2017 Jocelyn Bell Burnell Medal and Prize

Dr Jessica Boland of the University of Regensburg, who has developed novel techniques for characterising the charge carrier dynamics of semiconductor nanowires, enabling demonstration of single nanowire terahertz detectors and ultrafast optically switchable nanowire-based terahertz modulators for ultrafast wireless communication.

Dr Jessica Boland has developed a novel technique based on terahertz spectroscopy for accurate characterisation of doping densities and activation energies in semiconductor nanowires, which has enabled the nanowire carrier dynamics to be examined.

She has shown an enhancement of photoconductivity lifetime by more than a factor of two for shell-doped gallium-arsenic nanowires, as a direct result of doping-engineered bandbending. This is crucial for the implementation of nanowires in devices that require long carrier lifetimes – particularly solar cells. By modulation doping these nanowires, she has also shown that it is possibly to avoid the inherent reduction in carrier mobility associated with increased impurity scattering due to doping.

Dr Boland has demonstrated high electron mobility, comparable to an undoped reference, by physically separating the donor ions from photoexcited electrons. She has also shown that incorporating antimony in indium-arsenic nanowires can lead to a reduction in crystal defect density, and therefore an increase in both carrier lifetime and carrier mobility. This is a crucial result for the field, as it offers another way of tailoring nanowire optoelectronic properties for implementation in electronic devices. Finally, she has also demonstrated prototype nanowire-based terahertz devices.

Via terahertz measurements, Dr Boland has shown that single-nanowire indium-phosphorous terahertz detectors can be developed with comparable performance to bulk receivers, with a high signal-to-noise ratio of 40 and broad detection bandwidth of greater than 2 THz. She has also developed and demonstrated an ulfrafast optically switchable terahertz polariser based on gallium-arsenic nanowires, which perform comparably to graphene-based modulators, yet surpass carbon-nanotube polarisers.

Alongside her research, Dr Boland has been active in physics outreach, acting as a coordinator for the Early Academic Career Outreach Network at the University of Oxford, organising outreach events in local schools. She also acts as outreach assistant for numerous Oxford colleges and as a Ogden Trust careers adviser, and is developing a podcast series looking at the person behind the scientist, as well as developing science workshops for hearing-impaired students.

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