Graphene microwave transistors on sapphire substrates

TL;DR

This paper reports the development of graphene-based microwave transistors on sapphire substrates, achieving high-frequency operation and stability suitable for cryogenic low-noise amplification.

Contribution

It introduces a new fabrication of MOGFETs on sapphire with high transit frequency and low noise characteristics at cryogenic temperatures.

Findings

Transit frequency up to 80 GHz for monolayer graphene

Maximum power gain frequency around 3 GHz

High stability and low noise at low temperatures

Abstract

We have developed metal-oxide graphene field-effect transistors (MOGFETs) on sapphire substrates working at microwave frequencies. For monolayers, we obtain a transit frequency up to ~ 80 GHz for a gate length of 200 nm, and a power gain maximum frequency of about ~ 3 GHz for this specific sample. Given the strongly reduced charge noise for nanostructures on sapphire, the high stability and high performance of this material at low temperature, our MOGFETs on sapphire are well suited for a cryogenic broadband low-noise amplifier.