A Photoinduced Electrostatic Doping Effect in Carbon Nanotube Field-Effect Transistors

A photoinduced electrostatic doping effect based on bottom-gate carbon nanotube field-effect transistors (CNT-FETs) with poly (urea-urethane) as dielectric is reported for the first time. The transistors exhibit significant changes in their transfer characteristics as a result of low-intensity visible light illumination (~6.2 m W cm−2), mainly including the increase in the order of magnitude of the on-current and a shift in threshold voltage. The photoinduced phenomenon can be explained by a photoinduced electron trapping model, in which the photogenerated electrons in the Si-gate are trapped by the polymer dielectric layer at a negative gate voltage and induces more hole carriers in the semiconducting carbon nanotubes (S-CNTs) channel.