Method for fabricating a photonic crystal
View Patent ↗A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.
1. A method for fabricating a photonic crystal, comprising:
a) forming a lattice structure mold of a sacrificial mold material on a substrate by sequentially depositing a cavity-filling material in a plurality of alternating patterned layers of the sacrificial mold material and removing the cavity-filling material to leave the lattice structure mold; and
b) depositing a structural material into the lattice structure mold.
2. The method of claim 1 , further comprising polishing the surface of the deposited structural material after step b).
3. The method of claim 2 , wherein the polishing is chemical-mechanical polishing.
4. The method of claim 1 , wherein the depositing step b) comprises chemical vapor deposition, electroplating, or nanoparticle infiltration.
5. The method of claim 1 , wherein the sacrificial mold material comprises silica.
6. The method of claim 1 , wherein the substrate comprises silicon.
7. The method of claim 1 , wherein the cavity-filling material comprises polysilicon.
8. The method of claim 1 , wherein the structural material is selected from the group of chemical vapor deposited materials consisting of III-V compound semiconductors, II-VI compound semiconductors, single and mixed oxides, nitrides, oxynitrides, metals, and metal alloys.
9. The method of claim 1 , wherein the structural material comprises a refractory metal or non-metal.
10. The method of claim 9 , wherein the refractory metal comprises tungsten or tungsten alloy.
11. The method of claim 1 , wherein the structural material is selected from the group of electroplated metals consisting of copper, nickel, gold, iron, silver, cobalt, and chromium.
12. The method of claim 1 , wherein each of the layers of the plurality of alternating patterned layers has a thickness of less than 10 microns.
13. The method of claim 1 , wherein each of the layers of the plurality or alternating patterned layers has a thickness of less than 5 microns.
14. The method of claim 1 , wherein each of the layers of the plurality of alternating patterned layers has a thickness of less than 1 micron.
15. The method of claim 1 , wherein the photonic crystal comprises a Lincoln-Log type structure.
16. The method of claim 1 , further comprising removing the sacrificial mold material from the lattice structure mold after step b).
17. The method of claim 1 , wherein the forming step a) comprises:
a) depositing a layer of the sacrificial mold material on the substrate,
b) patterning the layer of the sacrificial mold material to form a plurality of cavities in the layer of sacrificial mold material,
c) depositing the cavity-filling material in the plurality of cavities,
d) depositing another layer of the sacrificial mold material on the filled patterned layer of the sacrificial mold material;
e) repeating steps b) through d) at least once,
f) patterning the last layer of sacrificial mold material from step d), and
g) removing the cavity-filling material to leave the lattice structure mold.
18. The method of claim 17 , wherein the patterning step b) comprises photolithographic exposure of the layer of sacrificial mold material through an etch mask, anisotropic etching of the exposed regions of the layer, and stripping of the etch mask.
19. The method of claim 17 , further comprising polishing the surface of the filled patterned layer of the sacrificial mold material after step c).
20. The method of claim 19 , when the polishing comprises chemical-mechanical polishing.