Ge-based graphene FET for low-temperature electronics

A graphene field-effect transistor (GFET) based on chemical vapour deposited (CVD) Ge-based graphene was reported and the low-temperature electrical characteristics primarily investigated. The self-alignment technique was used to fabricate a GFET to reduce parasitic effects and improve transconductance and cut-off frequency. To further explore the electrical properties, the direct current and radio frequency characteristics of the GFET were studied over a temperature range from 4.2 to 300 K, considering the temperature-dependent resistivity of intrinsic Ge. The direct current characteristic of the GFET for 110-nm gate length, particularly the transconductance performance, exhibits a tiny variation of only similar to$\sim$5% across this temperature range. However, the cut-off frequency experiences a considerable increase, improving several tens of times when the temperature decreases to 4.2 K, with a maximum value of 3.49 GHz. This work illustrates a meaningful advancement in applying GFETs in the low-temperature, high-frequency domain. A graphene field-effect transistor (GFET) based on chemical vapour deposited Ge-based graphene was reported and the low-temperature electrical characteristics primarily investigated. Its distinctly different temperature behaviours in direct current and radio frequency characteristics offer novel potential for the applications of GFETs at low temperatures. image