Low temperature carrier transport mechanism and photo-conductivity of WSe2

Abstract This work reports the electrical-transport and temperature-dependent photoconductivity in tungsten diselenide (WSe2) thin films. Temperature-dependent electrical conductivity has been demonstrated using different models. At lower temperatures ( 273 K) region, thermally activated conduction is dominated with two activation energies of ~138 meV and 98 meV. The peaks obtained in photoluminescent analysis attributes to the presence of mid-bandgap states or defect states which play an important role in the photoconductivity of WSe2. The transient photoconductivity measurements show consistent temperature-dependent behaviour. The effect of light intensity and wavelength variation on the photoconductivity of WSe2 thin films is also discussed. The photo-current is 1.19⁎10-5 A at 125 K, while at 350 K was observed to be 3.12⁎10-4 A. The light-on/off current cycles show that the current can recover to its initial state after various cycles, which points to the WSe2 thin-film device's stable and reversible properties that can be used in optoelectronic applications.