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Theoretical study of semiconductor InxAl1-xN/GaN heterostructures

Prof. Igor A. Abrikosov, Dr. Ferenc Tasnady

By growing semiconductor heterstructures one can engineer materials with new physical properties. In order to produce high quality samples, one is often trying to match lattice constants of different semiconductor alloys to minimize strains in the samples. In particular, one often aims to find the so-called "strain free" composition, which leads to very high quality heterostructures.

The search can be greatly accelerated by a priory knowledge of the dependence of the lattice constants of the alloys on their composition, because in this case one just needs to find a composition with matching lattice parameters for two systems which build the heterostructure.   Up to recently, one had to relay on the so-called Vegard's rule, which is simply a linear interpolation between the pure alloy components or end-member compounds. In particular, the Vegard's rule for ternary InxAl1-xN alloys connects the lattice constants of the alloy to the lattice constants of AlN and InN . Of course, this is an approximation, but until recently it was very difficult to make better theoretical predictions. However, with the advent of powerful computers and novel methodologies for the solution of quantum mechanics equations, we have learned how to solve this problem in general. Within this project, you will learn modern theory of alloys, and methodologies behind the simulations. You will use these state-of-the-art theoretical tools to calculate concentration dependence of the lattice parameters of InxAl1-xN alloys and to investigate the validity of the Vegard's rule in this system. Your results will be compared with experiment, which is currently carried out by our colleagues.

Responsible for this page: Fei Wang

Last updated: 05/08/08