Ballistic n-type carbon nanotube(CNT)-based field-effect transistors(FETs) have been fabricated by contacting semiconducting single-walled CNTs(SWCNTs) using Sc or Y.The n-type CNT FETs were pushed to their performance limits through further optimizing their gate structure and insulator.The CNT FETs outperformed n-type Si metal-oxide-semiconductor(MOS) FETs with the same gate length and displayed better downscaling behavior than the Si MOS FETs.Together with the demonstration of ballistic p-type CNT FETs using Pd contacts,this technological advance is a step toward the doping-free fabrication of CNT-based ballistic complementary metal-oxide-semiconductor(CMOS) devices and integrated circuits.Taking full advantage of the perfectly symmetric band structure of the semiconductor SWCNT,a perfect SWCNT-based CMOS inverter was demonstrated,which had a voltage gain of over 160.Two adjacent n-and p-type FETs fabricated on the same SWCNT with a self-aligned top-gate realized high field mobility simultaneously for electrons(3000 cm2 V-1 s-1) and holes(3300 cm2 V-1 s-1).The CNT FETs also had excellent potential for high-frequency applications,such as a high-performance frequency doubler. Ballistic n-type CNTs (CNTs) -based field-effect transistors (FETs) have been fabricated by contacting semiconducting single-walled CNTs (SWCNTs) using Sc or Y. The n-type CNT FETs were pushed to their performance limits through further optimizing their gate structure and insulator.The CNT FETs outperformed n-type Si metal-oxide-semiconductor (MOS) FETs with the same gate length and displayed better downscaling behavior than the Si MOS FETs.Together with the demonstration of ballistic p-type CNT FETs using Pd contacts, this technological advance is a step toward the doping-free fabrication of CNT-based ballistic complementary metal-oxide-semiconductor (CMOS) devices and integrated circuits. Taking full advantage of the perfectly symmetric band structure of the semiconductor SWCNT, a perfect SWCNT-based CMOS inverter was demonstrated, which had a voltage gain of over 160. Two adjacent n-and p-type FETs fabricated on the same SWCNT with a self-aligned top-gate realized high field mobility CNTs also have excellent potential for high-frequency applications, such as a high-performance frequency doubler.