Publications

Metrology of crystal defects through intensity variations in secondary electrons from the diffraction of primary electrons in a scanning electron microscope

Naresh-Kumar G, Alasamari A, Kusch G, Edwards P R, Martin R W, Mingard K P, Trager-Cowan C

Ultramicroscopy Vol 213 (2020)

https://doi.org/10.1016/j.ultramic.2020.112977

Structural and luminescence imaging and characterisation of semiconductors in the scanning electron microscope

Trager-Cowan Carol, Alasmari Aeshah, Avis William, Bruckbauer Jochen, Edwards Paul R, Ferenczi Gergely, Hourahine Benjamin, Kotzai Almpes, Kraeusel Simon, Kusch Gunnar, Martin Robert W, McDermott Ryan, Gunasekar Naresh, Nouf-Allehiani M, Pascal Elena, Thomson David, Vespucci Stefano, Smith Matthew David, Parbrook Peter J, Enslin Johannes, Mehnke Frank, Kuhn Christian, Wernicke Tim, Kneissl Michael, Hagedorn Sylvia, Knauer Arne, Walde Sebastian, Weyers Markus, Coulon Pierre-Marie, Shields Philip, Bai J, Gong Y, Jiu Ling, Zhang Y, Smith Richard, Wang Tao, Winkelmann Aimo

Semiconductor Science and Technology Vol 35 (2020)

https://doi.org/10.1088/1361-6641/ab75a5

Acceptor state anchoring in gallium nitride

Cameron D, O'Donnell KP, Edwards PR, Peres M, Lorenz K, Kappers MJ, Boćkowski M

Applied Physics Letters Vol 116 (2020)

https://doi.org/10.1063/1.5142168

Luminescence behavior of semipolar (10 11) InGaN/GaN "bow-tie" structures on patterned Si substrates

Bruckbauer Jochen, Trager-Cowan Carol, Hourahine Ben, Winkelmann Aimo, Vennéguès Philippe, Ipsen Anja, Yu Xiang, Zhao Xunming, Wallace Michael J, Edwards Paul R, Naresh-Kumar G, Hocker Matthias, Bauer Sebastian, Müller Raphael, Bai Jie, Thonke Klaus, Wang Tao, Martin Robert W

Journal of Applied Physics Vol 127 (2020)

https://doi.org/10.1063/1.5129049

Scanning electron microscopy as a flexible tool for investigating the properties of UV-emitting nitride semiconductor thin films

Trager-Cowan C, Alasmari A, Avis W, Bruckbauer J, Edwards P R, Hourahine B, Kraeusel S, Kusch G, Johnston R, Naresh-Kumar G, Martin R W, Nouf-Allehiani M, Pascal E, Spasevski L, Thomson D, Vespucci S, Parbrook P J, Smith M D, Enslin J, Mehnke F, Kneissl M, Kuhn C, Wernicke T, Hagedorn S, Knauer A, Kueller V, Walde S, Weyers M, Coulon P-M, Shields P A, Zhang Y, Jiu L, Gong Yipin, Smith R M, Wang T, Winkelmann A

Photonics Research Vol 7, pp. B73-B82 (2019)

https://doi.org/10.1364/PRJ.7.000B73

Synthesis of small gold nanorods and their subsequent functionalization with hairpin single stranded DNA

Mbalaha Zendesha S, Edwards Paul R, Birch David JS, Chen Yu

ACS Omega Vol 4, pp. 13740-13746 (2019)

https://doi.org/10.1021/acsomega.9b01200

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Research interests

My research is focussed on the use of spectroscopic and microscopic methods in the analysis of semiconductors. The main materials of current interest to me are those based on the group III nitride quaternary system, Al_xGa_yIn_(1-x-y)N, and in particular nano-scale structures based on them. These have applications in many different areas, including solid-state lighting, data storage, communications and water purification. The techniques I use to study these materials include photoluminescence and electroluminescence spectroscopy, as well multiple modes of scanning electron microscopy (such as cathodoluminescence, electron beam-induced current and X-ray microanalysis). I am also interested in the application of multivariate statistical analysis techniques in the processing of the multidimensional data that these experimental methods yield.

Professional activities

Microscopy & Microanalysis 2018

Invited speaker

9/8/2018

PDI Topical Workshop on Cathodoluminescence of Semiconductor Nanostructures

Participant

16/4/2018

UK Nitrides Consortium Winter Conference 2018

Speaker

10/1/2018

12th International Conference on Nitride Semiconductors (ICNS-12)

Participant

23/7/2017

Microscience Microscopy Congress (MMC2015)

Invited speaker

2/7/2015

13th Australian Microbeam Analysis Symposium

Invited speaker

12/2/2015

more professional activities

Projects

Monolithic on-chip integration of electronics & photonics using III-nitrides for telecoms

Martin, Robert (Principal Investigator) Edwards, Paul (Co-investigator)

01-Jan-2020 - 30-Jan-2023

Doctoral Training Partnership 2018-19 University of Strathclyde | Hunter, Daniel

Martin, Robert (Principal Investigator) Edwards, Paul (Co-investigator) Hunter, Daniel (Research Co-investigator)

01-Jan-2019 - 01-Jan-2023

Doctoral Training Partnership 2018-19 University of Strathclyde | Starosta, Bohdan

Hourahine, Ben (Principal Investigator) Edwards, Paul (Co-investigator) Starosta, Bohdan (Research Co-investigator)

01-Jan-2018 - 01-Jan-2022

Light-controlled manufacturing of semiconductor structures: a platform for next generation processing of photonic devices

Skabara, Peter (Principal Investigator) Dawson, Martin (Co-investigator) Edwards, Paul (Co-investigator) Martin, Robert (Co-investigator) Watson, Ian (Co-investigator)

"This Platform Grant (PG) will apply our internationally-leading expertise in structured illumination and hybrid inorganic/organic semiconductor optoelectronic devices to create new opportunities in the rapidly developing field of light-controlled manufacturing. Structured illumination fields can in principle be obtained from both inorganic (GaN) and organic LEDs, implemented on a macroscale via relay optics, or demagnified to a microscale. Novel manufacturing with photopolymerisable materials can firstly involve use of structured illumination as a novel means to control motorised stages. This technique can be combined with pattern-programmable UV excitation for mask-free photolithographic patterning, continuous photo-curing over larger fields, localised photochemical deposition, or other forms of photo-labile assembly. Process variants can also be envisaged in which arbitrarily positioned fluorescent objects or markers are 'hunted', and then subject to beam excitation for photocuring or targeted photoexcitation. This method could be used, for example, to immobilise individual colloidal quantum dots for use as emitters in quantum technology applications. Multifunctional devices with sensing ability, such as organic lasers for explosives detection, represent another excellent example of automated devices operating under remote conditions. Further examples of the envisaged uses of this technology include:

[1] LED microdisplay asset tags for management of high-value objects (artworks, nuclear fuel containers).
[2] Passive asset tags containing unique micro-patterns of fluorescent objects (eg. colloidal quantum dots, organic macromolecules) for higher-volume, anti-counterfeiting applications.
[3] Customisable continuous-flow micro-reactors for fine chemical manufacturing.
[4] Energy harvesting micro-modules to power other autonomous microsystems, where we will focus on organic PV and ambient-radiation (RF) approaches."

01-Jan-2017 - 30-Jan-2021

Quantitative non-destructive nanoscale characterisation of advanced materials

Hourahine, Ben (Principal Investigator) Edwards, Paul (Co-investigator) Roper, Marc (Co-investigator) Trager-Cowan, Carol (Co-investigator) Gunasekar, Naresh (Research Co-investigator)

"To satisfy the performance requirements for near term developments in electronic and optoelectronic devices will require pioneering materials growth, device fabrication and advances in characterisation techniques. The imminent arrival of devices a few atoms thick that are based on lighter materials such as graphene or boron nitride and also advanced silicon and diamond nano-structures. These devices pose new challenges to the currently available techniques for producing and understanding the resulting devices and how they fail. Optimising the performance of such devices will require a detailed understanding of extended structural defects and their influence on the properties of technologically relevant materials. These defects include threading dislocations and grain boundaries, and are often electrically active and so are strongly detrimental to the efficiency and lifetimes of nano-scale devices (a single badly-behaved defect can cause catastrophic device failure). These defects are especially problematic for devices such as silicon solar cells, advanced ultraviolet light emitting diodes, and advanced silicon carbide and gallium nitride based high power devices (used for efficient switching of large electrical currents or for high power microwave telecoms). For graphene and similar modern 2D materials, grain boundaries have significant impact on their properties as they easily span the whole size of devices.

Resolving all of these problems requires new characterisation techniques for imaging of extended defects which are simultaneously rapid to use, are non-destructive and are structurally definitive on the nanoscale. Electron channelling contrast imaging (ECCI) is an effective structural characterisation tool which allows rapid non-destructive visualisation of extended crystal defects in the scanning electron microscope. However ECCI is usually applied as a qualitative method of investigating nano-scale materials, has limitations on the smallest size features that it can resolve, and suffers from difficulties in interpreting the resulting images. This limits this technique's ability to work out the nature of defects in these advanced materials.

We will make use of new developments in energy resolving electron detectors, new advances in the modelling of electron beams with solids and the knowledge and experience of our research team and partners, to obtain a 6 fold improvement in the spatial resolution of the ECCI technique. This new energy-filtered way of making ECCI measurements will radically improve the quality of the information that can be obtained with this technique. We will couple our new capabilities to accurately measure and interpret images of defects to other advanced characterisation techniques. This will enable ECCI to be adopted as the technique of choice for non-destructive quantitative structural characterisation of defects in a wide range of important materials and provide a new technique to analyse the role of extended defects in electronic device failure."

01-Jan-2017 - 31-Jan-2021

Hysteretic photochromic switching (HPS) of europium-magnesium defects in gallium nitride: a potential route to a new solid-state qubit

O'Donnell, Kevin (Principal Investigator) Edwards, Paul (Co-investigator)

01-Jan-2015 - 03-Jan-2019

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