Wafer-scale high-κ dielectrics for two-dimensional circuits via van der Waals integration

Abstract

The practical application of two-dimensional (2D) semiconductors for high-performance electronics requires the integration with large-scale and high-quality dielectrics—which however have been challenging to deposit to date, owing to their dangling-bonds-free surface. Here, we report a dry dielectric integration strategy that enables the transfer of wafer-scale and high-κ dielectrics on top of 2D semiconductors. By utilizing an ultra-thin buffer layer, sub-3 nm thin Al₂O₃ or HfO₂ dielectrics could be pre-deposited and then mechanically dry-transferred on top of MoS₂ monolayers. The transferred ultra-thin dielectric film could retain wafer-scale flatness and uniformity without any cracks, demonstrating a capacitance up to 2.8 μF/cm², equivalent oxide thickness down to 1.2 nm, and leakage currents of ~10⁻⁷A/cm². The fabricated top-gate MoS₂ transistors showed intrinsic properties without doping effects, exhibiting on-off ratios of ~10⁷, subthreshold swing down to 68 mV/dec, and lowest interface states of 7.6×10⁹cm⁻² eV⁻¹. We also show that the scalable top-gate arrays can be used to construct functional logic gates. Our study provides a feasible route towards the vdW integration of high-κ dielectric films using an industry-compatible ALD process with well-controlled thickness, uniformity and scalability.

The integration of high-κ dielectric layers with 2D semiconductors is essential for electronic applications, but remains challenging. Here the authors report a dry transfer method of wafer-scale Al2O3 and HfO2 thin films for the realization of top-gated monolayer MoS2 transistors and logic gates.