Physical Review B, 72(23), 235205 (2005)

Passivation of copper in silicon by hydrogen

C. D. Latham (a), M. Alatalo (a), R. M. Nieminen (b), R. Jones (c), S. Öberg (d), P. R. Briddon (e)

(a) Department of Electrical Engineering, Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta, Finland

(b) Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, FIN-02015 HUT, Finland

(c) School of Physics, University of Exeter, Exeter, EX4 4QL, United Kingdom

(d) Department of Mathematics, University of Luleå, Luleå, SE-97187, Sweden

(e) Physics Centre, School of Natural Science, University of Newcastle upon Tyne, Newcastle NE1 7RU, United Kindom

(Received 27 May 2005; published 20 December 2005)

Abstract

The structures and energies of model defects consisting of copper and hydrogen in silicon are calculated using the AIMPRO local-spin-density functional method.  For isolated copper atoms, the lowest energy location is at the interstitial site with T_d symmetry.  Substitutional copper atoms are found to adopt a configuration with D_2d symmetry.  We conclude that the symmetry is lowered from T_d due to the Jahn-Teller effect.  Interstitial hydrogen atoms are found to bind strongly to substitutional copper atoms with an energy that is more than the difference in formation energy over the interstitial site for Cu.  The resulting complex has C_2v symmetry in the -2 charge state where the H atom is situated about 1.54 Å away from the Cu atom in a [100] direction.  In other charge states the symmetry of the defect is lowered to C_s or C₁.  A second hydrogen atom can bind to this complex with nearly the same energy as the first.  Two structures are found for copper dihydride complexes that have nearly equal energies; one with C₂ symmetry, and the other with C_s symmetry.  The binding energy for a third hydrogen atom is slightly more than for the first.  Calculated electronic levels for the model defects relative to one another are found to be in fair to good agreement with experimental data, except for the copper-dihydride complex.  The copper trihydride complex has no deep levels in the bandgap, according to our calculations.

DOI: 10.1103/PhysRevB.72.235205

PACS: 61.72.Bb, 61.72.Ji, 61.72.Tt, 71.15.Mb

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