Non-monotonic boundary resistivity for electron transport in metal nanowires

Abstract

Boundary scattering is the most widely encountered size effect in nanoscale transport phenomena, and the scattering rate is usually regarded as a constant that is proportional to the ratio of carrier velocity to the characteristic size. Here, through combined experimental measurements and numerical modeling, we show non-monotonic variations of the boundary scattering rate for free electrons in metal nanowires as temperature escalates. This observation is attributed to the change in the electron-phonon (e-ph) scattering angle as temperature reduces, which alters the surface scattering rate. In particular, at low temperatures, electrons traveling along the wire axis have to be first relaxed by e-ph scattering before they collide with the nanowire surface. Theoretical analysis indicates a transition temperature of 0.29 times Debye temperature. A theoretical model considering the effects of the scattering angle is proposed that can fit the measured experimental data for both copper and silver nanowires over a wide temperature range.