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 Ga As sample illuminated by red light (633 nm) were studied experimentall y for the 10-Hz-10-MHz frequency range. For light intensities of 1 mW/ mm(2) the space-charge grating is formed with the characteristic time of dielectric relaxation 10(-7)-10(-8) s, and this ensures the excelle nt adaptive properties of GaAs photodetectors based on this effect. On the other hand, slow processes in photoconductivity relaxation determ ine the high amplitude of the nonstationary current observed for frequ encies lower than 100 kHz. (C) 1997 Optical Society of America.