Abstract
The fabrication of Zn0.5Cd0.5Te thin film was reported in this study which was prepared via the common vacuum evaporation process at various temperatures (25, 100, 200, 300, 400 and 500 °C). On pre-cleaned glass substrates, the Zn0.5Cd0.5Te thin films were formed. The absorption coefficient was used to analyze the linear optical path in this study. The optical parameters, the optical constants, the dielectric constants, the quality factor of the studied thin films and the dispersion parameters were computed. The envelope approach, proposed by Swanepoel, was used to calculate the refractive indices and the thickness of the studied films in the transparent region. The optical energy gap was computed in the transmittance and reflectance spectrum's strong absorption zone. As the temperature of the examined system is increased, the refractive index, n, decreases while the energy gap rises. The annealed thin films have a crystalline structure with cubic phase and primarily oriented along the (111) plane, according to x-ray diffraction results. The crystalline structure of the examined thin films was confirmed by the top view of SEM profiles for the Zn0.5Cd0.5Te thin film at various temperatures. In the other part of this work, the photovoltaic characteristics of the fabricated n-Zn0.5Cd0.5Te/p-CdTe solar cell were investigated for a solar cell which fabricated by depositing a p-CdTe thin layer (200 nm) on the ZnCdTe thin films (∼1000 nm) prepared on the glass substrates (2 mm). The Ni/n-Zn0.5Cd0.5Te/p-CdTe/Pt heterojunction has been effectively assembled. The front and back contact electrodes were made of two high-work-function metals (Pt and Ni) so that surface electrons may travel freely and be easily removed from the surface by the influence of the lowest energy falling on the solar cell. The dark (current-voltage) characteristics of fabricated heterojunctions have been reported at different temperatures ranging from 25 to 500 °C, as well as for voltages ranging from −2 to 2 V. Based on the dependence of the forward and reverse current on the voltage, the effective and main parameters connected to the fabricated diode have been determined. The rectification ratio, the junction resistance, an ideality factor of the fabricated diode, the shunt and series resistances, the height of the barrier formed at the interface between the Zn–Cd–Te thin films and the p-CdTe thin layer, the carrier recombination, the activation energy in the exhausted region, Poole-Frenkel, and Schottky coefficients were all evaluated.
•The optical parameters, and dispersion parameters were calculated.•The structural parameters of the studied system were extracted.•The structural and optical properties improved with increasing temperature.•The dark (current-voltage) characteristics were studied in detail.•The photovoltaic parameters were computed.