Atomistic Insights into Composition-Dependent Structural Evolution and Phase Transition in Ga _1-x N _x Alloys

This study employs molecular dynamics simulations to investigate the effects of composition and temperature on the structural properties, phase transitions, and glass transition temperature of Ga 1-x N x compounds (x = 0.2, 0.4, 0.5, 0.6, 0.8). For GaN at 300 K, the Ga–N bond length is 2.05 Å, and this value remains constant across temperatures from 300 K to 4 K and doping concentrations from 20% to 80%, despite the simulated system size increasing from 5,324 to 27,436 atoms. Cooling reduces the system’s total energy, whereas higher doping concentrations increase it. Significant variations are observed in the populations of FCC, HCP, BCC, and amorphous structural units, with GaN exhibiting both amorphous and crystalline states. Cooling also decreases the total binding energy and enhances structural smoothness, while the amorphous-to-crystalline phase transition is identified at approximately 250 K. These results advance the understanding of GaN structural behavior under varying conditions and provide guidance for the design and optimization of GaNbased materials in advanced semiconductor applications.