One dimensional ternary Cu-Bi-S based semiconductor nanowires: Synthesis, optical and electrical properties

Ternary Cu-Bi-S based compounds have been thought to be alternative materials for well-known CuInS ₂ because of their abundance. Cu-Bi-S based nanomaterials have been less studied. We here report the synthesis, optical and electrical properties of single crystal Cu ₄Bi ₄S ₉ nanowires. High-quality Cu ₄Bi ₄S ₉ nanowires were synthesized through a modified solvothermal route by controlling the reaction sources and temperature. The optical bandgap for Cu ₄Bi ₄S ₉ nanowires were determined by using UV-vis-NIR and cyclic voltammetry techniques. Single nanowire devices were fabricated by using lithographic techniques. The devices exhibit photoconductive response with high external quantum efficiency (2.9 × 10 ⁸%). Temperature-dependent electrical transport properties were also investigated. We observed that the transport properties of Cu ₄Bi ₄S ₉ nanowire show typical semiconductor behaviour in the temperature region 10-140 K and metal-like character in the temperature region of 150-300 K. The carrier transport in Cu ₄Bi ₄S ₉ nanowires can be described by the small polaron model in temperature region of 60-140 K and the variable range hopping mechanism in temperature region of 10-50 K. We further studied the properties of Cu ₄Bi ₄S ₉ nanowires in field-emission devices. The devices exhibit a relatively low turn-on field (6.9 V μm ^-1). The potential applications of Cu ₄Bi ₄S ₉ nanowires as field emitting materials and light absorbers in detectors are indicated.