Trap Levels in Gallium Arsenide

Abstract

The effect of illumination on the capacitance of n- and p-type GaAs Schottky barrier diodes has been measured at 77°K. Capacitance change is observed in the photon energy range of (0.7 eV–1.45 eV) for the n-type diode and in the range of (0.5 eV–1.45 eV) for the p-type diode. This effect is explained in terms of the photoexcitation of traps in the space charge layer. It is found that two different kinds of traps are present in both n- and p-type GaAs, one being located at about 0.7 eV and another at about 0.95 eV, below the conduction band edge. The traps found in the present experiment are probably identical with those found in semi-insulating GaAs crystals.