Characterizations of Al₂O₃ gate dielectric deposited on n‐GaN by plasma‐assisted atomic layer deposition

Abstract

Abstract This paper briefly reviews the characterizations of Al 2 O 3 gate dielectric deposited by plasma‐assisted atomic layer deposition (PA‐ALD) on n‐GaN. We report on insulating and physical properties of PA‐ALD Al 2 O 3 film from I‐V characteristics of metal‐insulator‐semiconductor (MIS) diodes and analysis of X‐ray photoelectron spectroscopy (XPS), respectively. Compared to Al 2 O 3 film deposited by thermal ALD method, the PA‐ALD Al 2 O 3 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 Al 2 O 3 /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 Al 2 O 3 sample at the middle field range. From the XPS analysis, the band gap of PA‐ALD Al 2 O 3 was estimated about 6.7 eV. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)