Head of the Ctr for Electronic Devices & Materials
MERI-Materials and Research Engineering Institute
Materials and Engineering Research Institute
Sheffield Hallam University City Campus
44 (114) 2254037
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My research concentrates on the electrical and optical properties of impurities and defects in semiconductors, primarily, but not exclusively, those in Group IV, identifying the significance of the defects in semiconductor device operation. Such studies are in support of electronic device development. I use the electrical characterisation technique of Deep Level Transient Spectroscopy (DLTS), and the high resolution version Laplace DLTS, together with photoluminescence, electron microscopy and I work closely with theoreticians on a range of defect problems.
I am particularly interested in defects that occur as a result of device or material processing. Recent publications cover ion implantation damage in silicon, H in Si, and dislocations in Si. I am currently working on understanding mechanisms by which enhanced boron diffusion in IC processing can be prevented, how dislocation interactions with light elements can contribute to wafer hardening, and the defects present in p-wells in MOS transistors after very high dose ion implants for ultra shallow junctions. Since my move to Sheffield Hallam University, I have broadened my interests to include defects in semiconducting diamond and GaN. There is an urgent need in GaN to understand the electrical effects of Mg which is a promising candidate for an acceptor, but little understood. In all these areas I work closely with industry in the UK and in Europe on technologically relevant defect problems; our studies in MERI will enable them to better understand the impact of defects on the device performance, and to be able to relate this to processing routines.
I have also carried out extensive work on rare earths in Si as light emitters, and this work is now being extended into nanocluster-sensitised emission for visible light emitters in group IV semiconductors.
- 'High Resolution Deep Level Transient Spectroscopy applied to Extended Defects
in Silicon', J H Evans-Freeman, D Emiroglu, K D Vernon-Parry, J D Murphy,
P R Wilshaw, J Phys:Condensed Matter, 17, S2219, (2005)
- 'High resolution electrical studies of vacancy-rich and interstitial-rich
regions in ion-implanted silicon', N Abdelgader and J H Evans-Freeman, J Appl
Phys, 93, pp 5118 - 5124 (2003)
- 'High Resolution Minority Carrier Transient Spectroscopy of Si/SiGe/Si Quantum
Wells', M A Gad and J H Evans-Freeman, J Appl Phys 92 5252 (2002)
- 'High Resolution Deep Level Transient Spectroscopy Studies Of The Vacancy-Oxygen
and Related Defects In Ion-Implanted Silicon' J H Evans-Freeman, P Y Y Kan,
N Abdelgader, J Appl Phys 92 3755 (2002)
- High resolution deep level transient spectroscopy and process-induced defects
in silicon, J H Evans-Freeman , D Emiroglu, and K D Vernon-Parry, Mat Sci
Eng B, 114, 307-311 (2004)