The terahertz frequency range sits between the microwave and mid-infrared regions of the electromagnetic spectrum, but has long resisted exploitation owing to difficulties in fabricating convenient sources and detectors; terahertz radiation is too high in frequency to be generated by the electronic techniques used in mobile telephones, but too low in frequency to be produced by the optical techniques exploited in, for example, CD player lasers.
However, the last twenty years have witnessed a remarkable growth in the field owing to the development of innovative sources, detectors, and imaging systems—and in particular, the quantum cascade laser. These developments have enabled a wide range of imaging and spectroscopy studies in which the selective absorption or transmission of terahertz radiation has provided unique and fundamental information about the physical and chemical properties of materials in this relatively unexplored region of the spectrum. Recent commercial application of terahertz instrumentation is now finding application in the pharmaceutical and automotive industries, and in high-resolution fault isolation in semiconductor devices and 3D imaging of integrated circuits, inter alia. We are looking to support three postgraduate research projects, each addressing a complementary aspect of the terahertz field.
Through the use of broadband terahertz spectroscopy, a wide range of organic and inorganic crystalline materials, and gases, have been shown to exhibit characteristic spectra and vibrational modes in the terahertz frequency range. Carrier scattering and dephasing events in many solid-state materials including bulk semiconductors, conducting polymers, organic crystals, and superconductors, occur on timescales of tens to hundreds of femtoseconds making terahertz frequency techniques ideal for studying carrier dynamics. This has allowed fundamental phenomena to be addressed.
This PhD project will explore the use of terahertz techniques to investigate the fundamental properties of materials of contemporary relevance including nanostructures, quantum-confined structures such as two- and one-dimensional electronic systems, quantum dot devices, intersubband semiconductor devices, topological insulator materials, and solid-state Rydberg systems.
Funding covers the cost of tuition fees as well as a maintenance grant to match the standard Research Council rates (around £14,777 in session 2018/19). Funding duration is 3 years.