In Situ Selenization Engineered Dual Schottky Heterojunctions: A Novel Architecture for High‐Speed Broadband Photonic Communication Detector Arrays

2D transition metal dichalcogenide WSe₂ exhibits unique band structure tunability, and its van der Waals heterostructures with 3D semiconductors demonstrate significant potential for high-performance photodetection. However, inherent limitations (interface defects) in conventional thin-film transfer hinder their development. This study addresses interfacial defects and integration challenges in WSe₂-based 2D-3D heterojunction devices by proposing a GeSi diffusion barrier-mediated interfacial engineering strategy combined with dual-temperature-zone furnace-based in situ selenization, achieving controllable growth of high-quality WSe₂ films on GeSi/Ge substrates. The WSe₂/GeSi/n^--Ge 8 × 8 array photodetector fabricated by laser direct-writing lithography demonstrates distinct performance: broad spectral detection from 532 nm to 2200 nm with responsivity of 5.61 A/W and specific detectivity of 3.77 × 10¹² Jones at 1550 nm. The unique dual Schottky structure enables dual-exponential decay characteristics, delivering fast response times of 0.55/2.85 µs and 0.15/1.1 µs, along with high 3-dB cutoff frequencies of 234 and 374 kHz. The device simultaneously achieves short-wave infrared high-resolution imaging, polarization detection (dichroic ratio of 83.4 at 1550 nm), and high-speed data transmission, overcoming interface defect limitations of conventional transfer processes. This work establishes a technical paradigm for in situ large-scale integration of broad-spectrum, high-speed 2D,3D devices.