Room-temperature photoconductivity in superconducting tungsten meander wires

Abstract

Superconducting nanowires have attracted much interest for developing single photon detectors (SPDs), transition edge sensors (TESs), bolometers, and other devices, as they have unique advantages such as minimum energy requirement, low noise, and fast response at cryogenic temperatures. Furthermore, there is demand for such devices and photodetectors that can operate at room temperature, offering broadband and high-speed photodetection without the need of cryogenic cooling. Herein, we have selected focused ion beam (FIB) fabricated meander structured tungsten (MW) wires, which have a superconducting transition temperature (T_C) of ∼4.5 K. Furthermore, these MW wires were investigated for their photoresponse properties under the following light sources: halogen light and laser of wavelengths 532 nm, 1064 nm and 1550 nm at room temperature (300 K). We have observed first-time positive photoconductivity (PP) features in FIB-fabricated MW wires and have accomplished this study by the analysis of critical parameters such as responsivity, detectivity and quantum efficiency of the photoresponse performance. The observed PP features in MW wires are explained by the intrinsic nature of different elemental compositions/phases and structural features, which exhibit/enhanced photoresponse features via the plasmonic effect. Consequently, the analysis and evaluation of photoresponse features in these MW wires may play an important role for developing the room-temperature photodetectors, optical and telecommunication devices, SPDs, TESs, and below T_C as well. Furthermore, measuring the photoresponse properties of these MW wires as a function of temperature may reveal their applicability for bolometric applications.