Optical Characterization of SnO2 Thin Film Using Variable Angle Spectroscopic Ellipsometry for Solar Cell Applications

In this work, we prepared a nanostructure of TCO in a thin film of tin oxide using the spray pyrolysis method. The different deposition parameters have been set and optimized to prepare the source solution from Tin chloride dihydrate deposited on a cleaned glass substrate. The characterization of the thin layer of pure tin oxide deposited by spraying was achieved. The X-ray diffractometer shows that the tin oxide film is polycrystalline with a tetragonal structure, which consists mainly of orientations (101), (211) and other less intense. Ultra-violet-spectroscopy approved an excellent transparency of the thin layer of pure SnO2 with a transmission of 95 % at 600 nm. The optical gap value of the deposited sample is equal to 3.95 eV. The spectroscopic ellipsometry measurements of the Psi and delta parameters were carried out at various angles of incidence 65°, 70° and 75°. The optical constant of the SnO2 layer was modeled using a B-spline model. The goodness of the ellipsometric fitting was found at an incidence angle of 75°, which indicates a minimum MSE equal to 4.022. The SE characterization results of SnO2 thin film on the glass substrate have shown that the layer thickness, the refractive index and the extinction coefficient are equal to 219.78 nm, 1.41 and 0.123, respectively. The resulting structural and optical parameters confirmed that a thin SnO2 layer was formed. This layer showed a wide bandwidth and high transparency of a type of TCO semiconductor, which can be used as an anti-reflective layer in solar cell devices.