Graphene-on-Diamond Devices with Enhanced Current-Carrying Capacity: Carbon sp2-on-sp3 Technology

TL;DR

This paper demonstrates that replacing SiO2 with synthetic diamond in graphene devices significantly enhances their current-carrying capacity, reaching up to 18 times higher than conventional substrates, with implications for high-performance electronics.

Contribution

The study introduces a novel sp2-on-sp3 carbon-on-carbon technology using diamond substrates to substantially increase graphene's current capacity at ambient conditions.

Findings

Graphene on diamond achieves up to 18 uA/nm2 current density.

Current-induced breakdown in graphene is thermally activated.

Ultrananocrystalline diamond improves thermal management at lower costs.

Abstract

Graphene demonstrated potential for practical applications owing to its excellent electronic and thermal properties. Typical graphene field-effect transistors and interconnects built on conventional SiO2/Si substrates reveal the breakdown current density on the order of 1 uA/nm2 (i.e. 10^8 A/cm2) which is ~100\times larger than the fundamental limit for the metals but still smaller than the maximum achieved in carbon nanotubes. We show that by replacing SiO2 with synthetic diamond one can substantially increase the current-carrying capacity of graphene to as high as ~18 uA/nm2 even at ambient conditions. Our results indicate that graphene's current-induced breakdown is thermally activated. We also found that the current carrying capacity of graphene can be improved not only on the single-crystal diamond substrates but also on an inexpensive ultrananocrystalline diamond, which can be produced in a process compatible with a conventional Si technology. The latter was attributed to the decreased thermal resistance of the ultrananocrystalline diamond layer at elevated temperatures. The obtained results are important for graphene's applications in high-frequency transistors, interconnects, transparent electrodes and can lead to the new planar sp2-on-sp3 carbon-on-carbon technology.