CHARGE-STATE DEPENDENCES OF POSITRON TRAPPING RATES ASSOCIATED WITH DIVACANCIES AND VACANCY-PHOSPHORUS PAIRS IN SI

Charge state dependences of positron trapping rates associated with divacancies and vacancy-phosphorus pairs in Si have been studied by controlling the Fermi level systematically. The specific trapping rates of both a divacancy and a vacancy-phosphorus pair increase with an increase in the negative charge on them. A positively charged divacancy shows no detectable positron trapping. Such charge state dependences of the positron trapping rates clearly show that the long-range Coulomb interactions between a positron and a charged divacancy or a charged vacancy-phosphorus pair play an important role in the trapping process.