A positron beam study of vacancy–impurity complexes in inert gas ion-implanted silicon

Abstract

Silicon (100) wafers have been implanted with 1×1015 He+ or Ar+ ions/cm2 and the vacancy (V)–He or –Ar complexes induced have been investigated with positron lifetime and coincidence Doppler broadening measurements using a positron beam. He+ ion implantation into Si gives rise to formation of V2He complexes, which are transformed into VxHey (x–y=1) complexes by annealing at 300°C. The amorphous phase induced by Ar irradiation of Si is transformed into a crystalline phase around 700°C. The crystallization accompanies formation of V–Ar complexes with six vacant sites, and these complexes are found to be stable above 800°C. These results have proved that positrons are very useful probes to study the chemical state of vacancy-inert gas atoms complexes.