  We developed means to produce wafer scale, high-quality graphene films as
large as 3 inch wafer size on Ni and Cu films under ambient-pressure and
transfer them onto arbitrary substrates through instantaneous etching of metal
layers. We also demonstrated the applications of the large-area graphene films
for the batch fabrication of field-effect transistor (FET) arrays and
stretchable strain gauges showing extraordinary performances. Transistors
showed the hole and electron mobilities of the device of 1,100 cm2/Vs and 550
cm2/Vs at drain bias of -0.75V, respectively. The piezo-resistance gauge factor
of strain sensor was ~6.1. These methods represent a significant step toward
the realization of graphene devices in wafer scale as well as application in
optoelectronics, flexible and stretchable electronics.
