title: Control of the threshold voltage in ZnO nanobelt field-effect transistors by using MoO x thin film.
abstract: We report on the feasible control of the threshold voltage (V th) in ultra-thin ZnO nanobelt FETs by using substoichiometric molybdenum trioxide (MoO x , x < 3) either as a modification layer on the surface of ZnO nanobelts or as electrodes instead of the widely used Ti/Au. ZnO nanobelt FETs using Ti/Au as the electrodes usually exhibit a negative threshold voltage, indicating n-channel depletion mode behavior, whereas ZnO FETs with MoO x /Au electrodes instead of Ti/Au show a positive shift of threshold voltage, exhibiting an n-channel type enhancement mode, which can be explained by a high Schottky barrier created at the interface of MoO x and the ZnO channel. In contrast, the decoration on the surface of ZnO channel by MoO x significantly increases the zero-bias conductivity and electron carrier concentration, and then negatively shifts the threshold voltage. We propose that MoO x thin film may play a passivation effect role, much more so than the doping effect role, due to the large amount of adsorbed species on as-grown ZnO nanobelts, especially oxygen species.
authors.affiliation: Department of Physics & State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: Haolei
authors.initials: H
authors.lastname: Qian
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Fang
authors.forename: Lin
authors.initials: L
authors.lastname: Gu
authors.forename: Ren
authors.initials: R
authors.lastname: Lu
authors.forename: Ming
authors.initials: M
authors.lastname: Zhao
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Yewu
authors.initials: Y
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Sha