INORGANIC ELECTROLUMINESCENT DIODE AND METHOD OF FABRICATING THE SAME

• US 20070170446A1
• Filed: 09/25/2006
• Published: 07/26/2007
• Est. Priority Date: 01/09/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: KWON, Soon Jae, CHO, Kyung Sang, CHOI, Byoung Lyong, Kim, Byung Ki
• Granted Patent: US 8,017,952 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: C09K 11/565 with zinc cadmium
• CPC Class Codes: C09K 11/883 with zinc or cadmium
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/18 within the light emitting region
• CPC Class Codes: H01L 33/26 Materials of the light emitting region
• 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

Abstract

Disclosed are an inorganic electroluminescent diode and a method of fabricating the same. Specifically, this invention provides an inorganic electroluminescent diode, which includes a semiconductor nanocrystal layer formed of inorganic material, an electron transport layer or a hole transport layer formed on the semiconductor nanocrystal layer using amorphous inorganic material, and a hole transport layer or an electron transport layer formed beneath the semiconductor nanocrystal layer using inorganic material, and also provides a method of fabricating such an inorganic electroluminescent diode. According to the method of fabricating the inorganic electroluminescent diode of this invention, an inorganic electroluminescent diode can be fabricated while maintaining the properties of luminescent semiconductor material of the semiconductor crystal layer, and also an inorganic electroluminescent diode which is stably operated and has high luminescent efficiency can be provided.

Claims

1. A method of fabricating an inorganic electroluminescent diode, comprising:

forming a first electrode;

forming a first inorganic layer in electrical contact with the first electrode;

forming a semiconductor nanocrystal layer on a surface of the first inorganic layer;

forming a second inorganic layer which is amorphous on a surface of the semiconductor nanocrystal layer opposite the first inorganic layer by a solution coating method or a vapor coating method; and

forming a second electrode on and in electrical contact with a surface of the second inorganic layer opposite the semiconductor nanocrystal layer.

2. The method as set forth in claim 1, further comprising forming a protective layer on a surface of the semiconductor nanocrystal layer opposite the first inorganic layer after the forming the semiconductor nanocrystal layer.

3. The method as set forth in claim 2, wherein the forming of the protective layer is conducted by sputtering, e-beam evaporation, or vacuum deposition.

4. The method as set forth in claim 2, wherein the forming of the protective layer is conducted such that the protective layer has a thickness of 2 nm or less.

5. The method as set forth in claim 1, wherein the forming of the semiconductor nanocrystal layer is conducted such that semiconductor nanocrystals are arranged in at least one monolayer.

6. The method as set forth in claim 1, wherein the forming of the second inorganic layer which is amorphous is conducted by the solution coating method selected from the group consisting of a sol-gel process, spin coating, printing, casting, and spraying, or by the vapor coating method selected from the group consisting of chemical vapor deposition, sputtering, e-beam evaporation, and vacuum deposition.

7. The method as set forth in claim 1, wherein the forming of the first inorganic layer is conducted on a substrate by a crystal growth process including MOCVD or ALD, or by deposition of an amorphous thin film and then annealing thereof.

8. The method as set forth in claim 1, wherein the forming of the first inorganic layer is conducted on the first electrode by the solution coating method selected from the group consisting of a sol-gel process, spin coating, printing, casting, and spraying, or by the vapor coating method selected from the group consisting of chemical vapor deposition, sputtering, e-beam evaporation, and vacuum deposition.

9. An inorganic electroluminescent diode, comprising a lower electrode and an upper electrode having a semiconductor nanocrystal layer disposed therebetween, an inorganic electron transport layer formed of amorphous inorganic material and disposed between the semiconductor nanocrystal layer and the upper electrode, and a hole transport layer formed of inorganic material and disposed between the semiconductor nanocrystal layer and the lower electrode.

10. The diode as set forth in claim 9, wherein the inorganic material of the hole transport layer is amorphous inorganic material.

11. The diode as set forth in claim 9, wherein the inorganic material of the hole transport layer is crystalline inorganic material.

15. The diode as set forth in claim 9, further comprising a protective layer formed between the semiconductor nanocrystal layer and the inorganic hole transport layer.

16. The diode as set forth in claim 15, wherein the protective layer has a thickness of 2 nm or less.

17. The diode as set forth in claim 9, wherein the inorganic material of the electron transport layer is selected from the group consisting of:

oxides, including TiO₂, ZnO, SiO₂, SnO₂, WO₃, Ta₂O₃, BaTiO₃, BaZrO₃, ZrO₂, HfO₂, Al₂O₃, Y₂O₃, and ZrSiO₄;

nitrides, including InN, AlN, GaN, Si₃N₄, and mixtures thereof; and

semiconductors, including CdS, ZnSe, and ZnS.

18. The diode as set forth in claim 9, wherein the semiconductor nanocrystal layer is formed of material selected from the group consisting of Group II-VI compound semiconductor nanocrystals, including CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, and HgTe;

Group III-V compound semiconductor nanocrystals, including GaN, GaP, GaAs, InP, and InAs;

Group IV-VI nanocrystals, including PbS, PbSe, and PbTe;

Group IV nanocrystals, including Si and Ge; and

core/shell structures, including CdSe/ZnS, CdSe/ZnSe, CdTe/ZnS, CdTe/ZnSe, CdSe/CdS, CdS/ZnS, CdS/ZeSe, InP/ZnS, and PbSe/ZnS, in which the shell is formed of semiconductor material having a wider band gap.

19. The diode as set forth in claim 9, wherein the semiconductor nanocrystal layer is a monolayer of semiconductor nanocrystals.

20. The diode as set forth in claim 9, wherein the semiconductor nanocrystal layer is a multi-layered structure having one or more monolayers.

21. The diode as set forth in claim 9, wherein the inorganic material of the hole transport layer is selected from the group consisting of semiconductors, including CdTe, ZnTe, CdS, ZnSe, and ZnS;

metal oxides, including TiO₂, ZnO, SiO₂, SnO₂, WO₃, Si₃N₄, ZrO₂, HfO₂, Ta₂O₅, BaTiO₃, BaZrO₃, Al₂O₃, Y₂O₃, and ZrSiO₄; and

p-doped semiconductors.

12. An inorganic electroluminescent diode, comprising an upper electrode and a lower electrode having a semiconductor nanocrystal layer disposed therebetween, an inorganic hole transport layer formed of amorphous inorganic material disposed between the semiconductor nanocrystal layer and the upper electrode, and an electron transport layer formed of inorganic material disposed between the semiconductor nanocrystal layer and the lower electrode.

13. The diode as set forth in claim 12, wherein the inorganic material of the electron transport layer is amorphous inorganic material.

14. The diode as set forth in claim 12, wherein the inorganic material of the electron transport layer is crystalline inorganic material.

22. An inorganic electroluminescent diode, comprising:

a first electrode on a substrate;

an inorganic hole transport layer formed of inorganic material and in electrical contact with the first electrode;

a semiconductor nanocrystal layer on a surface of the inorganic hole transport layer;

an inorganic electron transport layer formed of amorphous inorganic material on a surface of the semiconductor nanocrystal layer opposite the inorganic hole transport layer; and

a second electrode on and in electrical contact with a surface of the inorganic electron transport layer opposite the semiconductor nanocrystal layer;

wherein the layers are sequentially formed on the substrate.

23. An inorganic electroluminescent diode, comprising:

a first electrode on a substrate;

an inorganic electron transport layer formed of inorganic material in electrical contact with the first electrode;

a semiconductor nanocrystal layer on a surface of the inorganic electron transport layer opposite the first electrode;

an inorganic hole transport layer formed of amorphous inorganic material on a surface of the semiconductor nanocrystal layer opposite the inorganic electron transport layer; and

a second electrode on and in electrical contact with a surface of the inorganic hole transport layer opposite the semiconductor nanocrystal layer;

wherein the layers are sequentially formed on the substrate.