All CVD Boron Nitride Encapsulated Graphene FETs with CMOS Compatible Metal Edge Contacts

Abstract

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.