Temperature Dependent Infra-red Detection in Graphene - Tellurium Nanowire Binary Hybrid with Ultra-high Sensitivity

Single layer graphene serves as a good candidate for ultra-sensititve photodetection by virtue of its high carrier mobility and lifetime. Also because of spatial charge separation and large optical gain, the optoelectronic performance of graphene based hybrid devices always becomes superior than usual photodetectors. Tellurium nanowire (TeNW), having a narrow direct bandgap (∼ 0.65 eV) is an excellent potential candidate for near infra-red (NIR) detection. In this work, we report a maximum photoresponsivity ∼ 10 ⁶ AW ^-1 at 175K for a graphene - TeNW binary hybrid in the NIR regime (920 nm - 1720 nm). The extracted noise equivalent power (NEP) can be as low as 2 × 10-¹⁸WHz^-1/2 and specific detectivity value exceeds 5 × 10¹³ Jones. A systematic temperature dependence of the photoconductivity has also been performed and we have observed a suppression of the photoconductivity at higher temperature by virtue of the conduction through the NWs. But the optimal operating range of temperature can still be improved by controlling the inter-wire electronic coupling and the defect density inside the TeNWs.

The authors acknowledge the DST (Department of Science and Technology), Govt. of India for financial support.