On The Role of Preparative Parameters in Growing Nanocrystalline PbS Thin Films by Liquid Phase Chemical Bath Deposition

A liquid phase chemical bath deposition(LPCBD)method for deposition of PbS thin films is presented.The growth kinetics and reaction mechanism have been discussed.For the deposition,triethanolamine complex of lead acetate was allowed to react with aqueous thiourea solution.Glass micro-slides were used as the substrates.The deposition of PbS films was carried out under different growth parameters such as temperature,time,and reaction pH.The growth rate,under different conditions,was measured in terms of a terminal layer thickness and the possible reaction kinetics and mechanism is discussed.The optimum values of the parameters to produce good quality films are 60 min,80℃and 10.5±0.1.An EDS analysis showed that the film stoichiometry is dependent on the reaction pH and the films tend to be almost stoichiometric in high alkaline environment(>10.5).The PbS deposits appeared smooth,tightly adherent,uniform and reflecting with blackish-grey colour.The XRD studies showed crystalline cubic type of structure with preferred orientation along(200)plane.The calculated d-values,intensities of reflections and lattice parameter have excellent match with that of the JCPD data.The crystallite size is found to be few tens of nanometer.The surface morphology revealed by SEM showed that the crystallites are randomly oriented and are of different shapes and sizes.Majority of the crystallites appeared smaller and spherical in shape whereas,growth of some elongated irregular crystallites;bit larger in size and differing in shapes,have also been favoured.

A liquid phase chemical bath deposition(LPCBD)method for deposition of PbS thin films is presented.The growth kinetics and reaction mechanism have been discussed.For the deposition,triethanolamine complex of lead acetate was allowed to react with aqueous thiourea solution.Glass micro-slides were used as the substrates.The deposition of PbS films was carried out under different growth parameters such as temperature,time,and reaction pH.The growth rate,under different conditions,was measured in terms of a terminal layer thickness and the possible reaction kinetics and mechanism is discussed.The optimum values of the parameters to produce good quality films are 60 min,80℃and 10.5±0.1.An EDS analysis showed that the film stoichiometry is dependent on the reaction pH and the films tend to be almost stoichiometric in high alkaline environment(>10.5).The PbS deposits appeared smooth,tightly adherent,uniform and reflecting with blackish-grey colour.The XRD studies showed crystalline cubic type of structure with preferred orientation along(200)plane.The calculated d-values,intensities of reflections and lattice parameter have excellent match with that of the JCPD data.The crystallite size is found to be few tens of nanometer.The surface morphology revealed by SEM showed that the crystallites are randomly oriented and are of different shapes and sizes.Majority of the crystallites appeared smaller and spherical in shape whereas,growth of some elongated irregular crystallites;bit larger in size and differing in shapes,have also been favoured.