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Professor John D. Murphy - ISIS Facility Development Studentship

Carrier lifetimes in silicon solar cells measured by muon spin spectroscopy

School of Engineering and ISIS Neutron and Muon Source

Qualification: Doctor of Philosophy in Engineering (PhD)

Start date: 3rd October 2022

Funding for: 3.5 years

Supervisor: Professor John Murphy and Dr Koji Yokoyama

Project Description:

Photovoltaic installations have recently reached the terawatt level and this is almost entirely due to the success of silicon-based solar cell technologies. Silicon PV is low-cost and stable for 25+ years, and cell efficiencies are unrivalled by other mass-market single-junction technologies. Improvements in silicon cells will have a real-world impact on climate change mitigation and improving energy supply security. The project will address important scientific questions of practical significance.

Charge carrier lifetime is the key parameter in silicon materials used for solar cells. Lifetime in silicon is influenced by defects at the atomic scale, and cells degrade during operation because of light-driven defect reactions. The Electronic Materials and Interfaces Group at Warwick has expertise in lifetime measurement in silicon, and the ability to fabricate test structures (including using state-of-the-art atomic layer deposition facilities). The Muon Group at ISIS has recently demonstrated that lifetime can be measured using a novel muon spin spectroscopy technique. This technique can be used on completed solar cell devices and can give information on carrier recombination at different depths, potentially enabling surface-related effects to be determined. The studentship links Warwick and ISIS, enabling the student to pursue a unique set of projects to understand lifetime-related issues in silicon photovoltaic materials. Areas of focus will include light and elevated temperature induced degradation (LeTID) in PERC cells, the fundamental properties of hydrogen in silicon, and the passivation of solar cell surfaces. There are also opportunities for involvement in instrument development at ISIS using a high-power laser system for the photoexcited muon spin spectroscopy, thus enabling new measurement approaches for a broad range of semiconductor materials systems.

Interested students should contact both Prof. John Murphy at Warwick ( and Dr Koji Yokoyama at ISIS ( with a CV for an informal discussion.


The award will cover the full tuition fees, plus a tax-free stipend of £16,062 per annum for 3.5 years of full-time study.


The project would suit a student with an undergraduate degree in Physics, Materials Science or Electrical/ Electronic Engineering. The student is expected to spend time at both Warwick and ISIS, and a travel/ subsistence budget is available to facilitate this.

How to apply:

Candidates should submit an expression of interest by sending a CV and supporting statement outlining their skills and interests in this research area to If this initial application is successful, we will invite you to make a formal application for study. All candidates must fulfil the University of Warwick entry criteria and obtain an unconditional offer before commencing enrolment.

The University of Warwick provides an inclusive working and learning environment, recognising and respecting every individual’s differences. We welcome applications from individuals who identify with any of the protected characteristics defined by the Equality Act 2010.