Method for making light-emitting device

• US 9,508,891 B2
• Filed: 11/21/2014
• Issued: 11/29/2016
• Est. Priority Date: 11/21/2014
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: Lu, Chih-Chiang, Lin, Yi-Chieh, Liao, Wen-Luh, Chen, Shou-Lung, Huang, Chien-Fu
• Primary Examiner(s): Everhart, Caridad
• Application Number:
  US14/550,016
• Publication Number:
  US 20160149072A1
• Time in Patent Office: 739 Days
• Field of Search: 438/44, 257/96
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/0062 for devices with an active region comprising only III-V compounds
• 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 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H04L 41/0668 by dynamic selection of recovery network elements, e.g. replacement by the most appropriate element after failure
• CPC Class Codes: H04L 41/0695 the faulty arrangement being the maintenance, administration or management system
• CPC Class Codes: H04L 41/0816 the condition being an adaptation, e.g. in response to network events
• CPC Class Codes: H04L 47/125 by balancing the load, e.g. traffic engineering

Abstract

A method for making a light-emitting device comprises the steps of: providing a growth substrate; forming a first light-emitting semiconductor stack on the growth substrate by epitaxial growth, and the first light-emitting semiconductor stack comprises a first active layer; forming a Distributed Bragg reflector on the first light-emitting semiconductor stack by epitaxial growth; forming a second light-emitting semiconductor stack on the Distributed Bragg reflector by epitaxial growth, and the second light-emitting semiconductor stack comprises a second active layer; and wherein the first active layer emits a first radiation of a first dominant wavelength, and the second active layer emits a second radiation of a second dominant wavelength longer than the first dominant wavelength.

Claims

1. A method for making a light-emitting device, comprising:

providing a growth substrate;

forming a first light-emitting semiconductor stack on the growth substrate by epitaxial growth, and the first light-emitting semiconductor stack comprises a first active layer;

forming a Distributed Bragg reflector on the first light-emitting semiconductor stack by epitaxial growth;

forming a protecting layer on the Distributed Bragg reflector by epitaxial growth;

forming a first contact layer on the Distributed Bragg reflector by epitaxial growth;

forming a second light-emitting semiconductor stack on the Distributed Bragg reflector by epitaxial growth, wherein the second light-emitting semiconductor stack comprises a second active layer;

forming a second contact layer by epitaxial growth after the step of forming the second light-emitting semiconductor stack and

wherein the first active layer emits a first radiation of a first dominant wavelength, and the second active layer emits a second radiation of a second dominant wavelength longer than the first dominant wavelength;

wherein the method further comprises forming a third contact layer on the growth substrate by epitaxial growth;

wherein the first light-emitting semiconductor stack further comprises a first semiconductor layer between the growth substrate and the first active layer and a second semiconductor layer between the first active layer and the Distributed Bragg reflector, wherein the second light-emitting semiconductor stack further comprises a third semiconductor layer between the first contact layer and the second active layer and a fourth semiconductor layer on the second active layer, wherein the second semiconductor layer has a first band gap, the third semiconductor layer has a second band gap, and the protecting layer has a third band gap between the first band gap and the second band gap.

2. The method according to claim 1, wherein the protecting layer has a doping concentration between 1×

10¹⁷/cm³ and 1×

10¹⁹/cm³.

3. The method according to claim 1, wherein the third semiconductor layer and the second semiconductor layer are of the same conductivity type.

4. The method according to claim 1, wherein the Distributed Bragg reflector has a higher reflectivity to the first dominant wavelength than that to the second dominant wavelength.

5. The method according to claim 1, further comprising a step of connecting the second light-emitting semiconductor stack to a second substrate by a bonding layer.

6. The method according to claim 5, further comprising a step of removing the growth substrate after the step of connecting the second light-emitting semiconductor stack to the second substrate by the bonding layer.

7. A method for making a light-emitting device, comprising:

providing a growth substrate;

forming a first light-emitting semiconductor stack on the growth substrate by epitaxial growth, and the first light-emitting semiconductor stack comprises a first active layer;

forming a Distributed Bragg reflector on the first light-emitting semiconductor stack by epitaxial growth;

forming a protecting layer on the Distributed Bragg reflector by epitaxial growth;

forming a second light-emitting semiconductor stack on the Distributed Bragg reflector by epitaxial growth, wherein the second light-emitting semiconductor stack comprises a second active layer;

wherein the first active layer emits a first radiation of a first dominant wavelength, and the second active layer emits a second radiation of a second dominant wavelength longer than the first dominant wavelength; and

wherein the first light-emitting semiconductor stack further comprises a first semiconductor layer between the growth substrate and the first active layer and a second semiconductor layer between the first active layer and the Distributed Bragg reflector, wherein the second light-emitting semiconductor stack further comprises a third semiconductor layer between the first light-emitting semiconductor stack and the second active layer and a fourth semiconductor layer on the second active layer, wherein the second semiconductor layer has a first band gap, the third semiconductor layer has a second band gap, and the protecting layer has a third band gap between the first band gap and the second band gap.

8. The method according to claim 7, further comprising a step of forming a first contact layer on the Distributed Bragg reflector by epitaxial growth, wherein the first contact layer and the Distributed Bragg reflector are of the same conductivity type.

9. The method according to claim 7, wherein the protecting layer and the first contact layer are of the same conductivity type.

10. The method according to claim 7, wherein the protecting layer has a thickness less than 1 um.

11. The method according to claim 7, wherein the protecting layer has a doping concentration between 1×

10¹⁷/cm³ and 1×

10¹⁹/cm³.

12. The method according to claim 7, further comprising a step of forming a first current spreading layer on the protecting layer by epitaxial growth after the step of forming the protecting layer on the Distributed Bragg reflector by epitaxial growth.

13. The method according to claim 7, wherein the third semiconductor layer and the second semiconductor layer are of the same conductivity type.

14. The method according to claim 7, wherein the Distributed Bragg reflector is electrically conductive.

15. The method according to claim 7, further a step of forming a first contact layer on the Distributed Bragg reflector by epitaxial growth and a step of forming a first electrode on the first contact layer, wherein the first contact layer is electrically common to the first light-emitting semiconductor stack and the second light-emitting semiconductor stack by ohmically contacting the first light-emitting semiconductor stack to the first electrode and ohmically contacting the second light-emitting semiconductor stack to the first electrode.

16. The method according to claim 7, further comprising a step of connecting the second light-emitting semiconductor stack to a second substrate by a bonding layer.

17. The method according to claim 16, further comprising a step of removing the growth substrate after the step of connecting the second light-emitting semiconductor stack to the second substrate by the bonding layer.

18. The method according to claim 7, wherein the Distributed Bragg reflector has a higher reflectivity to the first dominant wavelength than that to the second dominant wavelength.

19. The method according to claim 7, further comprising a step of forming a first contact layer on the Distributed Bragg reflector by epitaxial growth and a step of forming an etching stop layer on the Distributed Bragg reflector by epitaxial growth before the step of forming the first contact layer.

20. The method according to claim 19, further comprising a step of removing a part of the first active layer and a part of the etching stop layer to expose the first contact layer.