石墨烯封装单层二硫化钼的热稳定性研究

将单层二硫化钼用石墨烯进行封装，构造了石墨烯和二硫化钼的范德瓦耳斯异质结构，并且分别在氩气（Ar）和氢气（H₂）氛围下，详细研究了被封装的二硫化钼的热稳定性.结果表明：在氩气氛围中，石墨烯封装的二硫化钼在400–1000℃下一直保持稳定，而石墨烯和氧化硅上裸露的二硫化钼在1000℃时几乎全部分解；在氢气氛围中，石墨烯封装的二硫化钼在400–1000℃下一直稳定存在，而石墨烯和氧化硅上裸露的二硫化钼在800℃下已经完全分解.综上可得，在氩气和氢气的氛围下，被石墨烯封装的二硫化钼的热稳定性得到了显著的提高.该研究通过用石墨烯将单层的二硫化钼进行封装以提高其热稳定性，在未来以单层二硫化钼作为基础材料的电子器件中，可以保证其在高温下能够正常工作.该研究也为提高其他二维材料的热稳定性提供了一种可行的方法和思路.

Thermal stability of MoS2 encapsulated by graphene

Monolayer molybdenum disulfide (MoS₂), a semiconductor material with direct band gap, is considered to be an important fundamental material for the future development of the semiconductor industry. In order to apply the material to semiconductor devices, we have to investigate the electrical, optical and thermal properties of MoS₂. People have always been concerning about the electrical and optical properties, but pay little attention to the thermal properties of MoS₂, especially thermal stability. It is well known that semiconductor device generates a lot of heat when it works, sometimes even running in high temperature environment. The above conditions all require the material which has good thermal stability. So we focus on how to improve the thermal stability of MoS₂. In this paper, we report the construction of the van der Waals heterostructures of graphene and MoS₂ by encapsulating monolayer MoS₂ with graphene, and dissect the thermal stability of encapsulated MoS₂ in argon (Ar) and hydrogen (H₂) atmosphere respectively. The results show that in Ar atmosphere, MoS₂ encapsulated by graphene keeps stable when the temperature increases to 1000 ℃, while the exposed MoS₂ is decomposed almost completely at 1000 ℃. In H₂ atmosphere, MoS₂ encapsulated by graphene keeps stable when the temperature increases to 1000 ℃, but the exposed MoS₂ is decomposed completely at 800 ℃. In conclusion, the thermal stability of MoS₂ encapsulated by graphene can be improved significantly. We analyze the reason why MoS₂ encapsulated by graphene gains good thermal stability. Firstly, the covered graphene provides additional van der Waals forces, which increases the decomposition energy of MoS₂, making it more stable at high temperature environment. Secondly, graphene separates MoS₂ from the external environment, preventing MoS₂ from contacting and reacting with external gas, which greatly improves the thermal stability of MoS₂ at high temperature environment. Meanwhile, graphene covers the active defect site on MoS₂, making it difficult to react at defects. In summary, the monolayer MoS₂ devices can work normally at high temperature when MoS₂ is encapsulated by graphene. In addition, our work also provides a feasible approach to improving the thermal stability of other two-dimensional materials.