Group III nitride heterostructure for optoelectronic device

• US 9,660,133 B2
• Filed: 09/23/2014
• Issued: 05/23/2017
• Est. Priority Date: 09/23/2013
• Status: Expired

• Current Assignee: Sensor Electronic Technology Incorporated (Seoul Semiconductor Co., Ltd.)
• Original Assignee: Sensor Electronic Technology Incorporated (Seoul Semiconductor Co., Ltd.)
• Inventors: Jain, Rakesh, Shatalov, Maxim S., Yang, Jinwei, Dobrinsky, Alexander, Shur, Michael, Gaska, Remigijus
• Primary Examiner(s): PRENTY, MARK V
• Application Number:
  US14/493,388
• Publication Number:
  US 20150083994A1
• Time in Patent Office: 973 Days
• CPC Class Codes: H01L 33/0025 comprising only AIIIBV compounds
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

Heterostructures for use in optoelectronic devices are described. One or more parameters of the heterostructure can be configured to improve the reliability of the corresponding optoelectronic device. The materials used to create the active structure of the device can be considered in configuring various parameters the n-type and/or p-type sides of the heterostructure.

Claims

1. A heterostructure comprising:

a substrate;

an AlN buffer layer located on the substrate;

an Al_xGa_1-xN/Al_x′

Ga_1-x′

N first superlattice structure located on the buffer layer, wherein 0.6<

x≦

1, 0.1<

x′

<

0.9, and x>

x′

, and wherein each layer in the first superlattice structure has a thickness less than or equal to one hundred nanometers;

an Al_yGa_1-yN/Al_y′

Ga_1-y′

N second superlattice structure located on the first superlattice structure, wherein y′

<

x′

, 0.6<

y≦

1, 0.1<

y′

<

0.8, and y>

y′

, and wherein each layer in the second superlattice structure has a thickness less than one hundred nanometers;

an Al_zGa_1-zN n-type layer located on the second superlattice structure, wherein 0.1<

z<

0.75 and z<

y′

; and

an Al_bGa_1-bN/Al_qGa_1-qN active structure located on the n-type layer, wherein b-q>

0.05.

2. The heterostructure of claim 1, wherein the active structure is configured to emit electromagnetic radiation having a peak emission wavelength between 300 nanometers and 360 nanometers, and wherein 0.1<

x′

<

0.8, 0.1<

y′

<

0.65, 0.1<

z<

0.6, and 0<

q<

0.35.

3. The heterostructure of claim 1, wherein the active structure is configured to emit electromagnetic radiation having a peak emission wavelength between 260 nanometers and 300 nanometers, and wherein 0.6<

x′

<

0.9, 0.5<

y′

<

0.8, 0.4<

z<

0.75, and 0.2<

q<

0.6.

4. The heterostructure of claim 1, wherein the active structure is configured to emit electromagnetic radiation having a peak emission wavelength between 230 nanometers and 260 nanometers, and wherein 0.6≦

z<

0.75 and 0.45<

q<

0.75.

5. The heterostructure of claim 1, wherein at least one of x or y equals one.

6. The heterostructure of claim 1, further comprising:

an Al_BGa_1-BN electron blocking layer located on the active structure, wherein B is at least 1.05*b; and

a p-type GaN layer located on the electron blocking layer.

7. The heterostructure of claim 6, further comprising a graded p-type layer located between the electron blocking layer and the GaN layer, wherein the graded p-type layer has an aluminum molar fraction that decreases from B at a heterointerface between the electron blocking layer and the graded p-type layer to zero at a heterointerface between the graded p-type layer and the GaN layer.

8. The heterostructure of claim 6, wherein the GaN layer includes three sublayers, and wherein each sublayer has a doping concentration that differs from an immediately adjacent sublayer by at least ten percent.

9. The heterostructure of claim 1, further comprising a grading structure located between the second superlattice structure and the n-type layer, wherein the grading structure has an aluminum molar fraction that decreases from y′

at a heterointerface between the second superlattice structure and the grading structure to z at a heterointerface between the grading structure and the n-type layer.

10. The heterostructure of claim 1, further comprising a tensile/compressive superlattice located between the second superlattice structure and the n-type layer.

11. The heterostructure of claim 1, wherein the active structure is configured to emit electromagnetic radiation having a peak emission wavelength between 300 nanometers and 360 nanometers, wherein the n-type layer includes four sublayers, and wherein each sublayer differs from an immediately adjacent sublayer by at least one of:

doping concentration or aluminum molar fraction.

12. The heterostructure of claim 1, wherein the active structure is configured to emit electromagnetic radiation having a peak emission wavelength between 260 nanometers and 300 nanometers, wherein the n-type layer includes five sublayers, and wherein each sublayer differs from an immediately adjacent sublayer by at least one of:

doping concentration or aluminum molar fraction.

13. A heterostructure comprising:

a substrate;

a buffer layer located on the substrate, wherein the buffer layer is formed of a group III nitride material including aluminum;

a grading structure located on the buffer layer, wherein the grading structure is formed of a group III nitride material having an aluminum molar fraction that decreases from an aluminum molar fraction at a bottom heterointerface to an aluminum molar fraction at a top heterointerface;

a n-type layer located on the grading structure, wherein the n-type layer is formed of a group III nitride material including aluminum having a molar fraction z, and wherein 0.1<

z≦

0.9;

an active structure including quantum wells and barriers located on the n-type layer, wherein the quantum wells are formed of a group III nitride material including aluminum having a molar fraction q and the barriers are formed of a group III nitride material including aluminum having a molar fraction b, and wherein b-q>

0.05;

an electron blocking layer located on the active structure, wherein the electron blocking layer is formed of a group III nitride material including aluminum having a molar fraction B, and wherein B is at least 1.05*b;

a p-type GaN layer located on the electron blocking layer; and

a graded p-type layer located between the electron blocking layer and the GaN layer, wherein the graded p-type layer has an aluminum molar fraction that decreases from B at a heterointerface between the electron blocking layer and the graded p-type layer to zero at a heterointerface between the graded p-type layer and the GaN layer.

14. The heterostructure of claim 13, wherein the active structure is configured to emit electromagnetic radiation having a peak emission wavelength between 230 nanometers and 260 nanometers, and wherein 0.6≦

z≦

0.9 and 0.45<

q<

0.75.

15. The heterostructure of claim 13, further comprising:

a first superlattice structure located between the buffer layer and the grading structure, wherein the first superlattice structure is formed of a plurality of periods, each period including two layers formed of group III nitride materials including aluminum and having molar fractions x and x′

, where x>

x′

; and

a second superlattice structure located between the first superlattice structure and the graded structure, wherein the second superlattice structure is formed of a plurality of periods, each period including two layers formed of group III nitride materials including aluminum and having molar fractions y and y′

, where y>

y′

.

16. The heterostructure of claim 13, wherein the active structure is configured to emit electromagnetic radiation having a peak emission wavelength between 300 nanometers and 360 nanometers, and wherein 0.1<

x′

<

0.8, 0.1<

y′

<

0.65, 0.1<

z<

0.6, and 0<

q<

0.35.

17. The heterostructure of claim 13, wherein the active structure is configured to emit electromagnetic radiation having a peak emission wavelength between 260 nanometers and 300 nanometers, and wherein 0.6<

x′

<

0.9, 0.5<

y′

<

0.8, 0.4<

z<

0.75, and 0.2<

q<

0.6.

18. The heterostructure of claim 15, wherein z<

y′

<

x′

.

19. An optoelectronic device comprising:

a substrate;

a buffer layer located on the substrate, wherein the buffer layer is formed of a group III nitride material including aluminum;

a first superlattice structure located on the buffer layer, wherein the first superlattice structure is formed of a plurality of periods, each period including two layers formed of group III nitride materials including aluminum and having molar fractions x and x′

, where x>

x′

;

a second superlattice structure located on the first superlattice structure, wherein the second superlattice structure is formed of a plurality of periods, each period including two layers formed of group III nitride materials including aluminum and having molar fractions y and y′

, where y>

y′

;

a n-type layer located on the second superlattice, wherein the n-type layer is formed of a group III nitride material including aluminum having a molar fraction z, and wherein 0.1<

z≦

0.9; and

an active structure including quantum wells and barriers located on the n-type layer, wherein the quantum wells are formed of a group III nitride material including aluminum having a molar fraction q and the barriers are formed of a group III nitride material including aluminum having a molar fraction b, and wherein b-q>

0.05.

20. The optoelectronic device of claim 19, further comprising an electron blocking layer located on the active structure, wherein the electron blocking layer is formed of a group III nitride material including aluminum having a molar fraction B, and wherein B is at least 1.05*b.