Monolithic Te 1‐x Se x ‐on‐Si Photodiodes for Real‐Time Short‐Wave Infrared Trajectory Tracking

ABSTRACT Low‐cost, Si‐compatible photodetectors operating beyond the absorption edge of Si are critical for extending integrated photonics into the short‐wave infrared (SWIR) and telecommunication bands, but remain challenging to realize. Here, we demonstrate monolithic Te 1‐x Se x ‐on‐Si SWIR photodiodes with a response cutoff wavelength of up to 1550 nm in photovoltaic mode. Interfacial engineering facilitates carrier transport while suppressing defect‐assisted recombination, enabling self‐powered SWIR detection with a record‐low dark current density of 4.4 × 10 −10 A cm −2 , an enhanced photocurrent on‐off ratio of 1.2 × 10 5 , and a specific detectivity of 1.3 × 10 10 Jones. The low‐temperature, CMOS‐compatible fabrication process allows high‐yield monolithic photodiode arrays with uniform device performance. By incorporating four spatially separated electrodes, we realize a SWIR position‐sensitive photodetector that delivers a high sensitivity of 47.5 mV mm −1 , exceptional nonlinearity of 1.4%, and a spatial position resolution of ∼2 µm at 1342 nm. These findings further enable continuous coordinate extraction and dynamic visualization of SWIR trajectory tracking by integrating the detector with real‐time signal processing system. This work presents a scalable and cost‐effective strategy for Si‐based heterojunction SWIR optoelectronics, establishing a promising route toward their widespread implementation in consumer applications.