On Current Carrying Capacity of Single Wall Semiconducting Carbon Nanotubes

The current carrying capacity of single wall semiconducting carbon nanotubes (CNTs) in the presence of phonon scattering and band-to-band tunneling is studied by self-consistently solving Poisson and Schr\"{o}dinger equation using the non-equilibrium Green's function formalism. We show that the current delivery capacity of semiconducting CNTs strongly depends on the bias regime and is drastically different from metallic CNTs. A long metallic single wall CNT carries a saturation current of $\sim $25$\mu $A due to optical phonon (OP) scattering. In contrast, a semiconducting CNT can deliver a current well above 25$\mu $A in ambipolar transport regime even when the channel length is much longer than the OP scattering mean free path (mfp). When the channel length is short (comparable to the OP scattering mfp), a semiconducting CNT biased in unipolar transport regime can deliver a current larger than 25$\mu $A. Biasing the CNT in ambipolar transport regime, however, further doubles the current. The different current carrying capacity in the ambipolar transport regime is due to nearly uncoupled dissipative transport through both the lowest conduction and valence subbands in the channel.