Approximated dielectric tensor of the biaxial α-SnSe crystal

We present the principal components of the dielectric tensor for α-SnSe biaxial single crystal in the spectral range from 0.74 to 6.42 eV at room temperature (300 K) using spectroscopic ellipsometry. Aspnes’ first-order approximation method was applied to obtain approximated pseudodielectric response from the pseudodielectric tensor measured at an angle of incidence of ϕ = 68.8°. Multilayer calculations were then performed to extract the pure dielectric tensor without surface roughness artifacts. The Tauc–Lorentz model was applied to describe the critical point structures, and the optical constants along the principal axes of biaxial α-SnSe single crystal can be now calculated at arbitrary wavelength for device applications.