Fabrication and characterization of cadmium telluride thin films

In this study, the effect of deposition potantial on physical characteristics of CdTe thin films is studied. The best deposition potantial is researched. CdTe thin films are deposited on ITO substrate, changing deposition potential from -0,4 V to -1,1 V by a step of 0,1 V. The rate of Cd/Te, surface formation, morphological characteristics, conductivity types, carrier numbers, optical characteristics, forbidden energy band gaps and Nyquist curves of CdTe thin films are investigated depending on the deposition potantial. In the CV voltammogram, it is observed a peak at -0,4 V, which is belonging to CdTe. Forbidden energy band gaps of thin films have been determined between 1,61 eV–1,94 eV and thickness of thin films are determined between 72 nm–140 nm. Roughness values of CdTe thin films are found between 35 nm–191 nm from AFM measurements. Cd/Te rates of deposited CdTe thin films are reported between 1,03–1,55. Donor densities of CdTe thin films are found between 1017–1019 cm-3, while acceptor density of the CdTe thin film deposited at -0,9 V is 1020 cm-3. CdTe thin films deposited between -0,4 V and -0,8 V have n-type conductivity, while CdTe deposited on -0,9 V is p-type. From Mott-Schottky studies, it is concluded that Flat band potantials of CdTe thin films are between 0,28 V–0,60 V, and Flat band potantial of the CdTe deposited at -0,9 V is -0,30 V. In addition, Fermi energy levels of CdTe thin films are calculated between -3,57 eV–3,99 eV. Pore resistance values of the films are found between 0,787–306,1 kΩ•cm2 and charge transfer resistances of thin films are determined between 0,222–512,6 Ω•cm2. According to the XRD measurements of electrodeposited CdTe thin films, the films have hexagonal and monoclinic crystalline phases.