Modulation of electrical properties in carbon nanotube field-effect transistors through AuCl3 doping

Abstract

Carbon nanotube-based field-effect transistors (CNFETs), as a new generation of nanodevices, are still difficult to apply to actual logic circuits due to the lack of a mature threshold voltage control mechanism. Here in this work, a feasible and large-scale processing surface doping method is demonstrated to effectively modulate the threshold voltage of CNFETs through the p-type doping effect of gold chloride (AuCl₃). A comprehensive mapping from electrical parameters (<i>I</i>_on/<i>I</i>_off, <i>V</i>_th and mobility) to doping concentration is carefully investigated, demonstrating a p-doping effect induced by surface charge transfer between Au³⁺ and carbon nanotube networks (CNTs). Threshold voltage of CNFETs can be effectively adjusted by varying the doping concentration. More importantly, the devices doped with low concentration AuCl₃exhibit good electrical properties including greatly improved electrical conductivity, 2–3 times higher in mobility than intrinsic carbon nanotubes. Furthermore, the effects of annealing on the electrical properties of the AuCl₃-doping CNFETs are studied, demonstrating that the p-type doping effect reaches the optimized state at a temperature of 50 °C. Finally, first-principles calculation method is used to verify the doping control mechanism of Au³⁺to carbon nanotubes. This research provides important guidance for realizing large-area low-power logic circuits and high-performance electronic devices in the future.