Theory of alloy broadening of deep levels in semiconductor alloys: Effects of second-neighbor disorder

The effects of second-neighbor alloy disorder on deep levels produced by substitutional impurities in ternary semiconductor alloys is investigated using a generalization of a technique developed earlier to treat the effects of first-neighbor disorder on such levels. This technique is based on the embedded-cluster method and the theory of deep levels, and is generalizable to account for disorder in the higher-neighbor environment of the impurity as well. In the present application, the inhomogeneous alloy broadening of the deep levels associated with nitrogen and oxygen on the disordered (anion) sublattice in GaAs1-xPx is treated. Results are presented for the composition dependencies of the component lines, the centers, and the widths of the alloy-broadened spectra of these impurities.