Growing an improved P-GaN layer of an LED through pressure ramping

• US 9,312,432 B2
• Filed: 03/13/2012
• Issued: 04/12/2016
• Est. Priority Date: 03/13/2012
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: TSMC Solid State Lighting Ltd. (Epistar Corporation)
• Inventors: Lo, Ming-Hua, Hsia, Hsing-Kuo, Li, Zhen-Yu, Kuo, Hao-Chung
• Primary Examiner(s): Smith, Zandra
• Assistant Examiner(s): REIDA, MOLLY KAY
• Application Number:
  US13/418,663
• Publication Number:
  US 20130240831A1
• Time in Patent Office: 1,491 Days
• Field of Search: None
• US Class Current: 1/1
• 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 a disposition of the MQW layer relative to the first doped III-V compound layer allows a dopant from the first doped III-V compound layer to diffuse into the MQW layer;

wherein the first III-V compound layer has a doping concentration curve that includes a single exponential segment and an approximately linear segment, and wherein a highest point of the exponential segment corresponds to a boundary of the first III-V compound layer farther from the MQW layer, and wherein the approximately linear segment corresponds to a portion of the first III-V compound layer adjacent to the MQW layer, and

wherein the doping concentration curve is a function, of depth in a manner such that the doping concentration of the first III-V compound layer continuously decreases as the depth increases.

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 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.

4. The device of claim 3, wherein the first portion is at least several times thicker than the second portion.

5. The device of claim 1, 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.

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

7. 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.

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

a substrate;

a p-doped III-V compound layer and an n-doped 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 a disposition of the MQW layer relative to the p-doped III-V compound layer allows a dopant from the p-doped III-V compound layer to diffuse into the MQW layer,

wherein the p-doped III-V compound layer and the n-doped III-V compound layer are free of having a capping layer therebetween,

wherein the p-doped Ill-V compound layer includes a first region having an approximately linear doping concentration characteristic and a second region having an exponential doping concentration characteristic,

wherein the first region of the p-doped compound layer is adjacent to the MQW layer,

wherein the first region is defined from a first surface of the p-doped III-V compound layer,

wherein the second region is defined from a second surface of the p-doped III-V compound layer opposite the first surface, and

wherein a part of the second region at the second surface of the p-doped III-V compound layer has a greatest doping concentration and wherein a doping concentration level of the p-doped III-V compound layer continuously decreases from the second surface to the first surface.

9. The LED of claim 8, 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.

10. The LED of claim 8, wherein a depth of the first region exceeds a depth of the second region by a number of times.

11. The LED of claim 8, 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.

12. A device, comprising:

a first doped gallium nitride layer;

a multiple quantum well (MQW) layer disposed over the first doped gallium nitride layer;

a second doped gallium nitride layer disposed directly on the MOW layer, wherein the second doped gallium nitride layer includes a first portion with an approximately linear doping profile and a second portion with an approximately exponential doping profile, and wherein the first portion is adjacent to the MQW layer, and wherein a disposition of the MQW layer relative to the second doped gallium nitride lam allows a dopant from the second doped gallium nitride layer to diffuse into the MQW layer; and

a metal layer bonded to the second portion of the second doped gallium nitride layer, wherein the second portion has a greatest doping concentration level at an interface between the second portion and the metal layer, wherein a doping concentration level of the second doped gallium nitride layer continuously decreases from a first surface of the second doped gallium nitride layer bonded to the metal layer to a second surface of the second doped gallium nitride layer opposite the first surface.

13. The device of claim 12, wherein a doping concentration level of the second portion exponentially decreases as a function of a distance from the interface between the second portion and the metal layer.

14. The device of claim 12, wherein the first portion is at least multiple times thicker than the second portion.

15. The device of claim 12, wherein:

the first portion has a doping concentration level in a range from about 1.0×

10¹⁹ ions/centimeter³ to about 1.5×

10¹⁹ ions/centimeter³;

the second portion has a doping concentration level in a range from about 1.5×

10¹⁹ ions/centimeter³ to about 1.5×

10²⁰ ions/centimeter³.

16. The device of claim 12, further comprising a lighting module in which the first doped gallium nitride layer, the MQW layer, and the second doped gallium nitride layer are disposed.