Electrostatic gating of solid-ion-conductor on InSe flakes and InSe/h-BN heterostructures**Project supported by the National Key Research and Development Projects of China (Grant Nos. 2016YFA0202300 and 2018FYA0305800), the National Natural Science Foundation of China (Grant Nos. 61674170 and 61888102), the K. C. Wong Education Foundation, the Strategic Priority Research Program of Chinese Academy of Sciences (Grant Nos. XDB30000000 and XDB28000000), and

Abstract

We report the electrical transport properties of InSe flakes electrostatically gated by a solid ion conductor. The large tuning capability of the solid ion conductor as gating dielectric is confirmed by the saturation gate voltage as low as ∼1 V and steep subthreshold swing (83 mV/dec). The p-type conduction behavior of InSe is obtained when negative gate voltages are biased. Chemical doping of the solid ion conductor is suppressed by inserting a buffer layer of hexagonal boron nitride (h-BN) between InSe and the solid-ion-conductor substrate. By comparing the performance of devices with and without h-BN, the capacitance of solid ion conductors is extracted to be the same as that of ∼2 nm h-BN, and the mobility of InSe on solid ion conductors is comparable to that on the SiO2 substrate. Our results show that solid ion conductors provide a facile and powerful method for electrostatic doping.