Stability of radio-frequency graphene field-effect transistors in ambient

While many studies on radio-frequency (RF) graphene field-effect transistor (GFET) aimed to study its high performances, explorations of the long-term stability of RF GFETs in atmosphere may be required as well. In this paper, we investigated the stability of the RF GFETs stored in ambient for four years. Both the RF and direct current characteristics are measured and compared with the initial properties. Changes of current-gain cut-off frequency and field-effect mobility, reductions of maximum oscillation frequency, peak transconductance and gate capacitance are observed butthe extracted contact resistance remains unchanged. The permeation of water vapor and oxygen into the thin Al2O3 dielectric, the diffusion of Pd atoms from contact onto the graphene channel and the rougher Al2O3 surface may challenge the stability of RF GFETs. This work may pave the way for the fabrication of more stable RF GFETs, which further serve steady graphene-based RF circuits.