RF Performance Potential of Array-Based Carbon-Nanotube Transistors—Part I: Intrinsic Results

Carbon nanotube radio-frequency electronics

“…CNT FETs are expected to be promising for RF applications, because of the associated high carrier mobility, large saturation velocity, large current density and ultra-small intrinsic gate capacitance. Theoretically, the cut-off frequency of CNT FETs was predicted to exceed 10 THz [38][39][40], and potentially CNE FETs could be used to fill the blank frequency band between traditional electronic devices and optic devices, namely 300 GHz to 30 THz. The argument involves mainly the intrinsic RC delay, in which the resistance R comes from the output resistance and the capacitance C comes from the gate capacitance C g .…”

Potential of carbon nanotube field effect transistors for analogue circuits

“…1 b . It is worth mentioning that out of the two types of CNFETs namely Schottky barrier and MOSFET like, the latter is chosen as it has higher I ON / I OFF ratio, transconductance ( g m ), transition frequency f T , lower parasitic capacitances, better AC performance and higher fabrication feasibility [18]. In the MOSTFET‐like CNFET (henceforth, called just CNFET), the current flow between the source and drain contacts is achieved using CNTs.…”

“…Similarly, [17] reports an RF mixer mixing at 50 GHz using a single‐walled (SW) CNT transistor. References [18, 19] provide a quantitative measure of RF performance of array‐based CNFETs; however, the analysis is limited to the transistor level. Most of the above works, firstly, do not reflect the true RF potential of the CNFETs, and secondly do not provide a detailed improvement comparison over CMOS circuits so that the CNFET results can be put into perspective, especially at high frequencies.…”

About the charge injection limitation in Schottky barrier CNTFETs

“…Applying those models assumes the contact regions to be highly doped. Usually, doping concentrations in the range of 0.4 nm −1 to 1 nm −1 are used [8], [18], which correspond to a highly degenerate situation with Fermi levels at around 0.1 eV to 0.3 eV above the first conduction band. According to Fig.…”