Single Si nanowire (diameter ≤ 100 nm) based polarization sensitive near-infrared photodetector with ultra-high responsivity

We report the fabrication and optical response of boron-doped single silicon nanowire-based metal-semiconductor-metal photodetector. Typical single nanowire devices with diameter of ∼80-100 nm and electrode spacing of ∼1 μm were made using electron-beam lithography from nanowires, grown by a metal-assisted chemical etching process. A high responsivity, of the order of 10 4 A W −1 , was observed even at zero bias in a single nanowire photodetector with peak responsivity in the near-infrared region. The responsivity was found to increase with increasing bias and decreasing nanowire diameter. Finite element based optical simulation was proposed to explain the diameter dependent performance of a single nanowire. The observed photoresponse is sensitive to the polarization of exciting light source, allowing the device to act as a polarization-dependent near-infrared photodetector. Single silicon nanowire-based MSM photodetectors show ultra high responsivity (>10 4 A W −1 ) in the near-infra-red region, even at zero bias. The observed photoresponse is sensitive to the polarization of the exciting light, allowing the device to act as a polarization-dependent photodetector.