Western University Physics adn AstronomyWestern Science

Peter Simpson, Professor and Associate Vice-Provost

Peter Simpson

Contact Information

Office: PAB 210
Tel: (519) 661-2111 x83390
E-mail: psimpson [at] uwo [dot] ca

Personal Web Page
Interface Science Western

Research Areas

Condensed matter physics
Silicon photonics
Defects in materials
Positron annihilation

 


Research Interests

My research involves manipulating materials  at the nanoscale, including “defect engineering” – the use of defects to control or modify material properties.

In the area of silicon photonics (in collaboration with Prof. Lyudmila Goncharova) we create silicon nanocrystals, which can be used as light emitters.

Fibre-optic communication is used to transmit data at high speeds using light. There is a drive to develop all-optical processing, eliminating the conversion between light and electrical signals, and taking advantage of the superior speed that all-optical processing can offer. It is desirable that this capability be developed in silicon, rather than in more exotic materials, for reasons of materials cost, and compatibility with the existing highly evolved silicon processing techniques that have been developed over ~5 decades.

The vision of an all-silicon optical chip is hampered by the lack of a suitable silicon-based light source. A promising candidate for this role is silicon nanocrystals (Si-nc) formed in a matrix of silicon oxide. We  grow Si-nc by ion implantation and annealing, and study the physical processes involved in the growth, and the mechanisms of luminescence including quantum confinement.

I use positron annihilation as a technique to probe defects in materials. Point defects (vacancies, i.e. atoms missing from the crystal structure, and impurities) determine the electronic properties of materials used for integrated circuits. To develop new materials and processes, an understanding of defect structures and behaviour is vital, and will become more so in the future as devices are made smaller and faster. My laboratory includes a well equipped positron accelerator facility, and (in collaboration with Profs. Peter Mascher and Andy Knights, McMaster University) we are constructing a high-intensity positron facility using the McMaster Nuclear Reactor as a source of positrons for materials research.  This world class facility is funded by the Canada Foundation for Innovation (CFI).

 

Publications

Silicon photonics

  • Quantum confinement in Si and Ge nanostructures
    EG Barbagiovanni, DJ Lockwood, PJ Simpson, LV Goncharova, Journal of Applied Physics 111 (3), 034307-034307-9  (2012)
    (this was the third-most downloaded paper from JAP in the first quarter of 2013!)
  • Probing energy transfer in an ensemble of silicon nanocrystals
    H Jayatilleka, D Diamare, M Wojdak, AJ Kenyon, CR Mokry, PJ Simpson, AP ...
    Journal of Applied Physics 110 (3), 033522-033522-9  (2011)
  • Electronic structure study of ion-implanted Si quantum dots in a SiO_ {2} matrix: Analysis of quantum confinement theories
    EG Barbagiovanni, LV Goncharova, PJ Simpson
    Physical Review B 83 (3), 035112   (2011)
  • Role of vacancy-type defects in the formation of silicon nanocrystals
    CR Mokry, PJ Simpson, AP Knights
    Journal of Applied Physics 105 (11), 114301-114301-6 (2009)
  • Light emission from Si nanoclusters formed at low temperatures
    XD Pi, OHY Zalloum, T Roschuk, J Wojcik, AP Knights, P Mascher, PJ Simpson
    Applied physics letters 88 (10), 103111-103111-3    (2006)

Positron Annihilation

  • The effect of vacancies on the microwave surface resistance of niobium revealed by positron annihilation spectroscopy
    A Romanenko, CJ Edwardson, PG Coleman, PJ Simpson
    Applied Physics Letters 102, 232601  (2013)
  • Influence of isotopic substitution and He coimplantation on defect complexes and voids induced by H ions in silicon
    O Moutanabbir, B Terreault, M Chicoine, F Schiettekatte, PJ Simpson
    Physical Review B 75 (7), 075201  (2007)
  • Observation of fluorine-vacancy complexes in silicon
    PJ Simpson, Z Jenei, P Asoka-Kumar, RR Robison, ME Law
    Applied physics letters 85 (9), 1538-1540  (2004)

Professional Activities

Co-organizer of:

  • 2006 International Conference on Positron Annihilation ICPA-14
  • 1999 Positron Studies of Semiconductor Defects PSSD-99
  • 1990 Slow Positron Beam Techniques SLOPOS-4