White light emitting structures with controllable emission color temperature

• US 9,985,174 B2
• Filed: 06/03/2016
• Issued: 05/29/2018
• Est. Priority Date: 06/05/2015
• Status: Active Grant

• Current Assignee: Ostendo Technologies Inc.
• Original Assignee: Ostendo Technologies Inc.
• Inventors: El-Ghoroury, Hussein S., Kisin, Mikhail V., Yeh, Yea-Chuan Milton, Chuang, Chih-Li, Chen, Jyh-Chia
• Primary Examiner(s): Vu, David
• Assistant Examiner(s): Fox, Brandon
• Application Number:
  US15/173,511
• Publication Number:
  US 20160359084A1
• Time in Patent Office: 725 Days
• Field of Search: 257 79, 257 96, 257 98
• 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 33/32 containing nitrogen
• CPC Class Codes: H01S 5/0421 characterised by the semiconducting contacting layers electrodes H01S5/0425
• CPC Class Codes: H01S 5/0622 Controlling the frequency of the radiation
• CPC Class Codes: H01S 5/1096 in a single cavity
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/3407 characterised by special barrier layers
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
• CPC Class Codes: H01S 5/4043 with vertically stacked active layers
• CPC Class Codes: H01S 5/4093 Red, green and blue [RGB] generated directly by laser action or by a combination of laser action with nonlinear frequency conversion

Abstract

Disclosed herein are multi-layered optically active regions for semiconductor light-emitting devices (LEDs) that incorporate intermediate carrier blocking layers, the intermediate carrier blocking layers having design parameters for compositions and doping levels selected to provide efficient control over the carrier injection distribution across the active regions to achieve desired device injection characteristics. Examples of embodiments discussed herein include, among others: a multiple-quantum-well variable-color LED operating in visible optical range with full coverage of RGB gamut, a multiple-quantum-well variable-color LED operating in visible optical range with an extended color gamut beyond standard RGB gamut, a multiple-quantum-well light-white emitting LED with variable color temperature, and a multiple-quantum-well LED with uniformly populated active layers.

Claims

1. A multi-layer semiconductor light emitting structure comprising:

a first quantum confinement structure for emitting light of a first wavelength;

a first intermediate carrier blocking layer;

a second quantum confinement structure for emitting light of a second wavelength,

wherein the first intermediate carrier blocking layer is disposed between the first quantum confinement structure and the second quantum confinement structure and the first intermediate carrier blocking layer comprises a composition and a dopant to provide a first predetermined band-gap and band-offsets relative to each of the first quantum confinement structure and the second quantum confinement structure;

a second intermediate carrier blocking layer;

a third quantum confinement structure for emitting light of a third wavelength,

wherein the second intermediate carrier blocking layer is disposed between the second quantum confinement structure and the third quantum confinement structure and the second intermediate carrier blocking layer comprises a composition and a dopant to provide a second predetermined band-gap and band-offsets relative to each of the second quantum confinement structure and the third quantum confinement structure; and

the first, second and third quantum confinement structures emitting primary colors of red, green and blue respectively,

wherein the band-gaps and the band-offsets of the first and second intermediate carrier blocking layers are selected to cause the first, second and third quantum confinement structures to emit the primary colors with approximately equal CIE chromaticity at a predetermined injection current density, whereby the multi-layer semiconductor light emitting structure emits white light.

2. The multi-layer semiconductor light emitting structure of claim 1 wherein at least one of the first and second quantum confinement structures comprises a quantum wire.

3. The multi-layer semiconductor light emitting structure of claim 1 wherein at least one of the first and second quantum confinement structures comprises a quantum dot.

4. The multi-layer semiconductor light emitting structure of claim 1 wherein at least one of the first and second quantum confinement structures comprises a quantum well.

5. The multi-layer semiconductor light emitting structure of claim 1 wherein at least one of the first, second and third quantum confinement structures comprises multiple quantum wells.

6. The multi-layer semiconductor light emitting structure of claim 1 wherein the first, second and third quantum confinement structures emit the respective colors with approximately equal CIE at an injection current density of approximately 50 A/cm².

7. The multi-layer semiconductor light emitting structure of claim 1 wherein the first, second and third quantum confinement structures emit red, green and blue light with approximately equal CIE emissions for a particular injection current density, and when the particular injection current density increases, the blue emission increases and the green emission decreases.

8. The multi-layer semiconductor light emitting structure of claim 7 wherein an emission color temperature of the white-light-emitting device is controllable by controlling the injection current density.

9. The multi-layer semiconductor light emitting structure of claim 7 wherein the first, second and third quantum confinement structures emit the respective colors with approximately equal CIE emissions when the red emission is also decreasing with increasing injection current density.

10. The multi-layer semiconductor light emitting structure of claim 9 wherein the emission color temperature of the multi-layer semiconductor light emitting structure emitting white light is controllable by controlling the injection current density.

11. The multi-layer semiconductor light emitting structure of claim 1, wherein the first, second and third quantum confinement structures are disposed between an n-doped layer and a p-doped layer and the multi-layer semiconductor light emitting structure further comprises a first contact coupled to the n-doped layer and a second contact coupled to the p-doped layer, and wherein a carrier injection into each of the first, second and third quantum confinement structures is achieved through the first contact and the second contact.

12. A multi-layer semiconductor light emitting structure comprising:

a first quantum confinement structure for emitting light of a first wavelength, the first quantum confinement structure comprising at least one first optically active layer disposed between barrier layers;

a first intermediate carrier blocking layer;

a second quantum confinement structure for emitting light of a second wavelength, the second quantum confinement structure comprising at least one second optically active layer disposed between barrier layers;

a second intermediate carrier blocking layer; and

a third quantum confinement structure for emitting light of a third wavelength, the third quantum confinement structure comprising at least one third optically active layer disposed between barrier layers,

wherein the first intermediate carrier blocking layer is disposed between the first quantum confinement structure and the second quantum confinement structure and adjacent to a barrier layer of the first quantum confinement structure and adjacent to a barrier layer of the second quantum confinement structure and wherein the first intermediate carrier blocking layer comprises (1) a first band-gap greater than a band-gap of the adjacent barrier layer of the first quantum confinement structure and greater than a band-gap of the adjacent barrier layer of the second quantum confinement structure and (2) band-offsets relative to energy bands of the adjacent barrier layer of the first quantum confinement structure and relative to energy bands of the adjacent barrier layer of the second quantum confinement structure,

wherein the second intermediate carrier blocking layer is disposed between a barrier layer of the second quantum confinement structure and a barrier layer of the third quantum confinement structure and adjacent to a barrier layer of the second quantum confinement structure and adjacent to a barrier layer of the third quantum confinement structure and wherein the second intermediate carrier blocking layer comprises (1) a second band-gap greater than a band-gap of the adjacent barrier layer of the second quantum confinement structure and greater than a band-gap of the adjacent barrier layer of the third quantum confinement structure and (2) band-offsets relative to energy bands of the adjacent barrier layer of the second quantum confinement structure and relative to energy bands of the adjacent barrier layer of the third quantum confinement structure,

wherein the first, second and third quantum confinement structures emitting primary colors of red, green and blue, respectively, and

wherein the first and second intermediate carrier blocking layers each comprise a composition and a dopant to provide the first and second band-gaps and band-offsets selected to cause the first, second and third quantum confinement structures to emit the primary colors with approximately equal CIE chromaticity at a predetermined injection current density to emit white light.

13. The multi-layer semiconductor light emitting structure of claim 12 wherein at least one of the first and second quantum confinement structures comprises a quantum wire.

14. The multi-layer semiconductor light emitting structure of claim 12 wherein at least one of the first and second quantum confinement structures comprises a quantum dot.

15. The multi-layer semiconductor light emitting structure of claim 12 wherein at least one of the first and second quantum confinement structures comprises a quantum well.

16. The multi-layer semiconductor light emitting structure of claim 12 wherein at least one of the first, second and third quantum confinement structures comprises multiple quantum wells.

17. The multi-layer semiconductor light emitting structure of claim 12 wherein the first, second and third quantum confinement structures emit the respective colors with approximately equal CIE at an injection current density of approximately 50 A/cm².

18. The multi-layer semiconductor light emitting structure of claim 12 wherein the first, second and third quantum confinement structures emit red, green and blue light with approximately equal CIE emissions for a particular injection current density, and when the particular injection current density increases, the blue emission increases and the green emission decreases.

19. The multi-layer semiconductor light emitting structure of claim 18 wherein an emission color temperature of the white-light-emitting device is controllable by controlling the injection current density.

20. The multi-layer semiconductor light emitting structure of claim 18 wherein the first, second and third quantum confinement structures emit the respective colors with approximately equal CIE emissions when the red emission is also decreasing with increasing injection current density.

21. The multi-layer semiconductor light emitting structure of claim 20 wherein the emission color temperature of the multi-layer semiconductor light emitting structure emitting white light is controllable by controlling the injection current density.

22. The multi-layer semiconductor light emitting structure of claim 12, wherein the first, second and third quantum confinement structures are disposed between an n-doped layer and a p-doped layer and the multi-layer semiconductor light emitting structure further comprises a first contact coupled to the n-doped layer and a second contact coupled to the p-doped layer, and wherein a carrier injection into each of the first, second and third quantum confinement structures is achieved through the first contact and the second contact.