Atomic-Scale Insights into Ultrasonic Vibration-Assisted Polishing Mechanisms of 4H-SiC in H₂O₂ Solutions

This study employed reactive force field molecular dynamics simulations to investigate the mechanisms underlying the ultrasonic vibration-assisted polishing of 4H-SiC in hydrogen peroxide (H₂O₂) solutions. A model was developed to simulate scratching with a single diamond abrasive particle in an aqueous H₂O₂ environment to systematically examine the effects of vibration amplitude and frequency on friction forces, surface chemical reactions, material removal, surface morphology, and crystal structure. The results revealed that ultrasonic vibrations significantly influenced the fluctuation characteristics of the friction forces. Specifically, the frequency primarily determined the period of these fluctuations, whereas the amplitude determined their magnitude. Increasing both the amplitude and frequency promoted the formation of oxidation bonds, with the amplitude having a more pronounced influence. Ultrasonic vibrations promoted oxidation by increasing the number of dangling bonds on the surface, resulting in more oxidation bonds. Additionally, higher amplitudes facilitated the removal of atoms from silicon carbide (SiC) substrate, whereas variations in frequency had a marginal impact on atomic displacement. Lower frequencies and smaller amplitudes reduce amorphization, thereby preserving the crystalline structure of the SiC surface. However, high-frequency vibrations improve surface smoothness by shortening the single-cycle interaction time. These findings provide theoretical insights into the fundamental mechanisms of ultrasonic vibration-assisted polishing, guiding its optimized application in precision processing of SiC materials.