Effect of Coulomb Carrier Drag and Terahertz Plasma Instability in p+ - P - i - N - n+ Graphene Tunneling Transistor Structures

We evaluate the influence of Coulomb drag of electrons and holes in gated n and p regions caused by ballistic electrons and holes generated in a depleted i region due to interband tunneling on the current-voltage characteristics and impedance of p+-p-i-n-n+ graphene tunneling transistor structures (GTTSs). This drag leads to current amplification in the gated n and p regions and positive feedback between the amplified dragged current and the injected tunneling current. A sufficiently strong drag can result in a negative real part of the GTTS impedance, enabling a plasma instability and self-excitation of plasma oscillations in the terahertz (THz) frequency range. This effect might be used for the generation of THz radiation.