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

Abstract 2D transition metal dichalcogenide WSe ₂ 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 WSe ₂ ‐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 WSe ₂ films on GeSi/Ge substrates. The WSe ₂ /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 × 10 ¹² 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.