ROLE OF Cu DILUTE ON MICROSTRUCTURE, OPTICAL, MAGNETIC, PHOTOLUMINESCENCE AND ELECTRICAL PROPERTIES OF CdS FILMS

Abstract

Thin films of CdS1-xCux (with 0 ≤ x ≤ 0.10) were deposited using electron beam evaporation. Using XRD, EDX, SEM and UV-Vis-NIR spectroscopy, the impact of [Cu]/[S] on the film properties was examined. The influences of various concentrations of Cu are also elucidated on the optical parameters of the films. The XRD analysis shows that the thin films of CdS1-xCux have been improved and have hexagonal polycrystalline structure with the increase of Cu doping ratio. Additionally, the crystallite size is reduced while the micro-strain ε increases with enhancement of the incorporation of Cu in CdS lattice. The envelope method was used to extract the optical parameters of the undoped and Cu-doped CdS films. With the increase of Cu concentration, the energy optical bandgap decreased, and the variation values of band gap could play an important role in solar cell applications. Another optical parameter such as dissipation factor and real / imaginary dielectric constant parts were evaluated and demonstrated a strong Cu doping dependence. The shift observed in the photoluminescence spectra emission band confirmed Cu's substitution to CdS lattice. The measurements of magnetization using vibrating sample magnetometer illustrated a hysteresis loop in Cu-doped CdS films and confirmed the room temperature ferromagnetism. Finally, the Hall effect results show that the pure CdS film corresponds to an n-type semiconductor with a resistivity of 8.11×10-2 Ωcm and a carrier concentration of 29.6×1019 cm-3, and the CdS:Cu film is a p-type semiconductor and the resistivity is reduced from 6.8×10-2 to 3.7×10-2 Ωcm, and the carrier concentration is reduced from 26.4×1019 to 4.1×1019 cm-3, which has potential application prospects in solar cells.