Abstract
Electronic structures of a silicon-oxynitride (SiON) layer ( in thickness) epitaxially grown on were investigated on atomic-layer scale using soft x-ray absorption spectroscopy and x-ray emission spectroscopy (XAS and XES) and first-principles calculations. The SiON layer has a hetero-double-layered structure: an interfacial silicon nitride layer and a silicon oxide overlayer. The element-specific XAS and XES measurements revealed layer-resolved energy-band profiles. Measured gap sizes are at the nitride layer and at the oxide layer. The nitride and oxide layers have almost the same energy of conduction-band minimum (CBM) being higher than CBM of the SiC substrate. The energy-band profiles of the SiON layer are qualitatively reproduced by the calculations. The calculations show that broadening of bandgap of the substrate occurs only at an interfacial SiC bilayer.
- Received 19 December 2008
DOI:https://doi.org/10.1103/PhysRevB.79.241301
©2009 American Physical Society