  We demonstrate a fabrication scheme for clean suspended structures using
chemical-vapor-deposition-grown graphene and a dry transfer method on
lift-off-resist-coated substrates to facilitate suspended graphene
nanoelectronic devices for technology applications. It encompasses the demands
for scalable fabrication as well as for ultra-fast response due to weak
coupling to environment. The fabricated devices exhibited initially a weak
field-effect response with substantial positive ($p$) doping which transformed
into weak negative ($n$) doping upon current annealing at the temperature of 4
Kelvin. With increased annealing current, $n$-doping gradually decreased while
the Dirac peak position approached zero in gate voltage. An ultra-low residual
charge density of $9\times10^8 \mathrm{ \ cm^{-2}}$ and a mobility of $1.9
\times 10^5 \mathrm{\ cm^2/Vs}$ were observed. Our samples display clear
Fabry-P\'{e}rot (FP) conductance oscillation which indicates ballistic electron
transport. The spacing of the FP oscillations are found to depend on the charge
density in a manner that agrees with theoretical modeling based on Klein
tunneling of Dirac particles. The ultra-low residual charge, the FP
oscillations with density dependent period, and the high mobility prove
excellent quality of our suspended graphene devices. Owing to its simplicity,
scalability and robustness, this fabrication scheme enhances possibilities for
production of suspended, high-quality, two-dimensional-material structures for
novel electronic applications.
