High frequency performance of graphene transistors grown by chemical vapor deposition for mixed signal applications

This paper demonstrates high frequency performance of graphene transistors grown by chemical vapor deposition on copper foils. Using Ti/Pd/ Au-based ohmic contacts and a hybrid gate dielectric stack of 5 nm SiO2 and 15nm Al2O3 grown by atomic layer deposition, graphene transistors with an extrinsic current-gain cut-off frequency (fT) of 2 GHz and power-gain cut-off frequency, fmax, of 5.6GHz were obtained for a gate length of L_g = 1.6 μm. By applying a bias to the Si substrate the access resistances are reduced, which improved the fT and fmax in the devices to 3.5 and 6.5 GHz, respectively. Finally we demonstrate these devices in a real-application circuit for binary-phase shift keying.