Simulative Study on Electronically Tunable Metal Gated and Graphene Gated Terahertz Modulator based on Modulation Depth

Two dimensional electron gas (2DEG) based High Electron Mobility Transistor (HEMT) has been considered as the basic structure of the THz modulator, where three different metals, namely Ni, Zn and Al of 1 nm thickness, have been considered as the gate material of the HEMT. For graphene gated 2DEG based THz Modulator, 1 nm width of graphene layer and different 2DEG materials are considered for simulation. Electronically tuniable conductivity of the graphene gate is simulated in the range of -50 V to 50 V. Then beam attenuation of the metal-gated THz modulator is studied and its effect on the modulation depth is simulated. After that, intensity transmittance of the both metal and graphene gated THz modulator is simulated as a function of the metal and 2DEG sheet conductivity. Finally, the modulation depth of both metal and graphene gated THz modulator has been studied in terms of the conductivity of 2DEG sheet and graphene gate respectively. After analyzing these studies, graphene based THz modulator has been recommended as a suitable and efficient modulator for the modulation of incident THz radiation for its higher modulation depth than the metal gated modulators, and suggested to be very useful for long distance communication purpose.