Development of chemical beam epitaxy for the deposition of gallium nitride

Modern approaches to the growth of high quality gallium nitride thin films have focused on the use of metal-organic vapour phase epitaxy or plasma-assisted gas source molecular beam epitaxy. However, both of these techniques possess limitations. The present study therefore examined a new approach to GaN deposition using chemical beam epitaxy and the new nitrogen precursor, hydrogen azide. Thin films of gallium nitride (GaN) were successfully prepared. X-ray photoelectron spectroscopy reveals that stoichiometric materials is formed with little or no contamination when HN3 and a range of Ga precursors react on the substrate at temperatures down to 450°C. The results indicate that the incorporation efficiency of N in the GaN film from HN3 is high, suggesting the precursor may provide a more attractive route to the deposition of GaN films under low pressure molecular beam conditions than is currently offered using ammonia or plasma-excited nitrogen beam sources. Electrical measurements on the grown films are also reported.