Effect of transmutation and active elements on the surface stability of silicon carbide

Abstract

This study investigates the influence of transmutation (Be, Li, Al, Mg) and active elements (Mo, Ti, Zr, Y) on the surface stability of 3C-SiC using density functional theory. The findings reveal: i) Strong surface segregation of these elements, along with their segregation into the surface depth, induces abrupt changes in surface stability. The segregation energies of these elements are positively correlated with their solubility energies. ii) Surface segregation generally enhances stability. Be, Li, Al, Mo, Ti, Mg, and Y improve the stability of (111) and (011) surfaces, while Zr destabilizes the (111) surface. The mechanisms underlying multi-element attraction and repulsion are quantitatively explained through binding energy analysis. iii) Al and Y exhibit significant charge loss, destabilizing the surface by promoting chemical reactions and increasing defects. In contrast, Li resists charge loss, maintaining electronic stability, while Mg regulates charge distribution uniformly, stabilizing the surface structure irrespective of orientation or additional elements. This work provides valuable insights into the atomic-scale mechanisms governing SiC surface stability.