Broadband and high-speed micro-scale PtSe2/Si 2D-3D PIN photodetector for on-chip polarization-encoded communication and imaging

Journal article, 2026

Two-dimensional platinum diselenide (PtSe2) holds significant promise for broadband photodetection, particularly in the short-wave infrared (SWIR) regime beyond Si's cutoff. However, scalable synthesis of high-quality films and achieving self-driven, high-speed operation with large linear dynamic range (LDR) and high 3-dB bandwidth in CMOS-compatible architectures remain critical challenges. This work demonstrates a CMOS-process-integrated p-PtSe2/n⁻-Si/n⁺-Si PIN van der Waals photodetector that overcomes these limitations. A thermally assisted conversion (TAC) strategy enables the growth of highly oriented, near-stoichiometric PtSe2 films. The engineered PIN architecture generates a strong built-in electric field, facilitating self-driven operation with an exceptional 80 dB LDR and broadband responsivity from 532 nm to 2200 nm. The device achieves a record-high 3-dB bandwidth of 260 kHz for PtSe2/Si detectors (the fastest reported) with ultrafast rise/fall times of 0.5 µs/5.4 µs at 100 kHz, attributed to the film's high crystallinity and enhanced interfacial field control. Furthermore, the detector exhibits unique polarization response characteristics and successfully decodes polarization-encoded optical signals at telecommunication wavelengths (1310 nm and 1550 nm), enabling secure free-space communication. This work establishes a new benchmark for PtSe2/Si photodetectors in speed and functionality while providing a scalable, CMOS-compatible platform for integrating 2D materials into Si photonics for high-speed, energy-efficient optoelectronics.