This document summarizes research into using aluminum-induced crystallization to produce cheaper, more efficient solar cells. The researchers tested variables such as deposition method, annealing time and temperature, and inclusion of an aluminum oxide layer. Their best results came from a thermally evaporated sample annealed at 325°C for 20 hours, which produced large germanium grains oriented in the (111) direction needed for solar cell absorption. Further work is needed to optimize thickness and annealing conditions to improve crystallization for commercial viability.
The Role of IrO2 in Mediating Hole Transfer at the TiO2 Interfacekamatlab
A presentation of key information from our recently published paper:
DOI: 10.1021/jz200852m
Visit our website, KamatLab.com, for the latest news, publications, and research from our group.
The Role of IrO2 in Mediating Hole Transfer at the TiO2 Interfacekamatlab
A presentation of key information from our recently published paper:
DOI: 10.1021/jz200852m
Visit our website, KamatLab.com, for the latest news, publications, and research from our group.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
The superconductor accelerator cavity is one of the most important and perspective technology for an advance accelerator. For example, the International Committee for Future Accelerators decided that the Linear Collider design had been based on the superconductor technology. Moreover, the accelerator operating with continue wave (CW) mode must use the superconductor technology in stead of the normal conductor technology, such as the Accelerator-driven sub-critical reactor system (ADS), the Accelerator Transmutation of Waste (ATW), the Accelerator Production of Tritium (APT), and so on.
In order to meet all kinds of application, the scientific world interest is now focus on further developments of new resonant cavities fabrication techniques to reduce cost and improve the performance of the accelerator cavity. To realize this object, one of the important methods is to pursue research on new materials. The goal will be the achievement of superconducting cavity working better the Nb ones at 4.2K. For example, the better parameters of the Tc, the surface resistance, the critical field Hc and the Q value are needed.
Up to now, the most possible candidate is Nb3Sn. The Nb3Sn has not only the better superconductivity parameters, but also the stable property and the easy fabrication. There are two methods to fabricate the superconductor cavity with the Nb3Sn, which are including the diffusion method and the multilayer deposition method. In the thesis, we focus on the multilayer deposition method, and ......
The presentation file on workshop on Neutron and X-ray Characterisation on Caloric Materials, introduction to neutron scattering experiment with triple axis spectrometer for material scientist
The Albedo of Metallic Nanoparticles Computed from FDTDAI Publications
This manuscript presents the albedo, a measure of a nanoparticles light retention capability, for silver, aluminum, gold, chromium, copper, nickel and titanium throughout the visible spectrum. Lumerical’s finite-difference time-domain Maxwell’s equation solver was employed to analyze how light of various angles and polarizations interacts with such materials in three dimensions. All of the particles in this study are 50 nm in radius.
Dr. Ali Sayir presents an overview of his program, Aerospace Materials for Extreme Environments, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present briefings that highlight basic research programs beneficial to the Air Force.
Thermoluminescence in Pure and Nd+3 + K+ Doped Lead Germanate Single CrystalsAI Publications
Pure lead germanate was grown by Zochralski’stechnique.Nd+3 + K+ doped lead germanate was grown for comparative studies. Thermoluminescence studies were conducted on pure lead germanate and Nd+3 + K+ doped lead germanate. Thermoluminescence in pure lead germanate single crystals (LG) and Nd+3 + K+ doped lead germanate single crystals (DDLG) has been measured in terms of photomultiplier output current on Thermoluminescence Set Up. Thermoluminescence studies of LG revealed an increasing trend of Thermoluminescence output, with increasing temperature and sharp consistent maxima at 50°C and 100°C. TL studies of DDLG revealed a decreasing trend of Thermoluminescence output, with increasing temperature and a sharp consistent peak at 100°C and 120°C. It was further noted that doping increased Thermoluminescence output. Thermoluminescence in ferroelectric lead germanate was attributed to change in polarization with change in temperature and creation of defect states.
Perovskite Solar Cells
a short general overview presentation
hadi maghsoudi
device structure
crystal structure
preparation synthesis method
review papers
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.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
The superconductor accelerator cavity is one of the most important and perspective technology for an advance accelerator. For example, the International Committee for Future Accelerators decided that the Linear Collider design had been based on the superconductor technology. Moreover, the accelerator operating with continue wave (CW) mode must use the superconductor technology in stead of the normal conductor technology, such as the Accelerator-driven sub-critical reactor system (ADS), the Accelerator Transmutation of Waste (ATW), the Accelerator Production of Tritium (APT), and so on.
In order to meet all kinds of application, the scientific world interest is now focus on further developments of new resonant cavities fabrication techniques to reduce cost and improve the performance of the accelerator cavity. To realize this object, one of the important methods is to pursue research on new materials. The goal will be the achievement of superconducting cavity working better the Nb ones at 4.2K. For example, the better parameters of the Tc, the surface resistance, the critical field Hc and the Q value are needed.
Up to now, the most possible candidate is Nb3Sn. The Nb3Sn has not only the better superconductivity parameters, but also the stable property and the easy fabrication. There are two methods to fabricate the superconductor cavity with the Nb3Sn, which are including the diffusion method and the multilayer deposition method. In the thesis, we focus on the multilayer deposition method, and ......
The presentation file on workshop on Neutron and X-ray Characterisation on Caloric Materials, introduction to neutron scattering experiment with triple axis spectrometer for material scientist
The Albedo of Metallic Nanoparticles Computed from FDTDAI Publications
This manuscript presents the albedo, a measure of a nanoparticles light retention capability, for silver, aluminum, gold, chromium, copper, nickel and titanium throughout the visible spectrum. Lumerical’s finite-difference time-domain Maxwell’s equation solver was employed to analyze how light of various angles and polarizations interacts with such materials in three dimensions. All of the particles in this study are 50 nm in radius.
Dr. Ali Sayir presents an overview of his program, Aerospace Materials for Extreme Environments, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present briefings that highlight basic research programs beneficial to the Air Force.
Thermoluminescence in Pure and Nd+3 + K+ Doped Lead Germanate Single CrystalsAI Publications
Pure lead germanate was grown by Zochralski’stechnique.Nd+3 + K+ doped lead germanate was grown for comparative studies. Thermoluminescence studies were conducted on pure lead germanate and Nd+3 + K+ doped lead germanate. Thermoluminescence in pure lead germanate single crystals (LG) and Nd+3 + K+ doped lead germanate single crystals (DDLG) has been measured in terms of photomultiplier output current on Thermoluminescence Set Up. Thermoluminescence studies of LG revealed an increasing trend of Thermoluminescence output, with increasing temperature and sharp consistent maxima at 50°C and 100°C. TL studies of DDLG revealed a decreasing trend of Thermoluminescence output, with increasing temperature and a sharp consistent peak at 100°C and 120°C. It was further noted that doping increased Thermoluminescence output. Thermoluminescence in ferroelectric lead germanate was attributed to change in polarization with change in temperature and creation of defect states.
Perovskite Solar Cells
a short general overview presentation
hadi maghsoudi
device structure
crystal structure
preparation synthesis method
review papers
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.
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.
LGS crystal which melts congruently at 1470⁰C has been grown by Czochralski method. The langasite
crystal of length about 1cm grown along its Z-axis was cut in X and Y directions , polished and
subjected to various characterization studies. Phase and structure of the grown crystal was confirmed by
Powder XRD measurement. FTIR spectrum was carried out to confirm the functional groups present in
the grown crystals. The optical behavior was studied by UV–vis-NIR analysis. Electrical properties such as Dielectric constant, Resistivity, Conductivity and Piezoelectric coefficient have also been studied.
APS March Meeting 2020 - Nonisentropic Release of a Shocked SolidPatrickHeighway
A joint computational-experimental study of nonisentropic release of tantalum from the shock state. A shortened version of this presentation was intended to be delivered at the APS March Meeting 2020 in Denver.
2. What is a single junction solar cell?
Undergraduate Research Symposium 2015
August 7, 2015 Rochester, NY
¹ http://pveducation.org/pvcdrom/solar-cell-operation/solar-cell-structure ² William Shockley and Hans J. Queisser, "Detailed Balance
Limit of Efficiency of p-n Junction Solar Cells", Journal of Applied Physics, Volume 32 (March 1961), pp. 510-519; doi:10.1063/1.1736034
2
• Generation of light-generated carriers
• Collection light-generated carriers to
generate current
• Generation of large voltage across
solar cell
• Dissipation of power in load and
parasitic resistances
• Shockley-Queisser limit maximizes
single p-n junction with 1.34eV
bandgap at AM1.5 to be 33.7% ²
¹
3. What is a multi junction solar cell?
• III-V solar cells are direct bandgap
semiconductors, as opposed to Si and is are
great absorbers
• Multijunction cells can account for otherwise
lost photons
• Grown by MOCVD, GaInP/GaInAs/Ge cells can
reach 31.3% efficiency at AM1.5 and 41.6%
under concentration
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August 7, 2015 Rochester, NY
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4. History of AIC and its relation to our Goal
Undergraduate Research Symposium 2015
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• AIC uses inexpensive techniques, such as
sputtering or thermal evaporation, to work
towards these kinds of efficiencies; however,
much work is still needed to make it
commercially viable.
• Polycrystalline materials have grain
boundaries which act as defects, whereas
small grains can lead to increased
nonradiative recombination that impedes
current generation.
4
Highly (111)-oriented Ge thin films on insulators formed by Al-induced crystallizationToko, K. and Kurosawa, M. and Saitoh, N. and Yoshizawa,
N. and Usami, N. and Miyao, M. and Suemasu, T., Applied Physics Letters, 101, 072106 (2012), DOI:http://dx.doi.org/10.1063/1.4744962
Our goal is to pick up whereToko, et al, left off
in exploring different variables for increasing
grains size and preferential orientation.
5. Our Process and Tools
• Started with 1 1 1 Si wafers
• RCA cleaned them to proceed to grow a 1-micron oxide layer
• Sputtered/thermally evaporated 50nm of Al
• Broke vacuum for 30 mins/remained under vacuum
• Sputtered/thermally evaporated 50nm of Ge
• Annealed for 10/20 hour
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CVC 601 Sputter System Kurt J. Lesker PVD 75c Lindberg BlueTube Furnace
Si
SiO2
Al
Ge
Al2O3
Al2O3
Ge
6. Variable Time
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August 7, 2015 Rochester, NY
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Constants:
• 260 C anneal
• No Al2O3
• Sputtered
Pre anneal shows no Ge peak
meaning the Ge is amorphous
Both anneals showed Ge
peaks, meaning crystals
formed
20h Ge peak had a higher
intensity than the 10h,
showing a greater number of
crystals
7. Variable Time- SEM
Undergraduate Research Symposium 2015
August 7, 2015 Rochester, NY
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Constants:
• 260 C anneal
• No Al2O3
• Sputtered
Pre anneal shows no Ge peak
meaning the Ge is amorphous
Both anneals showed Ge
peaks, meaning crystals
formed
20h Ge peak had a higher
intensity than the 10h,
showing a greater number of
crystals
20 hour anneal
10 hour anneal
8. Scherrer Equation
A formula that relates X-ray diffraction readings to grain sizes.
𝜏 =
𝐾𝜆
𝛽𝑐𝑜𝑠𝜃
K is a dimensionless shape factor that has a typical value of 0.9, varying with crystalline structure.
𝜆 is the X-ray wavelength.
The Scherrer Equation is applicable up to 0.1 to 0.2um.
A K of 0.9 and the 𝜆 of Cu, 1.541838 Å, was used.
8
Sample FWHM (𝛽) Bragg Angle (𝜃) Mean Size (or less)
10h, no Al2O3 0.230 27.2º 6 Å
20h, no Al2O3 0.226 27.1º 6 Å
Patterson, A. (1939). "The Scherrer Formula for X-Ray Particle Size Determination". Phys. Rev. 56 (10): 978–982. Bibcode:1939PhRv...56..978P.doi:10.1103/PhysRev.56.978.
Undergraduate Research Symposium 2015
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9. With or Without Al2O3
Undergraduate Research Symposium 2015
August 7, 2015 Rochester, NY
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Constants:
• 10h period
• 260 C anneal
• Sputtered
SinceAl2O3 acts as a
barrier, layer transfer
cannot occur at such a
low temperature and
the Ge remains
amorphous
As the Al tries to
diffuse, it is impeded
by the Al2O3 and
forms dendritic grains
10. With or Without Al2O3
– Nomarski Microscopy
Undergraduate Research Symposium 2015
August 7, 2015 Rochester, NY
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Constants:
• 10h period
• 260 C anneal
• Sputtered
SinceAl2O3 acts as a
barrier, layer transfer
cannot occur at such a
low temperature and
the Ge remains
amorphous
The Al peak shift is
either an Al alloy
created or Al2O3
Without Al2O3
With Al2O3
11. Different Deposition Methods
Undergraduate Research Symposium 2015
August 7, 2015 Rochester, NY
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Constants:
• 20h period
• 260 C anneal
• With Al2O3
Neither method
shows Ge crystals
formed
Sputtering shows
larger peaks
meaning bigger
crystals or more
uniform crystal
orientation
12. Different Deposition
Methods - SEM
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August 7, 2015 Rochester, NY
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Constants:
• 20h period
• 260 C anneal
Neither method
shows Ge crystals
formed
Sputtering shows
larger peaks
meaning bigger
crystals or more
uniform crystal
orientation
Thermal Evaporation with Al2O3
Sputter without Al2O3
13. Variable Temperature
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August 7, 2015 Rochester, NY
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Constants:
• 20h period
• With Al2O3
• Thermally Evaporated
The Al2O3 barrier is
overcome and layer
transfer can occur at 325
C.This results in 111 Ge
grains.
14. Variable Temperature –
Nomarski Microscopy
Undergraduate Research Symposium 2015
August 7, 2015 Rochester, NY
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Constants:
• 20h period
• With Al2O3
• Thermally Evaporated
The Al2O3 barrier is
overcome and layer
transfer can occur at 325
C.This results in 111 Ge
grains.
325 C Anneal
260 C Anneal
15. Conclusions and Further Work
• THE THERMAL EVAPORATED SAMPLE AT 325 C SHOWED THE
BEST IMAGES THROUGH MICROSCOPY.
• THE 20H ANNEAL WITH NO VACUUM BREAK SHOWED THE
STRONGEST XRD PEAKS FOR 1 1 1 GERMANIUM.
• HYPOTHESIS IS THAT THE ALUMINUM GROWS DENDRITICALLY
AND THE GERMANIUM GROWS IN A MORE ROUNDED SHAPE.
• Changing the thicknesses ofAl and Ge
• More higher temperature anneals, >260 C, needed to find the “sweet
spot”
• Explore 20h anneal sputtered with Al2O3 layer.
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August 7, 2015 Rochester, NY
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16. Acknowledgements
• GEORGE NELSON
• MICHAEL SLOCUM, NATHAN COX, JASON STAUB
• ZAC BITTNER
• THE OFFICE OF NAVAL RESEARCH
Questions?
N00173-14-1-G011
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