研究目的
To investigate the mechanical property and microstructural deformation of B3-GaN films under indentation using molecular dynamics simulation.
研究成果
The mechanical property and microstructural deformation of B3-GaN films under indentation were studied using MD simulation. The P-h curve of the indentation on the GaN (001) surface reveals that the pop-ins are related to dislocation nucleation. The P-h curves for the indentation on the three planes exhibit anisotropy and show different depths at the onset of plasticity. Two mechanisms for the formation of prismatic loops were found. The dislocation densities are different in the samples under the indentations on different oriented surface.
研究不足
The study is limited to molecular dynamics simulations at low temperatures (10 K and 300 K), which may not fully represent the behavior of B3-GaN films at higher temperatures or under different conditions.
1：Experimental Design and Method Selection
Large-scale molecular dynamics (MD) simulation of nanoindentation was performed to study the plastic behavior and the corresponding mechanism of B3-GaN thin films. The Stillinger-Weber (SW) potential was selected to describe the Ga-N system.
2：Sample Selection and Data Sources
The B3-GaN thin film was the sample under investigation. The simulation box size was about 253 ? × 253 ? × 303 ?, comprising approximately 1,128,960 atoms.
3：List of Experimental Equipment and Materials
The indenter was set as a rigid sphere. The MD simulation was carried out using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), with a constant time step of 1 fs, and the simulation results were visualized with OVITO (Version 2.9.0).
4：Experimental Procedures and Operational Workflow
The specimen was optimized using the conjugate gradient (CG) algorithm to obtain the minimum equilibrium energy. The bottom atoms of the specimen were fixed to avoid movement during indentation. The temperature was kept at 10 K for most cases. The indenter moved downwards at a speed of 20 m/s.
5：Data Analysis Methods
The identify diamond structure (IDS) method was employed to analyze the structural deformation and dislocation nucleation. The dislocation extraction algorithm (DXA) was adopted to identify dislocation patterns and calculate the length of dislocation lines.
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