Self-powered, broadband, and polarization-sensitive pyroelectric-photoelectric photodetector based on silicon-water heterojunction

The coupling of pyroelectric and photoelectric effects is a new method to enhance transient response while maintaining steady-state response in photodetectors. Such photodetectors have recently attracted a great attention due to a wide range of potential applications including artificial electronic eyes, neuromorphic computing, color sensors, and optical communications. Here, we report a photodetector based on the pyroelectricity and photoelectricity effect in a silicon-water heterojunction for the first time. Facilitated by the polarity of water on the Si surface, this heterostructure serves as a pyroelectric-based photodetector with a responsivity as high as 754 mA/W and specific detectivity as high as 1.33 × 1013 Jones under a light wavelength of 400 nm at zero bias. Also, the formation of a built-in electric field at the silicon-water interface results in a photoelectric-based photodetector with a responsivity as high as 12.3 A/W and an ultrahigh detectivity of 2.18 × 1014 Jones at −2 V bias under steady-state conditions. Moreover, due to the polarization-sensitive reflection of light on the water surface, this structure is also polarization-sensitive. These photodetectors are suitable for liquid-compatible applications that require broadband detection, high responsivity, and polarization-sensitivity.