Nanotube-based vacuum devices
New, hybrid vacuum electron devices are proposed, in which the electrons are extracted from the nanotube into vacuum. Each nanotube is either placed on the cathode electrode individually or grown normally to the cathode plane. Arrays of the nanotubes are also considered to multiply the output current. Two- and three-terminal device configurations are discussed. In all the cases considered, the device designs are such that both input and output capacitances are extremely low, while the efficiency of the electron extraction into vacuum is very high, so that the estimated operational frequencies are expected to be in a tera-hertz range. New vacuum triode structure with ballistic electron propagation along the nanotube is also considered.
1. A diode, comprised of two electrodes laterally shifted from each other and placed on non conductive substrate, wherein the first electrode includes a dielectric layer deposited on the substrate, a conductive layer placed on top of said dielectric layer and a nanotube placed on top of said first conductive layer, the axis of said nanotube being essentially normal to one of the edges of the said conductive layer while said nanotube protrudes beyond said one of the edges of said conductive layer into the area of a second electrode which includes a conductive layer placed on the substrate next to said one of the edges of said first conductive layer, so that said nanotube is located above and protrudes into the area of said second electrode.
2. The diode of claim 1 wherein an additional metal layer is disposed on top of a major part of said nanotube leaving exposed the nanotube tip protruded into the area of said second electrode.
3. The diode of claim 1 wherein said additional metal layer is disposed onto entire nanotube including the nanotube tip.
4. The diode of claim 3 wherein said additional metal layer is made from a material with low work function for electron emission into vacuum.
5. The diode of claim 4 in which said additional metal layer is made from Cs.
6. A diode comprising two electrodes laterally shifted from each other and placed on an insulating substrate, wherein the first electrode contains a dielectric layer deposited on the substrate and the first conducting layer on top of said dielectric layer, while the second electrode contains the second conductive layer, placed on the substrate and disposed next to one of the edges of said first conductive layer, and a nanotube grown normally to the substrate plane and in close proximity to said one of the edges of said first conductive layer, the nanotube height being essentially equal to the thickness of said dielectric layer.
7. The diode of claim 6 , wherein an array of the nanotubes is grown along said one of the edges of said first conductive layer.
8. The diode of claim 6 wherein said additional metal layer is disposed onto the tip of the nanotube.
9. The diode of claim 8 wherein said additional metal layer is made from a material with a low work function for electron emission into vacuum.
10. The diode of claim 9 in which said additional metal layer is made from Cs.
11. A diode, comprised of two electrodes laterally shifted from each other and placed on non conductive substrate, wherein the first electrode includes a dielectric layer deposited on the substrate, a conductive layer placed on top of said dielectric layer and an array of the nanotubes placed on top of said first conductive layer, the axis of the nanotubes being essentially normal to one of the edges of the said conductive layer while said nanotubes protrude beyond said one of the edges of said conductive layer into the area of a second electrode which includes a conductive layer placed on the substrate next to said one of the edges of said first conductive layer, so that said array of the nanotubes is located above and protrudes into the area of said second electrode.