Influence of Ni Doping on the Structural, Morphological, Optical, and Electrical Properties of Nanocrystalline Cd1-xMnxS Thin Films

TL;DR

This study investigates how Ni doping alters the structural, optical, and electrical properties of Cd1-xMnxS thin films, aiming to enhance their suitability for optoelectronic applications like solar cells.

Contribution

It demonstrates that Ni doping effectively tunes the properties of Cd1-xMnxS thin films, improving their potential for optoelectronic devices.

Findings

Crystallinity increases with Ni doping, microstrain decreases.

Optical transmittance remains high (75-90%) in visible and NIR regions.

Electrical conductivity is enhanced and shows photoconductivity.

Abstract

Ni-doped Cd1-xMnxS (x=0.4) thin films were prepared via a cost-effective chemical bath deposition (CBD) method to investigate their suitability for optoelectronic applications. Incorporation of a secondary transition metal such as Ni is expected to influence lattice strain, defect density, and electronic structure through ionic size effects and sp-d exchange interactions, thereby providing an additional degree of freedom for tuning the properties of Cd1-xMnxS-based ternary systems. X-ray diffraction (XRD) analysis confirmed the cubic zinc blende structure of the Cd1-xMnxS crystal, which was further corroborated by high-resolution transmission electron microscopy (HRTEM). Crystallinity increases where as microstrain and dislocation density found to be decreases as the doping concentration of Ni increases. Field emission scanning electron microscopy (FESEM) analysis revealed uniform, dense, and crack-free films with grain size increasing as a function of Ni content, and the FESEM cross-sectional images indicated a nearly constant thickness in the range of 181.2-189.1 nm. The films exhibited high optical transmittance (75-90%) in the visible and near-infrared (NIR) regions. The optical band gap decreases from 2.72 to 2.62 eV as the Ni concentration increases from 1% to 4%. Current-voltage (I-V) measurements revealed enhanced electrical conductivity, which further increased under illumination, confirming the photoconducting nature of the films. These results demonstrate that Ni doping effectively tunes the properties of Cd1-xMnxS thin films, highlighting their potential as efficient window layer materials for thin-film solar cells and related optoelectronic devices.