Thesis (Ph. D.)--University of Florida, 1984. / Description based on print version record. Typescript. In "AlxGa₁₋xAs" in title, "x" is subscript. Vita. Includes bibliographical references (leaves 182-189).

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 111-114). Also available on the Internet.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 69-70). Also available in electronic version.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Dennis G. Deppe. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references. Also available in electronic version.

This study focuses on the characterization of InAs and InAs1-xSbx epitaxial layers by infrared reflectance and transmittance spectroscopy and Hall measurements. Reflectance measurements were performed in order to obtain the dielectric parameters and to extract from these information about the electrical properties (mobility and carrier concentration) of this important III-V material system. The transmittance measurements were used to determine the bandgap of InAsSb. Infrared reflectivity and transmittance measurements were performed in the wavelength range 200 – 2000 cm-1 on InAs and InAsSb layers grown on three types of substrates. A classical two oscillator model that takes into account both the free carriers and the lattice, was used to analyse the reflectance data using the BMDP® computer curve fitting software. The dielectric parameters and the electrical properties (carrier concentration and mobility) were extracted from the simulations. Due to the low free carrier concentration in the epitaxial structures, the plasma resonance frequency (ωp) values obtained from the simulations of reflectance spectra measured above 200 cm-1, were in the order of 20-30 cm-1. These low values were confirmed by direct measurements of ωp in reflectance spectra obtained in the range 15-200 cm-1. The simulated carrier concentration and mobility values determined optically were compared to the values determined by Hall measurements at room temperature and previously reported values by other researchers. The simulated values obtained were in reasonable agreement with the Hall values. The simulated and measured carrier concentrations obtained for InAs layers were significantly higher than the intrinsic carrier concentration for InAs at room temperature, indicating notable concentrations of donors resulting from the growth process.

No description available.

Optical Detection of Magnetic Resonance (ODMR) has been used to observe both paramagnetic and diamagnetic resonance of photo-excited electrons and holes in GaP, ZnTe and AgBr. Paramagnetic resonance of conduction electrons in GaP has been studied and the microwave frequency and power dependence of the effect analysed. The maximum signal strength was observed to produce approximately 1% change in luminescence at 1.6 K. The g value deduced from the resonance was 2.000 ± 0.005. The resonance was homogeneously broadened giving the electron lifetime as approximately 4 nanoseconds. Paramagnetic resonance of electrons and holes has also been detected in AgBr. The background signals present in ODMR experiments have been investigated and are shown to be caused by diamagnetic or cyclotron resonance heating of photoexcited carriers. Measurements at microwave frequencies of 9.2 and 36.3 GHz have been made on GaP,ZnTe and AgBr, and cyclotron resonance of electrons and holes observed. The effective masses of light and heavy holes in GaP were found to be 0.154 ± 0.01 and 0.626 ± 0.06 respectively while the electron effective mass was 0.36 ± 0.10. The electron scattering time was shorter than that for holes by a factor of approximately three, most likely due to scattering by isoelectronic nitrogen impurities. Resonances were observed in ZnTe at effective mass values of 0.30 ± 0.20 and 0.76 ± 0.20 corresponding to electrons and heavy holes. In both GaP and ZnTe resonances due to electrons and holes appeared in different luminescence bands indicating the sensitivity of different recombination centres to heating of either carrier type. Cyclotron resonance of electrons and holes was also observed in AgBr and showed the effects of conduction and valence band non-parabolicity. A feature in the electron resonance indicated enhanced trapping of electrons with certain energies by emission of one or more LO phonons. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

No description available.

published_or_final_version / abstract / toc / Physics / Master / Master of Philosophy