{311} defects in silicon: The source of the loops

Abstract
The annealing kinetics of extended defects in Si+-implanted Si have been investigated by in situ annealing plan-view transmission electron microscopy (TEM) samples in a TEM. A 〈100〉 Czochralski-grown silicon wafer was implanted with 100 keV Si+ at the subamorphizing dose of 2×1014 cm−2. Following implantation, the effect of annealing of 800 °C was studied by in situ annealing. After 5 min of annealing at 800 °C, a dense collection of both {311} defects (3×1011/cm2) and small subthreshold dislocation loops (1×1011/cm2) were observed. Upon subsequent annealing, the {311} defect density decreased rapidly and the loop density increased. The evolution of approximately 500 {311} defects could be followed as a function of annealing time. The unfaulting of a {311} defect was observed to be the source of every subthreshold loop observed to from (about 150 loops in the monitored region). After the initial 5 min anneal at 800 °C, the probability of a {311} unfaulting into a loop was about 50%. Based on these observations, it is concluded that unfaulting of the {311} defects is the source of the subthreshold dislocation loops in nonamorphized ion-implanted silicon. 70% of the loops formed were determined to have a Burgers vector of a/3〈111〉, while 30% were perfect with a Burgers vector of a/2〈110〉.

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