Carbon Nanotube Radiofrequency Transistors With f T/f MAX of 376/318 GHz

Aligned carbon nanotube (ACNT) array was regarded as an excellent channel material to build radio-frequency (RF) field-effect transistors (FETs) with an ultra-high frequency of up to THz regime due to the electrical performance advantages of high carrier mobility and saturation velocity, as well as low intrinsic capacitance. However, ACNT FET with extrinsic current-gain ( ${f}_{\text {T}}$ ) and maximum oscillation ( ${f}_{\text {MAX}}$ ) cut-off frequencies of simultaneously over 300 GHz has not yet been reported. In this letter, we report ACNT based RF FETs with record high dc performance of on-state current about 2.2mA/ $\boldsymbol {\mu } \text{m}$ and peak transconductance about 1.9mS/ $\boldsymbol {\mu } \text{m}$ at a bias of −1V. Especially, the ACNT based FETs show ${f}_{\text {T}}$ and ${f}_{\text {MAX}}$ of up to 376 and 318 GHz by scaling down gate length to 35 nm, indicating the actual RF performance into the THz regime. Radio-frequency amplifiers that exhibit power gain of over 24dB operating in K band is also demonstrated.