Near-surface defects in hydrogen-plasma-treated boron-doped silicon studied by positron beam spectroscopy

Near-surface vacancy-type defects have been studied by positron beam spectr oscopy in three boron-doped Si wafers; a control sample, second sample expo sed to atomic hydrogen in electron cyclotron resonance (ECR) plasma, and a third sample annealed at 500 degrees C following plasma treatment. From the analysis of the Doppler broadening spectra, measured as a function of posi tron implantation depth, we obtain positron diffusion lengths of about 100 and 250 nm for the damaged layer and bulk of the wafer, respectively. For t he plasma-treated wafer, our measurements provide a defect density of about 5 x 10(17) cm(-3).