Atomic characterization of nano-facet nitridation at SiC (11¯00) surface

Abstract

Nitridation effectively reduces the density of defects at SiO2/SiC interfaces. The SiC (11¯00) face, which appears at the nano-trench structure on the (0001) and (0001¯) surfaces, is composed of Si- and C-facets. To understand the nitridation mechanism of this face, we investigate the atomic arrangement of N at SiC (11¯00) surface with high temperature annealing in N2 ambient using x-ray photoelectron spectroscopy (XPS) and x-ray photoelectron diffraction (XPD). The N 1s spectrum indicates that N atoms cover about 5/6 of the monolayer and are bonded to Si atoms. The N 1s XPD pattern significantly differs from bulk Si 2p and the C 1s patterns, suggesting that the majority of N atoms occupy C sites at the topmost layer of the 4H-SiC substrate. Based on simulations of the N 1s spectrum and XPD pattern, we propose a local structure where N atoms replace C atoms at four different sites of the SiC (11¯00) surface and bond to three Si atoms.