Elipsometric Investigations of Nano Thickness Cu2ZnSnSe4 Films

Öz

An ellipsometric research of a thin layer of Cu₂ZnSnSe₄ with a thickness of approximately 100 nm obtained on a glass substrate by the method of magnetron sputtering of a target with a diameter of 10 cm made by pressing from the crushed nanopowder of the Cu₂ZnSnSe₄ crystal was carried out. The experimental results are in good agreement with the ε-spectrum calculated within the GW quasi-particle approximation, and the possible origin of the identified high-energy features is identified. Magnetron sputtering occurs during a gas discharge with a voltage of ~ 300 - 600 V and a current of ~ (3-5) A. SE measurements were performed using an angled spectroscopic ellipsometer (J.A. Woollam VASE) at room temperature. Ellipsometric parameters were obtained in the photon energy range (1.03 to 6.4 eV) and at 65⁰. The pseudo dielectric functions were mathematically modeled and then the energy dependence graphs of the dielectric functions (ε₁ and ε₂) were constructed. Here n - the real part of the refractive index k - and the imaginary part, that is, the extinction coefficient. Based on the relationship between the dielectric functions and the refractive index, the values of the dielectric functions were taken into account in the formula, and the values of the real part of the refractive index and the extinction coefficient were determined.  That is, in the Cu₂ZnSnSe₄ thin film, E_g=1.6 eV, and high energy features are determined at energies of 4 eV and 4.6 eV.