| The study of impurity and defect states in semiconductors is of great interest for improving the performance of semiconductor devices. In this work, two studies are presented which examine the influence of the two most technologically important defects in III-V compound semiconductors, the donor-related DX center and the stoichiometry-related midgap defect, generally known as EL2.; Ion implantation is used to modify the local environment of the silicon donor DX center in Al{dollar}sb{lcub}0.27{rcub}{dollar}Ga{dollar}sb{lcub}0.73{rcub}{dollar}As, and variations in DX center properties with subsequent rapid thermal annealing processes are examined using Deep Level Transient Spectroscopy. The capture properties of a subsidiary DX center peak are markedly altered in the ion implanted samples compared to the as-grown samples. It is proposed that regions of partial ordering and defect complexing in the AlGaAs film give rise to the various subsidiary DX center peaks observed.; The DX center capture and emission kinetics are compared to the Williams-Watts or stretched exponential decay of the form A(t) = exp ({dollar}-{dollar}(t/{dollar}tau{dollar}){dollar}spbeta{dollar}) and variations of this form. It is found that the time and temperature dependent behavior of the DX center capture and emission characteristics can be reproduced with a thermally activated time constant {dollar}tau{dollar} and a linear dependence of {dollar}beta{dollar} on temperature. This is a surprising result, since stretched exponential behavior is typically observed in amorphous semiconductors or polymeric materials. Implications of this model are discussed.; Double barrier GaAs/AlAs tunneling structures with 2.5:1 room temperature peak-to-valley current ratios are examined using Deep Level Transient Spectroscopy. Midgap deep level trap concentrations are found to be much greater in samples grown at 550{dollar}spcirc{dollar}C compared to those grown at 650{dollar}spcirc{dollar}C. For devices grown at 550{dollar}spcirc{dollar}C, an impedance switching effect due to a high concentration of deep levels is observed. The peak-to-valley current ratio of the tunneling devices is largely unaffected by the growth temperatures in this range, indicating that higher growth temperatures can be employed to grow resonant tunneling diodes than previously suggested in the literature. |
