Spatial Geometry Design for High-Throughput and Uniform Oblique Angle Deposition (OAD) of SERS Substrates

Abstract

Surface-enhanced Raman scattering (SERS) substrates require not only high enhancement but also spatial uniformity and scalable manufacturing. Oblique angle deposition (OAD) is a powerful method for fabricating tilted nanorod arrays, yet the conventional single-substrate configuration suffers from low throughput and inefficient material utilization. Here, we propose a source-centered circular spatial-geometry strategy for large-batch, uniform OAD fabrication of SERS substrates. The design uses curved substrate-supporting plates with concentric arc edges and trapezoidal cross sections to maintain comparable source-substrate distances and oblique-incidence angles across multiple positions. A modular circular holder assembled with alternating long and short arms enables the simultaneous deposition of up to 112 silicon substrates in one run. Using Ag nanorod arrays as a model system, we verified the morphological uniformity of the batch-fabricated substrates in terms of nanorod length, diameter, areal density, and estimated surface area. The resulting substrates exhibited reproducible SERS responses toward 4-mercaptobenzoic acid, with an intensity variation of 12.6%. The Ag nanorod substrates further enabled fingerprint detection of multiple molecules at 10–7 mol/L. Beyond Ag nanorod substrates, the same platform was extended to other deposited materials, binary kinked Co–Ag nanorods, and magnetic powder-based SERS detection. This work establishes spatial geometry design as an effective route for translating OAD from small-scale nanostructure preparation to high-throughput, uniform, and versatile SERS-substrate manufacturing.