis is because of the singular peak (002 at 2Ɵ ~ 34.31°-
34.35°). This is in line with the findings of other researchers such as [8]. A qualitative idea proposed by [22] for the
formation mechanism of the preferential oriented thin films suggests that it could be the minimization of the surface
energy of each crystal plane and usually films grows so as to minimize the surface energy. Due to the minimization of the
surface energy, heterogeneous nucleation readily happens at the interface of film and the substrate.
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Fig 2: XRD Pattern of ZnO thin films of 75.5nm and 130.5nm thick
The unit cell (lattice) parameters a and c of the films with (002) orientation were calculated using the relation in equation
2.The values calculated for a and c are 3.03A0
and 5.25 for the 75.5nm thick film and a = 3.2A0
while C = 5.19A0
, for the
130nm thick film respectively in agreement with lattice constants of ZnO powder sample of ASTM card: a = 3.2648A0
and C = 5.2194A0
. It has been noted that point defects such as Zn antisites, oxygen vacancies and extended defects such
as threading dislocation changes the lattice constant [17]. The 75.5nm thick film is noted to have the maximum deviation
from the ideal value.
TABLE III: CALCULATED STRUCTURAL PARAMETERS
Film thickness (nm) FWHM Grain size (D) Strain GPa Residual stressstress
75.5 0.9600 1.5059 1.77 4.13
130.5 0.3840 3.7798 0.05 0.12
A. Morphological properties:
The surface topography of thin film is very important tool to investigate the microstructure of the films. Scanning
Electron Microscopy (SEM) micrograph of the two samples is shown in fig. 3a and 3b with the presence tightly packed
grains.
(a) (b)
Fig 3: SEM micrographs of ZnO thin films at a thickness of (a) 75.5nm and (b) 130.5nm
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IV. CONCLUSION
The influence of thickness on electrical and structural properties of ZnO thin films by RF sputtering technique was
studied. The electrical conductivity is found to be dependent on the film thickness. The XRD pattern of the films showed
that the highest peak is located at 2 =34.310
and respectively. It is therefore reasonable to assume that the
observed changes in the electrical and structural properties of the samples are as a result of micro structural re-
arrangement initiated either during deposition or during annealing and these effects are interpreted in terms of density of
states model proposed by Mott and Davis.
ACKNOWLEDGMENT
The authors are indebted to the World Bank through the Science and Technology Post Basic (STEP-B) of the Usmanu
Danfodiyo University Sokoto Nigeria.
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