GaN/AlN digital alloy short-period superlattices by switched atomic layer metalorganic chemical vapor deposition

In this letter we report the fabrication of GaN/AlN short-period superlattices using switched atomic layer epitaxy. Superlattice structures with GaN well thicknesses ranging from 2.6 to 20.8 Å (with AlN barrier thicknesses of 2.5, 7.5, and 15 Å) were deposited over basal plane sapphire and characterized for their structure, crystallinity, and optical properties. Cross-sectional transmission electron micrographs indicate GaN/AlN interfaces and the superlattice surfaces are atomically smooth. The structures exhibit strong room temperature photoluminescence and a sharp absorption edge indicating a high optical quality.