Atomic Layer Deposition of Al₂O₃ Directly on 2D Materials for High-Performance Electronics

Due to the lack of surface dangling bonds of 2D materials such as graphene, hexagonal boron nitride, MoS₂ etc., deposition of high-κ dielectrics directly on such 2D materials by atomic layer deposition (ALD) is difficult and a nucleation layer is usually required. Here an ALD approach is developed to deposit high-κ dielectric layer, e.g., Al₂O₃, directly on 2D materials without the aid of the nucleation layer or introducing structural damages. In this approach, an individual deposition cycle includes one incremental organometallic pulse and multiple H₂O pulses to guarantee the uniform deposition of high-quality high-κ dielectric layers on graphene, MoS₂, and other 2D materials directly. Large-scale top-gated MoS₂ field-effect transistors (FETs) with Al₂O₃ as dielectric layers exhibit excellent performances including high on/off ratio exceeding 10⁸ and mobility up to 70 cm² V⁻¹ s⁻¹. The high-quality Al₂O₃ layer is also integrated into MoS₂ based flexible FETs and inverters, and a significant voltage gain of 412 is obtained. This ALD approach also works for other materials like gold with inert surfaces, showing great promise for novel electronics.