Time-Resolved Spectroscopy of Single Excitons Bound to Te Isoelectronic Pairs in ZnSe

Single Te impurity centers in ZnSe were probed with time-resolved photoluminescence spectroscopy. Resolution-limited peaks with an ultra-low spatial density originate in the recombination of excitons deeply bound to single nearest-neighbor isoelectronic Te pairs. This interpretation is confirmed by ab-initio calculations. The peaks reveal anti-bunched photon emission and a doublet structure polarized along $[110]$ and $[\bar {1}10]$. We analyze the time-resolved PL decay to clarify the role of the dark states in the spin relaxation and radiative recombination of single fine-structure split excitons.