Electrical transport, Meyer-Neldel rule and oxygen sensitivity of Bi2S3 nanowires

The electrical properties of Bi2S3 nanowire bundles were investigated. The nanowires were synthesized using a solventless reaction involving a single-source bismuth thiolate precursor and stabilizing organic ligands. For electrical testing, nanowires were dispersed in solution and drop cast onto a substrate with gold contact pads patterned by electron beam lithography techniques (EBL). Electrical connections were made by depositing platinum interconnect lines between the nanowires and the gold pads by focused ion beam (FIB) chemical vapour deposition. Current-voltage (I-V) curves were measured under nitrogen as a function of temperature. The data revealed activated transport that followed a Meyer-Neldel relationship. Annealing under vacuum decreased the nanowire resistance by nearly four orders of magnitude. The annealed nanowires followed an inverse Meyer-Neldel relationship. Illumination with UV light increased the current, and air exposure decreased the current under constant applied bias.