Interplay of temperature and composition in AlGaN film growth on GaN: An atomistic molecular dynamics study

Among the III-nitrides, AlGaN plays a crucial role in the development of advanced optoelectronic and high-power electronic devices. In this work, molecular dynamics simulations were performed to investigate the vapor deposition of AlGaN films on GaN substrates. Time- and position-dependent boundary conditions have been applied to achieve appropriate growth conditions. Growth studies of ternary AlxGa1 − xN films were performed by varying the deposition molar fraction of the Al content (x = 0.1–0.8) and temperature in the range 1400–2400 K. After the growth simulation, surface morphology, crystallinity, interfacial domain structure, and dislocation behavior were systematically analyzed. Results show that increasing substrate temperature significantly enhances crystalline quality, which also helps to reduce surface roughness and dislocation density. A sharp decrease in dislocation lines and a notable increase in crystallinity are observed above 1800 K. An increase in Al content leads to a pronounced rise in surface roughness and dislocation density, accompanied by a reduction in interfacial domain size and overall crystallinity. Additionally, local phase separation into AlN-rich regions is identified as a key factor governing structural inhomogeneity. These findings provide atomistic insights into AlGaN/GaN growth mechanisms and offer guidance for optimizing growth conditions to achieve high-quality AlGaN films.