Characterizations of Al 2 O 3 gate dielectric deposited on n‐GaN by plasma‐assisted atomic layer deposition

This paper briefly reviews the characterizations of Al2O3 gate dielectric deposited by plasma-assisted atomic layer deposition (PA-ALD) on n-GaN. We report on insulating and physical properties of PA-ALD Al2O3 film from I-V characteristics of metal-insulator-semiconductor (MIS) diodes and analysis of X-ray photoelectron spectroscopy (XPS), respectively. Compared to Al2O3 film deposited by thermal ALD method, the PA-ALD Al2O3 film exhibited higher breakdown field and several orders of magnitude lower leakage current density. Analysis of the current conduction mechanism reveals that the gate leakage current of PA-ALD Al2O3/n-GaN MIS diode consisted of Schottky emission (SE) and Fowler-Nordheim tunneling (FNT). In contrast, it is suggested that trap-assisted tunneling (TAT) mechanism was dominant in the gate leakage of T-ALD Al2O3 sample at the middle field range. From the XPS analysis, the band gap of PA-ALD Al2O3 was estimated about 6.7 eV. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)