  We investigate key electrical properties of monolayer graphene assembled by
chemical-vapor-deposition (CVD) as impacted by supporting substrate material.
Graphene field-effect transistors (GFETs) were fabricated with carbon channel
placing directly on hexagonal boron nitride (h-BN) and SiO2, respectively.
Small-signal transconductance (gm) and effective carrier mobility ({\mu}eff)
are improved by 8.5 and 4 times on h-BN, respectively, as compared with that on
SiO2. Compared with GFET with exfoliated graphene on SiO2, gm and {\mu}eff
measured from device with CVD graphene on h-BN substrate exhibits comparable
values. The experiment demonstrates the potential of employing h-BN as a
platform material for large-area carbon electronics.
