A transmission electron microscopic investigation was made of the elimination of defects which were produced by the implantation of fine (less than 50nm in diameter) columns. In the case of heavy doping with As or BF2, the as-doped structure was amorphous and recrystallization was observed after annealing at temperatures above 600C. In columns with diameters greater than 20nm, the typical defects were dislocations that were parallel to {111} planes, twins which formed on {111} planes, and Si micro-crystals which were misoriented with respect to the bulk substrate. No defects were observed in ultra-fine columns with diameters of less than 20nm. It was suggested that defects that formed during ion implantation diffused to the surface or to the Si/SiO2 interfaces of ultra-fine Si columns during annealing. The results indicated that it was possible to fabricate a one-dimensional pn junction with no defects.

H.Sukesako, T.Kawasaki, H.Sakaue, S.Shingubara, T.Takahagi, Y.Horiike: Japanese Journal of Applied Physics, 1996, 35[1-2B], 1045-8