The effects of heavy Sb ion implantation and annealing (at 800 to 1000C) upon B delta-doped superlattices in Si layers that had been grown by molecular beam epitaxy were analyzed. Secondary ion mass spectroscopic measurements of these structures were used to investigate the generation and diffusion of point defects. An enhanced diffusion of B, from delta-doped spikes in as-grown and Sb-implanted layers, was described theoretically by solving the diffusion equation; using a point defect model for various initial point defect distributions. In order to fit the experimental secondary ion mass spectrometry profiles, the diffusion coefficient of positively charged B interstitials had to be changed from a default value of 0.68, to 0.45cm2/s. It was found that the molecular beam epitaxial growth process produced interstitials and vacancies with an almost constant average value of about 5 x 1016/cm3. The Sb-implanted B modulation-doped superlattice permitted the depth profile of the defect concentration to be deduced. The main features of the B diffusion profile in the superlattice could be fitted by assuming a constant overlap of 5 x 1016/cm3 for interstitials and vacancies that were caused by the molecular beam epitaxial growth. The distribution which was deduced from damage calculations consisted of a flat high-concentration region with an exponential decrease towards the level of the molecular beam epitaxial layer.

Radiation Hardening of Pure Silica-Core Optical Fibers by Ultra-High Dose γ-Ray Pre-Irradiation. D.Krüger, U.Jagdhold, R.Kurps, H.P.Zeindl: Journal of Applied Physics, 1995, 78[8], 5008-12