Nitride Semiconductor Light Emitting Element

• US 20100224892A1
• Filed: 01/23/2007
• Published: 09/09/2010
• Est. Priority Date: 01/24/2006
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Nakahara, Ken
• Granted Patent: US 8,049,235 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

Provided is a nitride semiconductor light emitting element that has improved light extraction efficiency and a wide irradiation angle of outgoing light irrespective of the reflectance of a metal used for an electrode. An n side anti-reflection layer 2 and a p side Bragg reflection layer 4 are formed so as to sandwich an MQW active layer 3 that serves as a light emitting region, and the nitride semiconductor light emitting element has a double hetero structure. On top of the n side anti-reflection layer 2, an n electrode 1 is formed. Meanwhile, at the lower side of the p side Bragg reflection layer 4, a p electrode 5, a reflection film 7, and a pad electrode 8 are formed, and the pad electrode is bonded to a support substrate 10 with a conductive bonding layer 9 interposed in between. Both the n side anti-reflection layer 2 and the p side Bragg reflection layer 4 also serve as contact layers. The n side anti-reflection layer 2 is disposed on the light-extracting-direction side while the p side Bragg reflection layer 4 is disposed on the opposite side to the light-extracting-direction side. Consequently, the light extraction efficiency is improved.

Claims

1. A nitride semiconductor light emitting element provided at least with an n side electrode, an n type nitride semiconductor layer, a light emitting region, a p type nitride semiconductor layer, and a p side electrode, which are formed in this order, the nitride semiconductor light emitting element, wherein

the n type nitride semiconductor layer is formed to be an anti-reflection layer, and

the p type nitride semiconductor layer is formed to be a Bragg reflection layer.

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

the anti-reflection layer is formed of a multilayer film with InGaN semiconductor layers and GaN semiconductor layers being alternately formed in this order from the side of the light emitting region, and

the Bragg reflection layer is formed of a multilayer film with AlGaN semiconductor layers and GaN semiconductor layers being alternately formed in this order from the side of the light emitting region.

5. The nitride semiconductor light emitting element according to claim 3, wherein

each of the InGaN semiconductor layers and of the GaN semiconductor layers is formed to have a film thickness of an integer multiple of a quarter of the wavelength λ

of the emitted light, and

each of the AlGaN semiconductor layers and of the GaN semiconductor layers is formed to have a film thickness of an integer multiple of a half of the wavelength λ

of the emitted light.

2. A nitride semiconductor light emitting element provided at least with an n side electrode, an n type nitride semiconductor layer, a light emitting region, a p type nitride semiconductor layer, and a p side electrode, which are formed in this order, the nitride semiconductor light emitting element, wherein

the n type nitride semiconductor layer is formed to be a Bragg reflection layer, and

the p type nitride semiconductor layer is formed to be an anti-reflection layer.

4. The nitride semiconductor light emitting element according to claim 2, wherein

the anti-reflection layer is formed of a multilayer film with AlGaN semiconductor layers and GaN semiconductor layers being alternately formed in this order from the side of the light emitting region, and

the Bragg reflection layer is formed of a multilayer film with InGaN semiconductor layers and GaN semiconductor layers being alternately formed in this order from the side of the light emitting region.

6. The nitride semiconductor light emitting element according to claim 4, wherein

each of the AlGaN semiconductor layers and of the GaN semiconductor layers is formed to have a film thickness of an integer multiple of a quarter of the wavelength λ

of the emitted light, and

each of the InGaN semiconductor layers and of the GaN semiconductor layers is formed to have a film thickness of an integer multiple of a half of the wavelength λ

of the emitted light.

7. A nitride semiconductor light emitting element provided at least with an n side electrode, an n type nitride semiconductor layer, a light emitting region, a p type nitride semiconductor layer, and a p side electrode, which are formed in this order, the nitride semiconductor light emitting element, wherein

a part of the n type nitride semiconductor layer is formed to be a n type semiconductor multilayer film with InGaN semiconductor layer at the side of the light emitting region, and with function as an anti-reflection layer, and

the p type nitride semiconductor layer is formed to be a Bragg reflection layer, and a electrode contacted with the surface of the Bragg reflection layer is formed to be ZnO or ITO.

9. The nitride semiconductor light emitting element according to claim 7, wherein

the anti-reflection layer is formed of a multilayer film with InGaN semiconductor layers and GaN semiconductor layers being alternately formed in this order from the side of the light emitting region, and

the Bragg reflection layer is formed of a multilayer film with AlGaN semiconductor layers and GaN semiconductor layers being alternately formed in this order from the side of the light emitting region.

11. The nitride semiconductor light emitting element according to claim 9, wherein

each of the InGaN semiconductor layers and of the GaN semiconductor layers is formed to have a film thickness of an integer multiple of a quarter of the wavelength of the emitted light, and

each of the AlGaN semiconductor layers and of the GaN semiconductor layers is formed to have a film thickness of an integer multiple of a half of the wavelength λ

of the emitted light.

8. A nitride semiconductor light emitting element provided at least with an n side electrode, an n type nitride semiconductor layer, a light emitting region, a p type nitride semiconductor layer, and a p side electrode, which are formed in this order, the nitride semiconductor light emitting element, wherein

a part of the n type nitride semiconductor layer is formed to be a n type semiconductor multilayer film with InGaN semiconductor layer at the side of the light emitting region, and with function as a Bragg reflection layer, and

the p type nitride semiconductor layer is formed to be an anti-reflection layer, and a electrode contacted with the surface of the anti-reflection layer is formed to be ZnO or ITO.

10. The nitride semiconductor light emitting element according to claim 8, wherein

the anti-reflection layer is formed of a multilayer film with AlGaN semiconductor layers and GaN semiconductor layers being alternately formed in this order from the side of the light emitting region, and

the Bragg reflection layer is formed of a multilayer film with InGaN semiconductor layers and GaN semiconductor layers being alternately formed in this order from the side of the light emitting region.

12. The nitride semiconductor light emitting element according to claim 10, wherein

each of the AlGaN semiconductor layers and of the GaN semiconductor layers is formed to have a film thickness of an integer multiple of a quarter of the wavelength λ

of the emitted light, and

each of the InGaN semiconductor layers and of the GaN semiconductor layers is formed to have a film thickness of an integer multiple of a half of the wavelength λ

of the emitted light.