Control of insulated gate interfaces on AlGaN/GaN heterostructures for power devices

Interface properties of Al₂O₃ insulated gates on AlGaN/GaN structures prepared by atomic layer deposition have been characterized, focusing on the interface state density distribution at the Al₂O₃/AlGaN interface. We have developed a C-V calculation method taking into account electronic states charges at the Al₂O₃/AlGaN interface and a photoassisted C-V technique utilizing photons with energies less than the bandgap of AlGaN. These techniques were then applied to investigate the effect of the ICP etching of AlGaN on the interface properties.