Effect of indenter type on GaN single crystals in nanoindentation from the atomic perspective

SY Mao and TH Gao and B Wang and Q Chen, MATERIALS TODAY COMMUNICATIONS, 44, 112115 (2025).

DOI: 10.1016/j.mtcomm.2025.112115

Molecular dynamics simulations were employed to examine the influence of three prevalent indenters on the nanoscale deformation behavior and mechanical properties of gallium nitride (GaN) during nanoindentation processes. This paper focuses on analyzing critical stresses, atomic displacement, shear strain, Von Mises stress, dislocation distribution, dislocation density, phase transition, and plastic zone volume. The simulation results demonstrate that the nanoindentation depth at the initial pop-in emergence differs according to the indenter type, which in turn gives rise to variations in dislocation nucleation and atomic phase transitions. A strong correlation between atomic displacement and shear strain was observed, with regions of high atomic displacement precisely coinciding with areas of high shear strain, demonstrating that atomic displacement is predominantly driven by shear strain. Furthermore, there is a high degree of consistency between the distribution of high Von Mises stress atoms and the distribution of dislocations, indicating that the nucleation and diffusion of dislocations is primarily stress-driven. The high Von Mises stress field is concentrated in the deformed regions of the workpiece, which are precisely where the dislocations grow and propagate. These findings provide valuable insights for indenter selection in GaN nanoindentation experiments and offer fundamental understanding for optimizing device fabrication processes in semiconductor manufacturing.

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