Scaling of N-Type Field-Effect Transistors Based on Aligned Carbon Nanotube Arrays

Wafer-scale aligned carbon nanotubes (A-CNTs) are promising candidate semiconductors for building high-performance complementary metal-oxide-semiconductor (CMOS) transistors for future integrated circuits (ICs). A-CNT-based p-type field-effect transistors (P-FETs) have demonstrated excellent performance and scalability down to sub-10 nm nodes. However, the development of A-CNT n-type FETs (N-FETs) lags far behind, in regard to their electronic performance and device scaling. In this work, we fabricated top-gated N-FETs based on A-CNTs with a scandium (Sc)-contacted source and drain. High-performance A-CNT N-FETs were demonstrated with record on-state current (I_on) exceeding 1 mA/μm and peak transconductance (g_m) of 0.4 mS/μm. Interestingly, the A-CNT N-FETs exhibited abnormal scaling behavior owing to the lateral oxidation of low-work function source/drain contacts, leading to formidable challenges to scale both the gate length (L_g) and the contact length (L_c) at the same time. Understanding of the abnormal scaling behavior contributes to seeking solutions for high-performance A-CNT N-FETs, and it paves the way for future CNT CMOS digital IC technology.