Characterization of carbides by scanning tunneling microscopy

Abstract

Scanning tunneling microscopy and scanning tunneling spectroscopy were used to characterize several carbide surfaces. A single-crystal (6H) SiC growth surface parallel to the basal plane exhibited macroscopic growth steps and facets of the order of 1.4-3.0 nm. Three midgap electronic states were identified on this surface, which allowed imaging at relatively low biases for a large-band-gap semiconductor. Facets were observed on a TiC0.95(100) fracture surface with dimensions of five to ten times the unit-cell size. Surface reactions were observed by characterizing the SiC surfaces before and after exposure to the atmosphere and by in situ monitoring of a surface adsorbate on TiC. The first topographic images of a phase boundary were obtained in a polycrystalline Al2O3TiC composite. © 1988.