Influence of boron on radiation enhanced diffusion of antimony in delta-doped silicon

Abstract

The silicon samples used in this work contain a sequence of alternating boron and antimony spikes grown by molecular beam epitaxy. These samples were irradiated with 2.5 MeV protons at elevated temperatures ranging from 580 °C to 830 °C and characterized by secondary-ion mass spectrometry. The energy of the proton beam was chosen such that the generation rate of point defects can be considered as uniform throughout the delta-doped layers. For each sample the boron and the antimony diffusion coefficient are increased under irradiation as compared to their diffusivity in unirradiated areas. A measurable diffusion of antimony is observed in samples containing both boron and antimony spikes even at temperatures as low as 580 °C while a reference sample containing only an antimony spike do not exhibit any radiation enhanced diffusion, even at 830 °C. The boron diffusion coefficient increases as the irradiation temperature increases but the antimony diffusion coefficient decreases for the highest irradiation temperature investigated.