Abstract
Copper impurities affect optical and electronic properties in a diverse range of materials. Using IR spectroscopy, we provide evidence for a shallow Cu acceptor in Si. The observation of excitation lines indicates a Cu acceptor with a hole ionization energy of only 27 meV, which is shallower than any of the group-III acceptors. The observed center has an IR spectrum that is characteristic of a hydrogenic acceptor. Variable-temperature Hall-effect measurements confirm this result. The observation of shallow, hydrogenic behavior is consistent with a universal level model, in which the Cu acceptor level is fixed relative to vacuum, irrespective of the host.
- Received 10 September 2013
- Revised 18 August 2014
DOI:https://doi.org/10.1103/PhysRevB.90.165204
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