NITRIDE SEMICONDUCTOR LIGHT-EMITTING DEVICE AND METHOD FOR PRODUCING THE SAME

• US 20130001509A1
• Filed: 06/26/2012
• Published: 01/03/2013
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Sharp Fukuyama Laser Co., Ltd. (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: FUDETA, Mayuko, KOMADA, Satoshi, KAIHARA, Ryu
• Granted Patent: US 9,070,805 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• 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 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A nitride semiconductor light-emitting device has a first conductive-type nitride semiconductor layer, a superlattice layer provided on the first conductive-type nitride semiconductor layer, an active layer provided on the superlattice layer, and a second conductive-type nitride semiconductor layer provided on the active layer. An average carrier concentration of the superlattice layer is higher than an average carrier concentration of the active layer.

Claims

1. A nitride semiconductor light-emitting device comprising:

a first conductive-type nitride semiconductor layer;

a superlattice layer provided on said first conductive-type nitride semiconductor layer;

an active layer provided on said superlattice layer; and

a second conductive-type nitride semiconductor layer provided on said active layer, wherein

an average carrier concentration of said superlattice layer is higher than an average carrier concentration of said active layer.

2. The nitride semiconductor light-emitting device according to claim 1, wherein the average carrier concentration of said superlattice layer is greater than or equal to 1.2 times the average carrier concentration of said active layer.

3. The nitride semiconductor light-emitting device according to claim 1, wherein

said superlattice layer has a doped layer containing a first conductive-type impurity,

said active layer has a barrier layer, and

a proportion of thickness per one layer of said doper layer to thickness per one period of said superlattice layer is greater than or equal to a proportion of thickness per one layer of said barrier layer to thickness per one period of said active layer.

4. The nitride semiconductor light-emitting device according to claim 1, wherein a concentration of the first conductive-type impurity in said doped layer is greater than or equal to a concentration of the first conductive-type impurity in said barrier layer.

5. The nitride semiconductor light-emitting device according to claim 1, wherein

said superlattice layer has an undoped layer not containing a first conductive-type impurity,

said active layer has a well layer not containing said first conductive-type impurity, and

a proportion of thickness per one layer of said undoped layer to thickness per one period of said superlattice layer is less than or equal to a proportion of thickness per one layer of said well layer to thickness per one period of said active layer.

6. The nitride semiconductor light-emitting device according to claim 5, wherein said undoped layer is in contact with a lower face of said active layer.

7. The nitride semiconductor light-emitting device according to claim 3, wherein said superlattice layer has two or more layers of said doped layer.

8. The nitride semiconductor light-emitting device according to claim 3, wherein thickness per one layer of said doped layer is greater than or equal to 1.5 nm.

9. The nitride semiconductor light-emitting device according to claim 3, wherein concentration of the first conductive-type impurity in said doped layer is greater than or equal to 1×

10¹⁷ cm³.

10. The nitride semiconductor light-emitting device according to claim 3, wherein said barrier layer does not contain said first conductive-type impurity, or concentration of the first conductive-type impurity in said barrier layer is less than or equal to 8×

10¹⁷ cm<sup>−

3</sup>.

11. The nitride semiconductor light-emitting device according to claim 5, wherein said active layer has two or more layers of said well layer.

12. The nitride semiconductor light-emitting device according to claim 3, wherein thickness per one layer of said barrier layer is less than or equal to 7 nm.

13. The nitride semiconductor light-emitting device according to claim 1, wherein

between said first conductive-type nitride semiconductor layer and said superlattice layer, a short-period superlattice layer having a thickness per one period that is smaller than thickness per one period of said superlattice layer is provided, and

concentration of the first conductive-type impurity in said short-period superlattice layer is greater than or equal to 1×

10¹⁸ cm<sup>−

3</sup> and less than or equal to 5×

10¹⁹ cm<sup>−

3</sup>.

14. The nitride semiconductor light-emitting device according to claim 5, wherein

said superlattice layer is formed of lamination of said doped layer and said undoped layer,

said doped layer contains said first conductive-type impurity and Al_aGa_bIn_(1-a-b)N (0≦

a<

1, 0<

b≦

1), and

said undoped layer is formed of In_cGa_(1-c)N (0<

c≦

1).

15. The nitride semiconductor light-emitting device according to claim 5, wherein

said active layer is formed of lamination of said barrier layer and said well layer,

said barrier layer contains said first conductive-type impurity and Al_xGa_yIn_(1-x-y)N (0≦

x<

1, 0<

y≦

1), and

said well layer is formed of In_zGa_(1-z)N (0<

z≦

1).

16. The nitride semiconductor light-emitting device according to claim 1, wherein

each of said superlattice layer and said active layer contains In, and

wavelength of light emitted by said superlattice layer by photoluminescence is less than or equal to wavelength of light emitted by said active layer.

17. A method for producing the nitride semiconductor light-emitting device according to claim 1, comprising the steps of:

growing said first conductive-type nitride semiconductor layer on a substrate;

growing said superlattice layer on said first conductive-type nitride semiconductor layer;

growing said active layer on said superlattice layer; and

providing said second conductive-type nitride semiconductor layer on said active layer, wherein

a growth rate of said superlattice layer is greater than or equal to a growth rate of a well layer which is a part of said active layer.

18. The method for producing the nitride semiconductor light-emitting device according to claim 17, wherein a growth rate of a layer not containing a first conductive-type impurity of the layers forming said superlattice layer is greater than or equal to the growth rate of said well layer.

19. The method for producing the nitride semiconductor light-emitting device according to claim 17, wherein

a layer containing a first conductive-type impurity of the layers forming said superlattice layer is grown by using a first source gas and a first carrier gas, and

said first carrier gas contains greater than or equal to 0.3% by volume and less than or equal to 30% by volume of hydrogen gas.

20. The method for producing the nitride semiconductor light-emitting device according to claim 17, wherein a growth temperature of said superlattice layer is equal to a growth temperature of said active layer, or higher than the growth temperature of said active layer.

21. The method for producing the nitride semiconductor light-emitting device according to claim 17, wherein the growth rate of said well layer is greater than or equal to 10 nm/hour and less than or equal to 150 nm/hour.