PHOTOINDUCED CURRENT SPECTROSCOPY STUDY ON SEMIINSULATING LEC GAAS

Semi-insulating GaAs grown by the liquid-encapsulated Czochralski (LEG ) method was investigated by means of photo-induced current transient spectroscopy (PICTS). Surface and bulk contributions in the PICTS sign al are compared by studying sandwich and planar samples. It is shown t hat, when using PICTS on materials with a depletion region, it is poss ible to identify the nature of traps. The used criterion is discussed. In addition the effects of the excitation light wavelength upon posit ive and negative bias PICTS spectra are reported.