A B-doped epilayer was used to investigate the interaction between end-of-range dislocation loops (created by Ge+ implantation) and excess point defects which were generated by low doses (1014/cm2) of implanted B+. The B doping spike was grown in, by means of chemical vapor deposition, at a depth of 800nm below the surface. The intrinsic diffusivity of the B in the doped epilayer was determined by annealing the as-grown layer. The end-of-range (type-II) dislocation loops were created by using 2 overlapping room-temperature Ge+ implantations, of 75 and 190keV, to a dose of 1015/cm2. During annealing, the amorphous layer re-grew and a layer of type-II dislocation loops formed at a depth of about 230nm and with a density of about 8 x 1010/cm2. The enhanced diffusivity in the buried B layer, due to type-II loop formation by Ge+ implantation, was observed to increase (within some 150 to 300s), from 1500 to 2500 times the intrinsic diffusivity value, before falling back to intrinsic levels after 0.5h at 800C. Low-energy (8keV) implantation of B+, to a dose of 1014/cm2 and a range of 32nm, into material without loops resulted in an average enhancement to 1540 times the B epilayer diffusivity after 150s at 800C. The diffusivity fell back to intrinsic levels after 300s at 800C. When an annealed layer of loops was introduced (before, and deeper than, subsequent low-energy implanted B+), annealing of the implanted B+ produced no measurable enhancement of the buried B-layer diffusivity. It was deduced that the kinetics of interaction between the dislocation loop layer and the damage-induced interstitials were mainly diffusion-limited, and that the loops absorbed a significant fraction of the interstitials which were produced by low-energy B+ implantation.

J.K.Listebarger, H.G.Robinson, K.S.Jones, M.E.Law, D.D.Sieloff, J.A.Slinkman, T.O.Sedgwick: Journal of Applied Physics, 1995, 78[4], 2298-302