INVESTIGATION OF ULTRASHORT PHOTOCARRIER RELAXATION-TIMES IN LOW-TEMPERATURE-GROWN GAAS

Photocarrier relaxation times tau(r) in low-temperature-grown (LTG) Ga As have been determined with time-resolved reflectance measurements. M easured tau(r) values are extremely sensitive to the substrate tempera ture during LTG GaAs growth and postgrowth anneal. Photogenerated-elec tron relaxation times as short as 90 fs are found for LTG GaAs grown a t temperatures near 200 degrees C and annealed at temperatures below 5 80 degrees C. We report the results of a systematic investigation of t he dependence of tau(r) on growth temperatures between 180 and 260 deg rees C and anneal temperatures between 480 and 620 degrees C. (C) 1997 American Institute of Physics.