Mid-infrared photoconductivity of tellurium nanowire devices

Elemental tellurium is a narrow bandgap (0.34 eV) semiconductor, whose trigonal lattice is composed of weakly-bound, three-fold helical atomic chains. This unusual lattice allows the formation of nanowires with highly anisotropic electronic and optical properties. Here, we present photocurrent spectroscopy of single tellurium nanowire devices in the mid-infrared range close to the band gap, demonstrating interesting anisotropic features closely related to the linear polarization of the incident light and the resonant modes of the nanowires. It is found that the photosensitivity is strongly dependent on the temperature and the back-gate bias.