Deposition and Degradation Mechanism of Zinc Thiolate Thin Films via Hybrid Molecular Layer Deposition

Abstract

Many applications, such as those in energy, digital, and medical technologies, are driving the development of new materials. Recently studied materials such as hybrid metal organic thin films are of special interest because they provide the tunability of organic components while maintaining the functionality of the metal oxide or metal sulfide constituents. In this work, we developed a process for producing zinc thiolate thin films, which contain Zn–S–C bonds, via hybrid molecular layer deposition. Using two different organic linkers, we studied the effects of chain length on the final film structure and stability. The chemical composition of the as-deposited zinc thiolate film with a butyl chain was Zn:S_1.2±0.2:C_3.1±0.9:O_0.6±0.5 for a deposition temperature of 120 °C and Zn:S_1.5±0.2:C_4.1±1.1:O_0.4±0.3 for a deposition temperature of 100 °C, while the composition with an ethyl chain was Zn:S_0.9±0.2:C_2.3±0.6:O_1.2±0.7, determined via ex situ XPS analysis. We studied the degradation mechanism of these hybrid thiolate films and found them to degrade on a time scale of weeks, a much slower rate than that of previously reported analogous, alcohol-functionalized hybrid films, and to predominantly form ZnO and oxidized sulfur species in the film while releasing volatile species.