In this letter, the interface traps of Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) were characterized quantitatively by dynamic capacitance dispersion technique. An analysis of Al2O3/AlGaN interface states demonstrated deep traps in the range of 0.53 eV-1.16 eV below the conduction band, with trap density nearly constant and two orders of magnitude smaller than that at AlGaN surface due to the use of atomic layer deposition-grown Al2O3 insulator. As much as 2.23 × 1013 eV−1 cm−2 fast traps with time constant smaller than 0.3 μs were observed at AlGaN/GaN interface of MOS-HEMTs, which was consistent with the qualitative prediction from pulsed I-V test.

Interface states in Al 2 O 3 /AlGaN/GaN metal-oxide-semiconductor structure by frequency dependent conductance technique * Liao Xue-Yang(廖雪阳) a)b) † , Zhang Kai(张 凯) b) , Zeng Chang(曾 畅) a) , Zheng Xue-Feng(郑雪峰) b) , En Yun-Fei(恩云飞) a) , Lai Ping(来 萍) a) , and Hao Yue(郝 跃) b)