Realizing Large-Scale, Electronic-Grade Two-Dimensional Semiconductors

• Published in: ACS nano Vol. 12; no. 2; pp. 965 - 975
• Main Authors: Lin, Yu-Chuan, Jariwala, Bhakti, Bersch, Brian M, Xu, Ke, Nie, Yifan, Wang, Baoming, Eichfeld, Sarah M, Zhang, Xiaotian, Choudhury, Tanushree H, Pan, Yi, Addou, Rafik, Smyth, Christopher M, Li, Jun, Zhang, Kehao, Haque, M. Aman, Fölsch, Stefan, Feenstra, Randall M, Wallace, Robert M, Cho, Kyeongjae, Fullerton-Shirey, Susan K, Redwing, Joan M, Robinson, Joshua A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 27.02.2018
• Subjects: tungsten diselenide (WSe2); two-dimensional materials; field-effect transistors; transition metal dichalcogenides; metal−organic chemical vapor deposition (MOCVD); van der Waals epitaxy
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.7b07059

Atomically thin transition metal dichalcogenides (TMDs) are of interest for next-generation electronics and optoelectronics. Here, we demonstrate device-ready synthetic tungsten diselenide (WSe2) via metal–organic chemical vapor deposition and provide key insights into the phenomena that control the properties of large-area, epitaxial TMDs. When epitaxy is achieved, the sapphire surface reconstructs, leading to strong 2D/3D (i.e., TMD/substrate) interactions that impact carrier transport. Furthermore, we demonstrate that substrate step edges are a major source of carrier doping and scattering. Even with 2D/3D coupling, transistors utilizing transfer-free epitaxial WSe2/sapphire exhibit ambipolar behavior with excellent on/off ratios (∼107), high current density (1–10 μA·μm–1), and good field-effect transistor mobility (∼30 cm2·V–1·s–1) at room temperature. This work establishes that realization of electronic-grade epitaxial TMDs must consider the impact of the TMD precursors, substrate, and the 2D/3D interface as leading factors in electronic performance.