Overview

An overview of all projects currently available can be found here.  More detail on some projects follows.

Quantitative Scanning Probe Microscopy for Nanoscale Semiconductor Devices

Scanning probe microscopes offer a unique ability to study the local surface properties of nanoscale semiconductor devices and materials.  However, all forms of scanning probe interact with and modify the surface of the device they are measuring, masking the true properties of the surface. Understanding and compensating for the detrimental effects is crucial in the move towards truly quantitative measurements on electronic devices.  Successive editions of the International Technology Roadmap for Semiconductors, the driving force of semiconductor industry, highlight the need to decouple the probe-tip interactions from measurements in order to give us a ‘real picture’ of the surface.

Our School has a strong record in applying novel scanning probe techniques to study electronic semiconductor devices, as well as in modelling of scanning probe interactions with electronic devices. You will work with a research team adapting a semiconductor device simulator based on a quantum transport approach to simulate scanning probes interacting with semiconductor materials and devices. Later, thanks to the multidisciplinary nature of the centre, you will have the opportunity to collaborate with biologists and clinicians in order to extend this modelling approach to scanning probe measurements of biological systems. Ideally, you should have a background in physics or engineering, with an interest in high-performance computing and computational modelling.

This project will be supervised jointly by Dr Richard Cobley (RAEng/EPSRC Research Fellow) in the Multidisciplinary Nanotechnology Centre and Dr Karol Kalna (EPSRC Advanced Research Fellow) in the Civil and Computational Engineering Centre, both in the School of Engineering, Swansea University.  In the last Research Assessment Exercise, the Times Higher rated nanotechnology research at Swansea joint fifth in the UK under General Engineering, and Civil Engineering second in the UK. [i]

Informal enquires should be addressed to richard.j.cobley@swansea.ac.uk.

More detailed information

You will modify the existing code for simulation of electron transport in semiconductor transistors, in order to model accurately the interaction of scanning probes with semiconductor heterostructure devices .  The existing code is a 2D simulation which uses the non-equilibrium Green’s function (NEGF) approach to self-consistently solve Poisson’s and Schrodinger’s equations in order to simulate ballistic transport in nano-scaled metal-oxide-semiconductor field-effect transistors (MOSFETs).  Previously this was used mostly for digital applications like memories and CPUs. The non-equilibrium Green’s Functions approach effectively solves the time-independent Schrodinger equation in a 2D cross-section of the device. The self-consistently calculated electrostatic potential in the 10 nm gate length of a double gate MOSFET is shown in the figure.

Comparing scanning probe microscopes for studying nanoscale devices

Scanning probe microscopes offer a unique ability to study the local surface properties of nanoscale devices and materials.  However, it is well established that all forms of scanning probe interact with and modify the surface they are measuring, to varying degrees.  Scanning probe techniques are increasingly finding uses in characterising and assessing semiconductor devices, but debate is rife at the moment about which scanning probe technique is most suitable for analysing nano-scale electronic devices, and which, if any, can offer quantitative measurements at this scale.  The Multidisciplinary Nanotechnology Centre at Swansea has a vast array of equipment for nanotechnology, including several ultra high vacuum and ambient scanning probe microscopes, which offer a rare chance to compare competing techniques side by side.  With a history of developing novel scanning probe techniques to study active devices, and modelling scanning probe interactions, we are well placed to be at the heart of this debate.

The successful candidate will develop and continue work on scanning probe microscope analysis of semiconductor devices, both in ultra high vacuum and in air, with a view to evaluating the suitability of a range of competing techniques.  Candidates should ideally have a background in engineering, physics or a related subject.  Experience of using scanning probe microscopes is not essential.  The wider project involves both experimental and theoretical aspects of this field, and the PhD project can be adapted to suit the abilities and interests of the successful candidate.

This project will be supervised by Dr Richard Cobley in the Multidisciplinary Nanotechnology Centre in the School of Engineering at Swansea University.  In the last Research Assessment Exercise nanotechnology at Swansea was entered under General Engineering and was rated joint fifth in the UK by the Times Higher.¹   Informal enquires should be addressed to richard.j.cobley@swansea.ac.uk.