S. V. Dudiy

Type I to type II transition at the interface between random and ordered domains of AlxGa1−xN alloys

We analyze the optical and transport consequences of the existence of ordered and random domains in partially ordered samples of AlxGa1−xN alloys. Using atomistic empirical pseudopotential simulations, we find that the band alignment between random and ordered domains changes from type I to type II at x≃0.4. This leads to an increase by two to three orders of magnitude in the radiative lifetime of the electron–hole recombination. This can explain the experimentally observed mobility-lifetime product behaviors with changing Al concentration. The type I to type II transition results from a competition between the ordering-induced band folding effect and hole confinement on Ga-rich monolayers within the ordered structure.

The Inverse Band Structure Approach: Find the Atomic Configuration that has Desired Electronic Properties

In conventional band theory, one specifies first the atomic configuration, and then solves for the electronic properties. We consider the inverse process where one specifies first some target electronic properties, and then searches for atomic configurations that have such properties. Application of the Genetic Algorithm, with additional advantages from its parallel computer implementation, significantly extends our capabilities in treating more demanding IBS problems, as illustrated by searching for the configuration of nitrogen impurity clusters in GaP that have given properties.