Published: 06 August 2019

Mature students contribute to ground-breaking electronics research

In a great example of staff-student collaboration, mature students have worked with staff within Surrey’s Advanced Technology Institute (ATI) to demonstrate that an apparent drawback of source-gated transistors could be a benefit.

Mature students graduation image
(L-r) Eva Bestelink, Dr David Carey, Ray Drury, fellow graduate Huw Hallybone and Dr Radu Sporea.

Published in IEEE Electron Device Letters on 2 July 2019, the research is the work of Ray Drury and Eva Bestelink – who both studied for a degree in electronic engineering at Surrey – under the supervision of Dr Radu Sporea, lecturer in Semiconductor Devices within the Department of Electrical and Electronic Engineering.

The team have used simulations to show the effects of using source-gated transistors (SGTs) instead of conventional thin-film transistors (TFTs) to control the brightness of pixels. While SGTs have benefits such as uniformity and energy efficiency, it was previously thought that as the source and gate electrode overlap increased, switching speed would decrease (as it normally would with TFTs). Instead, the team have found that there is an optimum overlap for operating frequency.

Dr Sporea explains: “Increasing electrode size would potentially consume more area on the circuit, and their relatively large size could be a problem for use in small pixels. However a built-in capacitor forms in the overlap, which can be used to partly replace the area of a conventional capacitor which is usually used so that circuit area remains the same. This enables SGT-based designs to control relatively small pixels effectively.”

Talking about his experience as a mature student working on the project, Ray comments: “Having decided to undertake an undergraduate degree in Electronic Engineering at the age of 69, I was delighted to be accepted by both the younger students and lecturers without a problem, and when the opportunity to work on transistors as a third year project arose, I was keen to undertake the research.

He adds: “In my view the paper will help inform the development of pixel technology in the future.”

Eva, who is now studying for an Advanced Technology Institute PhD, says: “I’ve particularly enjoyed working with Ray, helping in any way I could with the technical aspects of simulation. At the same time, this helped with advancing my own knowledge of device operation while undertaking my PhD. I would encourage any mature student to become involved in electronic engineering, regardless of age. It truly is a fascinating and rewarding discipline.”

Dr Sporea comments: “Eva and Ray were part of the first undergraduate cohort I taught at Surrey, so we started together from the most basic concepts, and three years later we are tackling industrially relevant device optimisations. It is wonderful to witness their academic evolution and the impact that each individual makes on the life of the Department.”

The research paper, ‘Simulation study of overlap capacitance in source-gated transistors for current-mode pixel drivers’ was published in IEEE Electron Device Letters in July.


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