Analysis of polytype stability in PVT grown silicon carbide single crystal using competitive lattice model Monte Carlo simulations

Abstract

Polytype stability is very important for high quality SiC single crystal growth. However, the growth conditions for the 4H, 6H and 15R polytypes are similar, and the mechanism of polytype stability is not clear. The kinetics aspects, such as surface-step nucleation, are important. The kinetic Monte Carlo method is a common tool to study surface kinetics in crystal growth. However, the present lattice models for kinetic Monte Carlo simulations cannot solve the problem of the competitive growth of two or more lattice structures. In this study, a competitive lattice model was developed for kinetic Monte Carlo simulation of the competition growth of the 4H and 6H polytypes of SiC. The site positions are fixed at the perfect crystal lattice positions without any adjustment of the site positions. Surface steps on seeds and large ratios of diffusion/deposition have positive effects on the 4H polytype stability. The 3D polytype distribution in a physical vapor transport method grown SiC ingot showed that the facet preserved the 4H polytype even if the 6H polytype dominated the growth surface. The theoretical and experimental results of polytype growth in SiC suggest that retaining the step growth mode is an important factor to maintain a stable single 4H polytype during SiC growth.

Effects of thermal, elastic, and surface properties on the stability of SiC polytypes

“…To conclude, the thermodynamic stability of the bulk, including the vibrational free energy, cannot by itself explain experimental findings, in which 3C is observed at lower growth temperatures and 3C inclusion defects pose severe problems 15,107 . Note, however, that we did not take into account any anharmonic effects, which become increasingly important at these high processing temperatures and might affect the energetic ordering.…”

Effect of Deposition Flux on Polytypic Competitive Growth of SiC Crystal by Kinetic Monte Carlo Method

“…[ 22 ] A competitive KMC model is established to study the effect of the surface step on polytype stability during the growth of 4H‐SiC and 6H‐SiC crystals by the physical vapor transport (PVT) method. [ 23 ] The results show that retaining the step growth mode is very important to maintain the stable growth of a single 4H‐SiC crystal. Recently, a 3D competitive KMC model has been constructed.…”

Undulated Step Structure on the (0001¯) Facet of Physical Vapor Transport-Grown 4H-SiC Crystals

“…The step structure on the as-grown surface of SiC crystals has been studied by several research groups [6][7][8][9][10][11][12]. On the (0001) facet of 4H-SiC crystals grown in the c-axis direction, surface steps of half-unit cell height (0.5 nm) were predominantly observed, and they were often bunched into macrosteps of heights of approximately 6-10 nm.…”