Comparative ellipsometric analysis of silicon carbide polytypes 4$H$, 15$R$, and 6$H$ produced by a modified Lely method in the same growth process

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 4$H$, 15$R$, 6$H$ 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 (000$\bar1$) to the Si-face (0001).