Graphene-gated GaAs OPFET photodetector and oscillator for 5G applications

Abstract

With the advancement of technology, the RF communication bandwidth is switching towards 5G and 6G communications. To relieve the congestion of traffic imposed on RF communication, operating in the optical domain or integrating RF and optical communication is imperative. The core components in this scenario are the oscillators as transmitters and photodetectors as receivers. These devices should be capable of high-speed and high-gain operation simultaneously. In this paper, the potential of graphene-gated GaAs front-illuminated OPFET (Optical Field Effect Transistor) as oscillator and detector towards 5G applications is explored. The OPFET device exhibits an oscillation frequency of 1.63 GHz to 1.8 GHz, tuned with optical illumination. The gain can be varied between 3.94 dB to 4.5 dB at the oscillation frequency. Under photodetection mode of operation, the device exhibits a maximum 3-dB bandwidth of 2.234 GHz, an fT of 5.33 GHz at the bandwidth frequency, and a responsivity of 3.3 × 106 A/W at a photon flux density of 1019/m2-s. A drain bias voltage of 3.94 V and a gate bias voltage of 0 V are applied in both cases. The device responses are contrasted with that of the Au (gold) gated OPFET. The explored devices have great potential for sub-6 GHz 5G applications.