Capacitance-voltage characteristics of GaAs-AlAs heterostructures

Abstract
We report on an experimental study of the temperature and photosensitive capacitance‐voltage (CV) characteristics of GaAs‐AlAs‐GaAs heterostructures grown by metalorganic chemical vapor deposition. The structures consisted of a layer of AlAs either 2500 or 4000 Å thick sandwiched between layers of GaAs which were a few microns thick. CV curves were measured at 1 MHz, both with and without illumination. Measurements were made at 77 and 300 K. The CV showed hysteresis near zero bias with the capacitance being larger when the voltage was swept from reverse to forward bias in the dark. The CV displayed a light sensitive peak near zero bias. With illumination, the capacitance was greater, and no hysteresis was observed. We explain these phenomena as being due to deep levels near the AlAs‐GaAs interface.