Insight Into Ballisticity of Room-Temperature Carrier Transport in Carbon Nanotube Field-Effect Transistors

Carbon nanotube field-effect transistors (CNT FETs) with gate length down to 10 nm are fabricated and analyzed by fitting the experimental data through the virtual-source (VS) model. Due to the quasi-ballistic carrier transport property, it is shown that carriers in CNTs exhibit the injection velocity of 3 x 10(7) cm/s, approximately two times of the target velocity in the 10-nm gate length transistors required by International Roadmap for Devices and Systems (IRDS 2017). The transport parameters for the first time, namely, critical length, unidirectional thermal velocity, and backscattering mean free path (MFP), are extracted by the Lundstrom model from the measured data of quasi-ballistic short-channel CNT FETs to diffusive long-channel CNT FETs, which help arriving at a conclusion that, down to 10-nm gate length, the CNT FETs operate close to 73% of the ballistic regime.