Recombination-induced random walk diffusion of interstitial carbon in silicon

Abstract

Recombination events at interstitial carbon atoms in silicon cause the carbon to step to adjacent interstitial positions. DLTS inp-type silicon is used to measure the random walk from interstitial carbon to interstitial carbon-oxygen centers. Electron capture at the interstitial carbon defect causes the carbon to step with a frequency of once per 16 capture events. Using 100 keV electron irradiations to produce electron-hole recombination events, we measure: the step frequency, electron capture cross section, and the mean time between electron captures at the interstitial carbon defect. Measurement of athermal diffusion in the dark indicates that the time between recombination events at interstitial carbon is 0.92 × 1011 seconds if the electron density is 1 m−3. Interstitial carbon moves rapidly at low temperature by this random walk in p-type silicon.