[School of Natural Sciences PhD Scholarships] Understanding the physics of AlGaN for UV-C LEDs

About the project

About the Project Nitride semiconductors are an outstanding success story with InGaN based LEDs now largely replacing less efficient conventional lighting devices and GaN transistors offering major performance advances for high power and very high frequency applications. Efficient and durable far UVC (210-240 nm) LEDs based on AlGaN are another commercially important application of nitride semiconductor technology. Light in this spectral range is effective at sterilising surfaces, air and water but, unlike longer UV wavelengths, is also ‘skin-safe’ since it does not penetrate deep enough to reach living tissue. AlGaN LEDs are compact, portable, robust and Hg-free sources of far UVC radiation but currently have poor (<2.5% at 235 nm) wall-plug efficiency (WPE). WPE is determined by the operating voltage (Vop), charge injection efficiency (CIE), radiative recombination efficiency (RRE), and light extraction efficiency (LEE). Each of these factors is influenced by the nature and density of dopants, impurities and defects in the material. Ineffective doping due to high activation energies (EA) increases Vop through poor conductivity and Ohmic contacting. It also reduces the injection of carriers to the active area, reducing CIE. Impurities and defects can be channels for non-radiative recombination, lowering RRE, and compensate dopants, limiting their effectiveness further. Far UVC LEDs emit light parallel to the active region plane, which leads to low LEE if light is absorbed by impurity states stemming from e.g. oxygen and carbon prior to out-coupling from the diode. Overall, the manufacture of efficient far UVC-LEDs requires improved understanding of the properties of dopants, impurities, and defects in n- and p-type high Al content AlGaN. This PhD project will use temperature-, power- and time-dependent photoluminescence spectroscopies, and related spectroscopic methods, to understand the role played by different defects (e.g. nitrogen vacancies), dopants (Si and Mg) and impurities (e.g. C and O) in the efficiency of radiative recombination in samples of high Al content AlGaN. The samples will be supplied by our collaborators in Ireland and the experimental work will take place in established laboratories in the Photon Science Institute. There will be twice yearly travel to Ireland for project meetings, as well as to conferences in the UK and abroad to present results. The outcome of the project is an improved understanding of the factors limiting emission efficiency in AlGaN, which will then enable more useful UV-C LEDs to be produced and used to improve healthcare through easier prevention of microbial infection. This project is expected to start in September 2027. Before you apply: We strongly recommend that you contact the supervisors for this project before you apply. How to apply: To be considered for this project you must complete a formal application through our online application portal. If you already have an applicant account this link will directly open an application for PhD School of Natural Sciences Scholarships . If you don’t already have an applicant account, please follow the instructions here . When applying, please specify the full title and supervisor/s of the project, details of your previous study, and names and contact details of two referees. You must also upload a Supporting Statement describing your motivation to apply to the project, your CV and transcripts of awarded and in-progress university qualifications . Please note late or incomplete applications will not be considered. Equality, diversity and inclusion are fundamental to the success of The University of Manchester and central to all our activities. A diverse research community strengthens creativity, productivity and quality, while increasing the societal and economic impact of our work. We welcome applicants from all career paths, backgrounds and sections of the community, regardless of age, disability, ethnicity, gender, gender expression, sexual orientation or transgender status. We welcome applications from candidates returning to study after a career break or experience in other roles. Flexible study arrangements may be available, including part-time study at 50%, 60% or 80%, subject to the requirements of the project and funder. Eligibility: The standard academic entry requirement for this PhD is an upper second-class (2:1) honours degree (or international equivalent) in Physics, Materials Science or Electronic Engineering OR any upper-second class (2:1) honours degree and a Master’s degree at merit (or international equivalent) in Physics, Materials Science or Electronic Engineering. This project will remain open until filled. If your application is submitted by 1 st November 2026, you can expect a decision by 18 th December 2026. If your application is submitted by 15 th January 2027, you can expect a decision by 30 th March 2027. Self or externally funded students can also be considered for this project. FSESoNS

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