Comprehensive structural and optoelectronic characterizations of co-precipitated Mn-doped SnS nano-powders

This study investigates the physical characteristics of un- and Mn-doped SnS nanoparticles (NPs) synthesized through a co-precipitation method. The undoped SnS is referred to as Mn 0, while Mn 1, Mn 2, and Mn 3 samples are obtained by incorporating 1, 3, and 6 mL of Mn-dopant solution, respectively. Elemental analysis is done by means of energy-dispersive X-ray spectroscopy (EDX), confirming successful Mn incorporation into the SnS lattice. X-ray diffraction (XRD) studies validate the formation of the SnS phase with a preferred orientation at the (040) plane for all samples. The crystallite size (D) of SnS NPs initially increases and then decreases after Mndoping, confirmed by transmission electron microscopy (TEM) images. Field emission scanning electron microscopy (FESEM) images exhibit grain-shaped morphology with sizes ranging from 23 to 36 nm for all samples. The reduction in bandgap energy (Eg) upon Mn-doping is attributed to variations in grain size and the formation of impurity levels within the SnS band gap. Mott-Schottky analysis showed p-type conductivity for all samples. The semiconductor parameters of SnS, such as the acceptor concentration (NA) and the density of states (NV), improved after Mn-doping. Current-voltage (I-V) curves revealed that the conductivity and mobility of SnS after Mn-doping initially declined for Mn 1 and Mn 2 samples and then improved for the Mn 3 sample. Electrochemical impedance spectroscopy (EIS) results align with the I-V findings. Consequently, it can be concluded that Mn-doping leads to enhancements in optoelectronic properties of SnS.