Speaker
Description
Simulations of SiC crystal growth on an atomistic scale were, in the past, most commonly done with Monte Carlo (MC) based methods, such as kinetic lattice MC or kinetic super lattice MC. These, however, suffer from the fact that they have to use predefined deposition sites and reaction rates, making it difficult to realistically simulate defects, such as dislocations or stacking faults. With the rise of accurate interatomic potentials, MD simulations of SiC crystal growth have also been conducted. These, however, have the shortcoming of too small simulation times, therefore needing to use growth rates which are ~108 times larger than real-life SiC growth rates. A recently developed method, called the Minimal Energy Atomic Deposition (MEAD), combines both MD and MC and tries to seamlessly overcome both of these simulation hurdles.
The MEAD algorithm works by first scanning the surface of the substrate for deposition sites with low potential energy. Then these deposition sites are populated by either Si or C atoms. After this deposition step, temperature is applied to the system by using time-stamped force-biased MC (tfMC). This allows the system to get into equilibrium and for the deposited atoms to reach their minimum energy position at the required temperature. This three-step process of scanning the surface for potential deposition sites, then populating the lowest ones and applying temperature to the system, is then repeated until sufficient growth has been simulated.
In this talk, we will present our effort of applying the MEAD simulation method to the SiC system. We apply different temperatures ranging from 2300 to 2500 K and identify the polytypes grown, using this method on both the C-terminated and Si-terminated 4H SiC surface. In addition, defects, vacancies and add-atoms occurring during growth will be investigated, as well as growth on stepped surfaces. We also compare different interatomic potentials in terms of their predicted SiC growth structure. In this way, we hope to gain new insights into the atomistic mechanisms governing the growth process of SiC.