The Consequences of Phonon Connement on Carrier Transport in Nanodevices

In many modern semiconductor devices their physical dimensions are such that quantum effects dominate. Mathematical models and computer simulation tools have up to now focused on the electrons in order to predict the
consequences of physical confinement. In this project both the electron and phonon confinement will be studied. Phonons are the microscopic manifestation of heat which can be a serious challenge in nanodevices.

This project aims to understand the consequences of phonon confinement on electron transport in high-electron-mobility transistors (HEMTs) in relation to mobility and device self-heating. The project will extend the functionality
of the Monte-Carlo simulation tool developed by Dr Angela Dyson and the Dyson group to include the effects of phonon connement, and model two-dimensional semiconductor heterostructures such as HEMTs. These simulation
tools use Monte-Carlo simulations to model carrier scattering in III{V semiconductors, particularly gallium nitride (GaN) which is a promising green replacement for silicon. These tools will be united with a theoretical model, also
developed within the Dyson group over the last 5 to 10 years. The Monte-Carlo simulation tool models the microscopic motion of ~ 104 to ~ 105 electrons, modelled in bulk (3D) or conned (2D) conditions as appropriate. The polar
optical phonon, a major contributor to mobility degredation in GaN devices, can be modelled out of equillibrium, a feature shared with only one other code worldwide.

This will allow the identication of the cause of differing mobilities in nitrogen-polar and gallium-polar HEMTs, as well as engineering the interface phonon mode to control and ameliorate device self-heating.