TiC nanoisland formation on 6H-SiC(0001)_(Si)

摘要

Spontaneous formation of titanium carbide nanoislands on silicon carbide substrates has been studied with scanning tunneling microscopy and x-ray absorption near-edge spectroscopy. Scratch-free and atomically flat 6H-SiC(0001)_(Si) substrates were prepared by high temperature hydrogen etching. The surfaces were subsequently cleaned by in situ ultrahigh vacuum annealing. Titanium carbide nanoislands were formed by titanium deposition and annealing at 950℃. The average width (10-50 nm) and separation of the Ti islands was controlled by varying the titanium coverage (0.1-0.3 nm) and the annealing time (1-20 min). At the lowest coverage, the islands were uniformly distributed over the surface, while at higher coverage the islands tended to collect at the substrate step edges.