Al2O3 as a suitable substrate and a dielectric layer for n-layer MoS2

Sapphire (alpha-Al2O3) is a common substrate for the growth of single-to few-layer MoS2 films, and amorphous aluminium oxide serves as a high-kappa dielectric gate oxide for MoS2 based transistors. Using density-functional theory calculations with a van der Waals functional, we investigate the structural, energetic, and electronic properties of n-layer MoS2 (n = 1 and 3) on the alpha-Al2O3 (0001) surface. Our results show that the sapphire stabilizes single-layer and tri-layer MoS2, while having a negligible effect on the structure, band gap, and electron effective masses of MoS2. This combination of a strong energetic stabilization and weak perturbation of the electronic properties shows that alpha-Al2O3 can serve as an ideal substrate for depositing ultra-thin MoS2 layers and can also serve as a passivation or gate-oxide layer for MoS2 based devices. (C) 2015 AIP Publishing LLC.