Optical, Solid State and Structural Characterization of Optimized Grown Thin Films and their Possible Applications in Solar Energy

ABSTRACT

Solution growth technique was used to deposit thin films of Manganese Suphide (MnS), Calcium Sulphide (CaS), Magnesium Sulphide (MgS), Barium Sulphide (Bas), Zinc Fluoride (ZnFz) and Calcium Oxide (CaO) on micro-slides (Substrates) at different bath parameters which include temperature, molarity of solution, Volume of solution and water, time of d.eposition and pH. The absorbance, A was measured using spectrophotometer ranging from ultraviolet to visible regions. The Transmittance, TI Reflectance, R Energy band gap, E, Absorption coefficient, a, Extinction coefficient, K, Refractive index, n, Dielectric constant, 6, Optical conductivity, oop1 and Thickness t, were calculated. The percentage transmittance of the films were measured at infrared region using infrared spectrophotometer. Graphs of there properties were plotted against wavelength and photon energy to determine the behaviour of each film at ultraviolet, visible and Infrared regions of the electromagnetic spectrum. The topographic structure of the films were studied using photomicrography .method or optical microscope. Energy Dispersive X-Ray Fluorescence (EDXRF) was used to determine the elemental compositions of the films. The optical and solid state characteristics reveal that films of manganese sulphide (MnS) have thickness, t - 1.96-2.69pmI refractive index, n - 1.39 - 1.74 and energy bandgap, Eg - 2.60 - 3.90eV. Calcium Sulphide (CaS) films have t - 2.63 - 2.98pmt n - 1.37 - 1.43 and E, - 3.60 - 4.10eV. Magnesium Sulphide (MgS) films have t - 2.47 - 2.60pm, n - 1.44 - 1.53 and E, - 3.7 - 3.9eV. Barium Sulphide (Bas) films have t - 1.bl - 2.61pm1 n - 1.43 - 1.82 and E, - 3.2 - 3.5eV. Zinc Fluoride (ZnFz) films have t - 1.78 - 2.57pm, n - 1.39 - 1.82 and E, - 0.90 - 1.lOeV. Calcium Oxide (CaO) films have t - 1.94 - 2.33pm1 n - 1.51 - 1.69 and E, - 0.80 - 3.90eV. The above results show that MnS and MgS could be coated on solar collectors to enhance solar energy collection. Bas, ZnF2 and CaO films could be applied as window coatings to lower the temperature of a room. MgS, Bas, ZnFz and CaO could be joined with other films that have high reflectance in infrared region to .serve as heat mirror coatings. MnS, CaS, MgS, Bas, ZnF2 and CaO were found suitable as antireflection coatings while ZnF2 and CaO are good materials for use in the construction of transistor.