Cathodoluminescence study on the impurity behaviors at threading dislocations in GaN

The threading dislocations in GaN provide diffusion routes for impurity incorporation, which substantially influences GaN based optoelectronic devices. Here, we investigated the characteristics of the impurity incorporation at threading dislocations by HCl vapor phase etching and cathodoluminescence (CL) measurements. The distinctive etch pits induced by HCl vapor phase etching correspond definitely to different types of dislocations, and the etching process causes simultaneously H incorporation at a high temperature. CL spectra of the etch pits were analyzed, and the observed difference in the redshift of near band emission peak indicates that mix dislocations are more favorable for impurity incorporations than that of edge dislocations. The understanding on the impurity incorporation behavior at threading dislocations helps to obtain high quality GaN nanostructures.