In this paper, we propose a model for the quantitative analysis of the dependence of the dielectric function of hexagonal silicon carbide polytypes on the photon energy in the range 0.0–6.5 eV. This model consists of the sum of two Tauc-Lorentz oscillators (main and minor) with a total band gap. This approach is used to describe the three hexagonal polytypes of silicon carbide 4H, 15R, 6H obtained in one growth process. Both C-faces and Si-faces of each polytype are analyzed. A number of conclusions have been made about the dependence of the oscillator parameters on the polytype hexagonality degree and the type of surface face. The strongest dependence is an increase of the minor oscillator amplitude with an increase of polytype hexagonality degree. It should also be noted that the band gap increases upon transition from the C-face (0001 ̅) to the Si-face (0001).

A model is suggested for a quantitative analysis of the dependence of the dielectric function of hexagonal silicon carbide polytypes on photon energy in the range of 0.7–6.5 eV. The model, which is the sum of two Tauc–Lorentz oscillators (main and minor) with a common energy gap, is used to describe three hexagonal silicon carbide polytypes (4H, 15R, 6H) obtained in the same growth process. Both C- and Si-faces of each polytype are analyzed. A number of conclusions are drawn about how the oscillator parameters depend on the degree of hexagonality of a polytype and on the type of a surface face. The strongest dependence is that the amplitude of the minor oscillator grows with increasing degree of hexagonality of a polytype. The increase in the energy gap on passing from the C-face (000$$\bar {1}$$) to the Si-face (0001) is also worthy of note.

This paper presents the results of a nanoindentation study of the hardness and Young’s modulus of hexagonal silicon carbide SiC-4H, obtained by the modified Lely method, in thin surface layers near the C-terminated and Si-terminated faces at small penetration depths of the indenter. It is shown that differences in the elastic properties and hardness of SiC propagate from the surface into the crystal to a depth of about 60 nm. The Young's modulus at the C-terminated face practically coincides with the Young's modulus of the bulk SiC-4H sample (~ 400 GPa), which is approximately 2.3 times higher than the Young's modulus at the Si-terminated face at a depth of 0 to 35 nm (~ 170 GPa). The value of the SiC hardness is approximately 1.5 times higher at the surface of the C-terminated face than at the Si-terminated face, on average, at a depth of 0 to 60 nm. It is concluded from the obtained data that the surface energy of the C-terminated face is also approximately 1.5 times higher than the surface energy of the Si-terminated face since a new surface is formed upon deformation or cracking of the crystal

The results of hardness and Young’s modulus study of near-surface layers of 4H-SiC hexagonal silicon carbide obtained by the modified Lely method from the C-face (000$$\bar {1}$$) and Si-face (0001) at shallow depths of the indenter are presented. It is shown that the differences in the elastic properties and hardness of SiC propagate from the surface into the crystal at a depth of about 60 nm. The Young’s modulus at the C-face almost coincides with the Young’s modulus of the bulk 4H-SiC sample (~ 400 GPa), which is approximately 2.3 times higher than the Young’s modulus at the Si-face at a depth of 0–35 nm (~170 GPa). The hardness coefficient of SiC is on average about 1.5 times higher at the surface of the C-face (000$$\bar {1}$$) than at the Si-face (0001) at a depth of 0–60 nm. Since a new surface is formed upon deformation or destruction of the crystal (formation of cracks), based on the data obtained, it is concluded that the surface energy of the C-face is also about 1.5 times higher than the surface energy of the Si-face.

Abstract Silicon carbide substrates and epitaxial structures are investigated by nondestructive contactless methods. Parameters of the disrupted surface layer and roughnesses are determined using ellipsometry and atomic force microscopy. The free charge carrier concentration is determined by IR spectroscopy. The thicknesses in the multilayer epitaxial structure on SiC are determined using IR spectroscopy and scanning electron microscopy.