In Situ Au Nanoparticle Decorated Multilayer PdSe₂ Films for Enhanced Bolometric Photodetection

Two-dimensional (2D) PdSe₂ is a promising thermosensitive material for uncooled infrared (IR) detectors, owing to its layer-tunable bandgap, robust ambient stability, and compatibility with CMOS technology. However, its temperature coefficient of resistance (TCR)─a critical figure of merit for bolometric performance─is compromised in ultrathin films by gas adsorption and deteriorates markedly with increasing thickness, limiting practical deployment. To overcome this trade-off, we develop an in situ Au nanoparticle decoration strategy, enabling the synthesis of ultrathin (<15 nm) PdSe₂ films with precisely controlled Au concentrations on silicon substrates via magnetron cosputtering followed by a low-temperature selenization process. Systematic characterization reveals that optimal Au incorporation not only enhances optical absorption in the long-wavelength IR window (9-13 μm) by up to 9.61% but also significantly boosts thermoelectric response. At an Au concentration of 11%, the film achieves a decent TCR of -2.28%/K─representing a 53% improvement over the pristine sample (-1.49%/K)─alongside a moderate resistivity of 7.3 Ω·cm, enabling a high thermal resolution of 11.8 mK. Further tuning the Au content to 34% yields a responsivity of 2.9 A/W and a specific detectivity of 5.1 × 10⁸ Jones under 9.3 μm illumination. Using this engineered material, we fabricate an 8 × 8-pixel long-wave IR focal plane array and demonstrate high-fidelity, uncooled thermal imaging at room temperature, confirming excellent device uniformity, operational stability, and compatibility with standard microfabrication processes. Mechanistic analysis reveals that the Au nanoparticles synergistically enhance TCR through grain boundary engineering and Coulomb screening effects. This work establishes a scalable route toward high-performance, low-cost 2D-material-based IR detectors for next-generation thermal imaging applications.