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

TL;DR

This paper demonstrates the fabrication and characterization of CVD boron nitride-encapsulated graphene FETs with CMOS-compatible nickel edge contacts, showing promising electrical and RF performance for future nanoelectronics.

Contribution

It introduces a novel combination of CVD boron nitride encapsulation with CMOS-compatible nickel edge contacts for graphene FETs, including the first use of THz-TDS for device assessment.

Findings

Sheet conductivity >1 mS/sq and mobility of 2500 cm²/Vs

Maximum voltage gain of 6 dB in low frequency circuits

RF f_T x L_g of 2.64 GHz·μm and f_Max x L_g of 5.88 GHz·μm

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.