Thin films and a method for making the same

Patent metadata

Field	Value
Publication number	US-11029448-B2
Application number	US-201816160711-A
Country	US
Kind code	B2
Filing date	Oct 15, 2018
Priority date	Apr 18, 2016
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

Disclosed herein are embodiments of a porous aluminum oxide thin film having a surface RMS roughness value of less than 1 nm. The thin film may also comprise phosphorus. The disclosed thin films may have a refractive index of from 1 to 2, such as from 1 to 1.5. Also disclosed are embodiments of as method for making the disclosed thin films, comprising forming an aqueous solution of the alumina precursor, a surfactant and optionally a phosphorus-containing precursor, and depositing the solution on a substrate.

First claim

We claim:

1. A substrate with a porous aluminum oxide film disposed thereon, comprising:
the substrate; and
the porous aluminum oxide film, comprising a surface having a root mean square roughness value of from greater than zero to 1 nm and an index of refraction of from 1 to less than 1.5 at 550 nm.

2. The substrate of claim 1 , wherein the film has a reflection value of from greater than zero to 6%.

3. The substrate of claim 1 , wherein the film has a thickness of from greater than zero to 500 nm.

4. The substrate of claim 1 , wherein the film comprises pores having an average diameter of from greater than zero to 20 nm.

5. The substrate of claim 1 , wherein the film further comprises phosphorus.

6. A substrate with a porous aluminum oxide film disposed thereon, comprising:
the substrate; and
the porous aluminum oxide film, comprising a surface having a root mean square roughness value of from greater than zero to 1 nm, and wherein the film comprises a P:Al ratio of from greater than zero:1 to 3:1.

7. The substrate of claim 6 , wherein the film has a general formula Al 2 O 3-b P 2 O 5 , where b is from 0.25 to 2.

8. The substrate of claim 6 , wherein the film is a layered film.

9. The substrate of claim 8 , wherein the layered film comprises from 2 to 10 layers.

10. The substrate of claim 9 , wherein each layer independently has a refractive index of from 1 to less than 1.5.

11. The substrate of claim 9 , wherein the layered film comprises a composition gradient from a first composition having a first P:Al ratio to a second composition having a second P:Al ratio greater than the first P:Al ratio.

12. The substrate of claim 9 , wherein the layered film comprises one or more layers having a first refractive index and one or more layers having a second refractive index greater than the first refractive index.

13. The substrate of claim 12 , wherein the layered film comprises a refractive index gradient from the first refractive index to the second refractive index.

14. The substrate of claim 6 , further comprising phosphorus and having an P:Al ratio is from 0.4:1 to 1:1, wherein the root mean square roughness value is from 0.4 nm to 0.5 nm, and the film has a refractive index of from 1 to 1.35.

15. The substrate of claim 6 , wherein the film is a layered film comprising from 2 to 10 layers, each layer comprising phosphorus and having an P:Al ratio of from 0.4:1 to 1:1 and a refractive index of from 1 to 1.35, the layered film comprising:
a composition gradient from a first composition to a second composition wherein the second composition comprises a greater P:Al ratio than a P:Al ratio of the first composition; and
one or more layers having a first refractive index and one or more layers comprising a second refractive index greater than the first refractive index.

16. The substrate of claim 1 , wherein the substrate is a glass lens having the porous aluminum oxide film disposed thereon to form a coated lens.

17. A method, comprising
forming a first aqueous solution comprising a first alumina precursor and a first surfactant;
depositing the first aqueous solution on a substrate to form a first film; and
exposing the substrate to an annealing temperature to form a porous aluminum oxide thin film having a root mean square roughness value of from greater than zero to 1 nm.

18. The method of claim 17 , wherein:
the first alumina precursor is selected from aluminum nitrate, aluminum chloride, Al 13 (OH) 24 (NO 3 ) 15 , or a combination thereof;
the first surfactant is a block copolymer; or
a combination thereof.

19. The method of claim 17 , wherein the first aqueous solution further comprises a first phosphorus-containing precursor, and the method further comprises depositing a second aqueous solution comprising a second alumina precursor, a second surfactant, and a second phosphorus-containing precursor, on the first film prior to heating the substrate at the annealing temperature, to make a thin film comprising a first layer and a second layer, the second solution comprising an amount of the second phosphorus-containing precursor selected to provide a P:Al ratio for the second layer that is different from a P:Al ratio of the first layer.

Assignees

• Univ Oregon State

Inventors

• Perkins Cory K
• Mansergh Ryan Helmut
• Ramos Juan Carlos
• Keszler Douglas A

Classifications

• C03C17/25 Primary

  by deposition from the liquid phase · CPC title

• G02B1/113 Primary

  using inorganic layer materials only · CPC title

• C03C2217/425

  consisting of a porous layer · CPC title

• C03C2217/23

  Mixtures · CPC title

• C04B35/111

  Fine ceramics · CPC title