Atomic Layer Deposition of Dielectrics on Graphene Using Reversibly Physisorbed Ozone

Abstract

Integration of graphene field-effect transistors (GFETs) requires the ability to grow or deposit high-quality, ultrathin dielectric insulators on graphene to modulate the channel potential. Here, we study a novel and facile approach based on atomic layer deposition through ozone functionalization to deposit high-K dielectrics (such as Al2O3) without breaking vacuum. The underlying mechanisms of functionalization have been studied theoretically using ab initio calculations and experimentally using in situ monitoring of transport properties. It is found that ozone molecules are physisorbed on the surface of graphene, which act as nucleation sites for dielectric deposition. The physisorbed ozone molecules eventually react with the metal precursor, trimethylaluminum to form Al2O3. Additionally, we successfully demonstrate the performance of dual-gated GFETs with Al2O3 of sub-5 nm physical thickness as a gate dielectric. Back-gated GFETs with mobilities of similar to 19 000 cm(2)/(V.s) are also achieved after Al2O3 deposition. These results indicate that ozone functionalization is a promising pathway to achieve scaled gate dielectrics on graphene without leaving a residual nucleation layer.