Hybrid plasmonic gold-nanorod-platinum short-wave infrared photodetectors with fast response.

Short-wave infrared (SWIR) photodetectors, sensitive to the wavelength range between 1 and 3 μm, are essential components for various applications, which constantly demand devices with a lower cost, a higher responsivity and a faster response. In this work, a new hybrid device structure is presented for SWIR photodetection composing a coupling between solution-processed colloidal plasmonic gold (Au) NRs and a morphology-optimized resistive platinum (Pt) microwire. Pt microwires harvest efficiently the photothermal effect of Au NRs and in return generating a change of device resistance. A fast photon-heat-resistance conversion happens in these Au-NRs/Pt photodetectors exhibiting a response (rise) time of 97 μs under the illumination of a λ = 1.5 μm laser. Clear photoresponse can be observed in these devices at a laser illumination with a modulation frequency up to 50 kHz. The photoresponsivity of the current devices reached 4500 Ω W-1 under a laser power of 0.2 mW, which is equivalent to a responsivity of 340 mA W-1 under a DC bias of 1 V. A series of mapping experiments were performed providing a direct correlation between Au NRs and the device zone where resistance change happens under a laser illumination modulated at different frequencies.