Professor John Cunningham
- Position: Professor
- Areas of expertise: MHz to THz electronic devices and systems; Surface and bulk acoustic waves; on-chip GHz/THz devices and systems; semiconductor devices; interdisciplinary applications of high frequency electronics.
- Email: J.E.Cunningham@leeds.ac.uk
- Phone: +44(0)113 343 0618
- Location: 1.63 School of Electronic and Electrical Engineering
- Website: Googlescholar | ORCID
- Deputy Head of School
- Director of the UK Network for THz Science and Technology Teranet
My research is on the development of high frequency (megahertz to terahertz) electronic and photonic techniques for the interrogation and manipulation of a wide range of systems, with a particular emphasis on semiconductors.
A major theme of my work has been the development of on-chip terahertz systems, which provide a versatile way to confine THz radiation to length-scales far below the diffraction limit of free-space propagating THz radiation. In these systems, pulses of THz radiation are generated using an ultrafast laser, and are then guided through lithographically defined waveguides, where they interact with either samples or devices, before being detected. Since the size of these systems is limited only by lithographic considerations, they are ideally suited to study the THz response of individual mesoscopic systems and nanostructures, for example. We have used this technique to develop many spectroscopy, imaging, and sensing applications, including but not limited to the low temperature THz spectroscopy of polycrystalline chemicals, modulation and detection of plasmons and magnetoplasmons in 2D electron gases, and the scanned imaging of both semiconductors and biological samples.
A second theme of my work is the development of new applications for high frequency (MHz to 10's GHz) surface acoustic waves (SAWs). SAW filters find commercial application as delay lines in mobile phones, but we use SAWs as a way to provide a high frequency perturbations to micro- and nano-structures. The piezoelectric potential which accompanies the mechanical movement of a SAW can be used to push charge through semiconducting materials - the so-called acoustoelectric transport. We demonstrated this effect in graphene for the first time. We have also demonstrated the mechanical alignment and transport of micron scale particles in microfluidic systems mediated by SAWs, and are currently researching the interaction of SAWs with magnetic systems to move domains and skyrmions, with possible applications in low energy computing.
Another recent application for high frequency acoustic waves has been our demonstration of modulation of the light output of terahertz quantum cascade lasers. THz QCLs offer the potential for high data rate communications in both terrestrial and satellite communications, with the picosecond relaxation times in principle enabling modulation rates exceeding 100 GHz. However, in practice, electrical modulation frequencies are usually limited to 10s of GHz, owing to parasitic inductance/resistance of the circuits in which they are embedded. We showed that acoustic waves could be used to overcome these limits; our results were reported on internationally (see https://tinyurl.com/rltx6lm).
Much of the above work makes use of our extensive cleanroom fabrication facilities, which include electron beam lithography, while experiments are undertaken in our world-class high frequency and THz photonics laboratories. Our facilities include Ti:sapphire lasers, and a range of cryostats able to access low temperatures alongside THz excitation.
I am always interested in hearing from potential collaborators and PhD students. If you have ideas for new collaborative projects, or would like to discuss potential PhD topics in related areas, please send me an email.<h4>Research projects</h4> <p>Any research projects I'm currently working on will be listed below. Our list of all <a href="https://eps.leeds.ac.uk/dir/research-projects">research projects</a> allows you to view and search the full list of projects in the faculty.</p>
Research groups and institutes
- Pollard Institute
- Terahertz electronics and photonics