Interface state characterization of ALD‐Al₂O₃/GaN and ALD‐Al₂O₃/AlGaN/GaN structures

Abstract

Abstract We have characterized the interface states of Al 2 O 3 /GaN and Al 2 O 3 /AlGaN/GaN structures prepared by atomic layer deposition using the conventional and photo‐assisted capacitance‐voltage ( C–V ) measurements. In order to control the interface states, an N 2 O‐radical treatment was applied to the GaN and AlGaN surfaces prior to the deposition of the Al 2 O 3 layer. We observed good C–V behavior and a relatively low density of interface states for the N 2 O‐radical treated Al 2 O 3 /GaN structure. To estimate the state density distributions at the Al 2 O 3 /AlGaN interface, we applied the photo‐assisted C–V measurement to the Al 2 O 3 /AlGaN/GaN heterostructures. The present Al 2 O 3 /AlGaN structre showed higher interface state densities than the Al 2 O 3 /GaN structure. However, we found that the N 2 O‐radical treatment is effective in reducing the density of interface states at the Al 2 O 3 /GaN and Al 2 O 3 /AlGaN systems (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)