The relationship between refractive index-energy gap and the film thickness effect on the characteristic parameters of CdSe thin films

CdSe thin films were deposited on glass substrates using Successive Ionic Layer Adsorption and Reaction (SILAR) method at room temperature and ambient pressure. The relationship between refractive index and energy bandgap was investigated. The film thickness effect on the structural, morphological, optical and electrical properties of CdSe thin films was investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all the films exhibit polycrystalline nature with hexagonal structure and are covered well with glass substrates. The crystalline and surface properties of the films improved with increasing film thickness. The optical absorption studies revealed that the films are found to be a direct allowed transition. The energy bandgap values were changed from 1.93 to 1.87 eV depending on the film thickness. The electron effective mass (me⁎/mo), refractive index (n), optical static and high frequency dielectric constant (εo, ε∞) values were calculated by using the energy bandgap values as a function of the film thickness. The resistivity of the films changed between 106 and 102 Ω-cm with increasing film thickness at room temperature.

Research Highlights
► One of the newest solution methods for the deposition of thin films is SILAR method.
► CdSe thin films have been deposited on glass substrates using SILAR method.
► The refractive index(n) of semiconducting materials is very important indetermining the optical and electric properties of the crystal.
► The relationship between refractive index and energy bandgap.
► The electron effective mass, refractive index, dielectric constant values have been calculated by using the energy bandgap values as a function of the film thickness.