▎ 摘　　要

Ballistic model of a graphene bilayer field-effect transistor (GBL FET) was developed. It incorporates the exact graphene bilayer electronic spectrum reminding a "Mexican hat". The isotropic minimum shifted from the center of a band results in a conductance step at low temperature which was so far known for one-dimensional conductors due to conductance quantization. At room temperature a GBL FET exhibits an extremely high transconductance in ON-state. It makes a GBL FET promising for high-frequency analog circuits. We also point out to possibility of electron localization inside the channel on the top of potential barrier. (C) 2011 The Japan Society of Applied Physics