Light Trapping Effect Enhanced Self-Filtered NIR Narrowband Light Sensors Featuring Asymmetric MXene Electrodes for Optical Communication

Narrowband light sensing at the near-infrared (NIR) regime is of particular importance for many utilizations including medical diagnostics, optical communication, and specific band imaging. In this work, we demonstrate the design of a novel self-filtered NIR narrowband Si-based light sensor utilizing asymmetric MXene electrodes. Working on the joint mechanisms of the carrier collection narrowing and the self-filtering of Si substrate, a peak response at around 1060 nm featuring a full width at half maximum (FWHM) of 93 nm is attained. P-or n-type doping of MXene renders a remarkedly increase or decrease in its work function, which enables a pronounced built-in electric field between asymmetric electrodes. Combing with the strong light trapping effect of pyramidal microstructures, the narrowband light sensor exhibits an improved responsivity of 221.77 mA/W, a large specific detectivity of 3.73 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>12</roman></sup> Jones, a fast response speed of 238/141 μs, and a decent NIR/visible (1060/625 nm) rejection ratio of around 350. Owing to the prominent photoresponse properties, the device can act as a light signal receiver to transmit a text in an NIR optical communication system, demonstrating its potential for utilization in future NIR optoelectronic systems.