Morphological and Optical Properties of Cd_1-xCo_xS Thin Films by Liquid Phase Chemical Bath Deposition

Abstract

Cd1-xCoxS (0 x 0.5) thin films have been deposited by liquid phase chemical bath deposition method on glass substrate from a complex liquid phase formed by equimolar volumes of cadmium sulphate, thiourea and cobalt sulphate. For deposition various preparative parameters, such as speed, temperature, pH, and time were optimized and found to be 70 ± 2 rpm, 56 °C, 11±0.2 and 80 min. respectively. The samples were thin, uniform and tightly adherent with colour changing from orange red to dark chocolate as x was varied from 0 to 0.5. The films were characterized to evaluate the surface morphology, composition and optical measurements. The surface morphologies of these films revealed random orientation of the crystallites of elongated rhomboids with sharp and clear edges having leaf like appearance. The grain size is found to be enhanced continuously from x = 0 to x = 0.1 with fine and more clear grain boundaries and decreased for higher x values. Energy Dispersive X-ray analysis suggests that the deposits are Cd rich. The optical studies were performed on these samples in the range of wavelengths between 500 nm to 1300 nm and yield a high absorption coefficient (α 104-105 cm-1) with a direct type of transitions. The estimated band gap decreased from 2.42 eV to 1.94 eV as x was varied from 0 to 0.5.

First-principles investigation of structural electronic magnetic and thermodynamic properties of CdS alloyed with Co transition metal

“…Cd 1-x Co x S is a wide and direct band material with applications in optoelectronic devices [44]. To calculate the band gap, an efficient potential mBJ is used.…”