| This dissertation consists of two parts, one involving the development of a unique, ultra-short pulse cavity-dumped submillimeter-wave laser source, and the other involving the time-resolved photoconductive response measurements made utilizing the submillimeter-wave laser. The development of a consistent cavity-dumped submillimeter-wave laser was essential in performing the photoconductivity measurements on the time-scales documented in this dissertation.; The submillimeter-wave laser source produced 3 ns (full-width at half-maximum) pulses at 176.1 {dollar}mu{dollar}m and 281.27 {dollar}mu{dollar}m, with a peak power of approximately 1 kW. The amplitude stability of the cavity-dumped submillimeter-wave laser was within {dollar}pm{dollar}5% of the mean and the timing consistency was {dollar}pm{dollar}0.5 ns of a pulse-to-pulse-corrected trigger signal. These results were achieved through extensive modification of the hybrid transversely-excited atmospheric-pressure CO{dollar}sb2{dollar} laser used as the pump source, and through the development of a novel triggering system for the cavity-dumping of the submillimeter-wave laser system. These modifications and the resulting operating parameters for the submillimeter-wave laser source are documented in this dissertation.; The time-resolved photoconductive response of shallow donor impurity states of several high-purity n-type bulk GaAs samples and one GaAs/AlGaAs quantum well sample were measured. An initial, short-term, photoconductive response was observed, followed by a long-term exponential decay as the samples returned to their equilibrium state. The level of doping of the samples produced varying response times for the samples, which acted as photoconductive detectors. Further, the bias conditions applied to the detector samples caused these exponential response times to be extended, with increased bias current producing increased relaxation times beyond the minimum value observed for each sample. These results are documented in the second part of this dissertation. |
