
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 deeplevel defects in
semiconductors, in particular, silicon.
I am still personally involved in the following projects:
 Transitionmetalrelated defects in Si
 Isolated substitutional and interstitial defects
 The interaction of atomic hydrogen with transitionmetal
impurities.
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
Laplace
DLTS).
 Transitionmetal pairs: AuAu & AuFe
 Vacancy related defects in Si
 The study of the structure of the lattice
monovacancy in 5 different charge states. The metastability of the
positively charged state (D_{2d}) is analysed.

The structural and electrical properties of the lattice divacancy.
The models by Watkins & Corbett (rebondingbypairs) and
Saito & Oshiyama (resonantbond 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
vacancyH_{n}
complexes (n = 1, 2, 3 and 4)
Animated 3Dwavefunction
isosurface corresponding to the
highest occupied spinup KohnSham eigenvalue of neutral VH_{3}
 Oxygenvacancy pair (Si:Acentre) and its interaction
with H
 Phosphorusvacancy pair (Si:Ecentre)
 Germaniumvacancy pair
(Apparently Ge can lock
single vacancies. If you assume that this pair is still very
vacancylike, Ge_{Si}:V should exhibit similar deep levels to those of the
isolated single vacancy...)
 Tinvacancy pair
 Interaction of atomic hydrogen with the above: partially
Hpassivated V_{2}, E and Acentres.
The projects described above are being carried out in close
collaboration with two experimental groups:
 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
semiconductors.
This is a selfconsistent local density functional pseudopotential
cluster method.
A few notes about the AIMPRO
method... 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)
