Inorganic electroluminescent device and method of fabricating the same

• US 20040032203A1
• Filed: 08/07/2003
• Published: 02/19/2004
• Est. Priority Date: 08/07/2002
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Mikami, Akiyoshi
• Granted Patent: US 7,538,483 B2
• Time in Patent Office: Days
• US Class Current: 313/502
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• CPC Class Codes: H05B 33/26 characterised by the composition or arrangement of the conductive material used as an electrode
• CPC Class Codes: H05B 33/28 of translucent electrodes
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

A transparent electrode composed of ITO(indium-tin oxide), an insulating layer composed of ZrSiN, an underlayer composed of MgS with a thickness of 100 to 300 nm, a light emitting layer composed of Mg_1−xCa_xS, and an insulating layer composed of ZrSiN are formed in this order on a glass substrate. Electrodes composed of Al are formed on the insulating layer. The underlayer is formed by sputtering with the substrate temperature set to room temperature. The light emitting layer is formed by sputtering with the substrate temperature set to not lower than 100° C.

Claims

1. An inorganic electroluminescent device comprising in the following order:

an underlayer formed of a first compound semiconductor of Group IIa-VIb; and

a light emitting layer formed of a second compound semiconductor of Group IIa-VIb,

said first compound semiconductor and said second compound semiconductor having the same crystalline structure.

2. The inorganic electroluminescent device according to claim 1, wherein said first compound semiconductor and said second semiconductor have a rock-salt structure.

3. The inorganic electroluminescent device according to claim 1, wherein said first compound semiconductor and said second compound semiconductor have an orientation in a <

100>

direction.

4. The inorganic electroluminescent device according to claim 1, wherein the bandgap of said first compound semiconductor is larger than the bandgap of said second compound semiconductor.

5. The inorganic electroluminescent device according to claim 1, wherein said first compound semiconductor contains magnesium and sulfur, and said second compound semiconductor contains magnesium and sulfur.

6. The inorganic electroluminescent device according to claim 5, wherein said second compound semicondutor further contains calcium.

7. The inorganic electroluminescent device according to claim 1, wherein said second compound semiconductor contains Mg₁₋

xCa_xS, and the Ca composition ratio x is 0.1≦

x≦

0.15.

8. The inorganic electroluminescent device according to claim 1, wherein the thickness of said underlayer is not larger than 500 nm.

9. The inorganic electroluminescent device according to claim 8, wherein the thickness of said underlayer is not larger than 200 nm.

10. The inorganic electroluminescent device according to claim 1, wherein the thickness of said light emitting layer is larger than the thickness of said underlayer.

11. The inorganic electroluminescent device according to claim 1, wherein said light emitting layer contains a rare earth element or a transition metal element as a substance acting as a luminescent center.

12. The inorganic electroluminescent device according to claim 11, wherein said substance acting as the luminescent center is an element selected from the group consisting of europium, cerium, and manganese.

13. The inorganic electroluminescent device according to claim 1, wherein said second compound semiconductor contains Mg₁₋

xCa_xS, and Eu is doped into Mg<sub>1−

x</sub>Ca_xS as a substance acting as a luminescent center, and the composition ratio of Eu to Mg is not larger than 0.1.

14. The inorganic electroluminescent device according to claim 13, wherein the composition ratio of Eu to Mg is not larger than 0.01.

15. A method of fabricating an inorganic electroluminescent device, comprising the steps of:

forming an underlayer principally composed of a first compound semiconductor of Group IIa-VIb; and

forming on said underlayer a light emitting layer principally composed of a second compound semiconductor of Group IIa-VIb having the same crystalline structure as that of said first compound semiconductor and doped with a substance acting as a luminescent center.

16. The method according to claim 15, wherein

said step of forming a underlayer comprises the step of forming said underlayer at a first temperature, and

said step of forming a light emitting layer comprises the step of forming said light emitting layer at a second temperature higher than said first temperature.

17. The method according to claim 16, wherein

said first temperature is not higher than 100°

C., and said second temperature is higher than 100°

C.

18. The method according to claim 16, wherein

said second temperature is not lower than 150°

C. nor higher than 350°

C.

19. The method according to claim 15, wherein

said first compound semiconductor contains magnesium and sulfur, and said second compound semiconductor contains magnesium and sulfur.

20. The method according to claim 19, wherein

said second compound semiconductor further comprises calcium.