Ultrasonic nanowelding of carbon nanotubes to metal electrodes

A simple ultrasonic nanowelding technique has been developed to reliably bond single-wall carbon nanotubes (SWCNTs) onto metal electrodes, by pressing SWCNTs against electrodes under a vibrating force at ultrasonic frequency. The bonds formed have been demonstrated to be mechanically robust. Using this technique, a stable low-Ohmic contact between SWCNTs and metal electrodes was achieved, with resistances in the range of 8–24 kΩ for a 1 µm long metallic SWCNT at room temperature. The performance of carbon nanotube field-effect transistors (FETs) fabricated using this ultrasonic nanowelding method has also been greatly improved. Transconductance as high as 3.6 µS among the solid-state back-gate individual nanotube FETs has been achieved.