SPECTROSCOPY OF DONOR-ACCEPTOR PAIRS IN NITROGEN-DOPED ZNSE

Selective photoluminescence of donor-acceptor pairs (DAP) is used to s tudy the compensating donors in p-type ZnSe layers grown by molecular- beam epitaxy and doped with nitrogen produced by rf plasma. More than 13 lines are identified in the energy range of optical phonons. We dem onstrate that the dominant features are associated with local modes of nitrogen bound phonons. The transitions involving a shallow donor wit h a binding energy of 29.1+/-0.1 meV are also evidenced. This donor ha s never been reported before, and, contrary to what it is generally be lieved, it is not one of the residual impurities usually found in noni ntentionally doped layers. Finally, two lines are ascribed to the reso nant DAP photoneutralization in the n=2 states of a deep donor. The de ep-donor ionization energy is then precisely determined as 45.2+/-0.3 meV.