Enhanced device performance of AlGaN/GaN HEMTs using thermal oxidation of electron-beam deposited aluminum for gate oxide

We report on an AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistor (MOS-HEMT) using thermal oxidation of electron-beam deposited aluminum as the gate dielectric. This novel dielectric deposition process is simple, and less expensive than electron cyclotron resonance (ECR) plasma oxidation of Al or atomic layer deposited (ALD) Al₂O₃. The X-ray Photoelectron Spectroscopy (XPS) Ols spectrum showed that the Al₂O₃ with a bandgap of 7.8 eV was obtained in this specimen. The resulted MOS-HEMT exhibits several orders of magnitude lower gate leakage, larger drain saturation current and larger gate voltage swing compared to a conventional AlGaN/GaN high-electron-mobility transistor (HEMT) of similar design. The MOS-HEMT is therefore a viable alternative to regular HEMTs for high-power, high-frequency and high-temperature applications.