High-Performance SAW Device Based on Zinc-Oxide Substrate With Electric Field Regulating Graphene Film Conductivity for Signal Amplifier

In this study, a high-performance surface acoustic wave (SAW) device based on a multi-layer graphene amplifier is proposed, which is mainly composed of a zinc-oxide (ZnO) substrate, an interdigital transducer (IDT) input, a graphene sensing layer, metal electrodes and a fork finger transducer output. The sensor uses graphene’s unique band structure and the electron transport properties of the high mobility of the carrier with extremely small temperature influence to amplify the signal of the SAW caused by the sensing signal, thereby improving the sensitivity of the SAW sensor. The influence of graphene variable conductivity controlled by the uniform electric field on SAW amplifier devices in the near field is studied and analyzed. A small size surface acoustic wave device is fabricated with microelectromechanical system (MEMS) technology. The results show that the resonant frequency of the sensor is about 72 MHz, and the maximum amplification performance is 36 dB/cm. It is found that the SAW amplifier proposed in ZnO piezoelectric crystals exhibits superior performance in graphene-based SAW amplifiers.