High performance, large area graphene transistors on quasi-free-standing graphene using synthetic hexagonal boron nitride gate dielectrics

In recent years, hexagonal boron nitride (h-BN) has gained interest as a material for use in graphene based electronics, where its ultra-smooth two-dimensional structure, lack of dangling bonds, and high energy surface optical phonon modes are desirable when considering the effect of dielectric materials in introducing additional sources of scattering for carriers within graphene. Initial work has indicated that use of h-BN in place of SiO₂ supporting substrates can lead to 2-3x improvements in device performance [1,2], suggesting that h-BN may be an excellent choice as top-gate dielectric for graphene devices. In this work, we integrate h-BN with quasi-freestanding graphene (QFEG) for the first time and demonstrate a 2x improvement in radio frequency (RF) performance and the highest f_T·L_g product yet reported for h-BN integrated graphene devices (25 GHz·μm).