Abstract
This paper proposes a theoretical model of photo-controlled quantum capacitors in double-gated graphene-insulator-graphene (DGGIG) structure for terahertz (THz) frequency and phase modulations. In the model, the current-voltage characteristics of each segment of the DGGIG structure are controlled by different gate voltages. Using the different voltages, the DGGIG structure can be used to either generate plasma oscillation waves or shift phase in the terahertz band. Not only has the DGGIG structure various electrical properties, but also the optical properties are also excellent. Photoexcitation alters carrier concentration in DGGIG channel, and thus causes the change of the quantum capacitors. We propose a photo-controlled quantum capacitor model to quantify this phenomenon. The model shows that the quantum capacitors and photoexcitation have a sublinear dependence. An example of a device based on the model is given to describe the application of photo-controlled quantum capacitors in terahertz frequency and phase modulations. The modelled device shows that photoexcitation can change the frequency and phase of the plasma oscillation waves.
Highlights
With the increasing usage of high speed Internet and communication, the bandwidth and capacity requirements are increasing drastically
This paper presents a model of photo-controlled quantum capacitors in the double-gated graphene-insulatorgraphene (DGGIG) structure for THz frequency modulation and phase modulation (FM&PM)
We have demonstrated the application of photo-controlled quantum capacitors in double-gated graphene-insulator-graphene (DGGIG) structure for terahertz frequency and phase modulations
Summary
With the increasing usage of high speed Internet and communication, the bandwidth and capacity requirements are increasing drastically. If the photoexcitation is used to modulate the quantum capacitors in the GIG structure, the oscillator and phase shifter mentioned above will be modulated by photoexcitation to achieve a photo-controlled device. This paper presents a model of photo-controlled quantum capacitors in the double-gated graphene-insulatorgraphene (DGGIG) structure for THz frequency modulation and phase modulation (FM&PM). DOUBLE-GATED GIG Fig. 1(a) illustrates a sketch of the proposed photo-controlled THz device based on DGGIG structure. In the DGGIG structure, the VDS mainly affects the Dirac points of GLs. So, assuming a weak dependence of the Fermi level in graphene with VDS, the resonant tunneling current can be achieved by adjusting the gate voltages. All the NDC region can be used as a gain medium
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