Polarity Inversion of GaN via AlN Oxidation Interlayer Using Metal–Organic Vapor Phase Epitaxy

Abstract

The polarity inversion of GaN films grown on vicinal sapphire substrates is demonstrated using the metal–organic vapor phase epitaxy (MOVPE) method via an AlN oxidation interlayer for application in wavelength conversion devices. By annealing the N‐polar AlN surface at 900 °C in air, the pit‐free Ga‐polar GaN layer can be regrown. Anisotropic etching in KOH and transmission electron microscopy confirms the formation of a GaN polarity‐inverted structure. X‐ray diffraction measurements reveal an increase in threading dislocations due to the nucleation island formation by low‐temperature GaN layer and strain relaxation at the regrown interface. The simple fabrication process of the GaN polarity‐inverted structure using an AlN oxidation interlayer will pave the way for applications in new devices that require polarity‐controlled and/or polarity‐inverted stacking structures.