What makes good templates for HVPE GaN growth?

Abstract

MOCVD templates grown on sapphire with a Gallium Treatment Step (GTS) instead of a low temperature AlN or GaN nucleation layer are used for HVPE growth. Four templates are used with varying times of MOCVD buffer layer growth. 25 µm GaN is grown with HVPE on these templates. The HVPE layers are studied with optical microscopy and X-ray diffraction (XRD). The results show that the thickness of the buffer layer is not important for the quality of the HVPE grown layer once sufficient nucleation sites for HVPE growth are present. The excellent quality of the templates with GTS for HVPE growth is shown with a 100 µm thick HVPE layer on a 2″ template. No cracks in either sapphire or GaN are visible.