▎ 摘　　要

The deposition of high-quality dielectric films on graphene surfaces is crucial in fabricating high-performance graphene-based electronics. In this study, the first application of UV-assisted atomic layer deposition (UV-ALD) to graphene surfaces and the fabrication of graphene field-effect transistors (GFETs) with UV-ALD Al2O3 dielectric thin films is demonstrated. Optimal UV irradiation (5 s per cycle) during the ALD process results in denser and smoother Al2O3 dielectric films deposited on the graphene surface with the intimate graphene-dielectric interface, while excessive UV irradiation in turn prohibits the film nucleation. As a result, the GFETs with a high-quality dielectric layer deposited by UV-ALD show improved performance with a Dirac voltage close to 0 V and hole mobility of 1221 cm(2) V-1 s(-1), i.e., > 200% increase compared to those with thermal ALD. This study demonstrates that UV-ALD is an effective and simple option to realize a high-quality interface between 2D materials and ultra-thin dielectric films.