A New Switching Effect in Semi-Insulating GaAs and Its Use for Deep Level Spectroscopy

Publisher Website
Google Scholar
Abstract
Transient photocurrents of semi-insulating GaAs crystals were studied in the spectral range 0.5-3.0 µm as a function of the applied voltage. Measurements were made using rectangular pulses and diode structures with transparent electrolyte contacts. It was found that a new switching effect occurs at high electric fields (above 4×103 V/cm) from a semi-insulating state to a conducting state. This effect is very sensitive to extrinsic light and has two characteristic times (a delay time and a decay time of the conducting state). A mechanism for these results is proposed on the basis of a multi-level model of impact ionization of deep levels. Typical spectra of the peak photocurrents are also presented. From these spectra twelve energy levels were obtained and compared with published data regarding deep levels in GaAs.