Record Photoresponsivity in Hydrogenated Borophene Broadband Photodetector

Hydrogenated borophene (borophane) offers a bandgap, unlike graphene, and better electronic mobility than molybdenum disulfide (MoS2) to occupy a distinct place among the two-dimensional (2D) layered materials group. The provisions for optoelectronic tunability in borophane compel us to explore possible applications involving photoelectric conversion. In this study, we report synthesizing p-type borophane with an optical absorption gap of 2.55 eV. First, we characterized the material with electron microscopy, optical absorption, Raman spectroscopy, and synchrotron-based X-ray studies to confirm the morphology, structure, and composition. Next, we used a photolithographically prepatterned chip to fabricate a single flake borophane photodetector (PD), with focus ion beam drawn coplanar contacts, achieving the highest reported responsivity (R) among all borophene-based PDs to date. The device operates across 405 to 1550 nm, with a maximum R of 125.90 A W–1 (detectivity D* of 4.33 × 108 Jones) under 10 mW cm–2 of 405 nm laser illumination and a bias of 1 V. The spectral variation of R of the PD closely follows its optical absorption. This work establishes a new benchmark for borophene-based PDs and possible integration into next-generation optoelectronic and sensing technologies.