Electron transport in InAs-InAlAs core-shell nanowires

Evidence is given for the effectiveness of InAs surface passivation by the growth of an epitaxial In0.8Al0.2As shell. The electron mobility is measured as a function of temperature for both core-shell and unpassivated nanowires, with the core-shell nanowires showing a monotonic increase in mobility as temperature is lowered, in contrast to a turnover in mobility seen for the unpassivated nanowires. We argue that this signifies a reduction in low temperature ionized impurity scattering for the passivated nanowires, implying a reduction in surface states.