FEMTOSECOND OPTICAL-RESPONSE OF LOW-TEMPERATURE-GROWN IN0.53GA0.47AS

A femtosecond, tunable color center laser was used to conduct degenera te pump-probe transmission spectroscopy of thin film low temperature g rown molecular beam epitaxy In0.53Ga0.47As samples. Low temperature mo lecular beam epitaxy In0.53Ga0.47As exhibits a growth-temperature depe ndent femtosecond optical response when probed near the conduction ban d edge. Below T-g= 250 degrees C, the optical response time of the mat erial is subpicosecond in duration, and we observe induced absorption, which we suggest is due to the formation of a quasi-''three-level sys tem.''