Structure and Properties of Single-Layer MoS₂ for Nano-Photoelectric Devices

To meet the need for preparing high-performance nano-optoelectronic devices based on single-layer MoS₂, the effects of the heating method (one-step or two-step heating) and the temperature of the MoO₃ source on the morphology, size, structure, and layers of an MoS₂ crystal grown on a sapphire substrate using chemical vapor deposition are studied in this paper. The results show that MoS₂ prepared by two-step heating (the heating of the S source starts when the temperature of the MoO₃ source rises to 837 K) is superior over that of one-step heating (MoO₃ and S are heated at the same time). One-step heating tends to form a mixture of MoO₂ and MoS₂. Neither too low nor too high of a heating temperature of MoO₃ source is conducive to the formation of MoS₂. When the temperature of MoO₃ source is in the range of 1073 K to 1098 K, the size of MoS₂ increases with the rise in temperature. A uniform large-sized triangle with a side length of 100 μm is obtained when the heating temperature of MoO₃ is 1098 K. The triangular MoS₂ crystals grown by the two-step heating method have a single-layer structure.