Synthesis of Vertically Oriented GaN Nanowires on a LiAlO₂ Substrate via Chemical Vapor Deposition

Vertically oriented nanowires (NWs) of single-crystalline wurtzite GaN have been fabricated on a γ-LiAlO₂ (100) substrate coated with a Au layer, via a chemical vapor deposition process at 1000 ℃ using gallium and ammonia as source materials. The GaN NWs grow along the nonpolar [1010] direction with steeply tapering tips, and have triangular cross-sections with widths of 50–100 nm and lengths of up to several microns. The GaN NWs are formed by a vapor–liquid–solid growth mechanism and the tapering tips are attributed to the temperature decrease in the final stage of the synthesis process. The aligned GaN NWs show blue-yellow emission originating from defect levels, residual impurities or surface states of the GaN NWs, and have potential applications in nanotechnology.