Analysis of the band offsets between ultrathin GaN(0001̄) layers and sapphire (0001) by photoelectron spectroscopy

Abstract

Ultrathin layers of N-face GaN(0001) on c-plane sapphire have been grown via plasma assisted molecular beam epitaxy (PAMBE) and investigated in-situ via reflection of high energy electron diffraction (RHEED), Xray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Our studies of the electronic interface between substrate and adsorbate reveal a band offset about (1.7 ± 0.1) eV at the GaN-sapphire interface and an additional band bending of the GaN layer of 0.4 eV within the first 3 nm. Schematic illustration of the GaN/Al2O3 interface. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.