▎ 摘　　要

We investigate band gap tuning of bilayer graphene between hexagonal boron nitride sheets, by external electric fields. Using density functional theory, we show that the gap is continuously tunable from 0 to 0.2 eV and is robust to stacking disorder. Moreover, boron nitride sheets do not alter the fundamental response from that of free-standing bilayer gaphene, apart from additional screening. The calculations suggest that graphene-boron nitride heterostructures could provide a viable route to graphene-based electronic devices.