Abstract

Many investigators have made measurements of the mobility of carriers in the 2D system of GaAs/AIGaAs quantum wells (MQW). A variety of techniques have been utilized to measure actual transport through time-of-flight (TOF) rather than by response to electric fields. Among these have been time resolved measurements of photoinduced transient grating,¹ luminescence,² induced absorption/bleaching,³ and Raman scattering.⁴ We make use of the induced transparency at the heavy-hole exciton line in a 215 Å wide MBE grown multiple quantum well to detect the presence and dynamics of carriers from 5 ps to 5 ns after excitation. We have developed a picosecond absorption imaging TOF technique which reveals the time resolved spatial and spectral distribution of photoexcited carriers following a highly localized laser excitation.

© 1990 Optical Society of America