Proton-enhanced diffusion and vacancy migration in silicon

Publisher Website
Google Scholar
Abstract
Single crystals of silicon containing prediffused arsenic, boron, and phosphorus profiles are bombarded at 600–900 °C with 250–360‐keV protons. Under conditions approaching ideality (low impurity concentration and less than 1013 protons/cm2 sec) enhanced impurity diffusion appears to proceed in an uncomplicated manner which is well described by steady‐state kinetic treatment. At high temperatures and very low bombardment fluxes the enhanced‐diffusion coefficients are observed to be temperature independent and first‐order dependent upon flux. At moderately increased damage rates, particularly at lower temperatures, the diffusivities become temperature dependent and a half‐order flux dependence is observed. The results are explained by assuming proton‐enhanced diffusion to be controlled by the migration of split monovacancies (semivacancy pairs). Consistency with annealing studies of radiation‐induced defects at much lower temperatures and with thermally activated diffusion studies at higher temperatures is attained by assuming a 1.47‐eV migrational enthalpy and a 3.66‐eV enthalpy of formation for the uncharged defect.