The physics and technology of low-dimensional electronic systems at terahertz frequencies
Lead Research Organisation:
University of Leeds
Department Name: Electronic and Electrical Engineering
Abstract
Over the last 20 years, the study of mesoscopic quantum-confined electronic systems has revealed a wealth of exciting and fundamental physics. These studies show no sign of abating as advances in device fabrication and measurement techniques enable ever more intricate structures and more sophisticated experiments to be made. The characteristic energy scale in many important mesoscopic devices such as two-dimensional electron systems, layered semiconductor structures, semiconductor quantum dots, and laterally-confined wires, dots, and other geometries, corresponds to the terahertz (THz) frequency range (1 THz = 1x10^12 Hz = 4.1 meV), which until recently has been difficult to access. Furthermore, although the majority of studies of mesoscopic systems use dc transport or optical (near-infrared) techniques, invaluable information on the states and dynamics of carriers in condensed matter systems, not obtainable by dc transport methods, can potentially be accessed though the dynamic (high frequency) electronic response. Our vision is to create a step-change in the study of mesoscopic electronic systems by developing and exploiting THz fre-quency technology, and in particular, guided-wave techniques, to probe the THz frequency / picosecond response of quantum-confined electronic systems. We will develop quasi-optical techniques to generate (and detect) single-cycle THz / picosecond electronic pulses adjacent to the mesoscopic system in the cryostat, avoiding the RC bandwidth-limiting problems inherent in previous high frequency (up to the gigahertz range) electrical measurements. We will also develop the methodology to perform picosecond-resolution measurements capable of monitoring the spatial position of single electrons three orders-of-magnitude faster than achieved previously; this will provide a generic technology for the field of mesoscopic physics where the onset of, or change in, a quantum state occurs on a picosecond time scale. This programme, which comprises the symbiotic development of THz frequency science and technology in quantum con-fined electronic systems, will be unique internationally and will open an important new direction for mesoscopic physics.
Organisations
Publications
Burnett A
(2009)
Broadband terahertz time-domain spectroscopy of drugs-of-abuse and the use of principal component analysis
in The Analyst
Burnett AD
(2010)
Calculation and measurement of terahertz active normal modes in crystalline PETN.
in Chemphyschem : a European journal of chemical physics and physical chemistry
Burnett A
(2010)
Calculation of terahertz active normal modes in organic crystals
Hargreaves M
(2009)
Comparison of near infrared laser excitation wavelengths and its influence on the interrogation of seized drugs-of-abuse by Raman spectroscopy
in Journal of Raman Spectroscopy
Burnett AD
(2013)
Effect of molecular size and particle shape on the terahertz absorption of a homologous series of tetraalkylammonium salts.
in Analytical chemistry
Wu J
(2015)
Excitation, detection, and electrostatic manipulation of terahertz-frequency range plasmons in a two-dimensional electron system.
in Scientific reports
Bacon DR
(2016)
Free-space terahertz radiation from a LT-GaAs-on-quartz large-area photoconductive emitter.
in Optics express
Saeed K
(2011)
Impact of disorder on frequency scaling in the integer quantum Hall effect
in Physical Review B
Burnett A
(2012)
Infrared and Raman Spectroscopy in Forensic Science
Description | This project developed a novel technology for the sub-picosecond sampling of nanoscale condensed matter systems, at low temperatures and in high magnetic fields. The method developed uses fibre coupling of 100 fs laser pulses to both excite and detection terahertz frequency range radiation in the sample space of a dilution refrigerator, and led to the first picosecond pulsed measurements of confined plasmons in a 2DEG system. |
Exploitation Route | The project lead to an international patent for on-chip spectroscopy, with relevance to the pharmaceutical and defence sectors. The project provides a basis for the study of nanoscale systems in the terahertz frequency range, which can be exploited for the study of low dimensional semiconductors, nano magnetic (spin injection/detection) systems and picosecond switching devices. |
Sectors | Electronics,Pharmaceuticals and Medical Biotechnology |