Investigation of deep levels in semi-insulating GaAs by means of a thermally activated piezoelectric photoacoustic measurements

Abstract

The temperature variation of the piezoelectric photoacoustic (PPA) signal intensity of semi-insulating (SI) GaAs from 20 to 150K was measured. Four peaks at 50, 70, 110 and 125K were observed in the PPA signal. From the theoretical analysis based on the rate equations of electrons in the conduction band and several deep levels, we concluded that the observed four peaks were due to the nonradiative electron recombinations via EL6, EL7, EL15 and an unknown deep level, respectively. Deep levels with extremely low concentrations (1011–1015cm−3) were clearly identified conveniently in SI–GaAs by using the PPA method for the first time.