Selective etching in graphene–MoS2 heterostructures for fabricating graphene-contacted MoS2 transistors

Zeliang Sun,Chuyun Deng,Shiqiao Qin,Yi Zhang,Yuehua Wei,Mengjian Zhu,Gang Peng,Zheng Li,Xiangzhe Zhang,Zongqi Bai,Wei Luo

doi:10.1063/1.5141143

Abstract

Semiconducting molybdenum disulfide (MoS2) has drawn a lot of attention for its exceptional electronic and optoelectronic properties. Despite the potential advantages, the large contact resistance at the metal–MoS2 interfaces has been one of the biggest obstacles for the realization of ideal MoS2 transistors. One solution to improve the metal–MoS2 interfaces is to use the graphene electrodes. Here, we provide a selective etching method for fabricating graphene-contacted MoS2 transistors. It has been proved that the graphene could be totally etched with Ar+ plasma treatment, and the multilayer MoS2 flake can also be reduced layer by layer with Ar+ plasma treatment. By etching graphene selectively in graphene–MoS2 heterostructures, one can obtain graphene-contacted MoS2 transistors successfully. The transistor reported in this paper shows an on–off ratio about 106 and a carrier mobility about 42 cm2 V−1 s−1. This selective etching method would be beneficial for some other graphene-contacted electronic devices.

Highlights

Two-dimensional (2D) layered materials have drawn a lot of attention in recent research
The transistor reported in this paper shows an on–off ratio about 106 and a carrier mobility about 42 cm[2] V−1 s−1
The zero-gap band structure of graphene seriously restricts its applications in electronic devices, which leads to the development of 2D layered semiconductors.[4,5,6,7,8]

Summary

INTRODUCTION

Two-dimensional (2D) layered materials have drawn a lot of attention in recent research. The proper bandgap of MoS2 ensures that it is useful for energy-harvesting applications.[5] Despite such potential advantages, the ideal performances of the layered MoS2 FETs have not been realized so far due to the large resistance at their metal contact interfaces.[13–15]. We present a facile method for fabricating graphenecontacted MoS2 transistors by selectively etching graphene in graphene–MoS2 heterostructures. With PMMA spin coating on the heterostructure for protecting the un-etched graphene part, a desired graphene-contacted MoS2 transistor was fabricated by selectively etching graphene in the graphene–MoS2 heterostructures. This selective etching method makes the fabrication process more convenient, avoiding damages from the multi-transfer steps or transfer again after etching. The layer by layer reducing of MoS2 would be beneficial for fabricating precise layer numbers of MoS2 transistors with graphene electrodes.[21,22]

EXPERIMENTAL DETAILS

RESULTS AND DISCUSSION

CONCLUSIONS