Atomic layer deposition of sub-10 nm high-K gate dielectrics on top-gated MoS 2 transistors without surface functionalization

•Ultrathin Al2O3 nucleation layer was prepared at a low temperature.•No MoS2 oxidation occurred during the Al2O3 deposition.•Uniform sub-10 nm Al2O3 layer on MoS2 were achieved by atomic layer deposition.•Low hysteresis and subthreshold swing were demonstrated in the MoS2 transistors.