Fast and slow processes in the dynamics of near-surface space-charge grating formation in GaAs

Frequency dependences of the nonstationary holographic current in a GaAs sample illuminated by red light (633 nm) were studied experimentally for the 10-Hz–10-MHz frequency range. For light intensities of 1 mW/mm2 the space-charge grating is formed with the characteristic time of dielectric relaxation 10-7–10-8 s, and this ensures the excellent adaptive properties of GaAs photodetectors based on this effect. On the other hand, slow processes in photoconductivity relaxation determine the high amplitude of the nonstationary current observed for frequencies lower than 100 kHz.