Growth of 4H-SiC epilayers with low surface roughness and morphological defects density on 4° off-axis substrates

► We presented the results on surface roughness and morphological defects of 4H-SiC epilayers on 4° off-axis substrates with 100 mm diameter. ► The impacts of the etch processes on the surface roughness of substrates and grown epilayers were shown. ► Smooth epilayer surfaces without step-bunching were obtained by optimizing etch processes. ► The increase in the Cl/Si ratio was demonstrated to effectively suppress the morphological defects on the epilayers with smooth surfaces. ► We can obtain the total morphological defects density lower than 1 cm−2 on 4H-SiC epilayers with roughness of 0.2 nm.