Near-equilibrium growth of micropipe-free 6H-SiC single crystals by physical vapor transport

A process for growing micropipe-free single crystals has been developed by using the modified Lely method. The process parameters were kept close to thermal equilibrium. The maximum average thermal gradient inside the growth furnace leading to micropipe-free growth was 5 K/cm. A gradient of 7.5 K/cm already resulted in a strong defect formation and produced a high density of micropipes $\text{(>200\hspace{0.17em}}{\mathrm{cm}}^{\mathrm{-2}}\mathrm{).}$ The highest achieved growth rate providing micropipe-free growth was 0.27 mm/h. For the employed parameter range, 6H-SiC single boule crystals were grown on both the C face and the Si face of 6H-SiC Lely platelets. The grown crystals are electrically and optically characterized.