Abstract

Crystalline GaAs grown at low temperature (LT-GaAs) by molecular beam epitaxy has novel applications, such as high-voltage picosecond photoconductive switches¹ and GaAs MESFETs² because it can be prepared as a semi-insulating material with a carrier lifetime of less than a picosecond. However, little is known about the carrier dynamics in this material. Because of its short carrier lifetime, LT-GaAs also provides a unique opportunity to study non-equilibrium carrier effects with out the need for a subpicosecond excitation source since the short recombination time effectively serves as a "gate, Here, we present the first measurements of photoluminescence from LT-GaAs induced by 5-ps pulses from a 200-mW, 80- MHz dye laser with 610 run < L < 765 rati. In most of our experiments, spectra are obtained by integrating the luminescence over the pulse duration (and typically for 10^1D pulses) with the aid of a two-dimensional synchroscan streak camera. The picosecond pulses merely allow us to achieve sufficiently high densities to observe the weak bandband recombination.

© 1992 Optical Society of America