Interface Investigation of High-Temperature-Annealed Ultrathin-ALD-Al₂O₃/InAlN Structures

Abstract

The effects of high-temperature annealing on the properties of an Al2O3/InAlN interface formed by atomic layer deposition (ALD) is investigated by X-ray photoelectron spectroscopy (XPS). The interface between 2-nm-thick ALD Al2O3 and InAlN were annealed in N2 at 800, 850, or 950 • C. The shapes of the In 3d, In 4d, N 1s, and Al 2p core-level spectra were not changed by annealing, which indicated that significant intermixing was not induced at the Al2O3/InAlN interface by annealing at high temperatures of up to 950 • C. The O 1s spectra consisted of two components for all samples. The higher-energy component in the O 1s spectra, which was reduced in intensity but not removed by annealing, was revealed to be localized at the Al2O3 surface. The Fermi level position at the InAlN surface was also investigated but no change was observed upon annealing at all temperatures. By also considering results of the electrical measurement, the absence of Fermi level pinning at the Al2O3/InAlN interface is discussed.