Microwave assisted synthesis of quantum dots like ZnS nanoparticles for optoelectronic applications: An effect of CTAB concentrations

Nanoparticles (NPs) of ZnS with different weights of CTAB (cetyltrimethylammonium bromide) have been successfully synthesized by microwave assisted co-precipitation method. The x-ray diffraction patterns exhibited cubic phase crystal structure with crystallite size of ~3 nm. The morphological studies of the grown samples have been investigated using Scanning electron microscopy (SEM). Diffused reflectance spectra were employed to calculate energy gaps for prepared samples using Kubelka-Munk theory, and the values were in the range of 3.59–3.64 eV. Raman spectra confirm the synthesis of ZnS nanoparticles at all CTAB contents and it contains two major Raman modes at ~264 and 346 cm⁻¹ related to TO and LO modes which are shifted to lower wavenumbers indicates phonon confinement in the final products. The variations in the dielectric constant, ε' and dielectric loss were calculated. The values of ε' is higher in the low frequencies, whereas it is found almost stable between 1 MHz and 5 MHz and is increasing at higher frequencies. The dielectric study reveals that the samples possess high values of dielectric constant which are between 27 and 35 and low loss values. The electrical conductivity is noticed to be increased with increasing the frequency and also noticed to be varied with varying the CTAB content in ZnS. The synthesized low dimension NPs, high energy gap and dielectric constant and low loss values signifies that the prepared NPs are suitable for optoelectronics.