Transparent conductive windows, coatings, and method of manufacture

• US 4,710,433 A
• Filed: 07/09/1986
• Issued: 12/01/1987
• Est. Priority Date: 07/09/1986
• Status: Expired due to Fees

• Current Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Inventors: Modster, Rudolph W., Rowe, James M.
• Primary Examiner(s): Rutledge, L. Dewayne
• Assistant Examiner(s): Wyszomierski, George
• Application Number:
  US06/883,897
• Time in Patent Office: 510 Days
• Field of Search: 428/623, 428/629, 428/630, 428/632, 428/640, 428/641, 428/652, 428/654, 428/658, 428/672, 428/673, 428/428, 428/433, 428/469, 428/34
• US Class Current: 428/623
• CPC Class Codes: C03C 17/36 at least one coating being a metal
• CPC Class Codes: C03C 17/3618 Coatings of type glass/inorganic compound/other inorganic layers, at least one layer being metallic
• CPC Class Codes: C03C 17/3649 made of metals other than silver
• CPC Class Codes: C03C 17/3652 the coating stack containing at least one sacrificial layer to protect the metal from oxidation
• CPC Class Codes: C03C 17/3657 the multilayer coating having optical properties
• CPC Class Codes: C03C 17/3681 the multilayer coating being used in glazing, e.g. windows or windscreens
• CPC Class Codes: C04B 35/10 based on aluminium oxide
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/5025 with ceramic materials copper oxide or solid solutions thereof C04B41/5074
• CPC Class Codes: C04B 41/5031 Alumina
• CPC Class Codes: C04B 41/51 Metallising , e.g. infiltration of sintered ceramic preforms with molten metal covering materials with metals in general C23C; ceramic compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides, other than as macroscopic reinforcing agents C22C; infiltration of preforms containing free metal, e.g. cermets C22C
• CPC Class Codes: C04B 41/5116 Ag or Au
• CPC Class Codes: C04B 41/52 Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
• CPC Class Codes: C04B 41/89 for obtaining at least two superposed coatings having different compositions
• CPC Class Codes: Y10T 428/12549 Adjacent to each other
• CPC Class Codes: Y10T 428/1259 Oxide
• CPC Class Codes: Y10T 428/12597 Noncrystalline silica or noncrystalline plural-oxide component [e.g., glass, etc.]
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12667 Oxide of transition metal or Al
• CPC Class Codes: Y10T 428/12674 Ge- or Si-base component
• CPC Class Codes: Y10T 428/1275 : Next to Group VIII or IB metal-base component
• CPC Class Codes: Y10T 428/12764 : Next to Al-base component
• CPC Class Codes: Y10T 428/12792 : Zn-base component
• CPC Class Codes: Y10T 428/12889 : Au-base component
• CPC Class Codes: Y10T 428/12896 : Ag-base component

Abstract

Methods are disclosed for the manufacture of optical conductive transparent windows and coatings having high transparency over a wide bandwidth combined with a large acceptance angle of incidence. Particulars for making windows and coatings with gold films of high transparency and low sheet resistance using specified nucleating and barrier layers are given. Examples include windows and coatings constructed for operation in the infrared and ultraviolet.

Claims

1. An electrically conductive window having high optical transparency in the infrared, visible, or UV bands comprising

a substrate having at lease one smooth contiuous surface on one side thereof,

an intermediate dielectric impedance matching stack dsposited on said substrate surface,

a first difusion barrier layer deposited on said intermediate matching stack,

a nucleating layer deposited on said first barrier layer,

a conductive metal layer deposited on said nucleating layer in a film of continuous uniform thickness of about 10 nm or lesss with optical constants n, k,

said nucleating layer being selected to cooparate with said metal layer to allow the metal layer to form in a continuous thin film without agglomeration having optical constants n, k approximating these of the bulk metal and with a low sheet resistance,

said intermediate stack forming an impedance match between said substrate and said conductive layer,

a second diffusion barrier layer deposited on said metal layer, and

an outer dieletric anti-reflection stack deposited on said second barrier layer to form an impedance match between said conductive layer and air.

2. The window as in claim 1 in which said layer of conductive metal is selected from the group consisting of Au, Al, and Ag.

3. The window as in claim 1 in which said layer of conductive metal is gold and said nucleating layer is Al metal or oxygen deficient oxide aluminum.

4. The window as in claim 1 selected for operation in the infrared in which said layer of metal is gold, and said nucleating layer is Al metal or highly oxygen deficient aluminum oxide.

5. The window as in claim 4 in which the diffusion barrier is Al₂ O₃.

6. The window as in claim 4 in which said impedance matching stacks are made of layers of high index transparent materials.

7. The window as in claim 6 in which said materials are selected from the group consisting of and ZnS.

8. The window as in claim 6 in which said substrate is sapphire

9. The window as in claim 1 in which said conductive metal is aluminum and said nucleating layer is yttrium oxide.

10. The window as in claim 1 selected for operation in the ultraviolet in which said conductive metal layer is aluminum and said nucleating layer is Y₂ O₃.

11. The window as in claim 10 in which said impedance matching stacks are made of dielectric materials selected from the group consisting of yttrium oxide (Y₂ O₃) and silicon dioxide (SiO₂).

12. The window as in claim 1 in which said outer anti-reflection stack is constructed and arranged to cause the electric field of the electromagnetic waves at the band of transparency to have a minimum value in the metal layer.

13. An electrically conductive window having optical transparency in the infrared, visible, or UV bands comprising

a substrate transparent at said band and having a surface on one side thereof,

means for impedance matching energy of said band to said substrate,

means forming a first diffusion barrier at the surface of said last named means,

means forming a nucleating surface on said barrier,

a layer of substantially transparent conductive metal deposited on said nucleating means to a thickness yielding a resistance value of less than about 10 ohms/sq.,

said nucleating means being selected to cooperate with said metal layer to allow the metal layer to form in a continuous thin film without agglomeration having optical constants n, k approximating these of the bulk metal,

said first matching means forming an impedance match between said substrate and said conductive layer,

means forming a second diffusion barrier on said metal layaer, and

means on said second barrier to form a impedance match between the underlying means and layer, and air.

14. The window as in claim 13 in which said conductive metal is selected from the group consisting of Au, Al, and Ag.

15. The window as in claim 13 in which said conductive metal is gold and said nucleating layer is Al metal or oxygen deficient oxide aluminum.

16. The window as in claim 13 selected for operation in the infrared in which said conductive metal is gold, and said nucleating surface is made of Al metal or oxygen deficient aluminum oxide.

17. The window as in claim 16 in which the diffusion barriers are Al₂ O₃.

18. The window as in claim 16 in which said impedance matching means are made of layers of high index transparent materials.

19. The window as in claim 18 in which said materials are selected from the group consisting of Ge and ZnS.

20. The window as in claim 18 in which said substratae is sapphire.

21. The window as in claim 13 in which said conductive metal is aluminum and said nucleating means is yttrium oxide.

22. The window as in claim 13 selected for operation in the ultraviolet in which said conductive metal is aluminum and said nucleating means is Y₂ O₃.

23. The window as in claim 22 in which said impedance matching means are made of dielectric materials selected from the group consisting of yttrium oxide (Y₂ O₃) and silicon dioxide (SiO₂).

24. The window as in claim 13 in which said several means and metal layer are constructed and arranged to cause the electric field of the electromagnetic waves at the band of transparency to have a minimum value in the conductive metal layer.

25. A transparent, conductive window comprising

a substrate having an outer surface,

first means formed at said surface for matching the impedance of the substrate to overlaid material subsequently deposited or created,

second means formed at the outer surface of said first means for creating a barrier against diffusion of overlaid material therethrough,

third means formed at the outer surface of said second means for causing nucleation of overlaid material

fourth substantially transparent means deposited on siad third means for forming a conductive metal layer at the surface thereof having a surface conductivity of less than 10 ohms/sq.

fifth means formed on said fourth means for creating a barrier against upward outward migration of said fourth means, and

sixth means formed on said fifth means for matching the impedance of the previous means to air.

26. The window as in claim 25 in which the fourth means is made of gold.

27. The window as in claim 25 in which the second and fifth means are made of Al₂ O₃.

28. The window as in claim 25 in which the fourth means is made of gold and in which the third means is made of Al.

29. The window as in claim 25 in which said several means are constructed and arranged to cause the electric field of the electromagnetic waves at the predetermined frequency to have a minimum value in the fourth means.