Method of Producing Silicon Nanoparticles from Stain-Etched Silicon Powder

• US 20070237979A1
• Filed: 06/14/2007
• Published: 10/11/2007
• Est. Priority Date: 02/21/2003
• Status: Active Grant

• Current Assignee: Applied Nanotech Holdings Incorporated (Nano Magic, Inc.)
• Original Assignee: Nano-Proprietary, Inc. (Nano Magic, Inc.)
• Inventors: Li, Yunjun, Pavlovsky, Igor
• Granted Patent: US 7,514,369 B2
• Time in Patent Office: Days
• US Class Current: 428/613
• CPC Class Codes: C01B 33/02 Silicon forming single crystals or homogeneous polycrystalline material with defined structure C30B
• CPC Class Codes: C01B 33/021 Preparation chemical coating from the vapour phase C23C16/00
• CPC Class Codes: Y10S 977/90 having step or means utilizing mechanical or thermal property, e.g. pressure, heat
• CPC Class Codes: Y10T 428/12479 Porous [e.g., foamed, spongy, cracked, etc.]
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2993 Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Abstract

The present invention is for a porous silicon powder comprising silicon particles wherein the outermost layers of said particles are porous. The present invention is also directed to a method of making this porous silicon powder using a stain etch method. The present invention is also directed to a method of making silicon nonparticles from the porous silicon powders using a process of ultrasonic agitation. The present invention also includes methods of processing these silicon nanoparticles for use in a variety of applications.

Claims

1-9. -9. (canceled)

10. A method for making porous silicon powder comprising the steps of:

a) providing a quantity of silicon powder comprising a plurality of silicon particles; and

b) etching said silicon particles using a stain-etch process.

11. The method of claim 10, further comprising a process for making the silicon powder comprising the steps of:

a) providing a bulk silicon object;

b) grinding the bulk silicon object into smaller silicon pieces; and

c) ball milling the smaller silicon pieces into a silicon powder comprised of a plurality of silicon particles.

12. The method of claim 10, wherein the silicon powder has a purity which ranges from at least about 80 percent to at most about 100 percent.

13. The method of claim 10, wherein the silicon particles range in diameter from at least about 1 nanometer to at most about 1 millimeter.

14. The method of claim 10, wherein the silicon powder is n-doped.

15. The method of claim 10, wherein the silicon powder is p-doped.

16. The method of claim 10, wherein the silicon powder is doped with a species selected from the group consisting of P, B, As, Ga, Sb, Er, and combinations thereof.

17. The method of claim 10, wherein the stain-etch process comprises treatment of the silicon powder with a mixture of hydrofluoric acid and a nitro-containing species.

18. The method of claim 17, wherein the mixture of hydrofluoric acid and a nitro-containing species is dispersed in solution.

19. The method of claim 18, wherein the solution is aqueous in nature.

20. The method of claim 17, wherein the nitro-containing species is selected from the group consisting of nitric acid, iron nitrate, nitrous acid, cobalt nitrite, nickel nitrate, sodium nitrate, potassium nitrate, and combinations thereof.

21. The method of claim 17, wherein the nitro-containing species is iron nitrate.

22. The method of claim 10, wherein the stain-etch process has a rate that is monitored by nitrogen dioxide evolution.

23. The method of claim 10, wherein the stain-etch process has a rate that is modulated by temperature.

24. The method of claim 10, wherein the stain-etch process has a rate that is modulated by hydrofluoric acid and a nitro-containing species concentration.

25. The method of claim 10, wherein the stain-etch process has a rate that is modulated by the selection of particular nitro-containing species.

26. The method of claim 10, wherein the stain-etch process has a rate that is enhanced by illumination.

27. The method of claim 10, wherein the stain-etch process has a quiescent period.

28-36. -36. (canceled)