Near-edge x-ray absorption fine structure and x-ray photoemission spectroscopy study of the InN epilayers on sapphire (0001) substrate

Abstract

A polarization-dependent near-edge x-ray absorption fine structure (NEXAFS) study was performed on InN films epitaxially grown on sapphire (0001) substrates, in order to investigate the change in structure and crystallographic orientation of the film as a function of film thickness. For thin films, the N K-edge NEXAFS spectra showed a strong polarization-dependent spectral feature. The polarization dependence decreased with increasing film thickness and disappeared at a thickness of about 3000 Å. Chemical configuration in InN films was investigated using high-resolution x-ray photoemission spectroscopy (XPS). XPS analysis on the In 3d peak and the N 1s main peak at 396.4 eV suggested that indium and nitrogen are bound in the form of InN in all of the samples. An additional peak observed at 397.4 eV in the N 1s photoelectrons is believed to originate from the formation of oxynitrides at the topmost region of the film.