Low-Temperature Growth of Centimeter-Sized 2D PdSe by Self-Limiting Liquid-Phase Edge Epitaxy.

Two-dimensional (2D) PdSe atomic crystals hold great potential for optoelectronic applications due to their bipolar electrical characteristics, tunable bandgap, high electron mobility, and exceptional air stability. Nevertheless, the scalable synthesis of large-area, high-quality 2D PdSe crystals using chemical vapor deposition (CVD) remains a significant challenge. Here, we present a self-limiting liquid-phase edge-epitaxy (SLE) low-temperature growth method to achieve high-quality, centimeter-sized PdSe films with single-crystal domain areas exceeding 30 μm. The SLE growth mechanism, clarified by theoretical calculations and time-of-flight secondary ion mass spectrometry (ToF-SIMS), reveals that hydrogen ions on the precursor surface inhibit vertical growth while promoting lateral growth. The as-grown PdSe few-layer exhibits a surface roughness of 1.20 nm and an average conductivity of 1.67 × 10 S/m, demonstrating their smoothness and uniformity. Temperature-dependent electrical measurements and transfer characteristic curves confirm the orthorhombic PdSe's bipolar semiconductor behavior. The photodetector based on few-layer PdSe films exhibit excellent optoelectronic performance in the 405-1650 nm wavelength range, achieving a responsivity of 6262.37 A W, a detectivity of ∼10 Jones under 1064 nm illumination, and a fast response time of 37.1 μs, making them highly suitable for broadband photodetection applications. This work provides valuable insights into the scalable synthesis of PdSe few-layers and establishes a foundation for the development of PdSe-based integrated functional devices.