Study of morphology defects in 4H-SiC thick epitaxial layers grown on 4° off-axis Si-face substrates

Abstract

The crystallographic structure and origins of morphology defects observed in 4° off-axis Si-face thick 4H-SiC epitaxial layers were investigated by Nomarski microscope and Raman spectroscopy. The growth direction of these morphology defects is consistent with the step-flow direction, all of the defect include a certain core, which indicates that the defects were originated from certain cores. These cores of the morphology defects contain 3C poly-crystalline grains based on the Raman spectroscopy characterization. The head part of the defect formed during epitaxial layers growth and their formation is attributed to the foreign particles. The formation mechanisms of these obtuse morphology defects are discussed based on our model. It can be concluded that foreign particles fall down on the surface during the 4H-SiC epitaxy that disturb the normal step flow mode and lead to the 3C-SiC nucleation, which is the origination of the morphology defects.