Large‐Area Chemical Vapor Deposited MoS2 with Transparent Conducting Oxide Contacts toward Fully Transparent 2D Electronics

• Published in: Advanced functional materials 2017-11, Vol.27 (41), p.n/a
• Main Authors: Dai, Zhenyu, Wang, Zhenwei, He, Xin, Zhang, Xi‐Xiang, Alshareef, Husam N.
• Format: Article
• Language: English
• Subjects: 2D materials; Aluminum; Atomic layer epitaxy; Chemical vapor deposition; Conduction; Conductors; Electronic devices; Electronics; Materials science; Molybdenum disulfide; Monolayers; Offsets; Photonics; Semiconductor devices; Semiconductors; Switching; thin‐film transistors; Threshold voltage; Transistors; transparent electronics; Zinc oxide
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201703119

2D semiconductors are poised to revolutionize the future of electronics and photonics, much like transparent oxide conductors and semiconductors have revolutionized the display industry. Herein, these two types of materials are combined to realize fully transparent 2D electronic devices and circuits. Specifically, a large‐area chemical vapor deposition process is developed to grow monolayer MoS2 continuous films, which are, for the first time, combined with transparent conducting oxide (TCO) contacts. Transparent conducting aluminum doped zinc oxide contacts are deposited by atomic layer deposition, with composition tuning to achieve optimal conductivity and band‐offsets with MoS2. The optimized process gives fully transparent TCO/MoS2 2D electronics with average visible‐range transmittance of 85%. The transistors show high mobility (4.2 cm2 V−1 s−1), fast switching speed (0.114 V dec−1), very low threshold voltage (0.69 V), and large switching ratio (4 × 108). To our knowledge, these are the lowest threshold voltage and subthreshold swing values reported for monolayer chemical vapor deposition MoS2 transistors. The transparent inverters show fast switching properties with a gain of 155 at a supply voltage of 10 V. The results demonstrate that transparent conducting oxides can be used as contact materials for 2D semiconductors, which opens new possibilities in 2D electronic and photonic applications. Transparent, conducting aluminum‐doped zinc oxide (AZO) is optimized and used, for the first time, as contact material to fabricate fully transparent circuits based on 2D monolayer molybdenum disulfide (MoS2). The circuits show a high visible‐range transmittance of 85%. The transistors, rectifiers, and inverters show competitive performance to 2D devices that use opaque Si substrates and metal contacts.