We have investigated the dislocation of GaN films grown by hydride vapor phase epitaxy (HVPE) on c-plane sapphire substrates using transmission electron microscopy (TEM), etch pit density (EPD) characteristics, and micro photoluminescence (PL). Micro PL mapping is a nondestructive method for observing defect sites as dark spots which reveal the dislocations causing non-radiative recombination centers in the GaN film surface. The dark spots reveal a decrease in threading dislocation sites with increasing the thickness of GaN films. In order to illustrate the correlation between the thickness and the dislocation density of GaN, the micro PL analysis method was used to observe the dislocation densities of a GaN film with a low dislocation density.
