NEAR-INFRARED PHOTOACOUSTIC SPECTRA OF DEEP LEVELS IN GAAS GROWN BY LIQUID ENCAPSULATED CZOCHRALSKI METHOD

Piezoelectric photoacoustic measurements on semi-insulating (SI) and n-type GaAs were carried out at 90 K. A distinctive peak at 0.92 eV and a hump near 1.2 eV have been observed for the SI samples. By comparing with the optical absorption and the electron photoionization cross section spectra, it is considered that these features are due to the electron transition involving deep EL2 defect levels. The present experimental results show that the PA spectroscopic technique is a novel and a useful tool to characterize the deep levels in semiconductors.