Photoluminescence properties of ZnTeO and ZnSeO alloys with dilute O concentrations

The photoluminescence properties of ZnTeO and ZnSeO with dilute O concentrations are studied. The exciton bound to isolated O and its phonon replicas are observed in ZnTeO. The peak energies are hardly affected by O concentration, indicating the isoelectronic feature of O. On the other hand, the free exciton peak is shifted to lower energy in ZnSeO by increasing O concentration, even when the O concentration is as low as 0.015%. No isoelectronic emissions are observed. We find the increase of binding energy of free exciton due to the increase of the effective mass of the conduction band edge. This can be interpreted as the modification of the band structure by the repulsive interaction between the O localized level and the conduction band of ZnSe with the scheme of band anticrossing model. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)