Novel type of optical transition observed in MBE grown CdTe

A photoluminescence band with unusual spectral properties has been observed in MBE grown CdTe. It is particularly prominent in single crystal layers containing large concentrations of extended defects generated either by metallurgical imperfections or contamination at the substrate-layer interface. It is suggested that this luminescence results from electron-hole recombination at these extended defects. The weak LO phonon coupling may result from the delocalisation of the electronic binding potential between several nearly equivalent sites, while the spectral breadth of the no-phonon component may result from the influence of small environmental differences between these sites. Similar bands have been observed in ZnSe.