Structure and properties of single-layer MoS ₂ for nano-photoelectric devices

To meet the need for preparing high-performance nano-optoelectronic devices based on single-layer MoS ₂ , the effects of the heating method (one-step or two-step heating) and the temperature of the MoO ₃ source on the morphology, size, structure, and layers of an MoS ₂ crystal grown on a sapphire substrate using chemical vapor deposition are studied in this paper. The results show that MoS ₂ prepared by two-step heating (the heating of the S source starts when the temperature of the MoO ₃ source rises to 837 K) is superior over that of one-step heating (MoO ₃ and S are heated at the same time). One-step heating tends to form a mixture of MoO ₂ and MoS ₂ . Neither too low nor too high of a heating temperature of MoO ₃ source is conducive to the formation of MoS ₂ . When the temperature of MoO ₃ source is in the range of 1073 K to 1098 K, the size of MoS ₂ 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 MoO ₃ is 1098 K. The triangular MoS ₂ crystals grown by the two-step heating method have a single-layer structure.