Energy-Efficient Carbon Nanotube Field-Effect Phototransistors: Quantum Simulation, Device Physics, and Photosensitivity Analysis

In this paper, new nanoscale phototransistors based on carbon nanotube (CNT) are proposed and assessed using a quantum simulation-based computational methodology. The used numerical model is based on the self-consistent computation combining the Poisson solver and Schrödinger solver within the non-equilibrium Green’s function (NEGF) formalism while assuming a ballistic transport. The working principle of the proposed phototransistors is based on the light-induced gate photovoltage that alters the electrostatic gating of the transducers as well as the quantum mechanical transport in the zigzag CNT channel. The computational investigation includes two known carbon nanotube field-effect transistors (CNTFET) as photodetector, namely, the MOSFET-like CNTFET and the CNT tunneling FET (CNTTFET). The physics, quantum transport, and photosensitivity behavior of the nanoscale phototransistors were thoroughly investigated including the electron potential distribution, energy-position-resolved current spectrum, drain current, subthreshold swing, sensitivity behavior, and scaling capability. In addition, a parametric investigation was conducted to reveal the photosensitivity trends against the variation in physical and geometrical phototransistors parameters. The obtained results make the investigated CNT-based phototransistors intriguing photodetectors that can serve the cutting-edge nanoscale optoelectronics.