Borophene-Based Ultrasensitive and Broadband Photodetectors

Abstract

Photodetectors based on vertical junctions between 2D materials and silicon offer enhanced sensitivity, reduced size, and better integrability with other systems. In these detectors, 2D materials are typically grown on metallic crystalline substrates and then transferred onto silicon to form a van der Waals junction between the 2D and silicon. In this work, χ₃-phase borophene is directly grown on single-crystal silicon wafers, resulting in excellent Schottky junctions between borophene and silicon. This approach eliminates impurities often introduced during the transfer process, which is commonly performed using polymethyl methacrylate, ensuring a smooth fabrication process and a reliable electrical junction. Optoelectronic measurements of the borophene-based detector on n-type silicon demonstrate high sensitivity, reaching several amps per watt across a wide wavelength range from ultraviolet to infrared. This sensitivity is approximately ten times higher than that of detectors fabricated by transferring 2D materials onto silicon. Additionally, the response times of the fabricated detector are measured at 35 µs for the rise time and 225 µs for the fall time. These exceptional results are attributed to the superior junction formed through direct borophene growth on silicon, paving the way for advanced photodetectors with enhanced light–matter interaction efficiency in integrated silicon-based circuits and technologies.