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Novel nanocavities in wide bandgap semiconductors for quantum optical devices

This research project is in competition for funding with one or more projects available across the EPSRC Doctoral Training Partnership (DTP). Usually the projects which receive the best applicants will be awarded the funding. Find out more information about the DTP and how to apply.

The project will develop a novel processing technique to create gallium nitride (GaN) optical nanocavities.

GaN is a commercially important semiconductor with widespread use in solid state lighting, blue lasers and high power transistors. We will optimise the processing of GaN on various crystal planes by using an angled Faraday cage over the sample to create an angled inductively coupled plasma (ICP) etch. We will demonstrate new geometries of optical cavity which use fewer fabrication steps, simplifying the processing of manufacturable devices.


Nanoscale cavities change the optical density of states for localised emitters in semiconductors, changing their optical properties. A famous example is the Purcell effect where a single optical mode is localised in a small volume of space with a narrow frequency width, leading photon emission being preferentially guided into a single mode with high efficiency and high rate. To realise these cavities the semiconductor must be structured on a length scale smaller than one wavelength.

Project aims and methods

The objective of the project is to design, create and test optical cavities in GaN by angled etching. The angled etching is already developed in the ACES feasibility study, so the project can begin delivering useful devices.

You will create photonic crystal beams (which can lead to lasers with ultra-low threshold) and micro-discs (which can be used for lasers, frequency conversion and gas sensing). The project will also involve optical characterisation within a newly equipped lab with single photon sensitive detectors, high speed electronics and single frequency lasers.

The project will be completed within 3.5 years by following the structure:

Year 1

Understand the project. The student will perform a literature review and prepare a PhD project plan.  They will start learning the software for numerical simulations (Lumerical FDTD and Mode), as well as undergo cleanroom training.  They will start training on optical characterisation in the laboratory.

Year 2

Substantial research. The student will develop and optimise the fabrication procedures needed to make the devices.  They will characterise and test these devices in the laboratory, and compare the results against their own design specifications and theoretical models.

Year 3

becoming an independent researcher. The student will now be an expert in all aspects of the project, able to make independent contributions and will begin to write-up the results for dissemination. Final 6 months – finishing research and starting writing up. Throughout, the student will be monitored via the usual PHYSX procedures. This includes an initial review after 3 months, and an Annual Review after 9, 21, and 33 months (all recorded on SIMS), with interim reviews conducted midway.


Dr Daryl Beggs

Dr Daryl Beggs

Condensed Matter and Photonics Group

+44 (0)29 2251 0268
Dr Anthony John Bennett

Dr Anthony John Bennett

Advanced Materials and Devices - Sêr Cymru Research Group

+44 (0)29 2087 5404

Programme information

For programme structure, entry requirements and how to apply, visit the Physics and Astronomy programme.

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