Overlaid Shockley- and Frank-type stacking faults in 4H-SiC epitaxial layers

• Overlaid stacking fault structures along the growth c-direction of 4H-SiC epitaxial layer. • First report on the Shockley-type (4,3,2,3) stacking fault and its characteristic photoluminescence emission wavelength to 456 nm. • Determination of characteristic photoluminescence emission wavelength to 481 nm for the Frank-type (5,3,3,2) stacking fault. • Formation mechanisms for the Shockley-type (4,3,2,3) and Frank-type (5,3,3,2) stacking faults. • Theoretical calculation of the stacking fault energy for the Shockley-type (4,3,2,3) stacking fault to 6.3 mJ/m 2 . Overlaid Shockley-type stacking fault (SSF) and Frank-type stacking fault (FSF) structures in 4H-SiC epitaxial layers were investigated using photoluminescence (PL) mapping, spectral analysis, and HAADF HR–STEM. Overlaid SSFs was placed 390-nm apart along the c-direction of growth with a lower quadruple SSF (4,4) and an upper SSF (4,3,2,3). The SSF (4,3,2,3) were observed for the first time and a characteristic PL emission wavelength of 456 nm was determined. Overlaid FSFs with a lower intrinsic Frank-type SF (FSF) (5,2) and an upper FSF (5,3,3,2), placed 32-nm apart, were investigated. The characteristic PL emission wavelength of the FSF (5,3,3,2) was determined, for the first time, to 481 nm. Formation models for the SSF (4,3,2,3) from a SSF (4,4) and the FSF (5,3,3,2) from a FSF (5,2) were proposed. Stacking fault energies (SFEs) for SSFs (4,3,2,3) and (4,4) were theoretically calculated: 6.3 and 9.5 mJ/m 2 the SSF (4,3,2,3) and SSF (4,4), respectively. The smaller SFE for the SSF (4,3,3,2) supported its formation from SSF (4,4). The results showed formation and various geometries of SFs in atomic scale and expand our understanding of realistic SFs in 4H-SiC epitaxial layers, which are crucial in exploring their effects on SiC device performances.