講演情報
[23a-52A-2]Numerical Investigation on Critical Conditions for the Step Instability in Solution Growth of SiC
〇Xin Liu1, Toru Ujihara1 (1.IMaSS Nagoya Univ.)
キーワード：
Solution Growth、SiC、Step Instability
The dynamic equilibrium between carbon supply and consumption is the perfect state for the stable step growth of SiC crystal. Up to now, we could just realize the stable growth with a very low growth rate due to the complexity and sensitivity of TSSG-Si growing conditions.
Besides the unchangeable physical properties of solution, such as the carbon diffusivity and solubility, there are also the controllable growing conditions, such as the flow velocity, carbon gradient and off-angles, which could improve the stability of step growth. Previous numerical and experimental studies have verified the anti-parallel flow is favorable to the stable step growth, and the uniform step distribution on the whole crystal surface. However, the parallel and anti-parallel flow coexisted due to the switching rotations of SiC seed and graphite crucible. To ensure the stable and fast step growth, it is crucial to search for the critical conditions, which trigger off the step bunching and the unstable growth.
The present study investigated the step growth from stable to bunching on a vicinal face in TSSG-SiC growth by the mesoscale modeling. Three controllable parameters, including flow velocity, temperature difference, and off angle, were considered to investigate the critical conditions from stable to bunching. The surface roughness evolution was set as the instability criteria during the step growth process. It was found that there is a trade-off between fast and stable growth according to effects of the temperature difference and flow velocities. The effects of off-angle were also clarified for different velocities and temperature differences. The larger incorporation area from large-off angle increase could keep stable and fast growth with the moderate C flux.
Besides the unchangeable physical properties of solution, such as the carbon diffusivity and solubility, there are also the controllable growing conditions, such as the flow velocity, carbon gradient and off-angles, which could improve the stability of step growth. Previous numerical and experimental studies have verified the anti-parallel flow is favorable to the stable step growth, and the uniform step distribution on the whole crystal surface. However, the parallel and anti-parallel flow coexisted due to the switching rotations of SiC seed and graphite crucible. To ensure the stable and fast step growth, it is crucial to search for the critical conditions, which trigger off the step bunching and the unstable growth.
The present study investigated the step growth from stable to bunching on a vicinal face in TSSG-SiC growth by the mesoscale modeling. Three controllable parameters, including flow velocity, temperature difference, and off angle, were considered to investigate the critical conditions from stable to bunching. The surface roughness evolution was set as the instability criteria during the step growth process. It was found that there is a trade-off between fast and stable growth according to effects of the temperature difference and flow velocities. The effects of off-angle were also clarified for different velocities and temperature differences. The larger incorporation area from large-off angle increase could keep stable and fast growth with the moderate C flux.