Complementary optoelectronic effect in silicon nanomembrane-based heterojunction for broadband UV–visible–NIR photodetection

Semiconductor heterojunctions play a vital role in the fabrication of broadband photodetectors, which offer broad application prospects across fields including environmental monitoring, biomedical imaging, and optical communications. However, state-of-the-art technical routes for the fabrication of semiconductor heterojunctions face significant challenges, which could severely compromise their optoelectronic properties. Here, we report a simple and convenient approach for the fabrication of semiconductor heterojunctions, which contains silicon nanomembranes and liquid metal printed gallium oxide. Large-area gallium oxide with controllable thickness can be formed on the top of silicon nanomembranes through spontaneous oxidation of printed liquid gallium. Facilitated by the complementary optoelectronic effects, various light sources with wavelengths covering the solar blind, visible, and near-infrared bands could effectively activate electron–hole pairs in the depletion region of the heterojunction, which can be further separated by the built-in potential. Therefore, the fabricated photodetector exhibits high optoelectronic performances, including broadband photodetection (255–980 nm), high responsivity (3.18 A/W), and detectivity (1.0 × 1013 Jones), good stability, fast response time (8/10 ms), and self-powered capability. This work adds to the portfolio of material strategies and fabrication process in high-performance, large-area broadband photodetection platforms.