Characterization of the gate oxide of an AlGaN/GaN high electron mobility transistor

A subnanometer thick interfacial oxide layer present between the Ni/Au gate metal stack and semiconducting epilayers of an AlGaN/GaN high electron mobility transistor was characterized using high-angle annular dark-field scanning transmission electron microscopy and laser-assisted atom probe tomography. It was revealed that the oxide is composed of distinct Ni-oxide-rich and Al-oxide-rich layers with no Ga-oxide detected. The results provide information that is of potential importance in determining failure mechanisms and improving reliability of AlGaN/GaN high electron mobility transistors.