Duan Research Group

Hetero-integrated Nanostructures and Nanodevices


Uniform and ultrathin high-κ gate dielectrics for two-dimensional electronic devices

Weisheng Li, Jian Zhou, Songhua Cai, Zhihao Yu, Jialin Zhang, Nan Fang, Taotao Li, Yun Wu, Tangsheng Chen, Xiaoyu Xie, Haibo Ma, Ke Yan, Ningxuan Dai, Xiangjin Wu, Huijuan Zhao, Zixuan Wang, Daowei He, Lijia Pan, Yi Shi, Peng Wang, Wei Chen, Kosuke Nagashio, Xiangfeng Duan, Xinran Wang

Nat. Electron. 2, 563-571 (2019)

Two-dimensional semiconductors could be used as a channel material in low-power transistors, but the deposition of high-quality, ultrathin high-κ dielectrics on such materials has proved challenging. In particular, atomic layer deposition typically leads to non-uniform nucleation and island formation, creating a porous dielectric layer that suffers from current leakage, particularly when the equivalent oxide thickness is small. Here, we report the atomic layer deposition of high-κ gate dielectrics on two-dimensional semiconductors using a monolayer molecular crystal as a seeding layer. The approach can be used to grow dielectrics with an equivalent oxide thickness of 1 nm on graphene, molybdenum disulfide (MoS2) and tungsten diselenide (WSe2). Compared with dielectrics created using established methods, our dielectrics exhibit a reduced roughness, density of interface states and leakage current, as well as an improved breakdown field. With the technique, we fabricate graphene radio-frequency transistors that operate at 60 GHz, and MoS2 and WSe2 complementary metal–oxide–semiconductor transistors with a supply voltage of 0.8 V and subthreshold swing down to 60 mV dec−1. We also create MoS2 transistors with a channel length of 20 nm, which exhibit an on/off ratio of over 10^7.
UCLA, Department of Chemistry and Biochemistry
607 Charles E. Young Drive East, Box 951569
Los Angeles, CA 90095-1569
E-mail: xduan@chem.ucla.edu