The Effect of Deposition Methods on Gold Nanoparticle Thin Films: Insights into Material Distribution, Surface Roughness, Thickness, and Adhesion

Introduction: This research investigates the comparative performance of drop casting and spin coating as deposition techniques for Gold Nanoparticle (AuNP) films, fo-cusing on material distribution, morphology, thickness, and adhesion properties. Methods: Using single-layer deposition, Gold Nanoparticles (AuNPs) are applied to a gold thin film substrate, resulting in a double-layer configuration. Ultra-High Resolution Scan-ning Electron Microscopy (UHR SEM) and Atomic Force Microscopy (AFM) were used to characterize the distribution and surface features. Results: UHR SEM results show that spin coating provides more uniform material distribu-tion with reduced clustering compared to drop casting. AFM measurements reveal increased roughness for spin-coated samples. Film thickness analysis demonstrates that spin coating produces thinner films compared to drop casting. Adhesion testing indicates that drop cast-ing exhibits higher adhesion energy, approximately 4.3 times higher than spin coating. discussion: The results suggest that, under the specific experimental conditions of this study, drop casting offers advantages in adhesion and surface roughness, while spin coating may be optimized by adjusting the rotational speed. Discussion: Increased roughness in spin-coated samples is likely due to incomplete material spreading at 1000 rpm. Thinner films produced by spin coating are consistent with centrifu-gal forces during the spinning process. Higher adhesion energy observed in drop casting is likely due to the extended incubation time of 48 hours, allowing stronger bonding between the nanomaterial and substrate. These findings demonstrate the critical trade-off between film uniformity and adhesion strength, with significant implications for device performance optimization. However, this study is limited by the evaluation of only a single spin speed and incubation time, which may restrict its applicability to different nanomaterial-substrate combinations. Conclusion: Results suggest that, under the specific experimental conditions of this study, drop casting offers advantages in adhesion and surface roughness, while spin coating may be optimized by adjusting the rotational speed.