# US 11,029,448 B2 · Thin films and a method for making the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,448 B2 - Document ID: US11029448B2 - Status: Granted - Kind: B2 - Application number: 16/160,711 - Filed: 2018-10-15 - Published: 2019-02-14 - Granted: 2021-06-08 - Earliest claimed: 2016-04-18 - Assignees: Oregon State University - Applicants: Oregon State University - Inventors: Cory K. Perkins; Ryan Helmut Mansergh; Juan Carlos Ramos; Douglas A. Keszler - Web page: https://patentgrep.com/patent/US11029448B2 ## CPC - C03C 17/25: by deposition from the liquid phase - B32B 9/005: {comprising one layer of ceramic material, e.g. porcelain, ceramic tile (layered products with at least two ceramic layers composed mainly of ceramic B32B18/00)} - B32B 9/04: comprising such {particular} substance as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a glass layer B32B17/06; layered products with at least two ceramic layers composed mainly of ceramic B32B18/00)} - C04B 35/10: based on aluminium oxide - C04B 35/111: Fine ceramics - C04B 35/447: based on phosphates {, e.g. hydroxyapatite} - C04B 35/62218: {obtaining ceramic films, e.g. by using temporary supports} - C04B 35/63488: {Polyethers, e.g. alkylphenol polyglycolether, polyethylene glycol [PEG], polyethylene oxide [PEO]} - C23C 18/1216: {Metal oxides (C23C18/1212 takes precedence)} - G02B 1/113: using inorganic layer materials only - C03C 2217/214: Al2O3 - C03C 2217/23: Mixtures - C03C 2217/425: consisting of a porous layer - C03C 2217/732: made of a single layer - C03C 2218/113: by sol-gel processes - C04B 2235/3218: Aluminium (oxy)hydroxides, e.g. boehmite, gibbsite, alumina sol - C04B 2235/75: Products with a concentration gradient - C04B 2235/963: Surface properties, e.g. surface roughness - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## 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. ## Claims ### 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. ### Claim 2 (depends on 1) The substrate of claim 1, wherein the film has a reflection value of from greater than zero to 6%. ### Claim 3 (depends on 1) The substrate of claim 1, wherein the film has a thickness of from greater than zero to 500 nm. ### Claim 4 (depends on 1) The substrate of claim 1, wherein the film comprises pores having an average diameter of from greater than zero to 20 nm. ### Claim 5 (depends on 1) The substrate of claim 1, wherein the film further comprises phosphorus. ### Claim 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. ### Claim 7 (depends on 6) The substrate of claim 6, wherein the film has a general formula Al2O3-bP2O5, where b is from 0.25 to 2. ### Claim 8 (depends on 6) The substrate of claim 6, wherein the film is a layered film. ### Claim 9 (depends on 8) The substrate of claim 8, wherein the layered film comprises from 2 to 10 layers. ### Claim 10 (depends on 9) The substrate of claim 9, wherein each layer independently has a refractive index of from 1 to less than 1.5. ### Claim 11 (depends on 9) 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. ### Claim 12 (depends on 9) 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. ### Claim 13 (depends on 12) The substrate of claim 12, wherein the layered film comprises a refractive index gradient from the first refractive index to the second refractive index. ### Claim 14 (depends on 6) 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. ### Claim 15 (depends on 6) 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. ### Claim 16 (depends on 1) 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. ### Claim 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. ### Claim 18 (depends on 17) The method of claim 17, wherein: the first alumina precursor is selected from aluminum nitrate, aluminum chloride, Al13(OH)24(NO3)15, or a combination thereof; the first surfactant is a block copolymer; or a combination thereof. ### Claim 19 (depends on 17) 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.