Bartlomiej Makowski

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Student Details:

Bartlomiej is a first year PhD research student with Optics and Photonics research group at University of Nottingham. His background is a Master of Engineering undergraduate degree in Electrical and Electronic Engineering from the University of Nottingham. He is currently working on PhD project titled Phonon Lifetime Engineering by Vibrational Doping.

PhD Project: Phonon Lifetime Engineering by Vibrational Doping

Project Supervisors:

Professor Eric Larkins [1]

Professor Tony Kent [2]

Project Description:

This project aims to design and create novel semiconducting materials with significantly improved thermal performance through the control of hot phonon effects. Most ‘phonon engineering’ approaches focus on controlling the propagation of acoustic phonons, i.e. heat flow in semiconductor devices, 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.

In the proposed approach, the hot optical phonon generation will be suppressed by phonon engineering of the material using vibrational doping to reduce the longitudinal optical (LO) phonon lifetime. This will suppress the generation of hot phonons that heat the carriers within the device and degrade the performance of devices operating at higher power density. Our estimates show that reducing the LO phonon lifetime by 50% could lead to a 25% increase in maximum power and 22% decrease in thermal resistance In high-power laser diodes, and in GaN HFETs, where the channel temperature could be reduced by at least 30% and the transit time shortened by >10% with corresponding improvements in reliability and cut-off frequency.

Contact Details:

University Email: ezxbm1

Location: L4 Laboratories, Faculty of Engineering