Kinetics of a Solid-Solid Charge Transfer Reaction*

We present an analysis of the kinetics of charge transfer at a solid-solid interface. The study was enabled by measuring the conductance of ultra-thin, fully suspended single-crystalline silicon nanowires across 7 orders of magnitude with a detection sensitivity of order single event over a 10^3 μm^2 reaction area. We find that a classic, first-order process is unable to capture the reaction progress and propose a new kinetic model based on a continuum of reactant geometries inherently present at typical solid-solid interfaces. The new model captures the kinetic manifestation of heterogeneity in a single, global rate constant. Quantitative agreement with data and an analysis of the parameters suggest that this model may be generally applicable to charge transfer at solid-solid interfaces.