EFFECT OF SULFUR ION CONCENTRATION ON STRUCTURAL AND OPTICAL PROPERTIES OF LEAD SULFIDE THIN FILMS OBTAINED BY CHEMICAL BATH DEPOSITION METHOD

Abstract

In the present investigation PbS thin films were synthesized on glass substrate with various thiourea concentration from 0.1 M to 0.2 M by chemical bath deposition method. The XRD analyses revealed that the average crystalline size was decreased from 21.12 to18.7 nm with increasing thiourea concentration. The preferential orientation was along the (111) plane for 0.1 and 0.15 M where as it was changed to (200) for 0.2 M. The SEM study showed that the film consists of nearly spherical shaped grains, with different grain size. EDX
analysis showed that the film were consistent with the formation PbS compounds on glass slide substrate in the desired stoichiometric ratio. The optical characterization of the sample revealed that the optical band gap energy was increased from 0.95 to 1.3 eV with increasing thiouera concentration.