Fast self-powered n-InGaN layer/p-Cu2O microcrystal visible-light photoelectrochemical photodetector with high photocurrent and responsivity

An efficient visible-light photoelectrochemical photodetector based on a compact In-rich n-InGaN layer activated by p-Cu2O microcrystals operating as photoanode in the self-powered mode is demonstrated. The photocurrent density of 80 µA/cm2 under one-sun illumination is more than 10 times larger than that of a bare InGaN layer. Moreover, the photocurrent density, responsivity of 0.8 mA/W, specific detectivity of 4 × 109 Jones, and response times of 5-8 ms are more than five times better compared to those of our previously reported nanowire counterpart. The excellent performance is attributed to maximized photocarrier separation in the built-in electric field of the internal p-n junction for fully depleted Cu2O microcrystals with maximized height and the planar geometry, guaranteeing unhindered diffusion of the electrolyte to and from the photoanode surface.