NITROGEN STATES IN GA(AS,P) AND THE INTERMEDIATE-RANGE MODEL

The appearance of new single nitrogen lines in recent Ga(As,P): N photoluminescence data has been interpreted theoretically in terms of an impurity potential that has a short-range part and a more extended portion arising from strain effects. Two current theories have interpreted the range of the latter as either long or intermediate: the implications for impurity-induced lattice relaxation are quite different in the two cases. To resolve this issue, we examine the consistency of the data with a nearest-neighbor shell model as well as with more extended intermediate-range models. By introducing a soluble Green's-function model, we show that the former is inconsistent; from basic quantum-mechanical considerations, we show that monotonic, attractive potentials are not consistent unless their ranges are greater than ∼ 20-25. © 1979 The American Physical Society.