Morphological and Crystallographic Investigation of CVD-Grown MoS₂

This paper presents a study of the structural characteristics of a promising MoS2-based material obtained by chemical vapor deposition (CVD). Optimization of the synthesis process to obtain the desired structure is also presented. The optimal parameter for the synthesis of CVD MoS2 crystals was found to be the maximum sulfurization temperature of 780 °C with an exposure time of about 15 minutes, the heating temperature of the sulfur source zone of 250 °C, the distance between the sulfur and molybdenum sources of 25 cm, and the distance between the molybdenum source and the substrate was 1.5 cm. The morphology and elemental composition of the obtained samples were studied using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). Using SEM, it was revealed that MoS2 crystals are formed in a triangular shape and are evenly distributed over the surface of the substrate. The maximum sizes of crystallites reach 6 microns. EMF mapping of crystallites confirmed the homogeneous distribution of molybdenum and sulfur in the structure, revealing only minor variations in composition at the grain boundaries. The quality and quantity of the sample layer were studied using Raman spectroscopy. The results showed two characteristic peaks (vibrational modes E2g1 and A1g) of nanoscale MoS2. The peaks have a sharp shape and are located at a distance of ≈20.9 cm-1, which may indicate the high quality of the crystal structure of the obtained crystallites. The results obtained emphasize the effectiveness of the chosen approach and the importance of the work for the development of 2D materials technologies.