  The use of two truly two-dimensional gapless semiconductors, monolayer and
bilayer graphene, as current-carrying components in field-effect transistors
(FET) gives access to new types of nanoelectronic devices. Here, we report on
the development of graphene-based FETs containing two decoupled graphene
monolayers manufactured from a single one folded during the exfoliation
process. The transport characteristics of these newly-developed devices differ
markedly from those manufactured from a single-crystal bilayer. By analyzing
Shubnikov-de Haas oscillations, we demonstrate the possibility to independently
control the carrier densities in both layers using top and bottom gates,
despite there being only a nano-meter scale separation between them.
