Physics projects for Y3 and Y4 students

Project description

Spectroscopy of ultrathin films

(supervisor: Andrew Evans)

Nature of project: experimental, data analysis

Available to students on full-time physics degree schemes or joint students.

Project description and methodology

The properties of solid materials can be very different when the physical size in one or more dimension is reduced to the scale of nm. These low-dimensional structures can take the form of ultrathin films, wires and dots. Nanostructures of metals, for example, can exhibit large differences in optical absorption and electrical conductivity as the size is varied. In these metal nanostructures, electromagnetic radiation can effectively couple to collective electron oscillations or plasmons and this effect can be exploited, for example, in breaking the diffraction limit for the localisation of light. The physics of light absorption and charge transport in nanostructures is also central to the performance of light capture technologies such as photovoltaic cells. In this experiment, the optical transmission and reflection in thin conducting films will be investigated as the film thickness is reduced to the nanoscale and compared to the electrical conductivity. The project will require the set-up of optical and electrical measurement equipment using appropriate components and the use of existing pieces of apparatus and it will also involve the use of vacuum equipment for the growth of thin films of metals such as gold and silver on transparent substrates. The project will also involve instrument control software and computer modelling of the data.

A successful project will develop beyond the above in one/some of the following directions:
The project could be extended to other metal films and substrates that are transparent over selected wavelength ranges, in particular flexible substrates and materials that are both transparent and conducting. There is also scope to optimise the light source and detection systems.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: As a 4th year project, it will include in-situ measurements during thin film growth and will explore light absorption and charge transport in other low dimensional structures e.g. graphene

Please speak to Andrew Evans (dne) if you consider doing this project.

Initial literature for students:

  1. Optical Properties of Solids, Mark Fox (Primo)
  2. Surface Plasmon Resonance : Methods and Protocols, Nico J. Mol Fischer (Primo)
  3. Introduction to Metal-Nanoparticle Plasmonics, Matthew Pelton, Garnett W Bryant (Primo)

Novelty, degree of difficulty and amount of assistance required

Moderate difficulty that involves the use of some research equipment. Technical assistance will be required for the operation of the vacuum equipment

Project milestones and deliverables (including timescale)

milestoneto be completed by
Outline of optical/electrical systemsChristmas
Growth of semi-transparent metal filmsend of February
Data measurement system completeEaster
Data analysis finalisedEaster

Students taking this project will have to submit a full risk assessment form