Theoretical studies of the decomposition of Zn[(iPr)2PSSe]2 single-source precursor in the gas phase for the chemical vapor deposition of binary and ternary zinc chalcogenides

Understanding the reaction mechanism by which single-source precursors decompose is important to the design of suitable experimental procedure involved in the chemical vapor deposition (CVD) process. The possible reaction mechanisms for the thermal decomposition of Zn[(iPr)2PSSe]2 precursor and its species in the gas phase has been studied by density functional theory calculation at the M06/LACVP∗ level. The results reveal that the reaction pathways that lead to the formation of zinc sulfide on the singlet potential energy surface are favored kinetically over those that lead to zinc selenide and ternary ZnSexS1−x formation. On the doublet PES, the reaction pathways that lead to zinc selenide formation are favored kinetically over those that lead to zinc sulfide and ternary ZnSexS1−x formation. However, in terms of equilibrium thermodynamic, the reaction pathways that lead to ternary ZnSexS1−x formation are more favorable than those that lead to zinc selenide and zinc sulfide formation on both the singlet and the doublet PESs. Density functional theory calculations reveal that the formation of ternary ZnSexS1−x are more favorable on thermodynamic grounds, than on kinetic.