Lead Chief Investigator

Rui Yang Department of Computer Science, Faculty of Engineering, Australian National University

Project Title

First Principles Simulation of GaN Growth on Al2O3 Surfaces

Brief Description for General Publications

The group III nitride semiconductors (AlN, GaN and InN) have bandgap energies that can be tailored to produce a wide range of high performance optoelectronic and microwave devices. The bulk nitrides are, however, very difficult to produce and it is therefore necessary to grow them heteroepitaxially on a suitable foreign substrate. For GaN this substrate is usually Al2O3 (sapphire), but due to the large difference in the lattice parameters and in the thermal expansion coefficient between GaN and Al2O3 the growth of GaN epilayers on this substrate usually takes place in two pretreatment steps, i.e. nitridition and the formation of AlN buffer layers. Although such pretreatment steps have been applied for several years, their mechanisms remain unclear. The present project aims to systematically study these pretreatment steps using computer simulation. It will make extensive use of the recently developed periodic boundary condition (PBC) methods available in the Gaussian03 code. These methods use a localized basis set that will enable a detailed study of the bonding interactions involved. This will be in marked contrast to all other theoretical studies that have used plane-wave based methods. This project is expected to lead to fundamental improvements in our understanding of surface growth phenomenon, provide feedback that will improve the newly developed PBC methods within the Gaussian code, and possibly improved experimental techniques for the preparation of GaN films. Use of the APAC National Facility is required due to the significant computational, memory and disk requirements of the proposed calculations.