Source of the yellow luminescence band in GaN grown by gas-source molecular beam epitaxy and the green luminescence band in single crystal ZnO

In this paper we show that the origin of the yellow luminescence band in GaN and the green luminescence band in ZnO is best explained by a transition between a shallow donor and a deep level. High resolution photoluminescence spectroscopy measurements on GaN (0 0 0 1) films grown by gas-source molecular beam epitaxy are compared with theoretical predictions. These comparisons show that the makeup of the deep level in GaN is most likely a complex consisting of a gallium vacancy, V-Ga and a nearest neighbor donor consisting of an oxygen atom on a nitrogen site, O-N, or V-Ga-O-N. By analogy, the makeup of the deep level in ZnO is most likely a complex consisting of a zinc vacancy, V-Zn and a nearest neighbor donor consisting of a chlorine atom on an oxygen site V-Zn-Cl-O. Chlorine is suggested since it is a dominant donor in ZnO and is known to be present in the ZnO growth process. (C) 1998 Elsevier Science Ltd. All rights reserved.