Effect of Al doping on the natural growth direction of 6H-SiC crystals: from the DFT calculation to experiment

Low-temperature Acheson synthesis achieves energy-efficient SiC production; • DFT and experiments reveal the multiscale mechanism of 6H-SiC evolution; • Al-induced electronic reconstruction governs surface energy and morphology evolution. To achieve the regulation of 6H-SiC crystal morphology at low-temperatures in the Acheson process, this study investigates the growth direction evolution of 6H-SiC by altering the surface energy differences between crystal planes through Al doping, using a combination of density functional theory (DFT) calculations and experimental methods. DFT calculation results reveal that Al doping exerts differentiated effects on the surface energy of various 6H-SiC crystal planes through the modulation of electron distribution and reconstruction of local chemical bonding environments, which further alters the relative plane stability and surface energy anisotropy. This mechanism provides theoretical support for morphology regulation of 6H-SiC via doping in the low-temperature Acheson process. Experimental results demonstrate that Al doping facilitates the thickening of 6H-SiC particles and induces gradient morphological evolution correlated with the <0001> direction, which is consistent with the variation of surface energy anisotropy predicted by DFT calculations. Download: Download high-res image (106KB) Download: Download full-size image