Identification of fine structures at the surface of epi-ready GaN wafer observed by confocal differential interference contrast microscopy

Abstract

Confocal differential interference contrast microscopy detected dots and line contrasts on the surface of epi-ready (0001) GaN wafers. Large and small dots consisted of pits, ∼1.4 μm in width and ∼7 nm in depth, and ∼0.5 μm in width and ∼2.7 nm in depth, respectively; the pits mainly formed on the outcrops of dislocations, with Burgers vectors ≥ c and b = a, respectively, via inadequate chemical mechanical polishing. Lines consisted of scratches induced via polishing. Deep scratches accompanied dense basal plane dislocation loops.