Doping-Free Fabrication of Carbon Nanotube Based Ballistic CMOS Devices and Circuits

We have fabricated ballistic n-type carbon nanotube (CNT)-based field-effect transistors (FETs) by contacting semiconducting single wall CNTs using Sc. Together with the demonstrated ballistic p-type CNT FETs using Pd contacts, our work closes the gap for doping-free fabrication of CNT-based ballistic complementary metal-oxide semiconductor (CMOS) devices and circuits. We demonstrated the feasibility of this doping-free CMOS technology by fabricating a simple CMOS inverter on a SiO2/Si substrate using the back-gate geometry, but in principle much more complicated CMOS circuits may be integrated on a CNT on any suitable insulator substrate using the top-gate geometry and high-κ dielectrics. This CNT-based CMOS technology only requires the patterning of arrays of parallel semiconducting CNTs with moderately narrow diameter range, for example, 1.6−2.4 nm, which is within the reach of current nanotechnology. This may lead to the integration of CNT-based CMOS devices with increasing complexity and possibly find its way into the computers brain: the logic circuit.