Vertical ZnO Nanotube Transistor on a Graphene Film for Flexible Inorganic Electronics

Hongseok Oh; JunBeom Park; Woojin Choi; Heehun Kim; Youngbin Tchoe; Arpana Agrawal; Gyu-Chul Yi

doi:10.1002/smll.201800240

Vertical ZnO Nanotube Transistor on a Graphene Film for Flexible Inorganic Electronics

Small. 2018 Apr;14(17):e1800240. doi: 10.1002/smll.201800240. Epub 2018 Apr 3.

Authors

Hongseok Oh¹, JunBeom Park¹, Woojin Choi², Heehun Kim¹, Youngbin Tchoe¹, Arpana Agrawal¹, Gyu-Chul Yi¹

Affiliations

¹ Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea.
² Department of Electrical and Computer Engineering, University of California San Diego, San Diego, CA, 92093, USA.

PMID: 29611339
DOI: 10.1002/smll.201800240

Abstract

The bottom-up integration of a 1D-2D hybrid semiconductor nanostructure into a vertical field-effect transistor (VFET) for use in flexible inorganic electronics is reported. Zinc oxide (ZnO) nanotubes on graphene film is used as an example. The VFET is fabricated by growing position- and dimension-controlled single crystal ZnO nanotubes vertically on a large graphene film. The graphene film, which acts as the substrate, provides a bottom electrical contact to the nanotubes. Due to the high quality of the single crystal ZnO nanotubes and the unique 1D device structure, the fabricated VFET exhibits excellent electrical characteristics. For example, it has a small subthreshold swing of 110 mV dec^-1 , a high I_max /I_min ratio of 10⁶ , and a transconductance of 170 nS µm^-1 . The electrical characteristics of the nanotube VFETs are validated using 3D transport simulations. Furthermore, the nanotube VFETs fabricated on graphene films can be easily transferred onto flexible plastic substrates. The resulting components are reliable, exhibit high performance, and do not degrade significantly during testing.

Keywords: 1D-2D hybrid materials; ZnO; flexible electronics; graphene; vertical transistors.