Towards understanding the mechanisms of material removal and deformation in GaAs during nanomilling

Due to its exceptional electronic and optical properties, single crystal gallium arsenide (GaAs) has garnered significant attention in recent years. The utilization of nanostructures on GaAs holds significant potential across various applications. Therefore, comprehending the underlying mechanisms governing material removal and plastic deformation during mechanical nanomachining of GaAs is imperative for its widespread implementation. The fabrication of nanochannels on the GaAs surface is achieved through the utilization of an AFM tip-based nanomilling technique in this study. Furthermore, insights into the mechanisms underlying material removal and plastic deformation during the nanomilling process of GaAs are unveiled. The GaAs materials are observed to be removed in the form of chips and pile-ups, resulting from the extrusion by the tip. Transmission electron microscopy (TEM) observation and MD simulation reveal that dislocations, lattice distortions and amorphization are caused by the plastic deformation of GaAs. Additionally, the high-pressure exerted by the tip contributes to phase transformation. The effects of nanomilling parameters such as normal load and feed speed on the machining outcomes are also investigated. Nanochannels with a flat bottom are obtained when a small normal load is applied, which can be attributed to the slight torsional deformation of the tip. The machined width can be controlled by adjusting the driving voltage during nanomilling. These findings provide valuable insights into the mechanisms of material removal and plastic deformation in GaAs during nanomilling, offering guidance for fabricating nanostructures on GaAs samples.