Growth of GaN layer on patterned Al/Ti metal mask by metal-organic chemical vapor deposition

We report on high-quality GaN epitaxial growth by metal-organic chemical vapor deposition (MOCVD) on a stripe-patterned GaN template using a metal mask. A multiple Al/Ti metal system with 10 μm periodicity was used as a masking layer for the epitaxial lateral overgrowth (ELOG). The overgrowth of GaN on the patterned metal mask begins at the open window region between the stripes, and then ELOG leads to the formation of a continuous layer. Micro- cathodoluminescence (μ-CL) results show the improvement of optical properties and significant strain relaxation in the overgrown GaN layer. About a 2-order reduction of threading dislocation density was observed on the overgrown GaN on metal mask regions compared with that on GaN template regions.