Numerical study of carbon nanotube infra-red photo-detectors

Carbon nanotubes have been considered in recent years for future opto-electronic applications because of their direct band-gap and the tunability of the band-gap with the tube diameter. The numerical challenges for the analysis of carbon nanotube based photo-detectors are studied. The performance of infra-red photo-detectors based on carbon nanotube field-effect transistors is analyzed, using the non-equilibrium Greenpsilas function formalism. The relatively low ratio of the photo-current to the dark current limits the performance of such devices. We show that by employing a double gate structure this ratio can be significantly increased.