Cu doped ZnS was investigated as a potential p-type transparent conducting material. Thin films of Cu:ZnS were deposited via pulsed laser deposition using a segmented target to control Cu concentration between 1-20% mole fraction. The films exhibited 80% visible light transparency and crystallized in the desired wurtzite structure after annealing. However, conductivity was low due to most Cu occupying interstitial rather than substitutional sites in the ZnS lattice. Achieving sulfur-rich deposition conditions is needed to promote Cu substitution for Zn and improve hole concentration and conductivity.
Phillips - A brief discussion of conventional sputtering and energetic Conden...thinfilmsworkshop
http://www.surfacetreatments.it/thinfilms
A Brief Discussion of Conventional Sputtering and Energetic Condensation for Superconducting cavity applications (Larry Phillips - 25')
Speaker: Larry Phillips - JLab | Duration: 25 min.
Abstract
The history of niobium films produced by conventional magnetron sputtering and energetic condensation will be discussed in terms of their impact on SRF cavity performance.
A brief overview of current R&D in the energetic condensation of niobium films for this application will also be discussed.
Phillips - A brief discussion of conventional sputtering and energetic Conden...thinfilmsworkshop
http://www.surfacetreatments.it/thinfilms
A Brief Discussion of Conventional Sputtering and Energetic Condensation for Superconducting cavity applications (Larry Phillips - 25')
Speaker: Larry Phillips - JLab | Duration: 25 min.
Abstract
The history of niobium films produced by conventional magnetron sputtering and energetic condensation will be discussed in terms of their impact on SRF cavity performance.
A brief overview of current R&D in the energetic condensation of niobium films for this application will also be discussed.
This to demonstrate the laser ablation of hard materials to form a thin film for optical sensors. The work was done at DIllard University , New Orleans LA by Professor Abdalla Darwish. any comment e-mail adarwish@bellsouth.net.
In-situ TEM studies of tribo-induced bonding modification in near-frictionles...Deepak Rajput
A presentation on "In-situ TEM studies of tribo-induced bonding modification in near-frictionless carbon films" made by Deepak Rajput. This presentation was based on "critical review of a paper," in All Things Carbon course offered at the University of Tennessee Space Insitute at Tullahoma in Fall 2009.
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.
Shulze - Surface and Thin Film Characterization of Superconducting Multilayer...thinfilmsworkshop
http://www.surfacetreatments.it/thinfilms
Surface and Thin Film Characterization of Superconducting Multilayer films for application in RF (Roland Schulze - 30')
Speaker: Roland Schulze - Los Alamos National Laboratory | Duration: 30 min.
Abstract
The use of multilayer ultra-thin films on the interior surfaces of Nb superconducting RF cavities shows great promise in substantially improving the performance characteristics of superconducting RF cavities into the 100 MV/m range by increasing the RF critical magnetic field, HRF, through careful choice of new materials and thin film structures. However, there are substantial materials science challenges associated with producing such complex film structures, particularly for conformal application of uniform thin films on the interior surfaces of RF cavities. Here we present surface and thin film analysis of ultra-thin films of two candidate materials, MgB2 and NbN superconductors, deposited through several different methods, along with multilayers produced with alternating superconductor and dielectric films. We report on the analysis methods and techniques, using primarily x-ray photoelectron spectroscopy and Auger spectroscopy with ion sputter depth profiling, and describe results from variety of thin film samples. The materials stability, microstructure, chemistry, and thin film morphology are highly dependent on methods and parameters used in the thin film deposition. From our analysis, important factors for producing quality superconducting and dielectric films include chemical stoichiometry, impurity content, deposition temperature, substrate choice and conditioning, choice of dielectric material, and the nature of the thin film interfaces. These factors will be discussed in the context of the production methods used for these ultra-thin superconducting films.
Solar cell absorber Kesterite- type Cu2ZnSnS4 (CZTS) thin films have been prepared by Chemical Bath Deposition (CBD). UV–vis absorption spectra measurement indicated that the band gap of as-synthesized CZTS was about1.68 eV, which was near the optimum value for photovoltaic solar conversion in a single-band-gap device. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained by XRD. The average of crystalline size of CZTS is 27 nm
Band gap engineering of hybrid perovskites for solar cellsKiriPo
The research was conducted in summer 2014 under supervision of professor David Cahen at Optoelectronics Materials Group in Department of Materials and Interfaces at Weizmann Institute of Science (Rehovot, Israel).
This to demonstrate the laser ablation of hard materials to form a thin film for optical sensors. The work was done at DIllard University , New Orleans LA by Professor Abdalla Darwish. any comment e-mail adarwish@bellsouth.net.
In-situ TEM studies of tribo-induced bonding modification in near-frictionles...Deepak Rajput
A presentation on "In-situ TEM studies of tribo-induced bonding modification in near-frictionless carbon films" made by Deepak Rajput. This presentation was based on "critical review of a paper," in All Things Carbon course offered at the University of Tennessee Space Insitute at Tullahoma in Fall 2009.
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.
Shulze - Surface and Thin Film Characterization of Superconducting Multilayer...thinfilmsworkshop
http://www.surfacetreatments.it/thinfilms
Surface and Thin Film Characterization of Superconducting Multilayer films for application in RF (Roland Schulze - 30')
Speaker: Roland Schulze - Los Alamos National Laboratory | Duration: 30 min.
Abstract
The use of multilayer ultra-thin films on the interior surfaces of Nb superconducting RF cavities shows great promise in substantially improving the performance characteristics of superconducting RF cavities into the 100 MV/m range by increasing the RF critical magnetic field, HRF, through careful choice of new materials and thin film structures. However, there are substantial materials science challenges associated with producing such complex film structures, particularly for conformal application of uniform thin films on the interior surfaces of RF cavities. Here we present surface and thin film analysis of ultra-thin films of two candidate materials, MgB2 and NbN superconductors, deposited through several different methods, along with multilayers produced with alternating superconductor and dielectric films. We report on the analysis methods and techniques, using primarily x-ray photoelectron spectroscopy and Auger spectroscopy with ion sputter depth profiling, and describe results from variety of thin film samples. The materials stability, microstructure, chemistry, and thin film morphology are highly dependent on methods and parameters used in the thin film deposition. From our analysis, important factors for producing quality superconducting and dielectric films include chemical stoichiometry, impurity content, deposition temperature, substrate choice and conditioning, choice of dielectric material, and the nature of the thin film interfaces. These factors will be discussed in the context of the production methods used for these ultra-thin superconducting films.
Solar cell absorber Kesterite- type Cu2ZnSnS4 (CZTS) thin films have been prepared by Chemical Bath Deposition (CBD). UV–vis absorption spectra measurement indicated that the band gap of as-synthesized CZTS was about1.68 eV, which was near the optimum value for photovoltaic solar conversion in a single-band-gap device. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained by XRD. The average of crystalline size of CZTS is 27 nm
Band gap engineering of hybrid perovskites for solar cellsKiriPo
The research was conducted in summer 2014 under supervision of professor David Cahen at Optoelectronics Materials Group in Department of Materials and Interfaces at Weizmann Institute of Science (Rehovot, Israel).
Copper indium sulphide films were deposited by the
pulse plating technique with different OFF times in the range of
5s – 30s and at a constant current density of 5 mA cm-2. The
films exhibited single phase copper indium sulphide. The grain
size increased with decrease of OFF time. Optical band gap of the
films increased from 1.44– 1.497 eV with decrease of OFF time.
Optical constants (refractive index, n, and extinction co-efficient,
k) of the films have been obtained in the wavelength range 800 -
1700 nm by using spectrophotometric measurement. The
obtained results concerning the absorption index yield the energy
gap in addition to the type of the allowed optical transitions.
N/m* ratio has been obtained from refractive index data. The
dispersion of refractive index is analyzed by using a single
oscillator model.
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.
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.
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
Influence of Thickness on Electrical and Structural Properties of Zinc Oxide ...paperpublications3
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).
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.
Morphological and Optical Study of Sol-Gel SpinCoated Nanostructured CdSThin ...
Project presentation
1. Cu doped ZnS as a P-type Transparent Conducting Material
By Chris Wilshaw
Lab partner: Alex Tallon
Supervisor: Neil Fox
2. Transparent Conducting Materials
What are Transparent Conducting Materials (TCMs)?
Transparent across visible wavelengths
Electrically conductive
How?
Bandgaps above ~3𝑒𝑉 transmit visible
wavelengths but absorb UV
Low resistivity comes from doped charge carriers
𝐸 𝑣
𝐸𝑐
UV
3. Uses of Transparent Conducting Materials
The majority of TCMs are n-doped metal oxides
Industry standard is Tin-doped Indium Oxide (ITO), capable of
around 80% transmittance in the visible, and a conductivity of
~104
𝑆. 𝑐𝑚−1
Scarcity of Indium has led to research into alternatives using
abundant, cheap materials such as Al doped ZnO (AZO).
Generally used as electrodes in LED’s, PV and flat panel
displays p-Silicon
n-Silicon
ITO
4. P-type TCMs and their Potential
Applications of these n-type TCMs are limited
A p-type TCM would allow transparent pn-junctions, transistors, diodes
etc
Opens up the field of ‘Transparent Electronics’
These have however proved far harder to create than their n type
counterparts.
5. Cu doped ZnS as a P-type TCM
Zinc Sulphide has a wide, direct, bandgap of around 3.5eV
Calculations using the ‘supercell modelling method’ show that under Sulphur
rich conditions 𝐶𝑢1+ will replace 𝑍𝑛2+ in the ZnS lattice, leading to a surplus
of holes and thus a p-type semiconductor
Stable, non-toxic, abundant elements
ZnS has two stable crystalline phases: Zincblende (cubic) is most common at
room temperature, but Wurtzite (hexagonal) can be achieved at higher
temperatures.
Several good n-type TCMs with Wurzite structure, including AZO, but no p-
type ones
Zincblende
Wurzite
6. Prior work and Project Aims
Prior Work
Diamond et al. used Pulsed Laser Deposition to successfully fabricate thin films of
Cu:ZnS achieving 65% transmittance at 550nm, and a conductivity of 102
𝑆. 𝑐𝑚−1
.
However, they failed to control the Cu concentrations in the films and required
very high doping levels of Cu-about 25% as a mole fraction of the film. Raising
questions concerning the transfer of Cu into the film, as well as the efficiency of
the substitutional process.
The films also failed to exhibit clear Wurzite structure.
Thus our research aimed to make thin films of Cu:ZnS with high transparency, low
resistivity and a Wurzite structure in such a way that accurately controlled the
amount of Cu deposited in the films, and ensured efficient substitution of Cu for Zn.
7. Pulsed Laser Deposition (PLD)
A rotating target is hit repeatedly by
a high power LASER pulse.
Each pulse ablates the target
material into a plume, which then
travels across the chamber and
deposits as a thin layer on a heated
Sapphire substrate.
Under UHV
8. Pulsed Laser Deposition of our Samples
Conventionally use a mixed target containing a constant composition mix of each material throughout
(Technique used in prior work)
Instead, we used a new segmented target design
During deposition, as the target rotated, the LASER alternately ablated ZnS and Cu.
The concentration of Cu was dependent upon the Cu strip width and the LASER focus radius, and was
varied from 1% to 20% as a mole fraction of ablated material.
Target Plume Film growth
Substrate
9. Results: Crystal Structure
X-ray Diffraction revealed that annealing at
550 ⁰C for 30 minutes led to the desired
Wurtzite structure, as is clear from the
characteristic splitting of the main peak
into 3 separate peaks.
Xrd data also showed that the films had
good crystallinity, with average crystal sizes
up to 50nm, around double that reported
by Diamond et al.
Zincblende
Wurzite
(111)
(200)
(100)
(002)
(101)
10. Results: Transparency
The transparency of the films rely mainly on
thickness, bandgap and crystallinity
Focussed Ion Beam spectroscopy of the films
revealed film thicknesses of around 200nm, as
shown to the right. The image demonstrates
the uniformity of the films, which was
confirmed by Atomic Force Microscopy.
Ultraviolet-Visible spectroscopy showed that
post-annealed samples had band gaps of
around 3.8eV.
Average transmittance in the visible
wavelength range of ~80%.
200 nm
0
10
20
30
40
50
60
70
80
90
100
200 300 400 500 600 700 800
Transmittance
Wavelength (nm)
11. Results: Conductivity
The conductivity of the films will depend mainly upon the carrier density and mobility as well as the
thickness of the sample.
Energy Dispersive X-ray spectroscopy of the samples showed that the concentration of Cu in the films varied
substantially from the amount expected from the deposition conditions, with most films containing between
2 and 10% Cu as a mole fraction.
Hole Density
(𝑐𝑚−3
)
Hole Mobility
(𝑐𝑚2
𝑉−1
𝑠−1
)
Thickness
(nm)
Conductivity
(S. 𝑐𝑚−1
)
Cu:ZnS 2 × 1013
2 × 102 200 5 × 10−4
ITO ~1021 50 200 ~104
Hall measurements of our best film,
containing 5% Cu, compared to ITO.
These are surprisingly low given the amount of Cu in the film, suggesting that the vast majority of Cu took up
interstitial positions in the lattice rather than substitutional ones, resulting in relatively few holes.
EDX data also showed that the films tended to be Zn rich rather than S rich as required for 𝐶𝑢1+
ions to
substitute for 𝑍𝑛2+
ions. For this reason it is thought that the Cu was taking up interstitial positions between
crystal grains, and thus failing to act as a hole donor.
12. Conclusions and Further Work
Thin films of Cu:ZnS were successfully fabricated with 80% transparency, good crystallinity and the
desired Wurzite structure.
The segmented target approach, whilst quick and easy, did not lead to control of the Cu entering
the films
The conductivities of the films were poor, thought to be the result of layering in the film, or Zn rich
deposition conditions preventing Cu from substituting for the Zn
Further Work
Further work should concentrate on reducing layering within the film, and achieving Sulphur rich
deposition conditions.
Editor's Notes
Choose a semiconductor with a bandgap corresponding to the upper end of the visible spectrum
Okay so first things first, what is a tcm? Well as the name suggests they’re a class of material that are both transparent to visible light and capable of conducting electricity.
How are these properties achieved? If you think of a semiconductor with its bandgap like this, only light with energy greater than the bandgap can be absorbed, so for a TCM all you need is a semiconductor with a bandgap of 3ev or more-so it absorbs UV but not visible light
And the conductivity is achieved through doping, so the introduction of electrons or holes to act as charge carriers
Electrons carry the charge
3 orders of magnitude higher than Copper
Okay so that’s all well and good but the applications are pretty limited, they can only really assist other devices, they’re passive
Development of a p-type (hole conducting) TCM would facilitate the fabrication of fundamental electronic devices that are completely transparent
Refer to picture on previous slide
In this project we’re looking into using ZnS doped with Cu. ZnS has a wide bandgap of around 3.5ev
A first round of films were deposited using the Cu strip design, with the amount of Cu varied from 1% to 20%. They were insulating due to layering
The combination of these three adjustments led to films with measurable conductivity though still high.
So we proceeded to carry out wide range of characterisations were performed in order to determine the properties of the deposited films and establish the degree to which each of the three main criteria were met: transparency, conductivity & Wurtzite lattice structure.
A first round of films were deposited using the Cu strip design, with the amount of Cu varied from 1% to 20%. They were insulating due to layering
The combination of these three adjustments led to films with measurable conductivity though still high.
So we proceeded to carry out wide range of characterisations were performed in order to determine the properties of the deposited films and establish the degree to which each of the three main criteria were met: transparency, conductivity & Wurtzite lattice structure.