ABSTRACT
A distributed feedback dual-gate graphene-channel field-effect transistor (DFB-DG-GFET) was fabricated as a current-injection terahertz (THz) light-emitting laser transistor. Optical and/or injection pumping of graphene can enable negative-dynamic conductivity in the THz spectral range, which may lead to new types of THz lasers. The THz gain in optically pumped graphene has been experimentally confirmed. In this chapter, the authors fabricate a prototype current-injection-type graphene laser device in a DFB-DG-GFET structure and challenged for the first observation of THz radiation oscillations. Varying the DFB design parameters, quality of graphene layer, and thickness of substrate can largely affect the confinement of THz photon electric fields on to the active gain area, which can hugely alter the gain profile. A forward-biased graphene structure with a lateral p-i-n junction was implemented as a DFB-DG-GFET in which the current injection mechanism was realized using a dual-gate structure and the laser action mechanism was realized using a DFB cavity structure.
