Silicon‐Based Photodetectors with a Step‐Wise Structure for Broadband Wavelength Detection from Ultraviolet to Near‐Infrared

Abstract Wavelength sensors play a crucial role in various scientific and industrial applications, such as spectroscopy, autonomous vehicles, and safety monitoring. However, traditional wavelength sensors often suffer from several drawbacks, including complex device structures, narrow detection range, and low accuracy. To overcome these limitations and achieve miniaturization while expanding detection range, a single‐sided silicon‐based wavelength detector with a step structure is fabricated using a wet etching method. This sensor can quantitatively distinguish light wavelengths within the ultraviolet (UV) to near‐infrared (NIR) range. It features a convex step structure in the middle of silicon substrate, with two pairs of parallel gold (Au) electrodes deposited on the step and etching surfaces to form photodetectors 1 (PD1) and 2 (PD2). Due to the difference in carrier collection efficiency, which depends on the penetration depth of incident light, the two photodetectors based on unique device geometry exhibit different photoelectric characteristics under varying light sources. The corresponding photocurrent ratio shows a monotonically decreasing relationship with wavelength, allowing for wavelength discrimination in the range of 265–1050 nm, with a high resolution of ±4.91 nm. The simple device fabrication as well as the probability of high integration of this new concept will mature future integrated wavelength detection systems.