Optical and electrical properties of vertical MoS2 nanostructures

Ultrathin two-dimensional layered crystalline films of molybdenum disulfide have unique electrical properties and can be used in solar cells, photoelectric converters, thermoelectric and electrochromic devices. The highest quality thin films of molybdenum disulfide can only be obtained by thermally activated chemical vapor deposition. However, the nature of the influence of the conditions of formation of MoS2 films on their composition, structure, structure, and properties has not been systematically studied and remains unclear. In this regard, the task of establishing experimentally the main physicochemical regularities of the process of chemical deposition of MoS2 films from the gas phase becomes topical. This article describes the results of a study of the optical and electrical properties of vertical MoS2 nanostructures. Studies of absorption and reflection, photoluminescence, current-voltage characteristics, and the effect of temperature on resistance were carried out. We studied vertical nanopetals deposited at different temperatures (250°C, 550°C, and 750°C) and only one film with dendrites deposited at 350°C in the Mo(CO)6 - H2S system. Films deposited at 250°C, 550°C, and 750°C consist of vertical nanoparticles. The dimensions, thickness, and distance between them increase with increasing deposition temperature; a decrease in the deposition temperature reduces the size of the nanopetals. The film deposited at 350°C has a dendritic structure (vertical branched sheets). The obtained results of studying the properties of films show that their optical properties significantly depend not only on the size of the nanostructural elements that form the film, but also on their morphology. Films formed by both vertical nanoleaves and dendrites have unique electrophysical properties, demonstrating quantum conductivity represented by charge density waves. The discovered unique electrophysical properties are of great interest for modern optoelectronics.