Abstract-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 CNT diameter. The performance of infra-red photo-detectors based on carbon nanotube field-effect transistors is analyzed, using the non-equilibrium Green's 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. Carbon nanotubes (CNTs) have been extensively studied in recent years due to their exceptional electronic, optoelectronic, and mechanical properties. CNTs can be considered as a graphene sheet which has been wrapped into a tube. The way the graphene sheet is wrapped is represented by a pair of indices (n, m) called the chiral vector. The integers n and m denote the number of unit vectors along two directions in the honeycomb crystal lattice of graphene. If m = 0, the CNT is called zigzag. If n = m, the CNT is called armchair. Otherwise, it is called chiral. CNTs with n−m = 3 are metals, otherwise they are semiconductors. Semiconducting CNTs can be used as channels for transistors. Depending on the work function difference between the metal contact and the CNT, carriers at the metal-CNT interface encounter different barrier heights. Fabrication of devices with positive [1] and zero Some of the interesting electronic properties of CNTs are quasi-ballistic carrier transport [2], suppression of shortchannel effects due to one-dimensional electron transport IR photo detectors based on carbon nanotube field effect transistors (CNT-FETs) have been reported i
