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Oxygen diffusion in silicon

During his doctoral studies in Oxford and subsequently, John Murphy and his colleagues (particularly Peter Wilshaw, Robert Falster and Semih Senkader) used a novel dislocation locking technique to investigate the transport of oxygen in silicon. The analysis of the stress required to unpin locking impurities from dislocations pinned by oxygen for different times and temperatures allows us to deduce the diffusivity of oxygen. Our work on the transport of oxygen in Czochralski silicon reproduced existing measurements of diffusivity (including those by SIMS) at high temperatures (>700ºC), but at low temperatures where conventional techniques are unsuitable (350 to 600ºC) gave evidence for enhanced oxygen diffusion. The dependence of the behaviour on oxygen concentration strongly suggests that the oxygen dimer is responsible for this enhanced transport. The more recent work focussed on oxygen transport in silicon containing high concentrations of dopants (boron, arsenic, germanium) to understand the effect of lattice strain and Fermi level position.

Key publications

The stress required to move dislocations away from locking oxygen impurities

The effective diffusivity of oxygen in silicon