Low dislocation densities and long carrier lifetimes in GaN thin films grown on a SiNx nanonetwork

Abstract

Significant improvement of structural and optical qualities of GaN thin films on sapphire substrates was achieved by metal organic chemical vapor deposition with in situ SiNx nanonetwork. Transmission electron microscope (TEM) studies revealed that screw- and edge-type dislocations were reduced to 4.4×107 and 1.7×107cm−2, respectively, for a ∼5.5-μm-thick layer. Furthermore, room temperature carrier lifetimes of 2.22 and 2.49ns were measured by time-resolved photoluminescence (TRPL) for samples containing single and double SiNx network layers, respectively, representing a significant improvement over the previous studies. The consistent trends among the TEM, x-ray diffraction, and TRPL measurements suggest that in situ SiNx network reduces line defects effectively as well as the point-defect-related nonradiative centers.