▎ 摘　　要

We theoretically propose a bilayer graphene nanoribbon phototransistor (BGN-PT) based voltage-tunable terahertz/infrared (THz/IR) photodetector. The optical responsivity and quantum efficiency of our device, originated from interband transitions, are greater than those of GNR-PTs within the frequency range of THz to IR (0 < <(h)over bar>omega < 1 eV). We reveal that the metallic armchair (Dirac) BGN-PTs have a maximum external quantum efficiency of about 40% at low energies of incident photons (<(h)over bar>omega approximate to 0.4 eV), which is robust across a wide range of relevant temperatures. The dependence of the optical characteristics on geometric parameters and bias voltages is studied as well. The photocurrent growth with gate and drain-source voltages, in the Dirac family, is larger than in the other two configurations. Also, we investigate the frequency shift of the lowest-energy peak and asymmetric electronic transitions with the potential difference between the gates. Our simulations indicate that the THz/FIR sensitivity and voltage tunability of 3p + 2 BGN-PTs are dramatically larger than in the other two families. (C) 2016 Optical Society of America