Complexing in silicon induced by surface reactions: Electron paramagnetic resonance detection of a 6-platinum cluster

Complexing of 5dn impurities from supersaturated solutions in silicon occurs during thermal processing at intermediate temperatures subsequent to fast or retarded quenching. Doping of silicon with 5dn transition-metal ions in a wet chlorine-containing atmosphere provides the formation of various complex defects, which differ from those formed after doping under protecting conditions. As an example a 6-platinum cluster of trigonal symmetry is presented. The analysis of electron-paramagnetic-resonance data uniquely reveals six geometrically equivalent platinum ions strongly interacting with probably two silicon atoms. A tentative model assumes the introduction of hydrogen during the high-temperature surface reaction. Passivation of the platinum acceptors might be the condition for the formation of the clusters at intermediate temperatures. The formation of similar clusters at appropriate temperatures would explain the higher thermal stability of high-temperature passivation, recently reported.