Improvement of N-type carbon nanotube field effect transistor performance using the combination of yttrium diffusion layer in HfO₂ dielectrics and metal contacts

In this paper, we obtained n-type top-gate carbon nanotube (CNT) thin film field effect transistors (FET) with source/drain extensions structure through dielectrics optimization strategy, combining the yttrium layer with HfO₂ dielectric argon annealing process, and metal contacts. The mechanism for enhanced n-type conduction was explained as being due to the vertical diffusion of yttrium to the HfO₂ dielectric during argon annealing. This diffusion causes a bending of the energy band, which results in more positive fixed charges, and a reduction in the electron injection barrier between the low work function source/drain Cr electrode and CNT thin film. The optimized technology has great prospects for the low cost, large scale and high performance n-type CNT thin film FET to be used in integrated electronic devices.