Wafer-scale nanoparticle assemblies via low temperature shadow growth

Abstract

Functional nanoparticles and nanostructures are widely used in optics, sensing, catalysis, and photonics [1,2]. However, despite highly developed colloidal synthesis, wafer-scale integration of high-density nanoparticle layers remains challenging. Transfer- and assembly-based routes often require multi-step processing and suffer from limited reproducibility, making it difficult to simultaneously achieve large-area uniformity, high surface coverage, and controlled interparticle spacing [3]. Here, we propose a seedless direct-growth strategy based on low-temperature glancing angle deposition (GLAD) for wafer-scale nanoparticle integration [4]. By leveraging the GLAD shadowing effect while suppressing surface diffusion through substrate cooling, we obtain disordered yet densely packed nanoparticle assemblies with high surface coverage (~49.6%) and inter-particle isolation. This minimizes uncontrolled aggregation and enables monolayerlike nanostructures. Unlike synthesis-and-transfer approaches, our method performs simultaneous synthesis and assembly directly on the target substrate, reducing process complexity and improving run-to-run reproducibility. The approach is compatible with a broad library of PVD-processable materials and requires no seed layers, providing a general route to wafer-scale dense arrays of functional nanoparticles. Beyond standalone coatings, the platform can be extended to device-relevant architectures, including nanoparticle-on-mirror (NPoM) structures that offer strong field confinement for light–matter interaction engineering and sensing.