The annealing kinetics of extended defects inSi+-implanted Si have been investigated byin situannealing plan-view transmission electron microscopy (TEM) samples in a TEM. A ⟨100⟩ Czochralski-grown silicon wafer was implanted with 100 keVSi+at the subamorphizing dose of2×1014cm−2.Following implantation, the effect of annealing of 800&hthinsp;°C was studied byin situannealing. After 5 min of annealing at 800&hthinsp;°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&hthinsp;°C, the probability of a {311} unfaulting into a loop was about 50&percent;. 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&percent; of the loops formed were determined to have a Burgers vector ofa/3⟨111⟩,while 30&percent; were perfect with a Burgers vector ofa/2⟨110⟩.©1998 American Institute of Physics.