We investigate the high frequency performances of flexible field-effect transistors based on carbon nanotubes. A large density of mostly aligned carbon nanotubes deposited on a flexible substrate by dielectrophoresis serves as the channel. The transistors display a constant transconductance up to at least 6GHz and a current gain cutoff frequency (fT) as high as 1GHz at VDS=−700mV. Bending tests show that the devices can withstand a high degree of flexion characterized by a constant transconductance for radius of curvature as small as 3.3mm.

We investigate terahertz (THz) emission from heavy-ion-irradiated In0.53Ga0.47As photoconductive antennas excited at 1550 nm. The carrier lifetime in the highly irradiated In0.53Ga0.47As layer is less than 200 fs, the steady-state mobility is 490cm2V−1s−1, and the dark resistivity is 3Ωcm. The spectrum of the electric field radiating from the Br+-irradiated In0.53Ga0.47As antenna extends beyond 2 THz. The THz electric field magnitude is shown to saturate at high optical pump fluence, and the saturation fluence level increases with the irradiation dose, indicating that defect center scattering has a significant contribution to the transient mobility.