Broadband Flexible Graphene RF Power Detectors

Paper in proceeding, 2017

With the development of wearable radios, foldable Wi-Fi devices, and conformal wireless sensors, flexible radio frequency (RF) electronics have become a highly active research field [1, 2]. As an essential component for both RF transmitters and receivers, a power detector is required to withstand high levels of strain. The flexible RF power detectors based on laminated Si and III-V membranes on polymer substrates demonstrate poor mechanical reliability, restricting the range of applications [3, 4]. In contrast, graphene is an ideal candidate for the use in flexible RF power detectors, because it offers outstanding electrical and mechanical properties [5]. Furthermore, graphene can be grown over large areas by chemical vapour deposition and transferable to various flexible substrates [6]. In this work, we demonstrate RF power detection up to 67 GHz using coplanar access graphene field - effect transistors (GFETs) on flexible and transparent polyethylene terephthalate substrates. The frequency dependence of measured and modelled voltage responsivity at optimum gate bias is shown in Figure 1. At room temperature, this detector reveals voltage responsivity above 10 V/W over the frequency range from 1 GHz to 67 GHz. The measured voltage responsivity results are well fitted by the nonlinear empirical model [7] with all parameters extracted from S-parameter and DC measurements. In addition, we study the effects of interfacial capacitance, associated with traps, on the hysteresis of voltage responsivity. Figure 2 shows the measured voltage responsivity as a function of the gate voltage with reproducible hysteresis loop at 55 GHz.