Multiscale Analysis of Macroscopic Flow and Microscopic Adsorption in HVPE Growth of 4-in. GaN Crystals

High-quality, large-size gallium nitride (GaN) substrates are core materials for advanced optoelectronic and high-power devices. However, isolating macroscopic flow optimization from microscopic surface mechanisms during hydride vapor phase epitaxy (HVPE) restricts further quality improvements. Herein, we propose a multiscale strategy combining computational fluid dynamics (CFD) and density functional theory (DFT) to investigate flow field regulation and precursor adsorption in a vertical HVPE reactor. Results demonstrate that synergistically regulating rotation speed and susceptor inclination establishes centrifugal suction and aerodynamic acceleration, achieving uniform radial precursor transport. Furthermore, DFT calculations verify the precursors’ strong thermodynamic adsorption affinity and high configurational adaptability, atomically confirming that epitaxial growth is predominantly governed by macroscopic mass transfer. Guided by these insights, high-quality, large-size GaN crystals were experimentally fabricated, exhibiting a (002) plane fwhm of 58.89 arcsec and a dislocation density as low as 1.47 × 10 6 cm –2 . This study successfully establishes a logical linkage between macroscopic mass transfer and microscopic reactions, providing solid guidance for the efficient industrial production of large-size GaN substrates.