We report first-principles total-energy calculations based on real-space density-functional theory that unveil the atom-scale mechanisms of surface diffusion of adatoms on the Si-faced $3C$-SiC(111) stepped surface. The quality of the epitaxial layer of SiC affects the device performance. Therefore, fundamental knowledge of the microscopic mechanisms of epitaxial growth is crucial for the improvement of the quality of SiC power devices. However, adatom diffusion on the growing stepped SiC surfaces is still unknown. We identify diffusion pathways for three important adatom species of SiC chemical vapor deposition (CVD), Si, C, and H, and obtain the corresponding energy profiles for both on the surface terraces and near the surface steps, providing a complete picture of the adatom diffusion. We find that the Si adatom is most mobile on the terrace and shows prominent Ehrlich-Schwoebel (ES) effect in the inter-terrace diffusion, whereas the C and H adatoms show less ES effect and in an ascending diffusion even the inverse ES effect appears for the C adatom. The results obtained are fundamentals to explore the microscopic mechanism of the epitaxial growth on $3C$-SiC(111) surfaces and equivalently hexagonal SiC(0001) surfaces.

我们报告基于实空间密度泛函理论的第一性原理总能量计算，该理论揭示了硅原子上硅原子表面扩散的原子尺度机制 $3C$-SiC（111）台阶表面。SiC外延层的质量会影响器件性能。因此，外延生长的微观机理的基础知识对于提高SiC功率器件的质量至关重要。然而，在逐步生长的SiC表面上的原子扩散仍是未知的。我们确定了SiC化学气相沉积（CVD），Si，C和H的三种重要吸附原子种类的扩散途径，并获得了在表面阶地和表面台阶附近的相应能量分布，从而提供了吸附原子的完整图片扩散。我们发现硅吸附原子在平台上移动性最大，并且在层间扩散中显示出显着的埃利希·舒沃贝尔（ES）效应，而C和H原子显示较少的ES效应，并且在上升扩散中甚至对C原子显示反ES效应。获得的结果是探索外延生长的微观机制的基础。$3C$-SiC（111）表面和等效的六边形SiC（0001）表面。