Microscopic mechanisms of nitrogen doping in silicon carbide during epitaxial growth

We report first-principles calculations that unveil elementary processes of nitrogen donor doping during epitaxial growth of silicon carbide (SiC). We find that a N₂ molecule adsorbed on the terrace migrates to a particular step edge where under-coordinated Si atoms appear, or is directly adsorbed near the step edge, and then dissociated there via the step-molecule interaction. This results in the N atom being eventually incorporated at the C substitutional site of the step. The calculated energy barriers indicate that the N incorporation reactions at the step edges occur at a typically high temperature in SiC epitaxial growth.