Ni-doped CdTe nanostructures for photo response and nonlinear optical applications

Ni-doped CdTe nanostructures were successfully synthesized via a facile hydrothermal route, demonstrating the critical role of transition-metal doping in tailoring the functional properties of CdTe-based nanomaterials. Structural analysis using X-ray diffraction (XRD) confirmed the formation of a cubic CdTe phase, with a noticeable reduction in crystallite size from ∼28 to ∼24 nm upon Ni incorporation, indicating lattice modification and enhanced defect density. Field-emission scanning electron microscopy (FESEM) analysis revealed a predominantly nanoparticle-like morphology, suggesting uniform nucleation and growth during the hydrothermal process. X-ray photoelectron spectroscopy (XPS) further elucidated the elemental composition and oxidation states, confirming the successful incorporation of Ni into the CdTe lattice. Optical studies revealed a systematic blue shift in the band gap from 1.84 to 2.23 eV with increasing Ni concentration, accompanied by a decrease in refractive index from 2.95 to 2.55, suggesting tuneable optical dispersion characteristics. Photoconductivity measurements demonstrated a pronounced enhancement in photocurrent under illumination relative to dark conditions, with a maximum photocurrent of 94.05 mA and a detectivity on the order of 10⁶ Jones, indicating good photo response performance. Furthermore, nonlinear optical (NLO) investigations using the Z-scan technique revealed reverse saturable absorption (RSA) behaviour across all samples, as evidenced by positive nonlinear absorption coefficients. These findings collectively establish that Ni-doped CdTe nanostructures possess significant potential for next-generation optoelectronic applications, particularly in good-performance photodetectors and nonlinear optical devices.