Characterization of Lattice Plane Bending and Stress Distribution in Physical Vapor Transport-Grown 4H-SiC Crystals

Abstract

Basal plane bending and stress distribution in physical vapor transport-grown n-type 4H-SiC crystals were investigated. High resolution X-ray diffraction measurements were performed on commercially available 3-inch-diameter 4H-SiC substrates and along the growth front surface of as-grown 1-inch-diameter 4H-SiC boules. The measurements revealed that structural parameters such as the c-lattice constant, basal plane tilting, and FWHM showed characteristic variations across the substrates and as-gown boules, indicating that the crystals had a non-uniform distribution of dislocations comprising domain structures. Residual stress measured by micro Raman spectroscopy showed a similar behavior, which was an oscillatory spatial variation. On the basis of these results, defect structures in the crystals are elucidated.

Structural Characterization of the Growth Front of 4H-SiC Boules Grown Using the Physical Vapor Transport Growth Method

“…AFM images were obtained at 512 × 512 point resolution over 5-, 30-or 50-µm 2 square areas. At the same position, the basal plane tilt shows a maximum, which implies that the bending direction of the basal plane becomes opposite at this point [5]. On the other hand, FWHM appears to be almost constant from the facet through the outer regions, indicating that although the c-lattice constant changes at the facet boundary, the overall crystallinity is not much different among the three regions.…”