Low-Frequency Photocurrent Oscillations and Trapping Levels in High-Resistivity GaAs Doped with Oxygen

Low-frequency (0.1–1000 Hz) photocurrent oscillations together with photo and dark conductivity in oxygen-doped n -GaAs having room temperature resistivity of 3400 ohm-cm are investigated at or below room temperature. It is shown that the behavior of photoconductivity at low temperatures can be explained by considering three deep levels (about 0.49, 0.73, and 1.3 eV below the conduction band) and that the current oscillations are associated with the 0.73 eV level. The origin of the current oscillations attributable to the field-dependent trapping effect is discussed briefly.