Mechanisms of nucleation, dislocation formation, and stress evolution during atomistic growth of SiC films on miscut 4H-SiC substrates

Abstract

Atomistic simulations are performed to investigate the vapor-phase deposition and growth of silicon carbide (SiC) thin films on 4H-SiC substrates with varying miscut angles and substrate temperatures. Substrate temperatures of T = 2200, 2300, and 2400 K and miscut angles of θ=0°, 2°, 4°, and 8° are considered to reveal the atomic-scale mechanisms governing crystal nucleation, polytype evolution, defect formation, and film stress. Crystal nucleation is found to initiate only after complete surface coverage by an amorphous adatom layer, followed by growth through atomic rearrangement into predominantly hexagonal (2H/4H) stacking. Local cubic stacking faults form when limited surface mobility inhibits relaxation into the hexagonal stacking sequence. The thickness of the amorphous surface layer, ranging from approximately 0.1 to 3 nm, decreases systematically with increasing substrate temperature and is strongly influenced by the substrate miscut angle. Dislocations with Burgers vectors of 1/3⟨11¯00⟩, 1/3⟨12¯10⟩, and 〈0001〉 form during growth, with their density and temporal evolution governed by the coupled effects of substrate temperature and miscut angle. Increasing substrate temperature significantly reduces dislocation density and promotes dislocation annihilation, particularly for low-miscut angle substrates. The deposited films exhibit tensile residual stresses that increase monotonically during growth, while the stress magnitude decreases by approximately 10% with each 100 K increase in substrate temperature. These results identify substrate miscut angle and temperature as key physical parameters controlling defect formation, microstructural evolution, and stress relaxation during SiC thin-film growth, providing mechanistic insight relevant for optimization of low-defect SiC films for wide-bandgap semiconductor applications.