Built-in electric field at cubic GaN/GaAs(001) heterointerfaces investigated by phase-selected photoreflectance excitation

The built-in electric field applied at the cubic GaN/GaAs(001) heterointerfaces and its evolution during the growth process were evaluated using a phase-selected photoreflectance technique in combination with a variable-wavelength excitation light, to clarify the origin of the higher-electric-field signal observed in the previous photoreflectance study. The spectrum from LT-GaN/GaAs after 900 °C annealing contains a extremely-slow signal with a high electric-field strength and this signal became dominant with decreasing the penetration depth of the modulating light. This confirms the presence of a triangular well just beneath the GaN/GaAs interface regarding the direction of the band-bending investigated by the previous work, which can be attributed to the parallel-conduction path ideal for the holes to drift through.