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- Legacy Theses & Dissertations (2009 - 2024) (5)
- Electrical & Computer Engineering Faculty Publications (4)
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- Chemistry and Biochemistry Faculty Publications (2)
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- Duane D. Johnson (2)
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- Alexander H. King (1)
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Articles 1 - 30 of 32
Full-Text Articles in Physical Sciences and Mathematics
Development Of A Prototype Superconducting Radio-Frequency Cavity For Conduction Cooled Accelerators, Gianluigi Ciovati, J. Anderson, S. Balachandran, G. Cheng, B. Coritron, E. Daly, P. Dhakal, Alex Gurevich, F. Hannon, K. Harding, L. Holland, F. Marhauser, K. Mclaughlin, D. Packard, T. Powers, U. Pudasaini, J. Rathke, R. Rimmer, T. Schultheiss, H. Vennekate, D. Vollmer
Development Of A Prototype Superconducting Radio-Frequency Cavity For Conduction Cooled Accelerators, Gianluigi Ciovati, J. Anderson, S. Balachandran, G. Cheng, B. Coritron, E. Daly, P. Dhakal, Alex Gurevich, F. Hannon, K. Harding, L. Holland, F. Marhauser, K. Mclaughlin, D. Packard, T. Powers, U. Pudasaini, J. Rathke, R. Rimmer, T. Schultheiss, H. Vennekate, D. Vollmer
Physics Faculty Publications
The higher efficiency of superconducting radio-frequency (SRF) cavities compared to normal -conducting ones enables the development of high-energy continuous-wave linear accelerators (linacs). Recent progress in the development of high-quality Nb3Sn film coatings along with the availability of cryocoolers with high cooling capacity at 4 K makes it feasible to operate SRF cavities cooled by thermal conduction at relevant accelerating gradients for use in accelerators. A possible use of conduction-cooled SRF linacs is for environmental applications, requiring electron beams with energy of 1-10 MeV and 1 MW of power. We have designed a 915 MHz SRF linac for such …
Ab-Initio And Empirical Simulations Of Aluminum And Copper Metal, William Wolfs
Ab-Initio And Empirical Simulations Of Aluminum And Copper Metal, William Wolfs
UNLV Theses, Dissertations, Professional Papers, and Capstones
In this work, I perform detailed calculations on the bulk and electronic properties of aluminum and copper metal. Originally, I was motivated by experimental work on the solidsolid phase changes in pure aluminum. These phase changes were well predicted by density functional theory(DFT) but difficult or impossible to predict using embedded atom method potentials(EAM). EAM potentials are in wide use to describe many properties of bulk materials, and it seemed worrying that something so basic as a phase change could not be predicted. I began running high precision calculations with DFT and compared the results to EAM potentials which had …
Development And Implementation Of A Pressure-Temperature Control System For The Physical Vapor Deposition Of Copper And Niobium From A Molybdenum Filament In The Development Of Superconducting 3d Printed Rf Cavity Particle Accelerators, Chandler J. Fleuette
Student Research Projects
This report covers the development of the pressure-temperature control system used in the production of small superconducting RF cavities for particle accelerators. To test the validity of the created program, a model for the process was created and tested. The model was used to fine tune the control system before integrating it into the lab. The end goal of the control system is to measure the pressure inside of a deposition vacuum chamber, convert that pressure to a temperature, and use that temperature in tandem with a PID controller to control the current passing though a molybdenum filament which is …
Development And Implementation Of A Pressure-Temperature Control System For The Physical Vapor Deposition Of Copper And Niobium From A Molybdenum Filament In The Development Of Superconducting 3d Printed Rf Cavity Particle Accelerators, Chandler J. Fleuette
Honors Theses and Capstones
This report covers the development of the pressure-temperature control system used in the production of small superconducting RF cavities for particle accelerators. To test the validity of the created program, a model for the process was created and tested. The model was used to fine tune the control system before integrating it into the lab. The end goal of the control system is to measure the pressure inside of a deposition vacuum chamber, convert that pressure to a temperature, and use that temperature in tandem with a PID controller to control the current passing though a molybdenum filament which is …
A Multi-Layered Srf Cavity For Conduction Cooling Applications, Gianluigi Ciovati, G. Cheng, E. Daly, G. V. Eremeev, J. Henry, R. A. Rimmer, Ishwari Prasad Parajuli, U. Pudasaini
A Multi-Layered Srf Cavity For Conduction Cooling Applications, Gianluigi Ciovati, G. Cheng, E. Daly, G. V. Eremeev, J. Henry, R. A. Rimmer, Ishwari Prasad Parajuli, U. Pudasaini
Physics Faculty Publications
Industrial application of SRF technology would favor the use of cryocoolers to conductively cool SRF cavities for particle accelerators, operating at or above 4.3 K. In order to achieve a lower surface resistance than Nb at 4.3 K, a superconductor with higher critical temperature should be used, whereas a metal with higher thermal conductivity than Nb should be used to conduct the heat to the cryocoolers. A standard 1.5 GHz bulk Nb single-cell cavity has been coated with a ~2 µm thick layer of Nb₃Sn on the inner surface and with a 5 mm thick Cu layer on the outer …
Lithography-Free, Omnidirectional, Cmos-Compatible Alcu Alloys For Thin-Film Superabsorbers, Mariama Rebello De Sousa Dias, Chen Gong, Zachary A. Benson, Marina S. Leite
Lithography-Free, Omnidirectional, Cmos-Compatible Alcu Alloys For Thin-Film Superabsorbers, Mariama Rebello De Sousa Dias, Chen Gong, Zachary A. Benson, Marina S. Leite
Physics Faculty Publications
Superabsorbers based on metasurfaces have recently enabled the control of light at the nanoscale in unprecedented ways. Nevertheless, the sub‐wavelength features needed to modify the absorption band usually require complex fabrication methods, such as electron‐beam lithography. To overcome the scalability limitations associated with the fabrication of metallic nanostructures, engineering the optical response of superabsorbers by metal alloying is proposed, instead of tuning the geometry/size of the nanoscale building blocks. The superior performance of thin film AlCu alloys as the metallic component of planar bilayer superabsorbers is numerically demonstrated. This alloy outperforms its pure constituents as well as other metals, such …
Electronic Structure And Stability Of Ligated Superatoms And Bimetallic Clusters, William H. Blades
Electronic Structure And Stability Of Ligated Superatoms And Bimetallic Clusters, William H. Blades
Theses and Dissertations
Quantum confinement in small metal clusters leads to a bunching of states into electronic shells reminiscent of shells in atoms. The addition of ligands can tune the valence electron count and electron distribution in metal clusters. A combined experimental and theoretical study of the reactivity of methanol with AlnIm− clusters reveals that ligands can enhance the stability of clusters. In some cases the electronegative ligand may perturb the charge density of the metallic core generating active sites that can lead to the etching of the cluster. Also, an investigation is conducted to understand how the bonding …
Magnet Traveling Through A Conducting Pipe: A Variation On The Analytical Approach, Benjamin Irvine, Matthew Kemnetz, Asim Gangopadhyaya, Thomas Ruubel
Magnet Traveling Through A Conducting Pipe: A Variation On The Analytical Approach, Benjamin Irvine, Matthew Kemnetz, Asim Gangopadhyaya, Thomas Ruubel
Asim Gangopadhyaya
We present an analytical study of magnetic damping. In particular, we investigate the dynamics of a cylindrical neodymium magnet as it moves through a conducting tube. Owing to the very high degree of uniformity of the magnetization for neodymium magnets, we are able to provide completely analytical results for the electromotive force generated in the pipe and the consequent retarding force. Our analytical expressions are shown to have excellent agreement with experimental observations.
Properties Of Cu(In,Ga,Al)Se² Thin Films Fabricated By Magnetron Sputtering, Talaat A. Hameed, Wei Cao, Bahiga A. Mansour, Inas K. Elzawaway, El-Metwally M. Abdelrazek, Hani E. Elsayed-Ali
Properties Of Cu(In,Ga,Al)Se² Thin Films Fabricated By Magnetron Sputtering, Talaat A. Hameed, Wei Cao, Bahiga A. Mansour, Inas K. Elzawaway, El-Metwally M. Abdelrazek, Hani E. Elsayed-Ali
Applied Research Center Publications
Cu (In,Ga,Al)Se2 (CIGAS) thin films were studied as an alternative absorber layer material to Cu(InxGa1-x)Se2. CIGAS thin films with varying Al content were prepared by magnetron sputtering on Si(100) and soda-lime glass substrates at 350 °C, followed by postdeposition annealing at 520 °C for 5 h in vacuum. The film composition was measured by an electron probe microanalyzer while the elemental depth profiles were determined by secondary ion mass spectrometry. X-ray diffraction studies indicated that CIGAS films are single phase with chalcopyrite structure and that the (112) peak clearly shifts to higher 2θ …
Epr Methods For Biological Cu(Ii): L-Band Cw And Nars, Brian Bennett, Jason M. Kowalski
Epr Methods For Biological Cu(Ii): L-Band Cw And Nars, Brian Bennett, Jason M. Kowalski
Physics Faculty Research and Publications
Abstract: Copper has many roles in biology that involve the change of coordination sphere and/or oxidation state of the copper ion. Consequently, the study of copper in heterogeneous environments is an important area in biophysics. EPR is a primary technique for the investigation of paramagnetic copper, which is usually the isolated Cu(II) ion, but sometimes as Cu(II) in different oxidation states of multitransition ion clusters. The gross geometry of the coordination environment of Cu(II) can often be determined from a simple inspection of the EPR spectrum, recorded in the traditional X-band frequency range (9–10 GHz). Identification and quantitation of the …
Strain Relaxation In Nm-Thick Cu And Cu-Alloy Films Bonded To A Rigid Substrate, Ashley Herrmann
Strain Relaxation In Nm-Thick Cu And Cu-Alloy Films Bonded To A Rigid Substrate, Ashley Herrmann
Legacy Theses & Dissertations (2009 - 2024)
In the wide scope of modern technology, nm-thick metallic films are increasingly used as lubrication layers, optical coatings, plating seeds, diffusion barriers, adhesion layers, metal contacts, reaction catalyzers, etc. A prominent example is the use of nm-thick Cu films as electroplating seed layers in the manufacturing of integrated circuits (ICs). These high density circuits are linked by on-chip copper interconnects, which are manufactured by filling Cu into narrow trenches by electroplating. The Cu fill by electroplating requires a thin Cu seed deposited onto high-aspect-ratio trenches. In modern ICs, these trenches are approaching 10 nm or less in width, and the …
Magnet Traveling Through A Conducting Pipe: A Variation On The Analytical Approach, Benjamin Irvine, Matthew Kemnetz, Asim Gangopadhyaya, Thomas Ruubel
Magnet Traveling Through A Conducting Pipe: A Variation On The Analytical Approach, Benjamin Irvine, Matthew Kemnetz, Asim Gangopadhyaya, Thomas Ruubel
Physics: Faculty Publications and Other Works
We present an analytical study of magnetic damping. In particular, we investigate the dynamics of a cylindrical neodymium magnet as it moves through a conducting tube. Owing to the very high degree of uniformity of the magnetization for neodymium magnets, we are able to provide completely analytical results for the electromotive force generated in the pipe and the consequent retarding force. Our analytical expressions are shown to have excellent agreement with experimental observations.
Ruco To Extend The Scalability Of Ultra-Thin Direct Plate Liners, Daniel Verne Greenslit
Ruco To Extend The Scalability Of Ultra-Thin Direct Plate Liners, Daniel Verne Greenslit
Legacy Theses & Dissertations (2009 - 2024)
In traditional semiconductor technology a sputtered copper seed layer is used to improve the adhesion, microstucture, and electromigration characteristics of electrochemically deposited (ECD) copper. The seed layer is deposited on top of a Ta/TaN stack. The Ta layer acts as an adhesion and nucleation layer for the copper seed and the TaN serves as a diffusion barrier for the Cu. As the line widths continue to shrink, scaling each of these layers becomes more difficult. It would be advantageous for the interconnect to be composed of as much copper as possible, transitioning from the traditional liner seed stack to a …
The Influence Of Copper Substrate Orientation On Graphene Growth, Zachary Robert Robinson
The Influence Of Copper Substrate Orientation On Graphene Growth, Zachary Robert Robinson
Legacy Theses & Dissertations (2009 - 2024)
This dissertation is focused on determining the influence of the copper substrate on graphene grown by \ac{CVD}. Graphene, which can be grown in single atomic layers on copper substrates, has potential applications in future electronic devices. One of the key issues for the use of graphene grown by chemical vapor deposition for device applications is the influence of defects on the transport properties of the graphene. For instance, growth on metal foil substrates results in multi-domain graphene growth because the foil substrates themselves have a variety of different surface terminations. Therefore, they don't serve as a very good template for …
Pvd Cu Trench-Fill By Viscous Flow At High Temperatures, Zhiyuan Wu
Pvd Cu Trench-Fill By Viscous Flow At High Temperatures, Zhiyuan Wu
Legacy Theses & Dissertations (2009 - 2024)
The scaling of integrated circuits has led to new challenges in Cu interconnect fabrication. It is getting difficult to fill narrow trenches, e.g. 20 nm wide, by Cu electroplating. In this work, a high temperature PVD Cu viscous flow trench fill process was explored to overcome the difficulties of filling narrow and high aspect ratio trenches.
Nucleation, Wetting And Agglomeration Of Copper And Copper-Alloy Thin Films On Metal Liner Surfaces, Stephanie Florence Labarbera
Nucleation, Wetting And Agglomeration Of Copper And Copper-Alloy Thin Films On Metal Liner Surfaces, Stephanie Florence Labarbera
Legacy Theses & Dissertations (2009 - 2024)
One of the key challenges in fabricating narrower and higher aspect ratio interconnects using damascene technology has been achieving an ultra-thin (~2 nm) and continuous Cu seed coverage on trench sidewalls. The thin seed is prone to agglomeration because of poor Cu wetting on the Ta liner. Using in-situ conductance measurements, the effect of lowering the substrate temperature during Cu seed deposition has been studied on tantalum (Ta) and ruthenium (Ru) liner surfaces. On a Ta surface, it was found that lowering the deposition temperature to -65°C increases the nucleation rate of the Cu thin film, and reduces the minimum …
Extreme Ultraviolet Polarimetry With Laser-Generated High-Order Harmonics: Characterization Of Uranium, Nicole Brimhall
Extreme Ultraviolet Polarimetry With Laser-Generated High-Order Harmonics: Characterization Of Uranium, Nicole Brimhall
Theses and Dissertations
We developed an extreme ultraviolet (EUV) polarimeter, which employs laser-generated high-order harmonics as the light source. This relatively high-flux, directional EUV source has available wavelengths between 10 nm and 47 nm with easily rotatable linear polarization. The polarimeter has allowed us to characterize the optical constants of materials that may be useful for EUV optics. The instrument has a versatile positioning system and a spectral resolution of about 180, and we have demonstrated that reflectance as low as 0.1% can be measured repeatably at EUV wavelengths. We investigate the high harmonic source used for polarimetry measurements by documenting the spatial …
Electronic And Structural Properties Of Molybdenum Thin Films As Determined By Real Time Spectroscopic Ellipsometry, J. D. Walker, H. Khatri, V. Ranjan, Jian Li, R. W. Collins, S. Marsillac
Electronic And Structural Properties Of Molybdenum Thin Films As Determined By Real Time Spectroscopic Ellipsometry, J. D. Walker, H. Khatri, V. Ranjan, Jian Li, R. W. Collins, S. Marsillac
Electrical & Computer Engineering Faculty Publications
Walker, J.D., Khatri, H., Ranjan, V., Li, J., Collins, R.W., & Marsillac, S. (2009). Electronic and structural properties of molybdenum thin films as determined by real-time spectroscopic ellipsometry. Applied Physics Letters, 94(14). doi: 10.1063/1.3117222
Onset Of Tt0 Suppression Studied In Cu + Cu Collisions At Square Root Of Snn = 22:4, 62.4, And 200 Gev, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt
Onset Of Tt0 Suppression Studied In Cu + Cu Collisions At Square Root Of Snn = 22:4, 62.4, And 200 Gev, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt
Aerospace, Physics, and Space Science Faculty Publications
Neutral pion transverse momentum (pT) spectra at midrapidity (jyj & 0:35) were measured in Cu þ Cu collisions at ffiffiffiffiffiffiffiffi sNN p ¼ 22:4, 62.4, and 200 GeV. Relative to 0 yields in p þ p collisions scaled by the number of inelastic nucleon-nucleon collisions (Ncoll) the 0 yields for pT * 2 GeV=c in central Cu þ Cu collisions are suppressed at 62.4 and 200 GeV whereas an enhancement is observed at 22.4 GeV. A comparison with a jet-quenching model suggests that final state parton energy loss dominates in central Cu þ Cu collisions at 62.4 and 200 GeV, …
J=C Production In Square Root Of Snn = 200 Gev Cu + Cu Collisions, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt
J=C Production In Square Root Of Snn = 200 Gev Cu + Cu Collisions, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt
Aerospace, Physics, and Space Science Faculty Publications
Yields for J=c production in Cu þ Cu collisions at ffiffiffiffiffiffiffiffi sNN p ¼ 200 GeV have been measured over the rapidity range jyj < 2:2 and compared with results in p þ p and Au þ Au collisions at the same energy. The Cu þ Cu data offer greatly improved precision over existing Au þ Au data for J=c production in collisions with small to intermediate numbers of participants, in the range where the quark-gluon plasma transition threshold is predicted to lie. Cold nuclear matter estimates based on ad hoc fits to d þ Au data describe the Cu þ Cu data up to Npart 50, corresponding to a Bjorken energy density of at least 1:5 GeV=fm3.
Energy Pathways And Directionality In Deformation Twinning, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu
Energy Pathways And Directionality In Deformation Twinning, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu
Duane D. Johnson
We present ab initiodensity functional theory calculations of twinning energy pathways for two opposite twinning modes, (111)[112¯] and (111)[1¯1¯2], in fcc materials to examine the directional nature of twinning which cannot be explained by classical twin nucleationmodels or the “twinnability” criterion. By accounting for these energy pathways in a multiscale model, we quantitatively predict the critical twinning stress for the (111)[1¯1¯2] mode to be substantially higher compared to the favorable (111)[112¯] mode (whose predicted stresses are in agreement with experiment), thus, ruling out twinning in the (111)[1¯1¯2] mode.
Generalized Planar Fault Energies And Twinning In Cu–Al Alloys, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu
Generalized Planar Fault Energies And Twinning In Cu–Al Alloys, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu
Duane D. Johnson
We report ab initio density functional theory calculations of generalized planar fault energies of fcc Cu–xAl (x=0, 5.0, and 8.3at.%) alloys. We investigate the effects of substitutional solute Al on the unstable intrinsic γus and twin γutstacking faultenergies (SFEs). Our results reveal an increased tendency of Cu–Al to deform preferentially by twinning with increasing Al content, consistent with experiment. We attribute this mechanical behavior to appreciable lowering of the twinning barrier γut, along with the stable intrinsic and twin SFEs.
X-Ray Generation From Metal Targets Coated With Wavelength-Scale Spheres, D. R. Symes, H. A. Sumeruk, I. V. Churina, Thomas D. Donnelly, J. Landry, T. Ditmire
X-Ray Generation From Metal Targets Coated With Wavelength-Scale Spheres, D. R. Symes, H. A. Sumeruk, I. V. Churina, Thomas D. Donnelly, J. Landry, T. Ditmire
All HMC Faculty Publications and Research
X-ray yield measurements from targets coated with wavelength-scale spheres are compared with measurements from polished targets. Evidence for a hotter resonant electron temperature due to field enhancements from Mie resonances in the spheres is investigated.
Thickness Dependence Of Magneto-Transport In Cu-Co Granular Thin Films, Jian Qing Wang, Ngocnga Dao, Ham H. Kim, Scott L. Whittenburg
Thickness Dependence Of Magneto-Transport In Cu-Co Granular Thin Films, Jian Qing Wang, Ngocnga Dao, Ham H. Kim, Scott L. Whittenburg
Chemistry and Biochemistry Faculty Publications
This work explores the thickness dependence of magneto-transport properties in granular thin films with different thickness. These results are compared with silver-based film series studied earlier. It was observed that the thickness dependence of the GMReffect was sensitive to the surface chemistry of the films. The extraordinary Hall effect (EHE) in these films was measured and found to be different from the Ag-based system. In the Cu-based system, the EHE is a weak function of film thickness over the range studied. When the variation of the spontaneous magnetization is taken into account the effective EHE has a universal thickness dependence
Operation Parameters Of The Thermionic Vacuum Arc Discharge, Tamer Akan
Operation Parameters Of The Thermionic Vacuum Arc Discharge, Tamer Akan
Turkish Journal of Physics
The thermionic vacuum arc (TVA) discharge with evaporating anodes employing directly heated thermionic cathodes is investigated. The TVA discharge generates a pure, gas-free metal vapor plasma containing ions with a directed energy. The TVA is strongly controlled by the cathodic electron beam and there is a quite good stability of important operation parameters like the arc voltage and the arc current.
Magnetization Reversal Of Elliptical Co/Cu/Co Pseudo-Spin Valve Dots, Ngocnga Dao, Scott L. Whittenburg, Y. Hao, Leszek M. Malkinski, Jian Qing Wang, C. A. Ross
Magnetization Reversal Of Elliptical Co/Cu/Co Pseudo-Spin Valve Dots, Ngocnga Dao, Scott L. Whittenburg, Y. Hao, Leszek M. Malkinski, Jian Qing Wang, C. A. Ross
Chemistry and Biochemistry Faculty Publications
We present our recent simulated results on Cr (5 nm)/ Cu (5 nm)/ Co (5 nm)/ Cu (3 nm)/ Co (2 nm) pseudo-spin valve dots. The simulated results agree qualitatively with the experimental results. Three different sizes of elliptical dots, and were simulated. Our simulations show that in these types of dots magnetization reversal occurs by the formation of domain walls: for and for No domain wall was observed in the reversal of the dots. For such dots, the simulated loops show a small two-step reversal pattern with the thin upper layer partially reversing followed by complete reversal of both …
High-Efficiency Solar Cells Based On Cu(Inal)Se[Sub 2] Thin Films, S. Marsillac, P. D. Paulson, M. W. Haimbodi, R. W. Birkmire, W. N. Shafarman
High-Efficiency Solar Cells Based On Cu(Inal)Se[Sub 2] Thin Films, S. Marsillac, P. D. Paulson, M. W. Haimbodi, R. W. Birkmire, W. N. Shafarman
Electrical & Computer Engineering Faculty Publications
A Cu(InAl)Se2solar cell with 16.9% efficiency is demonstrated using a Cu(InAl)Se2thin film deposited by four-source elemental evaporation and a device structure of glass/Mo/Cu(InAl)Se2/CdS/ZnO/indium tin oxide/(Ni/Algrid)/MgF2. A key to high efficiency is improved adhesion between the Cu(InAl)Se2 and the Mo back contact layer, provided by a 5-nm-thick Ga interlayer, which enabled the Cu(InAl)Se2 to be deposited at a 530 °C substrate temperature. Film and device properties are compared to Cu(InGa)Se2 with the same band gap of 1.16 eV. The solar cells have similar behavior, with performance limited by recombination through …
Segregation Of Bismuth To Triple Junctions In Copper, K.-M. Yin, Alexander H. King, T.E. Hsieh, F.-R. Chen, J.J. Kai, L. Chang
Segregation Of Bismuth To Triple Junctions In Copper, K.-M. Yin, Alexander H. King, T.E. Hsieh, F.-R. Chen, J.J. Kai, L. Chang
Alexander H. King
Bismuth segregation in copper has been studied using energy-dispersive X-ray spectrometry (EDX) in a JEOL 2010F transmission electron microscope. In addition to the expected solute enrichment at grain boundaries, we have observed extremely high concentrations of bismuth at certain triple junctions, with significantly greater enrichment factors than in the adjacent grain boundaries. It is shown here that the triple junction segregation is a function of the parameters of the grain boundaries at the triple line, and existence of this type of segregation implies that the affected triple junctions embody excess free energy. At least one of the observed triple junctions …
Compensation And Characterization Of Gallium Arsenide, Randy A. Roush
Compensation And Characterization Of Gallium Arsenide, Randy A. Roush
Electrical & Computer Engineering Theses & Dissertations
The properties of transition metals in gallium arsenide have been previously investigated extensively with respect to activation energies, but little effort has been made to correlate processing parameters with electronic characteristics. Diffusion of copper in gallium arsenide is of technological importance due to the development of GaAs:Cu bistable photoconductive devices. Several techniques are demonstrated in this work to develop and characterize compensated gallium arsenide wafers. The material is created by the thermal diffusion of copper into silicon-doped GaAs. Transition metals generally form deep and shallow acceptors in GaAs, and therefore compensation is possible by material processing such that the shallow …
Influence Of Copper Doping On The Performance Of Optically Controlled Gaas Switches, St. T. Ko, V. K. Lakdawala, K. H. Schoenbach, M. S. Mazzola
Influence Of Copper Doping On The Performance Of Optically Controlled Gaas Switches, St. T. Ko, V. K. Lakdawala, K. H. Schoenbach, M. S. Mazzola
Electrical & Computer Engineering Faculty Publications
The influence of the copper concentration in silicon-doped gallium arsenide on the photoionization and photoquenching of charge carriers was studied both experimentally and theoretically. The studies indicate that the compensation ratio (NCu/NSi) is an important parameter for the GaAs:Si:Cu switch systems with regard to the turn-on and turn-off performance. The optimum copper concentration for the use of GaAs:Si:Cu as an optically controlled closing and opening switch is determined.