AlGaN channel HEMTs on AlN buffer layer with sufficiently low off-state drain leakage current

The buffer layer in AlGaN channel HEMTs to suppress the off-state drain leakage current is investigated. By employing an AlN for the buffer layer in Al 0.39 Ga 0.61 N/Al 0.16 Ga 0.84 N HEMTs, the off-state drain leakage current was sufficiently suppressed and the breakdown voltage was enhanced. It was considered that employing the AlN for the buffer layer is important for extracting the superior material properties of the AlGaN in the channel layer.