PhD: Innovative high-power semiconductors created with phonon lifetime engineering

Closing Date
Thursday, 30th September 2021

PhD Studentship Opportunity

 Innovative high-power semiconductors created with phonon lifetime engineering

Applications are being accepted for a PhD studentship to develop novel semiconductors, whose thermal properties have been enhanced using phonon lifetime engineering. This curiosity-driven project is a collaboration between the School of Physics & Astronomy and the Dept. of Electrical and Electronic Engineering and is funded by the U.S. government. 

The three-year project will provide the tuition fees and stipend for a home student or more than 75% of the tuition fees for an international student. The student will help set up an optical characterisation system for Raman spectroscopy, which they will use to measure the temperature-dependent optical phonon linewidth and determine its intrinsic lifetime. The student will require scientific curiosity, good experimental skills and the ability to analyze and interpret the results. The student will learn new experimental skills in laser-based spectroscopy and develop a good understanding of exciting non-linear physical processes (e.g. non-linear optics, anharmonic phonon decay). 

This project aims to create novel semiconducting materials with significantly improved thermal performance by controlling hot phonon effects. While most ‘phonon engineering’ approaches focus on controlling the propagation of acoustic phonons, i.e. heat flow, this fundamentally new and transformative approach seeks to suppress the accumulation of heat in stationary hot optical phonons, and so to facilitate the flow of energy from the hot carrier plasma to mobile acoustic phonons (see Fig. 1). We estimate that reducing the LO phonon lifetime by 50% can lead to a 25% increase in maximum power and 22% decrease in thermal resistance in high-power GaAs-based laser diodes. In GaN HFETs, we believe the channel temperature can be reduced by at least 30% and the transit time shortened by >10% - with corresponding improvements in reliability and operating frequency.

Interested students should contact Prof. Eric Larkins ( or Prof. Tony Kent ( for more information and details of the formal application process.