Electron dynamics in InxGa1-xAs shells around GaAs nanowires probed by terahertz spectroscopy

We present the electrical properties of GaAs/InxGa1-xAs core/shell nanowires measured by ultrafast optical pump - terahertz probe spectroscopy.
This contactless technique was used to measure the photoconductivity of nanowires with shell compositions of x = 0.20, 0.30 and 0.44. The results were fitted with the model of localized surface plasmon in a cylinder in order to obtain electron mobilities, concentrations and lifetimes in the InxGa1-xAs NW shells.
The estimated lifetimes are about 80 - 100 ps and the electron mobility reaches 3700 cm2/Vs at room temperature. This makes GaAs/InGaAs nanowires good candidates for the near-future realization of InGaAs based high-electronmobility transistor.