Amplification of terahertz radiation in carbon nanotubes

Abstract

We investigate theoretically the feasibility of amplification of terahertz radiation in aligned vachiral carbon nanotubes, a zigzag (12,0) and an armchair (10,10) in comparison with a super lattice using a combination of a constant direct current (dc) and a high-frequency alternate current (ac) electric fields. The electric current density expression is derived using the semi classical Boltzmann transport equation with a constant relaxation time. The electric field is applied along the nanotube axis. Analysis of the current density versus electric field characteristics reveals a negative differential conductivity behavior at high frequency, as well as photon assisted peaks. The photon assisted peaks are about an order of magnitude higher in the carbon nanotubes compared to the super lattice. These strong phenomena in carbon nanotubes can be used to obtain domain less amplification of terahertz radiation at room temperature