Influence of growth time on the properties of CdTe thin films grown by electrodeposition using acetate precursor for solar energy application

Abstract

Cadmium telluride (CdTe) thin films were deposited using a two-electrode electrodeposition configuration from an aqueous acidic solution. The electrolyte solution contains 1 M of cadmium acetate dihydrate (Cd (CH3OO) 2.2H2O) as cadmium precursor and 1 ml of tellurium dioxide (TeO2) as tellurium precursor. The thin films were grown for different deposition times of 60, 120, 180, 240, and 300 min to investigate the effect of the deposition period on the structural, optical, electrical, surface morphology, elemental composition, and surface roughness properties of the CdTe thin films in both as-deposited and heat-treated forms. X-ray diffraction (XRD) analysis indicates that the CdTe thin films have polycrystalline cubic zinc blend, orthorhombic and hexagonal structures. The result confirmed that the cubic phase is dominant and (111) plane is the preferential orientation peak. Ultraviolet-visible (UV-Vis) spectrophotometry study shows that the band gap of the as-deposited thin films varies from (1.41-1.45) eV, and after heat treatment, the band gap decreased to (1.35-1.42) eV. Photoelectrochemical cell (PEC) measurements show that CdTe thin films have n-type conductivity in both as-deposited and annealed forms. Scanning electron microscopy (SEM) analysis shows that the surface morphology of CdTe thin films changed as the deposition period increases. After heat treatment, the improvement in grain size was observed. Energy-dispersive X-ray spectroscopy (EDS) analysis shows that the percentage composition of as-deposited CdTe thin films varied with deposition time, with the best composition being recorded at 120 min deposition time. After post-deposition heat treatment (HT), the elemental compositions of Te decreased, and that of Cd increased. When the thin film was deposited at 120 min, the film with stoichiometric composition was observed after heat treatment. Scanning probe microscopy (SPM) measurements revealed that the average surface roughness of the thin films varied with deposition time, with the sample grown for 120 min showing the highest roughness.

Photovoltaic Cell Prepared from Nanoparticles of CdS/CdTe on ITO Substrate and its Characterization

“…The short-circuit current (Jsc) and open-circuit voltage (Voc) is also calculated [6]. The thin film CdTe based photovoltaic cell was also fabricated by using progressive method such as sputtering [7,8], electrodeposition [9], which proves to be simple and less expensive. The CdS layer thickness was taken to be between 50-110 nm as the layer should not be thick as well as not too thin.…”