Carrier Lifetime and Mobility Enhancement in Nearly Defect-Free Core−Shell Nanowires Measured Using Time-Resolved Terahertz Spectroscopy

We have used transient terahertz photoconductivity measurements to assess the efficacy of two-temperature growth and core−shell encapsulation techniques on the electronic properties of GaAs nanowires. We demonstrate that two-temperature growth of the GaAs core leads to an almost doubling in charge-carrier mobility and a tripling of carrier lifetime. In addition, overcoating the GaAs core with a larger-bandgap material is shown to reduce the density of surface traps by 82%, thereby enhancing the charge conductivity.