Pulsed KrF excimer laser dopant activation in nanocrystal silicon in a silicon dioxide matrix

Abstract

We demonstrate that a pulsed KrF excimer laser (λ = 248 nm, τ = 22 ns) can be used as a post-furnace annealing method to greatly increase the electrically active doping concentration in nanocrystal silicon (ncSi) embedded in SiO2. The application of a single laser pulse of 202 mJ/cm2 improves the electrically active doping concentration by more than one order of magnitude while also improving the conductivity. It is confirmed that there is no film ablation or significant change in ncSi structure by atomic force microscopy and micro-Raman spectroscopy. We propose that the increase in free-carrier concentration is the result of interstitial P/B dopant activation, which are initially inside the Si crystallites. Evidence of mobility limited carrier transport and degenerate doping in the ncSi are measured with temperature-dependent conductivity.