  We report on the fabrication and characterization of field effect transistors
(FETs) based on chemical vapor deposited (CVD) graphene encapsulated between
few layer CVD boron nitride (BN) sheets with complementary metal oxide
semiconductor (CMOS) compatible nickel edge contacts. Non-contact Tera-hertz
time domain spectroscopy (THz-TDS) of large-area BN/graphene/BN (BN/G/BN)
stacks reveals average sheet conductivity >1 mS/sq and average mobility of 2500
cm$^{2}$/Vs. Improved output conductance is observed in direct current (DC)
measurements under ambient conditions, indicating potential for radio-frequency
(RF) applications. Moreover, we report a maximum voltage gain of 6 dB from a
low frequency signal amplifier circuit. RF characterization of the GFETs yields
an f$_{T}$ x L$_{g}$ product of 2.64 GHz$\mu$m and an f$_{Max}$ x L$_{g}$
product of 5.88 GHz$\mu$m. This study presents for the first time THz-TDS usage
in combination with other characterization methods for device performance
assessment on BN/G/BN stacks. The results serve as a step towards scalable, all
CVD 2D material-based FETs for CMOS compatible future nanoelectronic circuit
architectures.
