US Patent 7400001 Nitride based hetero-junction field effect transistor

A nitride based hetero-junction field effect transistor includes a high resistance nitride semiconductor layer formed on a substrate, an Al-doped GaN layer formed on the high resistance nitride semiconductor layer and having an Al content of 0.1˜1%, an undoped GaN layer formed on the Al-doped GaN layer, and an AlGaN layer formed on the undoped GaN layer such that a two-dimensional electron gas (2DEG) layer is formed at an interface of the undoped GaN layer.