Characterizing the dielectric function of SnS on the ab-plane through parameterization

Since α-SnS has optically strong anisotropic characteristics, a simple method to determine its crystal orientation is strongly needed in device engineering. We report the parameter values ​​of the Tauc–Lorentz model (TL) which can be used to determine the dielectric function (ε=ε₁+iε₂) of α-SnS in the 1–5 eV spectral region with the full azimuthal angle range. The TL model was applied to describe dielectric function data of the SnS reported previously, and the reconstruction was successfully accomplished by eight TL oscillators, showing the asymmetric nature of the dielectric function. Using the interpolation of the obtained parameters, ε can be determined as a continuous function of energy and azimuthal angle within the limits given above. Orientation of the crystal axis of SnS device can be also decided by simple optical measurement.