Study of Dislocation Bending During Film Growth by a Multiscale Scheme

QR An and QC Nie and S Liu and HS Fang, CRYSTAL RESEARCH AND TECHNOLOGY, 57, 2100214 (2022).

DOI: 10.1002/crat.202100214

Depositing on the patterned substrate in chemical vapor deposition is one of the most effective approaches to produce low-dislocation-density films. Existing experiments indicate that dislocation bending is the main cause of decreasing dislocation. However, what drives dislocation segments (DSs) to bend remains unclear, and existing numerical methods do not explain the mechanism fully. In this study, a multiscale scheme based on molecular dynamics (MD) and kinetic Monte Carlo (KMC) is proposed to unravel the multiscale mechanism of DSs bending. In this scheme, MD is employed to identify the off-lattice structure and to calculate the diffusion activation energies. KMC is used to perform the temporal evolution of the deposition process. In a proof-of-concept, the growth rate and the film morphology in silane deposition are predicted in the cross-scale comparable to the experimental measurements. With the proposed multiscale scheme, the calculated activation energies show that the repeated lateral deposition and the obliquely upward deposition of the dislocated atoms contribute to DSs bending. Moreover, the sharp decrease of dislocation density is quantitatively elucidated by the scheme. The study provides fundamental insight into dislocation bending reduction during crystal thin film growth.

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