Annealed CVD molybdenum thin film surface

• US 4,431,708 A
• Filed: 12/19/1979
• Issued: 02/14/1984
• Est. Priority Date: 12/19/1979
• Status: Expired due to Term

• Current Assignee: United States Department of Energy (Government of the United States of America)
• Original Assignee: United States Department of Energy (Government of the United States of America)
• Inventors: Carver, Gary E., Seraphin, Bernhard O.
• Primary Examiner(s): Childs, S. L.
• Application Number:
  US06/105,338
• Time in Patent Office: 1,518 Days
• Field of Search: 427/160, 427/162, 427/163, 427/124, 427/229, 427/248.1, 427/250, 427/252, 427/255, 427/255.7, 427/383.3, 427/383.5, 427/383.7, 427/419.7, 427/404, 427/405 , 427/383.9, 428/432, 428/433, 428/446, 428/450, 428/457, 428/623, 428/627, 428/641, 428/663, 350/1.6, 350/1.7, 350/145, 350/146, 350/288, 350/148, 350/201, 148/6.3
• US Class Current: 428/641
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: F24S 70/225 for spectrally selective absorption
• CPC Class Codes: F24S 70/25 Coatings made of metallic material
• CPC Class Codes: F24S 70/30 Auxiliary coatings, e.g. anti-reflective coatings
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y10T 428/12576 Boride, carbide or nitride component
• CPC Class Codes: Y10T 428/12674 Ge- or Si-base component
• CPC Class Codes: Y10T 428/12826 Group VIB metal-base component

Abstract

Molybdenum thin films deposited by pyrolytic decomposition of Mo(CO)₆ attain, after anneal in a reducing atmosphere at temperatures greater than 700° C., infrared reflectance values greater than reflectance of supersmooth bulk molybdenum. Black molybdenum films deposited under oxidizing conditions and annealed, when covered with an anti-reflecting coating, approach the ideal solar collector characteristic of visible light absorber and infrared energy reflector.

Claims

1. A process for the manufacture of a highly reflective surface, comprising:

(a) fabricating on a substrate a thin adherent film by chemical vapor deposition of Mo(CO)₆ at about atmospheric pressure of an inert carrier gas, said film showing a face centered cubic-MoOC structure under X-ray diffraction;

(b) annealing said film in an atmosphere substantially devoid of oxygen at a temperature of at least 700°

C. for a duration of at least 3 minutes; and

(c) fabricating over said annealed film by chemical vapor deposition a layer of solar absorbing silicon.

2. The process of claim 1 wherein said film is fabricated at a temperature greater than 150°

C.

3. The process of claim 1 wherein said annealing atmosphere consists of flowing helium.

4. The process of claim 1 where said film is annealed at a temperature greater than 750°

C.

5. The process of claim 4 wherein said film is annealed at a temperature of 1000°

C. for 15 minutes.

6. The process of claim 1 including passivating said annealed film with a layer of oxidation preventing sealing material before said film oxidizes.

7. The process of claim 1 including fabricating over said silicon by chemical vapor deposition an anti-reflecting layer of Si₃ N₄.

8. A reflective surface manufactured according to the process of claim 1.

9. A laser reflector manufactured according to the process of claim 1.