X-ray diffraction measurement of doping induced lattice mismatch in n-type 4H-SiC epilayers grown on p-type substrates

High-resolution x-ray diffractometry was used to measure the lattice mismatch and misorientation in n-type 4H-SiC epilayers grown homoepitaxially on p-type 4H-SiC as function of different nitrogen doping levels. The spatially averaged lattice mismatch increased from 1.0×10−5 to 4.0×10−5, 6.3×10−5, 8.8×10−5, and 11.6×10−5 in epilayers doped 4.1×1017 cm−3, 2.6×1018 cm−3, 1.7×1019 cm−3, 2.2×1019, and 4×1019, respectively. The resolved multiple subsidiary peaks in the rocking curve of the epilayers doped 2.2×1019 and 4×1019 cm−3 are likely due to high density of domain boundaries. The increase in mismatch with doping, is attributed to the substitutional nitrogen incorporated preferentially in the host carbon sites of the 4H-SiC epilayer.