Reduction of Dislocations in GaN on Silicon Substrate Using In Situ Etching.

A gallium nitride (GaN) epitaxial layer with a low density of threading dislocations is successfully grown on a silicon substrate by using in situ gas etching. Silicon nitride (SiN_x) film is used as a mask, and ammonia is intermittently supplied in hydrogen ambient during the etching. After etching, high‐density deep pits appeared on the surface of a GaN template layer and corresponded to the threading dislocations in the layer. In this novel method, before growing an additional GaN layer on the template GaN layer, a second SiN_x layer is deposited after the etching process, and this layer prevents GaN nuclei from growing on the upper side‐walls of the pits. By using this method, the density of threading dislocations of the GaN surface is reduced to 6.7 × 10⁷ cm⁻². This method is cost effective, completing all the necessary processes in one growth run without taking samples out from a metalorganic chemical vapor deposition (MOCVD) reactor. [ABSTRACT FROM AUTHOR]