Investigation of pits in Ge-doped GaN grown by HVPE

Abstract

The pits in Ge-doped GaN grown by hydride vapor phase epitaxy were carefully studied. It was found that the pit density increases with Ge concentration and dislocation density. Cross-sectional cathodoluminescence (CL) image shows that the embedment of pit occurs immediately after the cut off of Ge precursor. Planar-view CL image shows that the center of every pit is a dislocation, which is further confirmed by transmission electron microscopy measurements. Ge droplets were found in the center of pits of heavily doped samples. These results are beneficial for the study on the origin of pits in Ge-doped GaN.