In Situ Selenization‐Engineered PtSe ₂ /PdSe ₂ Heterostructures for Short‐Wave Infrared Polarization‐Sensitive Photodetection and Information Transmission

Abstract This work proposes a synergistic thickness engineering and interface optimization strategy to achieve the controllable fabrication of high‐performance PtSe ₂ /PdSe ₂ van der Waals heterostructure photodetectors. Precise control over the PtSe ₂ layer thickness, which is achieved at target values of 30 and 40 nm using reactive ion etching, induces a transition from ambipolar to strong n‐type behavior, shortening the carrier transit path. Combined with the in situ preparation of PdSe ₂ using laser direct‐write lithography and thermal‐assisted conversion, an atomically matched heterointerface is formed, significantly reducing interfacial defect density. Broadband spectral response spanning 532 to 2200 nm, maintaining stable photocurrent response at 1850 and 2200 nm, a peak responsivity of 1.232 A W ⁻¹ (at 532 nm under a bias of −2 V), and a specific detectivity up to 9.82 × 10 ⁹ Jones (1310 nm), a 3‐dB cutoff frequency of 16.6 kHz with fast rise/fall times of 6.13/32.88 µs, enabling polarization‐resolved infrared imaging. Furthermore, a polarization‐modulated optical communication system is implemented, demonstrating the device's application potential. This work presents a scalable platform for high‐speed, polarization‐resolved photodetectors, establishing a new paradigm of thickness‐interface engineering in 2D heterostructures for advanced infrared imaging and intelligent sensing.