Fig. 3From: Investigation on Surface Polarization of Al2O3-capped GaN/AlGaN/GaN Heterostructure by Angle-Resolved X-ray Photoelectron SpectroscopyThe XPS Al 2p core-level spectra for a S1, b S2, and c S3, and the peak indicates the Al–O bond. Moreover, there is no significant BE variationBack to article page