Terahertz imaging has the potential to transform sensing, inspection, and medical diagnostics, yet current systems remain too complex for widespread commercial use. This project aims to overcome these barriers by developing a high‑resolution spatial light modulator based on high‑aspect‑ratio silicon pillars. The PhD researcher will advance scalable wet‑etch fabrication methods to create next‑generation THz modulators with applications in security screening and early cancer detection. 

Terahertz (THz) radiation is rapidly emerging as a transformative tool for imaging, non‑destructive testing, chemical sensing, and early‑stage cancer detection. However, current THz imaging systems rely on specialised, expensive, and complex equipment, limiting their widespread use. This PhD project aims to overcome these barriers by developing a new silicon‑based photo‑modulator capable of delivering faster imaging speeds and significantly higher spatial resolution.

The core concept is to exploit the photoconductive response of intrinsic silicon under illumination to modulate THz radiation for single‑pixel imaging. Achieving high‑resolution modulation requires preventing photo‑generated carriers from diffusing laterally—something made possible by fabricating high‑aspect‑ratio silicon pillars. Early feasibility work has demonstrated that such pillars can be produced using dry etching, but this approach is not scalable. This PhD will therefore explore wet chemical etching as a more cost‑effective, selective, and industry‑ready fabrication route, supported by Silson’s extensive expertise.

This project offers a unique opportunity to work at the intersection of semiconductor fabrication, photonics, and THz technology, contributing to the development of compact, high‑performance imaging systems (i.e. for security and medical applications).

Key Research Activities

1. Fabrication and Characterisation of Silicon Pillars:

• Develop silicon pillar arrays using dry etching, wet chemical etching, and saw micromachining.
• Systematically vary pillar geometry (height, diameter, pitch) and surface passivation.
• Characterise structures using SEM, profilometry, optical microscopy, photoluminescence imaging (PL), photoconductance decay (PCD), and THz imaging.

2. Modelling and Simulation:

• Build COMSOL models to predict carrier diffusion under photoexcitation.
• Simulate THz–pillar interactions to identify optimal geometries.
• Validate simulations against experimental data.

3. THz Modulation and Imaging Experiments:

• Integrate fabricated modulators into single‑pixel THz imaging systems.
• Measure modulation depth, response time, and spatial resolution.
• Benchmark pillar‑based modulators against planar silicon controls.

4. Data Analysis and Design Optimisation:

• Use COMSOL and/or MATLAB to quantify resolution improvements.
• Correlate fabrication parameters with imaging performance.
• Establish design rules for next‑generation THz modulators.

Scholarship:

The award will cover the UK tuition fee level, plus a tax-free stipend, currently £21,805, paid at the prevailing UKRI rate for 3.5 years of full-time study. The award also includes a £5,000 research training support grant.

Eligibility:

Home students are eligible to apply. The candidate should have a strong 2.1 Bachelors, or Masters degree in Physics, Materials Science, Electrical Engineering, Photonics, or related disciplines. We welcome applicants with a background in one or more of the following areas:

• Semiconductor processing or microfabrication
• Computational modelling (COMSOL, MATLAB, or similar)
• Experience with optical/THz systems is beneficial but not essential

Curiosity, problem‑solving ability, and enthusiasm for hands‑on experimental work are highly valued.

How to apply:

Candidates should submit an expression of interest by sending a CV and supporting statement outlining their skills and interests in this research area via the above 'Apply' button. If this initial application is successful, we will invite you to submit a formal application.