Surface Morphology Variation During Wet Etching Of Gan Epilayer Grown By Hvpe

In this paper, we investigated characteristics of etching induced surface morphology variation by wet etching of GaN epilayer were grown on sapphire (0001) substrate by hydride vapor phase epitaxy (HVPE). As a results of scanning electron microscope (SEM) observation, three types of hexagonal etch pits (Edge, Screw, Mixed) were formed by the GaN epilayer thickness variations. A lot of etch pits, attributed to screw and mixed type TD, were observed at thinner epilayer, leading to high etch pit density. On the other hand, the thickness of GaN epilayer increased with the number of etch pits corresponding to edge and mixed dislocations, which are the majority of TDs are observed.