Structural & Electronic Properties of Semiconductor Nanostructures studied through Atomistic Empirical Potentials & Empirical Tight Binding

The evolution of consumer electronics requires the constant development of smaller and more energy efficient devices. While over 90% of the worlds electronic devices are made of Silicon, the recent increase in the demand for optoelectronic devices (like lasers for CDs and DVD players or LED for miniaturised monitors) requires a different type of semiconductors, namely the III-Vs. These are alloys formed by atoms of group III (Indium, Gallium and Aluminium) and group V (Arsenic, Phosphorus, Antimony, Nitrogen) and unlike Silicon, can efficiently emit and absorb light. Also exploiting technique such as Molecular Bean Epitaxy (which relies on depositing one atomic sheet at the time) these materials can be used to make structures of dimensions of the order of 10-9m (nanometre), founding applications in a field that is commonly known as nanotechnology.This proposal is concerned with developing theoretical, computational and modelling techniques to enable us to build accurate models of some nanostructures and in particular the so called Quantum Dots: these are small clusters of atoms with a potential usually lower than the surrounding material, and hence allowing efficient trapping of electric charges.The methods we intend to develop rely heavily on using large clusters of very fast computers, in order to be able to calculate the interactions of systems composed of millions of atoms, and be therefore able to perform the most accurate simulations of nanostructures possible with the existing computational hardware.