Surface defects and accompanying imperfections in 4H–SiC: Optical, structural and electrical characterization

The optical, structural and electrical properties of the killer defects termed down-fall particles and their accompanying imperfections in 4H–SiC homoepitaxial films were studied using electron microscopy techniques. Down-fall particles are polycrystalline 3C–SiC several tens of microns in size. They show unexpected dark contrast at their band edge (525 nm) using cathodoluminescence (CL). Down-fall particles have different effects on epitaxial growth. Most of them (common ones) are accompanied by stacking faults (SFs) which luminesce at 471 nm, while some promote the occurrence of 3C inclusions nearby. Transmission electron microscopy has revealed that the displacement vector of the accompanying SF is in the {0 0 0 1} basal plane, whereas the interface between the 3C inclusion and 4H matrix is composed of Shockley-type and Frank-type partials. The effects of down-fall particles on epitaxial growth as well as their dark contrast in the CL images are discussed. The differences between the common and special particles and the correlation with the electrical properties of the device are also discussed. The detailed structure–property analysis in this study thus provides a fundamental understanding of defect formation and development during the homo- or hetero-epitaxial growth of various materials.