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Generation of Compositionally Graded Ga{sub 1-x}In{sub x}Sb Seed by Solute Diffusion

Description: Compositionally graded single crystalline <100> seed of Ga{sub 1-x}In{sub x}Sb has been grown in a single experiment using a solute diffusion method. The present technique is simple and less time consuming compared to the conventional boot-strapping approach previously used for generating ternary seeds. Starting from an InSb <100> single crystalline seed, a seed of Ga{sub 0.6}In{sub 0.4}Sb has been grown. The effect of temperature gradient on the crystalline quality of seeds grown using this method has been discussed.
Date: August 29, 2002
Creator: Dutta, P.S.; Rajagopalan, G.; Gutmann, R.J. & Nichols, G.
Partner: UNT Libraries Government Documents Department

Growth of Uniform Ga{sub 1-x}In{sub x}Sb Bulk Crystals by Self-Solute Feeding Technique

Description: Compositionally homogeneous, crack-free bulk crystals of Ga{sub 1-x}In{sub x}Sb with x as high as 0.4 has been grown for the first time using a self-solute feeding method. A balance between the growth rate and the spacing between the solute and the growth interface has been found to be crucial in maintaining uniform alloy composition.
Date: August 29, 2003
Creator: Dutta, P.S.; Rajagopalan, G.; Gutmann, R.J. & Nichols, G.
Partner: UNT Libraries Government Documents Department

A Single Step Lapping and Polishing Process for Achieving Surfaces of Compound Semiconductors with Atomic Flatness using a Sub-micron Agglomerate-free Alumina Slurry

Description: A novel approach for a single step lapping and final polishing of III-V and II-VI compounds using agglomerate-free alumina slurries has been developed. The agglomerate-free nature of the sub-micron slurry leads to removal rates comparable to conventional slurries (with larger particles of tens of microns) used for semiconductor lapping. Surfaces with minimal surface damage and extremely low surface roughness have been obtained using the sub-micron slurries and a soft pad. Strategies for post polishing surface cleaning have been discussed. The new methodology has been experimented on GaSb, InAs, GaAs, InP, InSb, CdTe, GaInSb, GaInAs, AlGaAsSb, GaInAsSb and HgCdTe. Selected results of surface analyses of GaSb and GaInSb using atomic force microscopy will be presented.
Date: August 29, 2002
Creator: Dutta, P.S.; Rajagopalan, G.; Gutmann, J.J.; Keller, D. & Sweet, L.
Partner: UNT Libraries Government Documents Department

A Simple Single Step diffusion and Emitter Etching Process for High Efficiency Gallium Antimonide Thermophotovoltaic Devices

Description: A single step diffusion followed by precise etching of the diffused layer has been developed to obtain a diffusion profile appropriate for high efficiency GaSb thermophotovoltaic cells. The junction depth was controlled through monitoring of light current-voltage (I-V) curves (photovoltaic response) during the post diffusion emitter etching process. The measured photoresponses (prior to device fabrication) have been correlated with the quantum efficiencies and the open circuit voltages in the fabricated devices. An optimum junction depth for obtaining highest quantum efficiency and open circuit voltage is presented based on diffusion lengths (or monitoring carrier lifetimes), carrier mobility and typical diffused impurity profile in GaSb.
Date: August 29, 2003
Creator: Rajagopalan, G.; Reddy, N.S.; Ehsani, E.; Bhat, I.B.; Dutta, P.S.; Gutmann, R.J. et al.
Partner: UNT Libraries Government Documents Department

Performance Limits of Low Bandgap Thermophotovoltaic Antimonide-Based Cells for Low Temperature Radiators

Description: This paper assesses the performance of antimonide-based thermophotovoltaic cells fabricated by different technologies. In particular, the paper compares the performance of lattice matched quaternary (GaInAsSb) cells epitaxially grown on GaSb substrates to the performance of ternary (GaInSb) and binary (GaSb) cells fabricated by Zn diffusion on bulk substrates. The focus of the paper is to delineate the key performance advantages of the highest performance-to-date of the quaternary cells to the performance of the alternative ternary and binary antimonide-based diffusion technology. The performance characteristics of the cells considered are obtained from PC-1D simulations using appropriate material parameters.
Date: August 29, 2000
Creator: Borrego, J.M.; Wang, C.A.; Dutta, P.S.; rajagopalan, G.; Bhat, I.B.; Gutmann, R.J. et al.
Partner: UNT Libraries Government Documents Department