Atomistic Simulations of Defects in Silicon Carbide

Spin defects in silicon carbide (SiC) are desirable platforms to create quantum technologies, such as quantum sensing, communication, and metrology. Notable spin defects are divacancies, which are formed when a silicon and carbon atom adjacent to one another are removed, generating a vacancy complex. Despite their importance, divacancies have been challenging to controllably synthesize experimentally. Here, we provide computational investigations into defect migration phenomena in 4H-SiC, a common polytype that is used experimentally but has not been studied theoretically. We employ classical and ab initio approaches to study the dependence of defect migration and formation on crystal structure, temperature, and defect concentration. We find that the choice of classical force field affects the melting behavior of 4H-SiC. We also find that vacancy migration occurs at an increased frequency for higher defect concentrations. Finally, we show how the crystal symmetry impacts the defect migration behavior across a range of temperatures, using both classical force fields and density functional theory (DFT) calculations.