Thickness Influence on Optical and Morphological Properties of HVPE GaN Layers Grown on MOCVD GaN Layers

Abstract

A new domain of growth experimentally observed in conditions of expected fast etching by HCl ensures growth rates of 50-60 μm/h without parasitic GaN deposit by using the suitable temperature profile. In these conditions, different thicknesses from 8 to 52 μm of GaN layers were obtained on MOCVD GaN templates varying only the time of growth. Reflectivity spectra performed at 4 K on the different samples reveal the three excitonic transitions attributed to the wurtzite structure, labelled A, B, and C. These signals attest the good optical quality of the HVPE layers investigated. Moreover, SEM images allow to observe the morphological quality of the layer surfaces and reveal different crack densities.