Van der Waals enabled formation and integration of ultrathin high-κ dielectrics on 2D semiconductors

A thin dielectric layer is an important constituent element in 2D materials-based electronics and photonics. Current methods of using hexagonal boron nitride (hBN) and direct deposition of dielectric layer induce either high leakage current or unintentional doping and defect. Here we report a technique for damaging free integration of dielectric layer to form high-quality van der Waals (vdW) heterostructure. The dielectric layer is grown by atomic layer deposition (ALD) on 2D materials and then deterministically transferred on the target 2D material. The much weaker binding energy between the ALD dielectric and the 2D materials enables the growth and exfoliation of the atomically thin dielectrics, which is confirmed by the X-ray photoelectron spectroscopy analyses and the density function theory calculations. The effectiveness of the technology is proven by the Raman and photoluminescence measurement on WS2 monolayer protected by the dielectric film through harsh plasma treatment. Furthermore, a 2D materials-based MOSFET is constructed as a demonstration of the viability of the technology for electronic device applications. The method produces flat surfaces and clean interfaces and would greatly benefit electronic and photonic applications as encapsulation or high-κ gate dielectric.