Report of Visit to UK by Professor Stefan Estreicher
(Texas Tech University)

19-25 March 1996

Visit to London by Professor Stefan Estreicher

Andrew Fisher
Department of Physics and Astronomy
University College London
Gower Street
London WC1E 6BT
Email: andrew.fisher@ucl.ac.uk

In the London part of his trip, Professor Estreicher visited the Condensed Matter and Materials Physics group at University College London. He gave a talk on `Passivation processes in silicon' on 25 March, which was attended by an audience of about thirty people. The audience was drawn from the group at University College, from the Physics Department at King's College, from the Semiconductor IRC at Imperial College, and from the Rutherford Appleton Laboratory.

There was a lively discussion at the seminar and over the lunch following, which focussed (among other things) on

1. The role of basis-set superposition error in electronic structure calculations of defects;

2. The importance of zero-point energy in the free energies of defects involving light interstitials (particularly hydrogen);

3. The possible identity of rapidly-diffusing passivating species which are implied by recent developments in solar cell technology;

4. The candidate structures for various defect-hydrogen complexes, and their possible uses in passivation.

Visit to Edinburgh by Professor Stefan Estreicher

Graeme Ackland
Dept. of Physics and Astronomy
The University of Edinburgh
James Clerk Maxwell Building
The King's Buildings
Mayfield Road
Edinburgh EH9 3JZ
Email: g.j.ackland@ed.ac.uk

Prof Eistreicher spent two days with us in Edinburgh, speaking with all members of the Condensed Matter Group involved with solid state simulation. We had very helpful discussions regarding the mechanism for neutral self-interstitial diffusion in silicon, a topic of mutual interest, and he had some interesting observations to make regarding our discovery of threefold rings of carbon atoms in amorphous carbon, in particular on the possibility that they might be remnants of C_3 clusters (stable as equilateral triangles) from the high temperature starting phase. His talk, on work carried out some time ago regarding diffusion in silicon, but excluding his very recent discoveries of hydrogen enhanced diffusion of oxygen, was delivered to a small audience of about 20.

Although, in the event, I was unable to arrange the good weather I had promised, Prof. Eistreicher also enjoyed a few days of being a tourist in Edinburgh. We also invited Stefan to a group meal which was well enjoyed by all, even the haggis pizza. The whole group found Prof Eistreicher's work of interest and him very approachable. In all it was a very successful visit, both scientifically and socially, and I should like to thank CCP5 for making it possible.