Issue 3, 2019

Growth of graphene with large single-crystal domains by Ni foam-assisted structure and its high-gain field-effect transistors

Abstract

High-quality graphene materials and high-performance graphene transistors have attracted much attention in recent years. To obtain high-performance graphene transistors, large single-crystal graphene is needed. The synthesis of large-domain-sized single-crystal graphene requires low nucleation density; this can lead to a lower growth rate. In this study, a Ni-foam assisted structure was developed to control the nucleation density and growth rate of graphene by tuning the flow dynamics. Lower nucleation density and high growth rate (∼50 μm min−1) were achieved with a 4 mm-gap Ni foam. With the graphene transistor fabrication process, a pre-deposited Au film as the protective layer was used during the graphene transfer. Graphene transistors showed good current saturation with drain differential conductance as low as 0.04 S mm−1 in the strong saturation region. For the devices with gate length of 2 μm, the intrinsic cut-off frequency fT and maximum oscillation frequency fmax were 8.4 and 16.3 GHz, respectively, with fmax/fT = 1.9 and power gain of up to 6.4 dB at 1 GHz. The electron velocity saturation induced by the surface optical phonons of SiO2 substrates was analyzed. Electron velocity saturation and ultra-thin Al2O3 gate dielectrics were thought to be the reasons for the good current saturation and high power gain of the graphene transistors.

Graphical abstract: Growth of graphene with large single-crystal domains by Ni foam-assisted structure and its high-gain field-effect transistors

Supplementary files

Article information

Article type
Paper
Submitted
11 Sep 2018
Accepted
12 Dec 2018
First published
13 Dec 2018
This article is Open Access
Creative Commons BY-NC license

Nanoscale Adv., 2019,1, 1130-1135

Growth of graphene with large single-crystal domains by Ni foam-assisted structure and its high-gain field-effect transistors

X. Gao, C. Yu, Z. He, X. Song, Q. Liu, C. Zhou, J. Guo, S. Cai and Z. Feng, Nanoscale Adv., 2019, 1, 1130 DOI: 10.1039/C8NA00203G

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