RELATION BETWEEN THE METASTABILITY OF EL2 AND THE PHOTOSENSITIVITY OFLOCAL VIBRATIONAL-MODES IN SEMIINSULATING GAAS

Recent infrared spectroscpic observations of local vibrational mode ab sorptions have revealed a number of photosensitive centers in semi-ins ulating GaAs. They include (OVAs) center which has three modes at 730 cm(-1) (A), 715 cm(-1) (B), and 714 cm(-1) (C), respectively, a sugges ted NH center related to a line at 983 cm(-1) (X(1)), and centers rela ted to hydrogen, such as (H-O) or (H-N) bonds, corresponding to a grou p of peaks in the region of 2900-3500 cm(-1). The photosensitivity of various local vibration centers was observed to have similar time depe ndence under near-infrared illumination and was suggested to be due to their charge-state interconversion. Mainly described in this work is the effect of the 1.25-eV illumination. It is confirmed that this phot oinduced kinetic process results from both electron capture and hole c apture, which are closely related to the photoionization behavior and metastability of the EL2 center.