GaN micro- and nanostructures selectively grown on profiled sapphire substrates using PA-MBE without lithography

Abstract

Purpose: Development of technology for the formation of ordered arrays of nanocolumns (NCs) of GaN microcrystals using plasma-activated molecular beam epitaxy from nitrogen (PA-MBE) on profiled sapphire substrates (SPS) of large diameter with a micro-cone profile. The proposed method eliminates the use of low-performance and expensive nanolithography methods. The article is aimed at a deeper understanding of the processes that determine the growth kinetics of III-N nanocolumns using PA MBE on patterned sapphire substrates with multiple orientations of various non-polar and polar planes. A new technological process for the fabrication of GaN NCs using PA-MPE is proposed, which ensures selectivity of their growth at the tops of PPS micro-cones and suppresses growth on the semipolar planes of these substrates. GaN NCs and microcrystals were grown using PA-MBE on commercially available PPS. A technology has been developed for the formation of discharged arrays of GaN nanocolumns without the use of lithographic procedures. Modes have been established that allow the formation of microcrystals and NCs with different diameters: from 30 nm to several microns. A diagram of the growth of GaN by the PA MBE method on PPS has been constructed, demonstrating the boundaries of the technological regimes for the formation of GaN NCs and microcrystals with different surface topography