Characterization of Deep Levels in Semi-Insulating GaAs Crystals by a Spectroscopic Photoelectrochemical Current

Abstract
A new method for detecting deep levels in semi-insulating GaAs crystals is proposed. With this method determination of deep level distributions over a wafer by a spectroscopic photoelectrochemical current is possible. The deep levels of 1.13 eV, 1.02 eV, 0.98 eV, and 0.70 eV have been detected in both undoped and Cr-doped materials. Two additional deep levels of 0.78 eV and 0.65 eV were detected in Cr-doped materials. A peak intensity ratio of the 1.13 eV band to the 1.43 eV increased linearly with increasing chromium content in the crystals. Nonuniform distribution of deep levels in LEC GaAs crystals has been found.