Quantitative estimation of nanoparticle/substrate adhesion by atomic force microscopy

Understanding nanoparticle adhesion to substrates is the key for their stability and performance in many applications, including energy systems, nanofabrication, catalysis, and electronic devices. In this study, we present a methodology for examining adhesion of copper nanoparticles to silicon substrates deposited under varying conditions using DC magnetron sputter inert gas condensation. Atomic force microscopy was utilized as a tool for the manipulation of the nanoparticles and to measure lateral forces for their displacement, with cantilever calibration achieved through wedge and diamagnetic lateral force calibrator methods. The work of adhesion was quantified by integrating the obtained lateral forces over the distance moved during manipulation, revealing a non-monotonic dependency on nanoparticle size with maximum adhesion observed for particles between 6 and 12 nm. In addition, an applied positive substrate bias voltage led to more energetic landing conditions and thus to increased adhesion forces. This study underscores the suitability of atomic force microscopy in characterizing adhesion on the nanoscale and offers insights into future strategies for tailoring nanoparticle/substrate interactions.