Abstract We discuss the PL spectra of Ga2O3(Gd2O3)/GaAs/In0.2Ga0.8As/GaAs quantum well with different annealing temperatures. First, we discuss the peak position of PL spectra. The peaks shift with different annealing temperatures, and it is due to the quantum well intermixing. Second, the excitation density dependence of In0.2Ga0.8As/GaAs quantum well is performed. We discuss the difference of 2D transition for quantum well and 3D transition for bulk GaAs.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 218-228).

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by Kan Chi Fai. / Title also in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 120-124). / Acknowledgements / Abstract / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Proposed mechanisms of the visible photoluminescence of porous silicon --- p.5 / Chapter Chapter 3 --- Sample Preparation --- p.15 / Chapter 3.1 --- Anodization of porous silicon in an electrochemical cell --- p.15 / Chapter 3.2 --- Appearances of samples --- p.18 / Chapter 3.3 --- Uniformity of samples --- p.21 / Chapter 3.4 --- Formation mechanism --- p.22 / Chapter 3.5 --- Measurements of current-voltage characteristics --- p.23 / Chapter 3.6 --- Current-Voltage (I-V) Characteristics --- p.24 / Chapter 3.7 --- Voltage monitored at constant anodizing current --- p.37 / Chapter 3.8 --- Mass lost due to anodization --- p.37 / Chapter Chapter 4 --- Transmittance and reflectance studies --- p.42 / Chapter 4.1 --- Transmittance and reflectance studies in the ultraviolet to near infrared range --- p.42 / Chapter 4.1.1 --- Experimental setup of transmittance and reflectance spectroscopic studies --- p.42 / Chapter 4.1.2 --- Transmittance spectra --- p.42 / Chapter 4.1.3 --- Reflectance spectra --- p.48 / Chapter 4.1.4 --- Optical thickness of the porous silicon layer --- p.60 / Chapter 4.1.5 --- Effective medium approximation --- p.61 / Chapter 4.1.6 --- "Determination of refractive index, porosity and thickness" --- p.66 / Chapter 4.1.7 --- Thickness measured by optical microscopy --- p.67 / Chapter 4.1.8 --- Validity of the effective medium approximation --- p.72 / Chapter 4.2 --- Infrared transmission studies --- p.76 / Chapter 4.2.1 --- Experimental setup --- p.76 / Chapter 4.2.2 --- Infrared spectra --- p.75 / Chapter Chapter 5 --- Photoluminescence and Photoexcitation --- p.82 / Chapter 5.1 --- Photoluminescence studies --- p.82 / Chapter 5.1.1 --- Experimental setup --- p.82 / Chapter 5.1.2 --- Calibration of the spectral response of setup --- p.84 / Chapter 5.1.3 --- The photoluminescence and the appearance of porous silicon --- p.88 / Chapter 5.1.4 --- Effect of laser radiation on porous silicon --- p.95 / Chapter 5.1.5 --- Photochemistry --- p.95 / Chapter 5.1.6 --- Aging and photoluminescence --- p.97 / Chapter 5.1.7 --- Annealing studies of porous silicon --- p.97 / Chapter 5.1.8 --- Photoluminescence spectra --- p.100 / Chapter 5.1.9 --- Interference --- p.106 / Chapter 5.2 --- Photoexcitation studies --- p.107 / Chapter 5.2.1 --- Experimental setup --- p.107 / Chapter 5.2.2 --- Result --- p.108 / Chapter Chapter 6 --- Discussions and conclusions --- p.112 / Chapter 6.1 --- Information from peer groups --- p.112 / Chapter 6.1.1 --- Raman scattering --- p.112 / Chapter 6.1.2 --- X-ray diffraction --- p.112 / Chapter 6.2 --- Photoluminescence and annealing --- p.113 / Chapter 6.3 --- Photoluminescence and the etching conditions --- p.114 / Chapter 6.4 --- Consideration of different models in the visible photoluminescence of porous silicon --- p.117 / Chapter 6.5 --- Conclusions --- p.118 / References --- p.120

Polarization dependent photoluminescence (PL) study in 10K of m-plane III-nitrides was discussed in this thesis. Two samples were investigated: m-plane GaN film grown on m-sapphire substrate and m-plane InGaN film grown on m-GaN/m-sapphire substrate by plasma -assisted molecular beam epitaxy (PAMBE). Polarized luminescence characteristics were told by polarization dependent PL spectra in these two samples. Circular polarized, linear polarized and unpolarized laser sources were used to excite the samples. The results showed the PL intensity along the a-axis of the sample was stronger than along the c-axis with a polarization ratio with 65%; moreover, the peak positions showed polarization independent characteristic under a low temperature environment with 10K.

Unintentionally doped InN thin films have been epitaxially grown on Si (111) by plasma-assisted molecular-beam epitaxy (PAMBE) with AlN buffer layers. The optical characteristics were investigated with photoluminescence (PL). In analyzing the PL spectra, we look into the variations in peak positions, intensities, and full¡Ðwidth ¡Ðat¡Ðhalf maximum (FWHM) by changing the temperature and the laser power. To cover both the visible and IR spectral ranges, two different detectors were used, PMT for the visible and PbS for the near-IR. A single namely, dominant peak was found in the near-IR regime. The temperature dependent PL line-shape is fitted with the Varshni equation. Excitation laser power dependent PL is found to follow a linear relation. The energy band gap of InN is inferred from the optical measurements.

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