GROWING AN IMPROVED P-GAN LAYER OF AN LED THROUGH PRESSURE RAMPING

• US 20130240831A1
• Filed: 03/13/2012
• Published: 09/19/2013
• Est. Priority Date: 03/13/2012
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: TSMC Solid State Lighting Ltd. (Epistar Corporation)
• Inventors: Li, Zhen-Yu, Hsia, Hsing-Kuo, Kuo, Hao-Chung, Lo, Ming-Hua
• Granted Patent: US 9,312,432 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01L 33/325 characterised by the doping materials
• CPC Class Codes: H01L 33/36 characterised by the electrodes

Abstract

The present disclosure involves an apparatus. The apparatus includes a photonic die structure that includes a light-emitting diode (LED) die. The LED die is a vertical LED die in some embodiments. The LED die includes a substrate. A p-doped III-V compound layer and an n-doped III-V compound layer are each disposed over the substrate. A multiple quantum well (MQW) layer is disposed between the p-doped III-V compound layer and the n-doped III-V compound layer. The p-doped III-V compound layer includes a first region having a non-exponential doping concentration characteristic and a second region having an exponential doping concentration characteristic. In some embodiments, the second region is formed using a lower pressure than the first region.

Claims

1. A device, comprising:

a first doped III-V compound layer having a first type of conductivity;

a second doped III-V compound layer having a second type of conductivity different from the first type of conductivity; and

a multiple quantum well (MQW) layer disposed between the first and second doped III-V compound layers;

wherein the first III-V compound layer has a doping concentration curve that includes an exponential segment.

2. The device of claim 1, wherein:

the first doped III-V compound layer is a p-type doped gallium nitride (p-GaN) layer; and

the first doped III-V compound layer is doped with magnesium (Mg).

3. The device of claim 1, wherein the doping concentration curve is a function of depth.

4. The device of claim 1, wherein the doping concentration curve further includes an approximately linear segment.

5. The device of claim 4, wherein:

the first III-V compound layer include a first portion and a second portion, the first portion being disposed closer to the MQW layer than the second portion;

the approximately linear segment of the doping concentration curve corresponds to the first portion of the first III-V compound layer; and

the exponential segment of the doping concentration curve corresponds to the second portion of the first III-V compound layer.

6. The device of claim 5, wherein the first portion is at least several times thicker than the second portion.

7. The device of claim 4, wherein:

the exponential segment has a doping concentration level in a range from about 1.5×

10¹⁹ ions/centimeter³ to about 1.5×

10²⁰ ions/centimeter³; and

the approximately linear segment has a doping concentration level in a range from about 1.0×

10¹⁹ ions/centimeter³ to about 1.5×

10¹⁹ ions/centimeter³.

8. The device of claim 1, wherein the device includes a vertical light-emitting diode (LED) die.

9. The device of claim 1, further comprising:

a lighting module in which the first and second doped III-V compound layers and the MQW layer are implemented.

10. A light-emitting diode (LED), comprising:

a substrate;

a p-doped III-V compound layer and an n-doped III-V compound layer each disposed over the substrate; and

a multiple quantum well (MQW) layer disposed between the p-doped III-V compound layer and the n-doped III-V compound layer;

wherein the p-doped III-V compound layer includes a first region having a non-exponential doping concentration characteristic and a second region having an exponential doping concentration characteristic.

11. The LED of claim 10, wherein the first region of the p-doped III-V compound layer is located closer to the MQW layer than the second region of the p-doped III-V compound layer.

12. The LED of claim 10, wherein:

the p-doped III-V compound layer contains a gallium nitride material;

the first region of the p-doped III-V compound layer has a doping concentration level in a range from about 1.0×

10¹⁹ ions/centimeter³ to about 1.5×

10¹⁹ ions/centimeter³; and

the second region of the p-doped III-V compound layer has a doping concentration level in a range from about 1.5×

10¹⁹ ions/centimeter³ to about 1.5×

10²⁰ ions/centimeter³.

13. The LED of claim 10, wherein the non-exponential doping concentration characteristic includes a substantially linear doping concentration curve.

14. The LED of claim 10, wherein a depth of the first region exceeds a depth of the second region by a number of times.

15. The LED of claim 10, wherein:

the LED is a vertical LED; and

the substrate is a gallium nitride substrate, a silicon submount, a ceramic submount, or a metal submount.

16. A method of fabricating a light-emitting diode (LED), comprising:

growing a first doped III-V compound layer over a substrate in a chamber;

growing a multiple quantum well (MQW) layer over the first doped III-V compound layer in the chamber; and

growing a second doped III-V compound layer over the MQW layer in the chamber, the second doped III-V compound layer having a different type of conductivity than the first doped III-V compound layer;

wherein the growing the second doped III-V compound layer includes varying a chamber pressure during the growing of the second doped III-V compound layer.

17. The method of claim 16, wherein the second doped III-V compound layer is a p-type doped gallium nitride compound layer, and wherein the growing the second doped III-V compound layer comprises:

growing a first portion of the second III-V compound layer using a first pressure, such that the first portion has a substantially linear doping concentration curve; and

growing a second portion of the second III-V compound layer using a second pressure lower than the first pressure, such that the second portion has a substantially exponential doping concentration curve.

18. The method of claim 17, wherein the first portion is multiple times thicker than the second portion.

19. The method of claim 17, wherein the first portion has a substantially lower doping concentration level than the second portion.

20. The method of claim 16, further comprising, after the growing the second doped III-V compound layer:

forming a metal layer over the second doped layer;

bonding the metal layer to a submount;

thereafter removing the substrate to expose the first doped III-V compound layer;

roughening a surface of the first doped III-V compound layer; and

forming one or more metal contacts on the roughened surface of the first doped III-V compound layer.