Dr Carol Trager-Cowan

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Physics

Personal statement

I use electron beams to interrogate the structure, defects and light emission from solids. Together with students and colleagues here at Strathclyde and from across the world, I work on new developments and novel applications of the scanning electron microscopy techniques of electron backscatter diffraction, electron channelling contrast imaging and cathodoluminescence imaging. In particular we have developed novel techniques to rapidly and non-destructively analyse defects in nitride semiconductors used for production of UV and visible LEDs and transistor structures.

I have taught solid state physics; biophysical instrumentation; medical physics; optical; electron and scanning probe microscopy; and public engagement of research. I am presently teaching Introduction to Astronomy; electromagnetism and mechanics. I teach in undergraduate laboratories and supervise student projects.

I am also committed to public engagement giving lectures, writing articles, running workshops, quizzes, street busking, leading science street tours and providing kits to schools. I am a past Vice President of the Royal Philosophical Society of Glasgow, I am an enthusiastic contributor to the Glasgow Science Festival and to Explorathon (European Researchers Night Scotland). I was elected as a Fellow of the Royal Society of Edinburgh in 2014.

Publications

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Publications

Strain-induced modifications of thin film silicon membranes by physical bending: Margariti Eleni, Bruckbauer Jochen, Winkelmann Aimo, Guilhabert Benoit, Gunasekar Naresh-Kumar, Trager-Cowan Carol, Martin Robert, Strain Michael; Materials Vol 18 (2025); https://doi.org/10.3390/ma18102335
Strain and luminescence properties of hexagonal hillocks in N-polar GaN: Bruckbauer Jochen, Cios Grzegorz, Sarua Andrei, Feng Peng, Wang Tao, Hourahine Ben, Winkelmann Aimo, Trager-Cowan Carol, Martin Robert; Journal of Applied Physics Vol 137 (2025); https://doi.org/10.1063/5.0259840
Role of the electron transport layer in dictating the nanoscale heterogeneity in all-inorganic perovskite absorbers – correlating the optoelectronic and crystallographic properties: Nicholson Stefan, Bruckbauer Jochen, Edwards Paul R, Trager-Cowan Carol, Martin Robert W, Ivaturi Aruna; Journal of Materials Chemistry A Vol 13, pp. 11003-11014 (2025); https://doi.org/10.1039/D4TA07152B
Investigation of (mis-)orientation in zincblende GaN grown on micro-patterned Si(001) using electron backscatter diffraction: Waters Dale M, Thompson Bethany, Ferenczi Gergely, Hourahine Ben, Cios Grzegorz, Winkelmann Aimo, Stark Christoph J M, Wetzel Christian, Trager-Cowan Carol, Bruckbauer Jochen; Journal of Applied Physics Vol 137 (2025); https://doi.org/10.1063/5.0244438
Unravelling the chloride dopant induced film improvement in all-inorganic perovskite absorbers: Nicholson Stefan, Bruckbauer Jochen, Edwards Paul R, Trager-Cowan Carol, Martin Robert W, Ivaturi Aruna; Journal of Materials Chemistry A Vol 12, pp. 25131-25139 (2024); https://doi.org/10.1039/D4TA01259C
Imaging threading dislocations and surface steps in nitride thin films using electron backscatter diffraction: Hiller Kieran P, Winkelmann Aimo, Hourahine Ben, Starosta Bohdan, Alasmari Aeshah, Feng Peng, Wang Tao, Parbrook Peter J, Zubialevich Vitaly Z, Hagedorn Sylvia, Walde Sebastian, Weyers Markus, Coulon Pierre-Marie, Shields Philip A, Bruckbauer Jochen, Trager-Cowan Carol; Microscopy and Microanalysis Vol 29, pp. 1879-1888 (2023); https://doi.org/10.1093/micmic/ozad118

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Research

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Research Interests

Our research is driven by the need for rapid, non-destructive techniques to reveal and analyse defects in crystalline materials, in particular in nitride semiconductor thin films. III-nitride materials are presently the basis of a fast-growing, multi-billion dollar solid-state lighting industry and commercial AlGaN/GaN electronic devices are now in use in cell phone base stations, satellite communication systems and cable television networks. However, the ultimate performance of these nitride semiconductor based light emitters and electronic devices is limited by extended defects such as threading dislocations (TDs), partial dislocations (PDs), stacking faults (SFs) and grain boundaries (GBs). If we want to develop LEDs to be an effective replacement for the light bulb, or have sufficient power to purify water or develop efficient power electronics for electric vehicles, we need to eliminate these defects as they act as scattering centres for light and charge carriers and give rise to nonradiative recombination and to leakage currents, severely limiting device performance. The first step to this goal is the detection of these defects – we exploit electron channeling contrast imaging (ECCI) and electron backscatter diffraction (EBSD) in a field emission scanning electron microscope to rapidly and non-destructively detect and analyze TDs, PDs, SFs, GBs and map crystal structure, texture, and strain with a lateral and depth resolution on the order of tens of nanometers.

We are involved in both the development and exploitation of the ECCI and EBSD techniques. For example, in collaboration with the Universities of Glasgow and Oxford and the National Physical Laboratory, we are developing new direct electron imaging detectors for electron backscatter diffraction. We are exploiting the digital complementary metal-oxide-semiconductor hybrid pixel detector, Timepix. Timepix is one of the outcomes of an international collaboration (Medipix) hosted at CERN, established to provide a solution for a range of problems in X-ray and gamma-ray imaging in hostile conditions. Using the Timepix allows digital direct electron detection and energy filtering; it enables electron backscatter diffraction patterns to be acquired with reduced noise and increased contrast, and an unprecedented increase in detail is observed in the patterns. This is allowing us to interrogate the fundamental physics of pattern formation and will enable, in the longer term, the application of the EBSD technique to be expanded to materials for which conventional EBSD analysis is not presently practicable. For more information see: Web pages of Semiconductor Spectroscopy and Devices Group.

Collaborators

We collaborate with researchers from around the globe including the Universities of Sheffield; Nottingham; Cambridge; Oxford; Bristol; Bath; Tyndall Institute/University College Cork; Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Poland; CRHEA-CNRS, France; Technischen Universität Berlin; Ferdinand-Braun-Institut, Berlin; Rensselaer Polytechnic Institute, USA; and The National Physical Laboratory.