Influence of Secondary Patterning on the Crystalline Quality of Epitaxial GaN Films

Abstract Molecular dynamics simulations were employed to investigate the effects of planar, single-patterned, and secondary-patterned epitaxy on the crystalline quality of GaN thin films. Secondary-patterned epitaxy significantly improves atomic ordering, promotes the formation of stable wurtzite structures, and effectively suppresses stress accumulation and dislocation propagation during epitaxial growth. The average residual stresses of the planar, single-patterned, and secondary-patterned epitaxial films are −3.86 ± 0.32 GPa, −2.74 ± 0.24 GPa, and −0.98 ± 0.07 GPa, respectively. After patterning treatment, the dislocation density of epitaxial GaN thin films decreases from (4.10 ± 0.23) × 1013/cm2 on planar substrates to (2.49 ± 0.37) × 1013/cm2 after primary patterning and (1.12 ± 0.22) × 1012/cm2 after secondary patterning, reducing the dislocation density of the epitaxial thin films by 1 order of magnitude. Meanwhile, the proportion of wurtzite structures increases from 54.1% to 62.0%, while the fraction of high-stress atoms increases from 7.5% to 4.0%. The multi-level cylindrical structures introduced by secondary patterning provide additional lateral growth channels and stress-relief pathways, which facilitate atomic rearrangement, lattice relaxation, and defect annihilation, thereby significantly enhancing the structural stability and crystalline quality of epitaxial GaN thin films.