Study of the Optical, Electrical, Structural and Morphological Properties of Electrodeposited Lead Manganese Sulphide (PbMnS) Thin Film Semiconductors for Possible Device Applications

Abstract

Semiconductor thin films of lead manganese sulphide (PbMnS) have been successfully deposited on florinated tin oxide (FTO) conductive glass substrate using an electrodeposition method. Lead acetate (Pb(CH3COO)2), manganese sulphate (MnSO4.H2O) and thiourea (CH4N2S) were the precursor used for cadmium (Cd2+), manganese (Mn2+) and sulphur (S2-) sources respectively. The concentration of manganese (Mn2+) was varied while keeping the concentrations of Pb2+ and S2- constant at 0.2 M and 0.1 M respectively. The deposited films were annealed at temperature of 250 oC and subjected for optical, electrical, structural and morphological characterizations. The results of the characterizations showed that the deposited thin films of PbMnS have high absorbance, high absorption coefficient throughout VIS and NIR regions. The band gap energy of the films is tuned to the order of 1.9 eV to 2.0 eV and tends to constant as concentration of Mn2+ increased. The electrical properties (electrical resistivity and conductivity) of the films are dependent on the concentration of Mn2+ and film thickness. The range of values of the electrical properties is found to be within the range of values for semiconductor materials. The XRD analysis revealed that the deposited thin films of PbMnS is crystalline but the crystallinity declined with increase in concentration of Mn2+. The SEM morphology showed that the surfaces of the films are highly homogeneous in nature and particle sizes are uniform on the substrate with the majority of the particles been spherical in shape. These observed properties exhibited by the deposited thin films of PbMnS make the films good materials for many optoelectronic and electronic applications such as solar cell, light emitting diode (LED), photodetector etc.