Semiconductor light-emitting element and optical coupling device

• US 9,847,447 B2
• Filed: 08/05/2015
• Issued: 12/19/2017
• Est. Priority Date: 09/02/2014
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Fujimoto, Kenji, Kamakura, Takanobu
• Primary Examiner(s): Hossain, Moazzam
• Assistant Examiner(s): Lu, Farun
• Application Number:
  US14/819,196
• Publication Number:
  US 20160064599A1
• Time in Patent Office: 867 Days
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table

Abstract

A semiconductor light-emitting element includes a semiconductor stacked body that includes a light emitting layer in which n well layers (where n is, for example, an integer of 1 to 10) formed of In_x (Ga_1-yAl_y)_1-xAs (0<X≦0.2, 0<y<1), and (n+1) barrier layers formed of Ga_1-zAl_zAs (0<z<1) and are alternately stacked with the well layer. The light emitting layer in some embodiments can emit light having a peak wavelength in a range of from 700 nm or more to 870 nm or less.

Claims

1. A semiconductor light-emitting element, comprising:

a semiconductor substrate;

a first electrode on a first side of the semiconductor substrate, the first electrode comprising a circular pad above a central portion of the semiconductor substrate;

a second electrode on a second side of the semiconductor substrate opposite the first side;

a first semiconductor layer of a first conductivity type between the semiconductor substrate and the first electrode;

a second semiconductor layer of a second conductivity type between the first semiconductor layer and the first electrode; and

a light emitting layer between the first and second semiconductor layers, the light emitting layer including a well layer formed of In_x(Ga_1-yAl_y)_1-xAs (0<

x≦

0.1, 0<

y<

1), and two barrier layers formed of Ga_1-zAl_zAs (0<

z<

1), wherein the well layer is between the two barrier layers, wherein

the light emitting layer has a forward direction voltage that does not decrease by more than 8% from an initial forward voltage level during a 4000 hour galvanization test at 85°

C. and 85% humidity with 10 mA operation current.

2. The semiconductor light-emitting element according to claim 1, wherein

a thickness of the well layer is 11 nm or less, and

a thickness of each of the two barrier layers is 10 nm or more and 50 nm or less.

3. The semiconductor light-emitting element according to claim 2, wherein x is greater than or equal to 0.02 and less than or equal to 0.1.

4. The semiconductor light-emitting element according to claim 2, wherein x is greater than or equal to 0.04 and less than or equal to 0.1.

5. The semiconductor light-emitting element according to claim 1, wherein x is greater than or equal to 0.02 and less than or equal to 0.1.

6. The semiconductor light-emitting element according to claim 1, wherein x is greater than or equal to 0.04 and less than or equal to 0.1.

7. The semiconductor light-emitting element according to claim 1, further comprising:

a Bragg reflector configured to reflect light emitted from the light emitting layer, the first semiconductor layer being between the Bragg reflector and the light emitting layer.

8. The semiconductor light-emitting element according to claim 1, wherein

the light emitting layer comprises a number n of well layers formed of In_x(Ga_1-yAl_y)_1-xAs (0<

x≦

0.1, 0<

y<

1),

the light emitting layer comprises a number n+1 of barrier layers formed of Ga_1-zAl_zAs (0<

z<

1), and

the well layers and the barrier layers are stacked in an alternating manner with each other, and

n is an integer less or equal to 10 and equal to or greater than 1.

9. The semiconductor light-emitting element according to claim 8, wherein

each well layer has a thickness that is 11 nm or less, and

each barrier layer has a thickness that is 10 nm or more and 50 nm or less.

10. The semiconductor light-emitting element according to claim 9, wherein x is greater than or equal to 0.02 and less than or equal to 0.1.

11. The semiconductor light-emitting element according to claim 9, wherein x is greater than or equal to 0.04 and less than or equal to 0.1.

12. The semiconductor light-emitting element according to claim 1, further comprising:

a buffer layer on a semiconductor substrate, the buffer layer formed of GaAs, the first semiconductor layer contacting the buffer layer;

a third semiconductor layer of the second conductivity type on the second semiconductor layer; and

a fourth semiconductor layer of the second conductivity type on the third semiconductor layer, the fourth semiconductor layer have an impurity concentration that is greater than an impurity concentration of the third semiconductor layer.

13. The semiconductor light-emitting element according to claim 1, wherein the light emitting layer emits light having a peak wavelength that is in a range of 700 nm or more to 870 nm or less.

14. A light-emitting element, comprising:

a semiconductor substrate;

a first electrode on a first side of the semiconductor substrate, the first electrode comprising a circular pad above a central portion of the semiconductor substrate;

a second electrode on a second side of the semiconductor substrate opposite the first side;

a buffer layer between the semiconductor substrate and the first electrode;

a first semiconductor layer of a first conductivity type between the buffer layer and the first electrode;

a second semiconductor layer of a second conductivity type between the first semiconductor layer and the first electrode;

a light emitting layer disposed between the first and second semiconductor layers, the first and second semiconductor layers being of opposite conductivity types, the light emitting layer comprising;

n well layers formed of In_x(Ga_1-yAl_y)_1-xAs (0<

x≦

0.1, 0<

y<

1), where n is the number of well layers in the light emitting layer,

n+1 barrier layers formed of Ga_1-zAl_zAs (0<

z<

1), where n+1 is the number of barrier layers in the light emitting layer, and

n is an integer that is greater than or equal to 1 and less than or equal to 10, wherein

the light emitting layer has a forward direction voltage that does not decrease by more than 8% from an initial forward voltage level during a 4000 hour galvanization test at 85°

C. and 85% humidity with 10 mA operation current.

15. The light-emitting element according to claim 14, wherein

a thickness of each well layer is 11 nm or less, and

a thickness of each barrier layer is 10 nm or more and 50 nm or less.

16. The light-emitting element according to claim 15, wherein x is greater than or equal to 0.02 and less than or equal to 0.1.

17. The light-emitting element according to claim 15, wherein x is greater than or equal to 0.04 and less than or equal to 0.1.

18. An optical coupler, comprising:

a light-receiving element outputting an electrical signal according to a light signal output by a light-emitting element, the light-emitting element including;

a first semiconductor layer of a first conductivity type;

a second semiconductor of a second conductivity type on the first semiconductor layer; and

a light emitting layer between the first and second semiconductor layers, the light emitting layer including a well layer formed of In_x(Ga_1-yAl_y)_1-xAs (0<

x≦

0.1, 0<

y<

1), and two barrier layers formed of Ga_1-zAl_zAs (0<

z<

1), wherein the well layer is between the two barrier layers, wherein

the optical coupler has an optical coupling efficiency that does not decrease by more than 8% during a 4000 hour galvanization test at 85°

C. and 85% humidity with 10 mA operation current supplied to the light emitting layer.

19. The optical coupler according to claim 18, wherein the light emitting layer comprises:

n well layers formed of In_x(Ga_1-yAl_y)_1-xAs (0<

x≦

0.1, 0<

y<

1), where n is the number of well layers in the light emitting layer,

n+1 of barrier layers formed of Ga_1-zAl_zAs (0<

z<

1), where n+1 is the number of barrier layers in the light emitting layer,

n is an integer that is greater than or equal to 1 and less than or equal to 10, and

the well layers and the barrier layers are stacked in an alternating manner with each other.

20. The optical coupler according to claim 19, wherein

a thickness of each well layer is 11 nm or less, and

a thickness of each barrier layer is 10 nm or more and 50 nm or less.