▎ 摘　　要

Room temperature magnetron sputtering is used to deposit SiO2 and Si3N4 encapsulation layers on top of back gated graphene transistors, which are fabricated with CVD grown graphene transferred onto SiO2 and Si3N4 substrates. Raman spectroscopy with 514 nm laser excitation was performed on bare and encapsulated devices. A small increase in D peak of the encapsulated spectrum indicates minimal increase in defect density for both SiO2 and Si3N4 deposition. Graphene on Si3N4 exhibits an average mobility of similar to 4000 cm(2)/V.s at a carrier density of 10(12) cm(-2) and up to 80% mobility is retained upon encapsulation with Si3N4, while on SiO2 the average mobility is similar to 2000 cm(2)/V.s with mobility retention of up to 55% with SiO2 encapsulation. (C) 2012 Elsevier B.V. All rights reserved.