Thermal-oxidation-induced local lattice distortion at surface of 4H-SiC(0001) characterized by in-plane X-ray diffractometry

Local lattice distortions at the surface of 4H-SiC(0001) after various thermal oxidation processes were investigated by in-plane X-ray diffractometry. Our results showed that dry oxidation induced lattice distortion, observed as the increase of interplanar spacing, became higher with increasing oxidation time. Lattice constant changes of up to ∼0.4% were observed by increasing the oxide thickness to 44 nm. This lattice distortion was not recovered after removal of the SiO2 layer by chemical etching, although it was partially reduced by Ar gas annealing, suggesting that strain relaxation requires removal of oxidation-induced defects in the 4H-SiC surface region.