Method of integrating a single nanowire into a nanocircuit
A non-volatile bistable nano-electromechanical switch is provided for use in memory devices and microprocessors. The switch employs carbon nanotubes as the actuation element. A method has been developed for fabricating nanoswitches having one single-walled carbon nanotube as the actuator. The actuation of two different states can be achieved using the same low voltage for each state.
1. A method of integrating a single nanowire into a nanocircuit, the method comprising the steps of:
providing a nanosubstrate, a surface of the nanosubstrate comprising two conductive terminals separated by an insulating area;
adding a liquid suspension of nanotubes to the surface of the nanosubstrate to cover the conductive terminals;
performing dielectrophoresis by applying a voltage between the first and second conductive terminals; and
removing excess nanotubes using a stream of gas, whereby only one nanotube remains in electrical contact with both conductive terminals.
2. The method of claim 1 , wherein the step of performing dielectrophoresis comprises applying an AC voltage in the range from about 1 to about 5 volts.
3. The method of claim 2 , wherein the AC voltage has a frequency of about 1 MHz.
4. The method of claim 1 , wherein dielectrophoresis is performed using a phase shifter to provide an electrical field gradient at the ground electrode of opposite phase to that at the phase electrode.
5. The method of claim 1 , further comprising iteratively performing the method while adjusting the concentration of nanotubes in the liquid suspension to identify a concentration at which only one nanotube is attached to both conductive terminals.
6. The method of claim 1 , further comprising iteratively performing the method while adjusting the duration of performing dielectrophoresis to identify a duration at which only one nanotube is attached to both conductive terminals.
7. The method of claim 1 , wherein the liquid suspension comprises single-walled carbon nanotubes (SWNT) and the integrated single nanowire is an SWNT, or the liquid suspension comprises multi-walled carbon nanotubes (MWNT) and the integrated single nanowire is an MWNT.
8. The method of claim 1 , wherein each of the first and second conductive terminals comprises a pointed tip and the terminals are oriented with the tips pointing towards each other.
9. The method of claim 8 , wherein each tip has a profile which forms an acute angle of about 30 degrees or less.
10. The method of claim 1 , wherein the nanosubstrate comprises plural pairs of conductive terminals, each pair separated by an insulating area, and a single nanowire is integrated into said nanocircuit at each pair of conductive terminals such that each integrated nanowire is in electrical contact with a pair of conductive terminals.
11. The method of claim 1 , wherein the insulating area forms an insulating gap separating the conductive terminals, the gap being about 800 nm in length.
12. The method of claim 1 , wherein the conductive terminals comprise a material selected from gold, chromium, silver, and combinations thereof.
13. The method of claim 1 , wherein the insulating area comprises a material selected from silicon, silicon dioxide, and silicon nitride.
14. The method of claim 1 , wherein the stream of gas comprises nitrogen.
15. The method of claim 1 , wherein the stream of gas is pressurized at 15 psi, and the stream is blown over the liquid suspension on the surface of the nanosubstrate from a height of about 1 mm above the nanosubstrate for a duration of about 20 seconds.