Oblique nanomachining of Gallium Arsenide explained using AFM experiments and MD simulations

Gallium Arsenide (GaAs) continues to remain a material of significant importance due to being a preferred semiconductor substrate for the growth of quantum dots (QDs) and GaAs-based quantum devices used widely in fifth-generation (5G) wireless communication networks. In this paper, we explored aspects of oblique nanomachining to investigate the improvement in the machining quality as well as to understand plasticity and transport phenomena in GaAs using atomic scale machining experiments and simulations. We studied the influence of the direction vector of the cutting tip (e.g. tip alignment) during the surface generation process in GaAs. We noticed a novel observation that when the AFM tip’s cutting edge presented two acute angles (i.e., 30° angles each) between the cutting face and the cutting direction (which can be regarded as an oblique cutting condition), the cutting configuration involved early avalanche of dislocations compared to other tip configurations (e.g., orthogonal cutting). Orthogonal cutting involved the least coefficient of friction but the highest specific cutting energy compared to oblique cutting. High-resolution transmission electron microscopy (HRTEM) examination revealed that the shuffle-set slip on the {1 1 1} slip system due to the <1 1 0> type dislocation paves the way for plasticity during nanometric cutting of GaAs. Overall, a particular condition of oblique cutting was inferred to be the best for nanofabrication of high-quality wafers using an AFM.