One dimensional ternary Cu–Bi–S based semiconductor nanowires: synthesis, optical and electrical properties

Abstract

Ternary Cu–Bi–S based compounds have been thought to be alternative materials for well-known CuInS₂ 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 Cu₄Bi₄S₉ nanowires. High-quality Cu₄Bi₄S₉ nanowires were synthesized through a modified solvothermal route by controlling the reaction sources and temperature. The optical bandgap for Cu₄Bi₄S₉ 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 × 10⁸%). Temperature-dependent electrical transport properties were also investigated. We observed that the transport properties of Cu₄Bi₄S₉ 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 Cu₄Bi₄S₉ 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 Cu₄Bi₄S₉ nanowires in field-emission devices. The devices exhibit a relatively low turn-on field (6.9 V μm⁻¹). The potential applications of Cu₄Bi₄S₉ nanowires as field emitting materials and light absorbers in detectors are indicated.