Overcoming the Leakage and Contact Resistance Challenges in Highly Scaled PMOS and NMOS Carbon Nanotube Transistors

In this work, we address the off-state leakage current challenge, while simultaneously demonstrating high drive current per CNT, in NMOS and PMOS carbon nanotube field-effect transistors (CNFETs). Increasing the bandgap from 0.6 to 0.85 eV reduces the minimum current from 10^-8 A/μm to 10^-11 A/μm at V_DS = -0.5 V with a channel length of 50 nm. By utilizing titanium as the contact metal and the YO/AlN solid-state electrostatic doping technique, isoperformance NMOS and PMOS are demonstrated in large bandgap CNFETs. We examined the contact properties of large bandgap CNT FETs by measuring the contact barrier height and report the contact resistance with contact lengths scaled down to 18 nm. Projections for high-density CNT arrays indicate promising potential for using large bandgap CNTs as channel materials in high-performance and low-power applications.