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Physics Seminar

Optoelectronics of 2D semiconductor devices

Speaker: Dr Freddie Withers (University of Exeter)
Date: Wednesday 29 May 2019
Time: 15:00
Venue: Queens Buildings N/3.28

2D semiconductors hold promise for future lighting, photovoltaic and novel quantum technologies. The class of van der Waals materials known as transition metal dichalcogenides (TMDC's) are especially interesting. When they are thinned to single unit cell thickness the band gap is transformed from indirect to direct gap making monolayers suitable for light emission technologies. I will discuss results of a variety of electrically pumped light emitting quantum well devices and show how the choice of monolayer TMDC effects the light output efficiency and discuss how this is linked to the unique spin and valley coupled band spectrum. I will discuss the physics that can arise when these materials are placed within an optical microcavity. I will also discuss scalable device synthesis from 2D material inks which are compatible with ink-jet printing. Finally, I will show a novel approach to incorporate an ultra thin high-K dielectric within van der Waals heterostructures, which allows for the fabrication of light emission, detection and memory devices. Reference Nature Materials 14(3), 301 (2015) Nano Letters 15(12), 8223-8228 (2015) Nature Communications 6, 8579 (2015) Nature Nanotechnology 12(4), 343 (2017) Science Advances 5(1) eaau0906 (2019)