Interstitial-carbon defects in Si1-xGex -: art. no. 233202

The interstial-carbon (C-i) defect in molecular-beam epitaxy grown, strain relaxed n-or p-type Si1-xGex for 0 less than or equal tox less than or equal to0.50 has been created by 2-MeV proton or electron irradiations, and studied by deep-level transient spectroscopy on p(+)n- and n(+)p-mesa diodes. The energy difference between the shallow acceptor and donor levels of the C-i defect remains at a constant value of 0.8 eV as the Ge content is varied. The migration enthalpy of C-i is independent of composition in the composition range 0 less than or equal tox less than or equal to0.15. The observed increased stability of the C-i defect with increasing x is the result of a decrease in the entropy of the process.