Overview. The LDSD group in the Department of Physics and Astronomy was founded in 1991 and currently has 23 PhD students and 14 postdoctoral workers involved in 5 main research topics covering both experimental and theoretical semiconductor physics. The five main topics are spin control in individual quantum systems, nano-optical structures and circuits, non-linear polariton phenomena in microcavities, coherent control on the nanoscale, 2D materials and quantum cascade and quantum dot lasers. Full details of the research are given under the specific research headings on our research pages. The success of our research at top levels in the last 5 years may be judged for example by our 14 publications in Nature family journals, 11 in Physical Review Letters and 110 invited talks over this period (for a listing of our publications, please click on the link Publications).
Funding and laboratories. The research carried out by the group is funded principally by EPSRC, but also through a variety of European Grants including the European Research Council, Marie Curie ITN and Future and Emerging Technology STREPs. This funding has permitted us to establish a variety of well equipped labs covering the spectral ranges from the mid-IR to the ultraviolet, a variety of timescales from continuous wave to ultrafast, spatially resolved capabilities (below 100nm) and temperatures from room temperature down to liquid helium temperature. Substantial investment continues to be made into infrastructure, including in the last five years a streak camera with 5psec time resolution, 6 separate experimental setups equipped with low temperature piezo-stages with nanometre scale stability over many hours/days coupled with high magnetic fields up to 10Tesla, a vector magnet with programmable field direction, high stability lasers and advanced charge coupled device detectors.
Group Meetings. An important part in our activities is played by weekly group meetings where talks are given by PhD students and postdocs, approximately every 2-4 weeks by seminars by respected external speakers, monthly progress meetings attended by the whole group and six monthly Away Days. Links to these programmes are given at the top left of this page.
The group is concerned with the study of the optical, electronic and vibrational properties of a wide range of bulk and low dimensional semiconductor structures and devices.The focus over the last five years is concerned with the understanding and control of quantum properties in nanoscale systems. These are studied both for their fundamental interest and for their application in light emitting applications.
Details of the activities of the research sections may be found on the subpages provided for this overview. In the following text we provide an overview of the experimental techniques we employ and of the equipment available.
Experimental methods include photoluminescence (PL), electroluminescence (EL), photoluminescence excitation (PLE), photocurrent, (PC) and ultrafast spectroscopy, together with reflection, Raman scattering, magneto-optical and transport studies. In many cases these techniques are now applied to the study of nanoscale systems using highly stable low temperature setups, based around piezo-electrically controlled stages with nanometre scale precision.
The group is very well equipped to carry out a wide range of experimental studies, using continuous wave gas and solid state lasers, both cw and pulsed tunable lasers, and high stability ring and semiconductor single mode lasers. Spectroscopy is carried out using high resolution single and double monochromators, Fourier transform spectrometers, tunable lasers and high precision wavelength meters, with detection by a wide variety of charge coupled device detectors and avalanche photodiodes. Structure and device studies are carried out over a wide temperature range from 1.5K to above room temperature, using custom designed cryostat systems.
Most of our research is carried out in close collaboration with the National Centre for III-V Semiconductors at Sheffield where the majority of our structures and devices are grown and fabricated. This facility contains two MBE reactors for the growth of GaAs and InP based materials and three MOVPE reactors for the growth of similar materials. The presence of this high technology facility in Sheffield is highly advantageous for our research, and also provides the capability for high level training of PhD students in device fabrication, as well as in advanced physics.
Our present contacts include: University of Nottingham, Cambridge University, Oxford University, University of Southampton, University of St Andrews, University of Bristol, University of Cardiff, Paul Drude Institute Berlin, University of North Carolina, ENS Paris, LPN France, EPFL Switzerland, University of Dortmund, Institute for Solid State Physics Chernogolovka and Toshiba Research Laboratories Cambridge.