Transport properties of Mo 6 S 3 I 6 nanowire networks

We present measurements of resistivity on Mo 6 S 3 I 6 nanowire networks under different conditions. The room-temperature values of conductivity of as-grown nanowire networks are on the order of σ 300 K = 0.04 S ∕ m and show linear current-voltage characteristics, indicating that-in agreement with band structure calculations-there is a finite density of states at the Fermi level. The conductivity of pristine samples is thermally activated, closely following three-dimensional variable range hopping (VRH) behavior of the form σ = σ 0 exp − ( T 0 ∕ T ) β , where β = 1 ∕ 4 . Removal of interstitial iodine from the network by annealing in a vacuum gives rise to a cross over to one-dimensional VRH with β = 1 ∕ 2 and a concurrent increase in room-temperature conductivity. The introduction of water vapor leads to a decrease in conductivity and reveals that the resistivity of the network is sensitive to interstitial water molecules.