Ultrafast dynamics and phase changes in crystalline and amorphous GaAs

Abstract

The femtosecond-time-resolved response of the spectral dielectric function provides a great wealth of information on carrier and lattice dynamics in highly photoexcited semiconductors. We present measurements of the dielectric function of crystalline and amorphous GaAs over a broad spectral energy range (1.7--3.4 eV), with sub-100-fs time resolution. A detailed analysis of the data reveals many insights into the dynamics and phase changes in semiconductors at high excitation fluences up to and beyond the damage threshold.