Self-compensation in nitrogen-doped ZnSe

Nitrogen-doped and nitrogen-implanted ZnSe epitaxial layers grown by molecular-beam epitaxy are studied through photoluminescence (PL), selective PL, and PL-excitation spectroscopies. The results are compared with those obtained from samples implanted with other impurities. All N-containing samples, and only those, give rise to transitions corresponding to a dominant shallow donor with a binding energy of 29.1 meV. This donor is not a residual impurity in ZnSe but is associated with nitrogen. We propose that it involves nitrogen located on interstitial sites. In addition, the deep compensating donor is already present in lightly doped samples. Our results demonstrate that N doping of ZnSe is accompanied by the concomitant creation of N-related defects, both shallow and deep ones, from the onset of doping. An inescapable dramatic compensation of N acceptors ensues.