The integration of high-k dielectric on two-dimensional crystals by atomic layer deposition

We investigate the integration of Al 2 O 3 high-k dielectric on two-dimensional (2D) crystals of boron nitride (BN) and molybdenum disulfide (MoS 2 ) by atomic layer deposition (ALD). We demonstrate the feasibility of direct ALD growth with trimethylaluminum and water as precursors on both 2D crystals. Through theoretical and experimental studies, we found that the initial ALD cycles play the critical role, during which physical adsorption dominates precursor adsorption at the crystal surface. We model the initial ALD growth stages at the 2D surface by analyzing Lennard-Jones potentials, which could guide future optimization of the ALD process on 2D crystals.