Evidence for nonlinear screening and enhancement of scattering by a single Coulomb impurity for dielectrically confined electrons in InAs nanowires

摘要

The conductance due to scattering by a single repulsive Coulomb impurity is measured as a function of gate voltage in backgated InAs nanowires by analysis of random telegraph noise. Comparison with a quantum mechanical theory for carrier response and scattering reveals that the large dielectric mismatch between the nanowire and its surroundings enhances the Coulomb interaction, produces a nonlinear screening process that weakens dielectric response, and enhances the self-consistent Coulomb-impurity barrier of a single repulsive impurity, as nanowire diameter is reduced. Consequently, the scattering rate by such an impurity is enhanced by nearly two orders magnitude for 30 nm diameter InAs nanowires. A dramatic asymmetry of scattering by repulsive and attractive impurities, where the latter produce majority carriers, explain how a single repulsive impurity can control the conductance of a 1 μm long InAs nanowire. Relevance to proposed nanoelectronic and sensing devices is discussed.