System and method for 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 system for integrating a single nanowire into a nanocircuit, the system comprising a nanosubstrate, a liquid suspension of nanotubes disposed on a surface of the nanosubstrate, and a device for applying a gas jet to said surface;
wherein the nanosubstrate comprises first and second conductive terminals disposed on said surface and separated by an insulating gap; and
wherein two or more nanotubes from the suspension span the gap and contact both the first and second conductive terminals, each of said two or more nanotubes forming an electrically conductive pathway between the terminals.
2. The system of claim 1 , wherein the nanosubstrate comprises a material selected from silicon, silicon dioxide, and silicon nitride.
3. The system of claim 1 , wherein the conductive terminals comprise a material selected from gold, chromium, silver, and combinations thereof.
4. The system 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.
5. The system of claim 4 , wherein each tip has a profile which forms an acute angle of about 30 degrees or less.
6. The system of claim 1 , wherein the insulating gap separating the conductive terminals is from about 800 nm to about 1400 nm in length.
7. The system 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 system of claim 1 , wherein the nanosubstrate forms a portion of a microprocessor chip or a non-volatile memory device.
9. The system of claim 1 , wherein the nanosubstrate together with the first and second conductive terminals are configured to function as components of a nanoswitch.
10. The system of claim 9 , wherein the nanoswitch functions as a latch, flip-flop, register, or relay.
11. The system of claim 1 , further comprising a source of gas for supplying said device for applying a gas jet.
12. The system of claim 11 , wherein the gas is nitrogen.
13. The system of claim 1 , wherein the device for supplying a gas jet is capable of supplying gas pressurized at 15 psi.
14. The system of claim 1 , wherein the device for supplying a gas jet is configured to blow a stream of gas over the liquid suspension on the surface of the nanosubstrate from a height of about 1 mm above the nanosubstrate.
15. The system of claim 1 , further comprising a voltage source for performing electrophoretic assembly of nanotubes from the suspension to provide said two or more nanotubes spanning the gap, contacting both the first and second conductive terminals, and forming an electrically conductive pathway between the terminals.
16. The system of claim 15 , wherein the voltage source is capable of providing an AC voltage in the range from about 1 to about 5 volts at a frequency of about 1 MHz between the first and second conductive terminals.
17. The system of claim 15 , wherein the voltage source is capable of providing phase shifting between the first and second conductive terminals.
18. A method of integrating a single nanotube into a nanocircuit, the method comprising the steps of:
providing the system of claim 1 ; and
directing a gas jet onto said surface using said device, whereby one or more nanotubes are disconnected from the first and/or second conductive terminals, and only a single nanotube remains spanning said gap and forming an electrically conductive pathway between the terminals.
19. The method of claim 18 , further comprising performing dielectrophoresis by applying a voltage between the first and second conductive terminals in the presence of said liquid suspension of nanotubes to provide said two or more nanotubes from the suspension spanning the gap, contacting the first and second conductive terminals, and forming an electrically conductive pathway between the terminals.
20. The method of claim 19 , wherein performing said dielectrophoresis comprises using phase shifting between said first and second conductive terminals.
21. The method of claim 18 , 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.
22. The method of claim 18 , 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.
23. The method of claim 19 , 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.