Date of Award


Document Type


Degree Name

Master of Science in Applied Physics


Department of Engineering Physics

First Advisor

Matthew J. Bohn, PhD


GaAs is a potential semiconductor material for producing both mid-infrared and terahertz radiation using the new technique of quasi-phase matching in an orientationally patterned GaAs (OP-GaAs) crystal. OP-GaAs is grown using a fast growth process called hydride vapor phase epitaxy (HVPE). Unfortunately, HVPE produces a high number of defects. These defects cause Shockley-Read-Hall recombination rates to dominate over Auger and radiative recombination rates. The carrier lifetime from four OP-GaAs samples are reported here using two different experimental techniques. The first experiment used a streak camera to measure the carrier lifetime via time-resolved photoluminescence. The temporal resolution of the streak camera can resolve the fast decay rate of the HVPE grown OP-GaAs samples. The second experiment used time-resolved pump-probe reflectivity to measure the carrier lifetime. This experiment used two laser beams; one was to excite the sample and the other was to measure the change in the index of refraction caused by the carrier excitation. The results of the lifetimes of these two experiment methods differ with each other.

AFIT Designator


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