The interstitial-C (Ci) defect in molecular-beam epitaxy grown, strain-relaxed n- or p-type Si1–xGex (where x ranged from 0 to 0.50) was created by 2MeV proton or electron irradiation, 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 Ci defect remained at a constant value of 0.8eV as the Ge content was varied. The migration enthalpy of Ci was independent of composition in the x-value range of 0 to 0.15. The observed increased stability of the Ci defect with increasing x was the result of a decrease in the entropy of the process.

Interstitial-Carbon Defects in Si1–xGex. A.Nylandsted Larsen, A.Bro Hansen, D.Reitze, J.J.Goubel, J.Fage-Pedersen, A.Mesli: Physical Review B, 2001, 64[23], 233202 (4pp)