A clean van der Waals interface between the high-k dielectric zirconium oxide and two-dimensional molybdenum disulfide

Abstract

Two-dimensional transition metal dichalcogenide semiconductors possess ideal attributes for meeting industry scaling targets for transistor channel technology. However, the development of scaled field-effect transistors (FETs) requires industry-compatible gate dielectrics with low equivalent oxide thicknesses. Here we show that zirconium oxide (ZrO2)-an industry-compatible high-dielectric-constant (k) oxide-can form a clean interface with two-dimensional molybdenum disulfide (MoS2). Photoelectron spectroscopy analysis shows that although silicon dioxide and hafnium oxide substrates introduce the doping of MoS2, ZrO2 exhibits no measurable interactions with MoS2. Back-gated monolayer MoS2 FETs using ZrO2 as a dielectric exhibit stable and positive threshold voltages of 0.36 V, subthreshold swings of 75 mV dec-1 and ON currents of more than 400 mu A. We also use ZrO2 dielectrics to fabricate p-type tungsten diselenide FETs with ON-state currents of more than 200 mu A mu m-1. Atomic-resolution imaging of ZrO2 deposited on top of MoS2 reveals a defect-free interface, which leads to top-gated FETs with an equivalent oxide thickness of 0.86 nm and subthreshold swing values of 80 mV dec-1. The clean interface between ZrO2 and monolayer MoS2 allows the effective modulation of threshold voltage in top-gated FETs via gate metal work-function engineering.