Сравнительные кинетические исследования химического осаждения PbSe селеносульфатом натрия и селеномочевиной с установлением влияния их природы на состав и морфологию пленок

Abstract

After analyzing the literature, one can note the increased interest in lead selenide in the thin-film state, used in various fields: from microelectronics to solar energy converters. There are physical and chemical methods for producing PbSe films, each of which has its own advantages and disadvantages. However, researchers prefer chemical deposition from aqueous media, which eliminates the need for complex, expensive equipment, heating to high temperatures and creating high pressures. The Ural school of thin-film synthesis has developed and tested a kinetic-thermodynamic method for predicting the chemical deposition of metal chalcogenides. The thermodynamic assessment carried out in our previous publication indicated only the principal possibility of the formation of lead selenide when using selenocarbamide СSe(NH2)2 and sodium selenosulfate Na2SeSO3. For a more complete understanding of this process, a comprehensive approach is necessary, taking into account the patterns of the deposition of the solid phase of PbSe in time, depending on thermodynamic factors - temperature and concentration of reagents. Therefore, in this work, we studied the kinetics of the chemical deposition of lead selenide with selenourea and sodium selenosulfate from solutions containing lead acetate, sodium citrate, ammonium hydroxide and iodide, in the temperature 303 -353 K under conditions of spontaneous nucleation of the solid phase. As a result of the studies, the partial kinetic reaction orders for chalcogenizers were determined, amounting to 0.86 (СSe(NH2)2) and 0.78 (Na2SeSO3), as well as the activation energy of the formation of lead selenide, which amounted to 45.1 and 25.07 kJ/mole, respectively. Hydrochemical deposition of selenocarbamide and sodium selenosulfate produced PbSe films on substrates of sitall and glass with a thickness of 200-300 nm. Energy dispersive analysis and scanning electron microscopy showed the influence of the nature of the substrate, type chalcogenizer on the morphology, particle size distribution and elemental composition of lead selenide layers. An elemental analysis showed that PbSe films precipitated with sodium selenosulfate contain an excess of lead compared to selenium (Pb/Se = 1.25-1.32), and the stoichiometric composition ensures the use of selenocarbamide (Pb/Se = 0.99-1.05).