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

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 µA. We also use ZrO₂ dielectrics to fabricate p-type tungsten diselenide FETs with ON-state currents of more than 200 µA µm^-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.