Electrical and optical inhomogeneity in N-face GaN grown by hydride vapor phase epitaxy

•We revealed two distinctive regions in N-polar face GaN by the wet etching method.•The two regions show very different densities and sizes of dodecagonal pyramids.•The two regions show non-homogeneous electrical and optical properties.•Surface potentials related to the level of carrier concentration in GaN were studied using Kelvin Probe Force Microscopy.

A detailed study on electrical and optical inhomogeneity in N-face GaN grown by hydride vapor phase epitaxy is presented. There are two distinctive regions with non-homogeneous electrical and optical properties in N-face of GaN revealed by wet etching, Raman and cathodoluminescence. One region exclusively exhibited stronger donor–acceptor pair emission and higher carrier concentration due to impurity incorporation. A strong red-shift of near band edge emission of ∼24 meV was also observed owing to additional carrier concentration. Furthermore, the activation energy difference of the etching process between the two regions is ∼0.12 eV. The distinctive etching topography was probably due to the difference of surface potentials related to the level of carrier concentration in GaN.