The emission and reflection spectra of ZnO have been investigated in the intrinsic region and the data have been interpreted in terms of the wurtzite crystal band structure. Free-exciton emission is observed for the first time. Both the Γ5 and Γ6 state excitons associated with top valence band have been identified. This identification has established the valence-band symmetry ordering in ZnO.
Reynolds, D. C.,
Look, D. C.,
Litton, C. W.,
& Harsch, W. C.
(1999). Valence-Band Ordering in ZnO. Physical Review B, 60 (4), 2340-2344.