The role of defects on radiative transitions in nitrogen doped ZnSe

The radiative emission in nitrogen doped ZnSe grown by molecular beam epitaxy (MBE) and metalorganic molecular beam epitaxy (MOMBE) has been studied by means of time-resolved spectroscopy at 18 K. The lifetime of the free exciton emission and the oscillator strength of the acceptor bound exciton transition decreases with increased nitrogen incorporation. ZnSe:N MOMBE grown samples show different or additional compensation mechanism compared with MBE grown ZnSe:N due to higher defect concentration. The characteristic lifetime of the donor-acceptor pair emission is found to increase with increased incorporation of nitrogen as longer radiative lifetime of more localized carriers is expected as the carriers are trapped in deeper potential wells.