Scaling down contact length in complementary carbon nanotube field-effect transistors

We performed an experimental investigation on contact length (L_c) scaling of carbon nanotube (CNT) complementary field-effect transistors (FETs). Contact resistances of Sc-contacted (for n-type) and Pd-contacted (for p-type) CNT FETs are respectively retrieved based on the experimental data through the transfer length method (TLM). The performance of L_c scaling of Sc/CNT is proved to be comparable to that of the Pd/CNT contact with L_c larger than approximately 40 nm, but it degrades sharply when further scaling down L_c mainly owing to the surface oxidation of the Sc film. After decoupling the effect of oxide thickness, the intrinsic contact scaling behavior of Sc-contacted CNT FETs is found to be as good as that of the Pd-contacted ones, which can further satisfy the requirement of developing complementary CNT FET technology scaled down to the 14 nm node.