First-principles studies of nitrogen doping in 4H-SiC

Nitrogen (N) doping is crucial in 4H-SiC for preparing n-type electronic devices and for creating useful color centers. However, due to the doping complexity, such as N doping concentrations, growth or annealing temperatures, and chemical potentials, accurate control of N doping in 4H-SiC still remains largely unexplored both experimentally and theoretically. In this work, we systematically investigate the defect properties of N-doped 4H-SiC using first-principles calculations. By comprehensively investigating the effects of growth temperatures, chemical potentials, and the total amount of incorporated N on defect concentrations, Fermi levels, and carrier densities, we identify optimal doping conditions in 4H-SiC for achieving improved n-type electrical and optical properties in terms of color center concentrations. Our thermodynamic simulations indicate that, higher N incorporation, higher growth or annealing temperatures, and Si-rich conditions are favored for obtaining better n-type electricity while higher concentrations of Si vacancy and nitrogen-vacancy color centers can be achieved with more N incorporation, higher growth or annealing temperatures, and C-rich conditions. Our work provides valuable theoretical insights for optimizing N doping in 4H-SiC, which can guide the design of advanced n-type electronic devices and enhance the performance of color centers for quantum applications.