Bulk ZnO samples, epitaxially grown ZnO layers, and ZnO nanostructures frequently exhibited a characteristic emission band at 3.31eV photon energy whose origin was controversial. In part, this omnipresent band was attributed to (e,A0) transitions of conduction band electrons to acceptors, which were present in a relatively high concentrations but had not been positively identified. In particular, the band was often reported after intentional p-type doping of ZnO, preferentially with group V species. Here, a study was made of the 3.31eV band using low-temperature cathodoluminescence with high spatial resolution, by scanning electron microscopy and by transmission electron microscopy. Line-shape analyses at various temperatures furnished clear evidence that the band originated from an (e,A0) transition, where the acceptor binding energy was 130meV. The 3.31eV luminescence was exclusively emitted from distinct lines on sample surfaces and cross-sections representing intersections with basal planes of the wurtzite hexagons. Correlating monochromatic cathodoluminescence images with transmission electron microscopic images, it was concluded that the localized acceptor states causing the 3.31eV luminescence were located in basal plane stacking faults.

Stacking Fault Related 3.31eV Luminescence at 130meV Acceptors in Zinc Oxide. Schirra, M., Schneider, R., Reiser, A., Prinz, G.M., Feneberg, M., Biskupek, J., Kaiser, U., Krill, C.E., Thonke, K., Sauer, R.: Physical Review B, 2008, 77[12], 125215