Theory of alloy broadening of deep levels in semiconductor alloys: Nitrogen in AlxGa1-xAs

The inhomogeneous alloy broadening of deep levels produced by substitutional impurities in crystalline semiconductor alloys is investigated with use of a technique based upon the embedded-cluster method and the theory of deep levels. Results are presented for the composition dependences of the center, width, and component lines of the alloy-broadened spectrum of nitrogen on the arsenic site in AlxGa1-xAs. For the present application, only the effects of the alloy disorder in the nearest-neighbor environment of the impurity are accounted for by the theory. In principle, however, the method outlined here is generalizable to account for such effects in the impuritys second- and more-distant-neighbor environments.