Cathodo-/electro-luminescent device and method of fabricating a cathodo-/electro-luminescent device using porous silicon/porous silicon carbide as an electron emitter

• US 20030218416A1
• Filed: 04/16/2003
• Published: 11/27/2003
• Est. Priority Date: 05/27/1999
• Status: Active Grant

• Current Assignee: University of North Carolina At Charlotte (University of North Carolina System)
• Original Assignee: University of North Carolina At Charlotte (University of North Carolina System)
• Inventors: Hasan, Mohamed Ali, Elqaq, Deirdre Heyde
• Granted Patent: US 6,764,368 B2
• Time in Patent Office: Days
• US Class Current: 313/496
• CPC Class Codes: H01J 1/304 Field-emissive cathodes
• CPC Class Codes: H01J 31/127 using large area or array sources, i.e. essentially a source for each pixel group

Abstract

The invention consists of a flat panel display device that combines the simplicity of manufacture of a TFEL display with the phosphor stimulation capabilities of an FED. A phosphor such a ZnS:Mn can act as both an EL phosphor and as a cathodoluminescent phosphor. The phosphor is deposited on a porous silicon underlayer that contains a labyrinth of fissures, voids, hillocks, and microscopically rough surfaces. At the phosphor-porous silicon interface, the labyrinthine surface possesses hundreds to thousands of electric field line compression points that can be characterized by an average field enhancement. When this underlayer is the cathode, high energy electrons are injected into the phosphor producing substantial light emission even at low applied fields. Additionally, the surrounding silicon is available to integrate drive circuitry and provide a TFT at each pixel, if needed.

Claims

1. A method for fabricating a cathodoluminescent/electroluminescent device, said method comprising:

forming a transparent conductive layer;

depositing an insulator onto the transparent conductive layer;

forming a porous silicon layer from crystalline silicon wafers;

depositing a phosphor onto the insulator;

forming an intermediate device by positioning the porous silicon layer so that a porous surface of the porous silicon layer is adjacent the phosphor;

annealing the intermediate device; and

depositing a metal layer on a non-porous surface of the porous silicon layer.

2. A method in accordance with claim 1, wherein said forming a conductive layer step includes depositing conductive grid. lines of indium tin oxide onto a substrate.

3. A method in accordance with claim 1, wherein said depositing an insulator step includes selecting an insulator from the group consisting of yttrium oxide, silicon dioxide, aluminum oxide, and silicon nitride.

4. A method in accordance with claim 1, wherein said forming a porous silicon layer includes anodizing a single crystalline silicon wafer in a mixture of hydrogen fluoride and ethanol.

5. A method in accordance with claim 1 further comprising the step of hardening the porous silicon layer prior to forming the intermediate device.

6. A method in accordance with claim 5, wherein said hardening step comprises reacting the porous silicon layer with methane.

7. A method in accordance with claim 1, wherein said annealing step is performed at a temperature of about 500°

C. in a nitrogen atmosphere.

8. A cathodoluminescent/electroluminescent device fabricated by a process comprising the steps of:

forming a porous silicon layer by anodizing a crystalline silicon wafer in a mixture of hydrogen fluoride and ethanol; and

preparing a laminate having sequentially a transparent conductive layer, an insulator, a phosphor, the porous silicon layer, and a metal layer.

9. A cathodoluminescent/electroluminescent device for use in flat panel displays, said device comprising:

a transparent conductive layer;

an insulator deposited onto said transparent conductive layer;

a phosphor deposited onto said insulator;

a porous silicon layer having a porous surface and a non-porous surface substantially opposing said porous surface, said porous surface positioned adjacent said phosphor; and

a metal electrode deposited onto said non-porous surface of said porous silicon layer.

10. A cathodoluminescent/electroluminescent device according to claim 9, wherein said transparent conductive layer includes a patterned layer of indium-tin-oxide.

11. A cathodoluminescent/electroluminescent device according to claim 9, wherein said insulator is selected from the group consisting of yttrium oxide, silicon dioxide, aluminum oxide, and silicon nitride.

12. A cathodoluminescent/electroluminescent device according to claim 9, wherein said phosphor is ZnS:

Mn.

13. A cathodoluminescent/electroluminescent device according to claim 9, wherein said porous silicon layer is a single crystalline silicon wafer anodized in hydrogen fluoride and ethanol.

14. A cathodoluminescent/electroluminescent device according to claim 9, wherein said metal electrode is aluminum.