Method for manufacturing nanostructures and cathode for field emission lighting arrangement

1. A method for manufacturing a plurality of nanostructures comprising:

providing a plurality of protruding base structures arranged on a surface of a first substrate;

providing a seed layer mixture, comprising a solvent and a seed material, in contact with said protruding base structures;

providing a second substrate arranged in parallel with said first substrate adjacent to said protruding base structures such that a majority of said seed layer mixture is enclosed between said first and second substrates;

evaporating said solvent, thereby forming a seed layer comprising said seed material on said protruding base structures;

removing said second substrate;

providing a growth mixture, comprising a growth agent, in contact with said seed layer; and

controlling the temperature of said growth mixture so that nanostructures are formed on said seed layer,

wherein said second substrate comprise a plurality of protruding base structures corresponding to the protruding base structures of the first substrate.

2. Method according to claim 1 , wherein the nanostructure is composed of ZnO.

3. Method according to claim 1 , wherein the temperature of said growth mixture is controlled to be between 60 and 100° C., preferably between 80 and 95° C. and most preferably between 88 and 92° C.

4. Method according to claim 1 , wherein said protruding base structures of said first and said second substrate are shaped as square pyramids.

5. Method according to claim 4 , wherein providing a second substrate arranged in parallel with said first substrate further comprises arranging said second substrate such that the protruding base structures of the second substrate non-contactingly engage the protruding base structures of the first substrate.

6. Method according to claim 1 , wherein the plurality of protruding base structures are arranged in an array having a center-to-center distance of 10 μm to 100 μm, more preferably 10 μm to 60 μm, and most preferably 10 μm to 40 μm.

7. Method according to claim 1 , further comprising coating said protruding base structures with a conductive material.

8. Method according to claim 1 , wherein said seed material comprises a plurality of ZnO particles having a median particle size (D50) in the range of 20 nm to 150 nm.

9. Method according to claim 1 , wherein said growth mixture comprises zinc nitrate hexahydrate and at least one amine.

10. Method according to claim 1 , wherein said growth mixture comprises hexamethylenetetramine and a capping agent.

11. Method according to claim 1 , wherein providing a growth mixture in contact with said seed layer comprises arranging said first substrate in said growth mixture so that said seed layer faces a downward direction.

12. A cathode configured to be used in a field emission lighting arrangement, said cathode comprising:

a substrate comprising an array of protruding base structures, each protruding base structure comprising a plurality of nanostructures arranged thereon fabricated according to the method of claim 1 .

13. Cathode according to claim 12 , wherein

said protruding base structures are shaped as square pyramids.

14. Cathode according to claim 13 , wherein the protruding base structures are square pyramids having a base size of 20 to 40 μm.

15. Field emission arrangement comprising:

an anode structure at least partly covered by a phosphor layer, said anode structure being configured to receive electrons emitted by a field emission cathode according to claim 12 ;

an evacuated chamber in which said anode structure and field emission cathode is arranged; and

a power supply connected to the anode and the field emission cathode configured to apply a voltage so that an electron is emitted from the cathode to the anode.