I have just finished a PhD in theoretical physics,
working in the Theoretical Semiconductor Physics Group under the supervision of Dr. Bob Jones.
The aim of my PhD was the study of deep-level defects in
semiconductors, in particular, silicon.
I am still personally involved in the following projects:
The projects described above are being carried out in close
collaboration with two experimental groups:
- Transition-metal-related defects in Si
- Isolated substitutional and interstitial defects
- The interaction of atomic hydrogen with transition-metal
Using a Local Density Functional cluster method (see
below) with an
empirical correction, we can extract the donor and acceptor levels
with an accuracy of around 0.2 eV.
This allows the characterisation of defects responsible for deep traps
observed by capacitance measurements (e.g., DLTS or
- Transition-metal pairs: Au-Au & Au-Fe
- Vacancy related defects in Si
- The study of the structure of the lattice
mono-vacancy in 5 different charge states. The meta-stability of the
positively charged state (D2d) is analysed.
The structural and electrical properties of the lattice di-vacancy.
The models by Watkins & Corbett (rebonding-by-pairs) and
Saito & Oshiyama (resonant-bond model) are to be compared,
using a very large cluster of 386 atoms.
- The structural and electrical properties of
defects in irradiated & implanted silicon:
- The vibrational and electrical properties of
complexes (n = 1, 2, 3 and 4)
isosurface corresponding to the
occupied spin-up Kohn-Sham eigenvalue of neutral VH3
- Oxygen-vacancy pair (Si:A-centre) and its interaction
- Phosphorus-vacancy pair (Si:E-centre)
- Germanium-vacancy pair
(Apparently Ge can lock
single vacancies. If you assume that this pair is still very
vacancy-like, GeSi:V should exhibit similar deep levels to those of the
isolated single vacancy...)
- Tin-vacancy pair
- Interaction of atomic hydrogen with the above: partially
H-passivated V2, E- and A-centres.
- J. Weber (MPI, Stuttgart - Germany)
- B. Bech Nielsen (IPA, Aarhus - Denmark)
AIMPRO - an acronym for Ab
Initio Modelling PROgram - allows the study of structural,
electrical and vibrational properties of defects in
This is a self-consistent local density functional pseudopotential
A few notes about the AIMPRO
Or the full monty:
The Ab Initio Cluster Method and the
Dynamics of Defects in Semiconductors
By R. Jones and P. Briddon
(To appear in Identification of Defects in Semiconductors,
Ed. M. Stavola and Semiconductors and Semimetals Treatise
Eds. R. K. Willardson, A. C. Beer and E. R. Weber, Academic Press)