Chemical Vapor Deposition Grown Wafer‐Scale 2D Tantalum Diselenide with Robust Charge‐Density‐Wave Order

• Published in: Advanced materials (Weinheim) 2018-11, Vol.30 (44), p.e1804616-n/a
• Main Authors: Shi, Jianping, Chen, Xuexian, Zhao, Liyun, Gong, Yue, Hong, Min, Huan, Yahuan, Zhang, Zhepeng, Yang, Pengfei, Li, Yong, Zhang, Qinghua, Zhang, Qing, Gu, Lin, Chen, Huanjun, Wang, Jian, Deng, Shaozhi, Xu, Ningsheng, Zhang, Yanfeng
• Format: Article
• Language: English
• Subjects: Charge density; charge‐density‐wave; Chemical vapor deposition; Cloth; Foils; Gold; Magnetism; Materials science; Monolayers; Organic chemistry; Phase diagrams; Phase transitions; Quantum theory; supercapacitors; Tantalum; tantalum diselenide; Thickness; Transition metal compounds; Transition temperature; Transmission electron microscopy; Unconventional superconductivity; wafer‐scale
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201804616

2D metallic transition metal dichalcogenides (MTMDCs) are benchmark systems for uncovering the dimensionality effect on fascinating quantum physics, such as charge‐density‐wave (CDW) order, unconventional superconductivity, and magnetism, etc. However, the scalable and thickness‐tunable syntheses of such envisioned MTMDCs are still challenging. Meanwhile, the origin of CDW order at the 2D limit is controversial. Herein, the direct synthesis of wafer‐scale uniform monolayer 2H‐TaSe2 films and thickness‐tunable flakes on Au foils by chemical vapor deposition is accomplished. Based on the thickness‐tunable 2H‐TaSe2, the robust periodic lattice distortions that relate to CDW orders by low‐temperature transmission electron microscopy are directly visualized. Particularly, a phase diagram of the transition temperature from normal metallic to CDW phases with thickness by variable‐temperature Raman characterizations is established. Intriguingly, dramatically enhanced transition temperature from bulk value ≈90 to ≈125 K is observed from monolayer 2H‐TaSe2, which can be explained by the enhanced electron–phonon coupling mechanism. More importantly, an ultrahigh specific capacitance is also obtained for the as‐grown TaSe2 on carbon cloth as supercapacitor electrodes. The results hereby open up novel avenues toward the large‐scale preparation of high‐quality MTMDCs, and shed light on their applications in exploring some fundamental issues. Wafer‐scale uniform monolayer 2H‐TaSe2 films and thickness‐tunable flakes are synthesized on Au foils by chemical vapor deposition (CVD) and a phase diagram of the CDW phase transition temperature with layer thickness is established. The enhanced transition temperature from bulk to monolayer is explained by the electron–phonon coupling mechanism. An ultrahigh specific capacitance is also obtained for as‐grown TaSe2 on carbon cloth as electrodes.