A Structural Analysis Study of Epitaxial Layers Grown on 4H-SiC Wafers

This study investigated the structural and crystallographic properties and the local strain accommodation behavior by growing silicon carbide (SiC) epitaxial layers with a thickness of 12μm on a SiC wafer. Because epitaxy involves the substrate and the epitaxial layer sharing the same crystal structure and lattice constant, the occurrence of defects due to lattice mismatch was significantly reduced compared to heterojunctions. The SiC epitaxial layers formed under appropriate growth conditions exhibited excellent surface morphology and the same crystal structure as the substrate, and the residual stress generated near the interface could be alleviated through local strain accommodation. Therefore, by comprehensively applying various analytical techniques—atomic force microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy (HR-TEM) —the SiC homo-epitaxial structure and local strain accommodation behavior of the epitaxial layer grown on the SiC substrate were structurally analyzed. Specifically, since studies directly analyzing atomic-scale local strain accommodation and the fine displacement behavior of Si atomic columns at interfaces where homo-epitaxial structures are formed are relatively limited, the structural stability of the epitaxial layer was confirmed using high-angle annular dark-field–scanning transmission electron microscopy images and fast Fourier transform pattern analysis.