Nanoscale optoelectronic characterisation of low-dimensional Dirac materials for terahertz device applications

点击翻译按钮获取中文摘要

Dirac materials have emerged as promising candidates for energy-efficient device applications, owing to their perfectly-conducting surface states and doping tuneability. Recent studies have also demonstrated that are good emitters of terahertz radiation. By exploiting their bandstructure topology, all-optical control of the emitted THz waveform can also be accomplished. In particular, polarisation control can be achieved simply by switching the helicity of photoexcitation light. This is an important result for terahertz device applications, as to date polarisation control has been elusive and required pulse shaping. This project will investigate novel low-dimensional topological materials, such as the Dirac semi-metal cadmium arsenide, to assess the suitability for terahertz device applications. Terahertz spectroscopy and microscopy will be used to perform non-contact, non-destructive optoelectronic characterisation of these materials on micron and nanometre length scales respectively. This will allow key transport parameters, such as mobility, carrier lifetime and extrinsic carrier concentration, to be mapped on both length scales, providing unique insight into the underlying physical mechanisms governing transport in these materials that will directly feed into development of next-generation devices (namely terahertz photodetectors).