Polarity Control of an All-Sputtered Epitaxial GaN/AlN/Al Film on a Si(111) Substrate by Intermediate Oxidization.

The ability to control the polarity of an all-sputtered epitaxial GaN/AlN/Al film on a Si(111) substrate via intermediate oxidization was investigated. A stable surface of GaN on a Si substrate is a N-terminated surface (-c surface); hence, for electric device applications, the Ga-terminated surface (+c surface) is preferable. The GaN/AlN/Al film on Si(111) showed a -c surface, as confirmed by time-of-flight low-energy atom scattering spectroscopy (TOFLAS) and X-ray photoelectron spectroscopy (XPS).