Copper passivation of boron in Si1-xGex alloys and boron reactivation kinetics

Copper passivation of boron in SiGe layers has been investigated by the use of Schottky barrier structures prepared by the deposition of copper on bor on-doped SiGe alloys at room temperature. The boron passivation occurs at r oom temperature after Cu deposition and diffusion in the alloy. The Cu diff usivity is enhanced by dislocations and retarded by increasing the Ge conte nt and (or) the compressive strain. The mechanisms for passivation seem sim ilar to those evidenced for pure silicon: the fast-diffusing interstitial C u+ passivates the boron accepters by forming neutral B-Cu complexes. The re activation of boron is partially obtained after annealing at 200 degreesC w hile the Cu3Si1-xGex phase is formed. The reaction kinetics are first order with an activation energy of 0.76 eV. (C) 2001 Elsevier Science B.V. All r ights reserved.