Squared-off semiconductor coatings for quantum dots (QDs)

Patent metadata

Field	Value
Publication number	US-10186631-B2
Application number	US-201515311839-A
Country	US
Kind code	B2
Filing date	May 14, 2015
Priority date	May 16, 2014
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

Squared-off semiconductor coatings for quantum dots (QDs) and the resulting quantum dot materials are described. In an example, a semiconductor structure includes a quantum dot structure having an outermost surface. A crystalline semiconductor coating is disposed on and completely surrounds the outermost surface of the quantum dot structure. The crystalline semiconductor coating has a geometry with squared-off ends.

First claim

What is claimed is:

1. A semiconductor structure, comprising:
a quantum dot structure having an outermost surface; and
a crystalline semiconductor coating disposed on and completely surrounding the outermost surface of the quantum dot structure, and having a geometry with squared-off ends, the crystalline semiconductor coating comprising:
a first sub-layer comprising a blended CdZnS layer directly grown from a CdS material of the quantum dot structure, and
a second sub-layer comprising essentially pure ZnS.

2. The semiconductor structure of claim 1 , wherein the quantum dot structure is a rod-shaped structure having a long axis, and wherein the squared-off ends of the crystalline semiconductor coating are aligned with respective ends of the long axis of the quantum dot structure.

3. The semiconductor structure of claim 2 , wherein respective ends of the long axis of the quantum dot structure are rounded ends.

4. The semiconductor structure of claim 1 , wherein the semiconductor structure has a PLQY of greater than 75% under conditions of a temperature greater than approximately 100 degrees Celsius and a flux greater than approximately 10 W/cm 2 .

5. The semiconductor structure of claim 1 , wherein the second sub-layer is stabilized with oleylamine molecules.

6. The semiconductor structure of claim 1 , wherein the quantum dot structure is in alignment with a global center of the crystalline semiconductor coating.

7. The semiconductor structure or claim 1 , wherein the quantum dot structure is not in alignment with a global center of the crystalline semiconductor coating.

8. A semiconductor structure, comprising:
a nanocrystalline core of a first semiconductor material;
a nanocrystalline shell of a second semiconductor material different from the first semiconductor material, the second semiconductor material comprising cadmium sulfide (CdS), the nanocrystalline shell disposed on and surrounding the nanocrystalline core; and
a crystalline semiconductor coating of a third semiconductor material different from the first and second semiconductor materials, the third semiconductor material comprising a first sub-layer comprising a blended cadmium zinc sulfide (CdZnS) layer directly grown from the CdS material of the nanocrystalline shell, and a second sub-layer comprising essentially pure zinc sulfide (ZnS), the crystalline semiconductor coating disposed on and completely surrounding the nanocrystalline shell, and having a geometry with squared-off ends.

9. The semiconductor structure of claim 8 , wherein the nanocrystalline shell is a rod-shaped structure having a long axis, and wherein the squared-off ends of the crystalline semiconductor coating are aligned with respective ends of the long axis of the nanocrystalline shell.

10. The semiconductor structure of claim 9 , wherein respective ends of the long axis of the nanocrystalline shell are rounded ends.

11. The semiconductor structure of claim 8 , wherein the semiconductor structure has a PLQY of greater than 75% under conditions of a temperature greater than approximately 100 degrees Celsius and a flux greater than approximately 10 W/cm 2 .

12. The semiconductor structure of claim 8 , wherein the first semiconductor material is cadmium selenide (CdSe).

13. The semiconductor structure of claim 8 , wherein the second sub-layer is stabilized with oleylamine molecules.

14. The semiconductor structure or claim 8 , wherein the nanocrystalline shell is in alignment with a global center of the crystalline semiconductor coating.

15. The semiconductor structure or claim 8 , wherein the nanocrystalline shell is not in alignment with a global center of the crystalline semiconductor coating.

16. A lighting apparatus, comprising:
a housing structure;
a light emitting diode supported within the housing structure; and
a light conversion layer disposed above the light emitting diode, the light conversion layer comprising a plurality of quantum dots, each quantum dot comprising:
a nanocrystalline core of a first semiconductor material;
a nanocrystalline shell of a second semiconductor material different from the first semiconductor material, the nanocrystalline shell disposed on and surrounding the nanocrystalline core; and
a crystalline semiconductor coating of a third semiconductor material different from the first and second semiconductor materials, the crystalline semiconductor coating disposed on and completely surrounding the nanocrystalline shell, and having a geometry with squared-off ends, the crystalline semiconductor coating comprising:
a first sub-layer comprising a blended CdZnS layer directly grown from a CdS material of the nanocrystalline shell, and
a second sub-layer comprising essentially pure ZnS.

17. The lighting apparatus of claim 16 , wherein, for each quantum dot, the nanocrystalline shell is a rod-shaped structure having a long axis, and the squared-off ends of the crystalline semiconductor coating are aligned with respective ends of the long axis of the nanocrystalline shell.

18. The lighting apparatus of claim 17 , wherein, for each quantum dot, respective ends of the long axis of the nanocrystalline shell are rounded ends.

19. The lighting apparatus of claim 16 , wherein, for each quantum dot, the quantum dot has a PLQY of greater than 75% under conditions of a temperature greater than approximately 100 degrees Celsius and a flux greater than approximately 10 W/cm 2 .

20. The lighting apparatus of claim 16 , wherein, for each quantum dot, the first semiconductor material is cadmium selenide (CdSe) and the second semiconductor material is cadmium sulfide (CdS).

21. The lighting apparatus of claim 16 , wherein, for each quantum dot, the second sub-layer is stabilized with oleylamine molecules.

22. The lighting apparatus of claim 16 , wherein, for each quantum dot, the nanocrystalline shell is in alignment with a global center of the crystalline semiconductor coating.

23. The lighting apparatus of claim 16 , wherein, for each quantum dot, the nanocrystalline shell is not in alignment with a global center of the crystalline semiconductor coating.

Assignees

• Pacific Light Tech Corp
• Osram Opto Semiconductors Gmbh

Inventors

• Carillo Matthew J
• Hughes Steven

Classifications

• Y10S977/89

  Deposition of materials, e.g. coating, cvd, or ald · CPC title

• C09K11/56

  containing sulfur · CPC title

• C09K11/02

  Use of particular materials as binders, particle coatings or suspension media therefor · CPC title

• C09K11/025

  non-luminescent particle coatings or suspension media · CPC title

• C09K11/883

  with zinc or cadmium · CPC title