Electrostatically Controllable Channel Thickness and Tunable Low-Frequency Noise Characteristics of Double-Gated Multilayer MoS2 Field-Effect Transistors with h-BN Dielectric.

Abstract

Two-dimensional transition-metal dichalcogenide (TMD) materials have attracted increasing attention in efforts to overcome fundamental issues faced by the complementary metal-oxide-semiconductor industry. Multilayer TMD materials such as MoS2 can be used for high-performance transistor-based applications; the drive currents are high and the materials handle low-frequency (LF) noise well. We fabricated double-gated multilayer MoS2 transistors using the h-BN dielectric for the top gate and silicon dioxide for the bottom gate. We systemically investigated the bottom gate voltage (Vb)-controlled electrical characteristics and the top/bottom interface-coupling effects. The effective thickness of the MoS2 channel (tMoS2_eff) was well modulated by Vb, and tMoS2_eff reduction by negative Vb dramatically improved the Ion/Ioff ratio. Numerical simulation and analytical modeling with a variation of the depletion depth under different bias conditions verified the experimental results. We were also the first to observe Vb-tuned LF noise characteristics. Here, we discuss the Vb-affected series resistance and carrier mobility in detail. Our findings greatly enhance the understanding of how double-gated multilayer MoS2 transistors operate and will facilitate performance optimization in the real world.