All-silicon spherical-Mie-resonator photodiode with spectral response in the infrared region.

Silicon is the material of choice for visible light photodetection and solar cell fabrication. However, due to the intrinsic band gap properties of silicon, most infrared photons are energetically useless. Here, we show the first example of a photodiode developed on a micrometre scale sphere made of polycrystalline silicon whose photocurrent shows the Mie modes of a classical spherical resonator. The long dwell time of resonating photons enhances the photocurrent response, extending it into the infrared region well beyond the absorption edge of bulk silicon. It opens the door for developing solar cells and photodetectors that may harvest infrared light more efficiently than silicon photovoltaic devices that are so far developed.