This research will provide theoretical investigations of several areas which are crucial to the emerging class of wide bandgap semiconductor compounds comprised of group three-nitrides. A range of basic properties, including the electronic transport and optical properties of aluminum nitride, gallium nitride and indium nitride, will be calculated by means of first-principles methods. Calculations of the dependence of the electronic properties on strain and optical phonon distortions will provide information needed in the modeling of high temperature transport. The optical response functions and other spectroscopic information will be calculated for both the zincblende and the wurtzite forms. The nitrogen vacancy, an important defect for the quality of the material, will be investigated. The project will study the corresponding properties for ternay alloy systems composed of aluminum and gallium, and indium and gallium with nitrogen, as well as the pseudo-binary alloy of silicon carbide with aluminum nitride. This part of the work will make use of appropriate statistical models in the treatment of disorder. The optical properties of small period superlattices and the band-offsets of heterostructures will be studied. The work is expected to have a significant impact on the characterization efforts of material produced by novel growth techniques currently under development. This will assist the development of opto-electronic devices operating at short wavelengths and at high temperatures. %%% Computationally intensive research will be conducted in order to calculate the properties of a new class of semiconductor compounds which have the potential for many applications. These complex materials, which are based on the nitrides, are particularly useful for their optical properties in addition to their electronic ones. Also, these are hard materials which can function at high temperatures. Thus, applications requiring opto-electronic devices operating at high temperatures will benefit.
