CHARACTERIZATION OF DONORLIKE INTERFACE STATES WHICH PLAY A DOMINANT ROLE IN THE SURFACE-POTENTIAL PINNING IN AIN GAAS INTERFACES

The interface states at the AlN/GaAs interface, which play a dominant role in pinning the surface potential, are studied by means of quasi-static and high-frequency capacitance transient methods. Their charge transfer processes are found to be well described based on the simple deep-level picture. The observation of both behavior as electron traps as well as hole traps has provided evidence that the ionization of these states, not the surface inversion, is the surface potential pinning mechanism in the present insulator-semiconductor system. The time-variant field effect on the electron emission process is observed and reveals the donor nature of the relevant interface states. It is also argued that a defect-related origin is favored rather than a continuously distributed scheme for the interface states examined in the study.