title: Control of Ambipolar Transport in SnO Thin-Film Transistors by Back-Channel Surface Passivation for High Performance Complementary-like Inverters.
abstract: For ultrathin semiconductor channels, the surface and interface nature are vital and often dominate the bulk properties to govern the field-effect behaviors. High-performance thin-film transistors (TFTs) rely on the well-defined interface between the channel and gate dielectric, featuring negligible charge trap states and high-speed carrier transport with minimum carrier scattering characters. The passivation process on the back-channel surface of the bottom-gate TFTs is indispensable for suppressing the surface states and blocking the interactions between the semiconductor channel and the surrounding atmosphere. We report a dielectric layer for passivation of the back-channel surface of 20 nm thick tin monoxide (SnO) TFTs to achieve ambipolar operation and complementary metal oxide semiconductor (CMOS) like logic devices. This chemical passivation reduces the subgap states of the ultrathin channel, which offers an opportunity to facilitate the Fermi level shifting upward upon changing the polarity of the gate voltage. With the advent of n-type inversion along with the pristine p-type conduction, it is now possible to realize ambipolar operation using only one channel layer. The CMOS-like logic inverters based on ambipolar SnO TFTs were also demonstrated. Large inverter voltage gains (>100) in combination with wide noise margins are achieved due to high and balanced electron and hole mobilities. The passivation also improves the long-term stability of the devices. The ability to simultaneously achieve field-effect inversion, electrical stability, and logic function in those devices can open up possibilities for the conventional back-channel surface passivation in the CMOS-like electronics.
authors.affiliation: †Division of Functional Materials and Nano Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, People's Republic of China.
authors.forename: Hao
authors.initials: H
authors.lastname: Luo
authors.affiliation: †Division of Functional Materials and Nano Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, People's Republic of China.
authors.forename: Lingyan
authors.initials: L
authors.lastname: Liang
authors.affiliation: †Division of Functional Materials and Nano Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, People's Republic of China.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Cao
authors.affiliation: ‡Department of New Energy Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, People's Republic of China.
authors.forename: Mingzhi
authors.initials: M
authors.lastname: Dai
authors.affiliation: §Department of Electrical and Computer Engineering, Rutgers University, Piscataway, New Jersey 08854, United States.
authors.forename: Yicheng
authors.initials: Y
authors.lastname: Lu
authors.affiliation: †Division of Functional Materials and Nano Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, People's Republic of China.
authors.forename: Mei
authors.initials: M
authors.lastname: Wang
keywords: CMOS-like inverters; SnO; ambipolar thin-film transistors; back-channel; passivation