Method of spark-processing silicon and resulting materials

• US 6,955,745 B1
• Filed: 08/01/2003
• Issued: 10/18/2005
• Est. Priority Date: 08/01/2002
• Status: Expired due to Fees

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: Shepherd, Nigel D., Hummel, Rolf E.
• Primary Examiner(s): Elms, Richard
• Assistant Examiner(s): Luhrs, Michael K.
• Application Number:
  US10/632,598
• Time in Patent Office: 809 Days
• Field of Search: 438/23, 438/29, 438/61, 438/69, 438/96, 438/466, 438/584, 257/13, 257/79, 257/103, 313/141, 313/169.3, 424/59, 424/65, 315/169.3, 423/348, 427/204, 427/580, 427/535, 427/540, 204/178, 204/192.23, 204/192.37, 204/164, 205/157, 164/134.2
• US Class Current: 204/164
• CPC Class Codes: C01B 33/02 Silicon forming single crystals or homogeneous polycrystalline material with defined structure C30B
• CPC Class Codes: C01B 33/18 Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C

Abstract

The subject invention pertains to a method of spark processing silicon and resulting materials. The subject invention also relates to electroluminescent devices incorporating the materials produced by the subject method. The subject method for spark-processing can enhance the EL output, as compared with conventional spark-processed (sp) silicon. The enhancement of EL output can be due, at least in part, to increasing the light emitting area. The subject method can smooth the sp surface, so as to allow more complete coverage of the sp area with a continuous, semitransparent, conducting film. The smoothening of the sp surface can be accomplished by, for example, introducing into the spark plasma a volatile liquid, such as methanol, ethanol, acetone, in which particles can be suspended and/or in which a heavy ion salt is dissolved. The particles preferably float in the volatile liquid, rather than settle quickly. In a specific embodiment, silicon particles in the range of about 0.2 μm to about 20 μm in size can be suspended in the volatile liquid, such as methanol. The volatile liquid/silicon-particle suspension or volatile liquid/heavy ion salt solution, can then be inserted into a means for applying the mixture to the surface of a silicon wafer during spark-processing.

Claims

1. A method for spark-processing silicon, comprising:

applying to silicon sparks of sufficiently high voltage to effect the production of spark-processed silicon, wherein applying to the silicon sparks of sufficiently high voltage to effect the production of spark-processed silicon creates a spark plasma; and

introducing into the spark plasma a volatile liquid in which particles are suspended.

2. The method according to claim 1,

wherein introducing into the spark plasma a volatile liquid in which particles are suspended during the production of the spark-processed silicon enhances the electroluminescence of the spark-processed silicon.

3. The method according to claim 1,

wherein Si particles are suspended in the volatile liquid.

4. The method according to claim 3,

wherein Si particles having a size in the range of about 0.2 μ

m to about 20 μ

m are suspended in the volatile liquid.

5. The method according to claim 1,

wherein SiO₂ particles are suspended in the volatile liquid.

6. The method according to claim 5,

wherein SiO₂ particles having a size in the range of about 0.2 μ

m to about 20 μ

m are suspended in the volatile liquid.

7. The method according to claim 1,

wherein Si₃N₄ particles are suspended in the volatile liquid.

8. The method according to claim 7, wherein Si₃N₄ particles having a size in the range of about 0.2 μ

m to about 20 μ

m are suspended in the volatile liquid.

9. The method according to claim 1,

wherein the volatile liquid comprises methanol.

10. The method according to claim 1,

wherein the volatile liquid comprises ethanol.

11. The method according to claim 1,

wherein the volatile liquid comprises acetone.

12. The method according to claim 1,

wherein introducing into the spark plasma a volatile liquid in which particles are suspended creates an aerosol of the volatile liquid in which particles are suspended.

13. The method according to claim 1,

wherein applying to the silicon sparks comprises applying a voltage between an electrode and the silicon.

14. The method according to claim 13,

wherein introducing into the spark plasma a volatile liquid in which particles are suspended comprises introducing into the spark plasma a volatile liquid in which particles are suspended via a means for introducing into the spark plasma a volatile liquid in which particles are suspended which is in electrical contact with the electrode.

15. The method according to claim 13,

wherein introducing into the spark plasma a volatile liquid in which particles are suspended comprises introducing into the spark plasma a volatile liquid in which particles are suspended via a means for introducing into the spark plasma a volatile liquid in which particles are suspended which is electrically isolated from the electrode.

16. The method according to claim 13,

wherein a tip of the electrode is separated from the silicon by a distance between about 0.5 mm and about 10 mm.

17. The method according to claim 13,

wherein a tip of the electrode is separated from the silicon by a distance between about 3 mm and about 4 mm.

18. The method according to claim 14,

wherein the means for introducing into the spark plasma a volatile liquid in which particles are suspended comprises a metal needle, wherein the metal needle acts as the electrode.

19. The method according to claim 18,

wherein the tip of the needle is modified such that an aerosol of the volatile liquid in which particles are suspended is introduced into the spark plasma.

20. A method for spark-processing silicon, comprising:

applying to the silicon sparks of sufficiently high voltage to effect the production of spark-processed silicon, wherein applying to the silicon sparks of sufficiently high voltage to effect the production of spark-processed silicon creates a spark plasma; and

introducing into the spark plasma a volatile liquid in which a salt of a heavy ion is dissolved.

21. The method according to claim 20,

wherein the salt of a heavy ion is a transition metal salt.

22. The method according to claim 21,

wherein the transition metal salt is manganese chloride.

23. The method according to claim 20,

wherein the salt of a heavy ion is rare earth ion salt.

24. The method according to claim 20,

wherein the salt of a heavy ion is a lanthanide ion salt.

25. The method according to claim 24,

wherein the lanthanide ion salt is selected from the group consisting of:

cerium chloride, terbium chloride, and europium chloride.

26. The method according to claim 20,

wherein introducing into the spark plasma a volatile liquid in which a salt of a heavy ion is dissolved during the production of the spark-processed silicon creates an aerosol of the volatile liquid in which a salt of a heavy ion is dissolved.