Hydrogenated Borophene-Graphene Broadband Photodetectors for Ultrahigh Photoresponsivity

2D nanomaterials like graphene, hexagonal boron nitride (h-BN), black phosphorous (BP), and transition metal dichalcogenides (TMDs) have gained significant attention in the past two decades due to their distinct thermal, electrical, optical, and magnetic properties compared to their bulk counterparts[1]. In contrast, borophene, a unique 2D nanomaterial composed entirely of boron atoms, stands out for its advantages in optoelectronic device applications. These include high electrical conductivity, optical transparency in the visible spectrum, strong light-matter interaction, notable mechanical properties (high tensile strength and flexibility), the potential for superconductivity, and good chemical stability, making it suitable for harsh environments[2]. Here, we synthesized hydrogenated borophene through the thermal decomposition of NaBH₄ in the presence of H₂. Subsequently, we fabricated a 2-terminal coplanar Borophene/Graphene/SiO₂/Si broadband (405-1064 nm) photodetector (PD) with high photoresponsivity (R). The Borophene/Graphene/SiO₂/Si PD exhibits an outstanding R~ 3.65 x 10³ A/W under 405 nm laser illumination (@1V bias, 0.05 mW/cm²). This performance surpasses previously reported values for Borophene-based PDs, which ranged from 0.48 to 9.13 A/W [3-5]. Our PD shows short response, and recovery times of 82, and 83 ms under 633 nm laser illumination compared to previous reports in the range of 110 to 660 ms [3-5]. Our results may stir interest in Borophene for nanophotonics, and optoelectronics devices.<br/>References<br/>[1] G. Wang et al., "Two dimensional materials based photodetectors," Infrared Physics & Technology, vol. 88, pp. 149-173, 2018/01/01/ 2018, doi: https://doi.org/10.1016/j.infrared.2017.11.009.<br/>[2] Z. Xie et al., "Two-Dimensional Borophene: Properties, Fabrication, and Promising Applications," Research, vol. 2020, doi: 10.34133/2020/2624617.<br/>[3] Y. Liu, G. Tai, C. Hou, Z. Wu, and X. Liang, "Chemical Vapor Deposition Growth of Few-Layer β12-Borophane on Copper Foils toward Broadband Photodetection," ACS Applied Materials & Interfaces, vol. 15, no. 11, pp. 14566-14574, 2023/03/22 2023, doi: 10.1021/acsami.2c23234.<br/>[4] Z. Wu et al., "van der Waals Epitaxial Growth of Borophene on a Mica Substrate toward a High-Performance Photodetector," ACS Applied Materials & Interfaces, vol. 13, no. 27, pp. 31808-31815, 2021/07/14 2021, doi: 10.1021/acsami.1c03146.<br/>[5] Z. Wu et al., "Epitaxial growth of borophene on graphene surface towards efficient and broadband photodetector," Nano Research, 2023/09/27 2023, doi: 10.1007/s12274-023-6109-9.