Nitride semiconductor light emitting element

• US 20100065812A1
• Filed: 05/26/2006
• Published: 03/18/2010
• Est. Priority Date: 05/26/2006
• Status: Abandoned Application

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Nakahara, Ken, Ito, Norikazu, Tsutsumi, Kazuaki
• Application Number:
  US12/227,693
• Publication Number:
  US 20100065812A1
• Time in Patent Office: Days
• US Class Current: 257/13
• 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 33/32 containing nitrogen

Abstract

Provided is a nitride semiconductor light emitting element having an improved carrier injection efficiency from a p-type nitride semiconductor layer to an active layer by simple means from a viewpoint utterly different from the prior art. A buffer layer 2, an undoped GaN layer 3, an n-type GaN contact layer 4, an InGaN/GaN superlattice layer 5, an active layer 6, an undoped InGaN layer 7, and a p-type GaN-based contact layer 8 are stacked on a sapphire substrate 1. A p-electrode 9 is formed on the p-type GaN-based contact layer 8. An n-electrode 10 is formed on a surface where the n-type GaN contact layer 4 is exposed as a result of mesa-etching. The undoped InGaN layer 7 is included in an intermediate semiconductor layer formed between the p-type GaN-based contact layer 8 and a well layer closest to a p-side in the active layer having a quantum well structure. The carrier injection efficiency into the active layer 6 can be improved by making the total film thickness of the intermediate semiconductor layer 20 nm or less.

Claims

1. A nitride semiconductor light emitting element with a structure in which an active layer is sandwiched between a p-type nitride semiconductor layer and an n-type nitride semiconductor layer, the active layer having a quantum well structure with a well layer made of a nitride containing In, the nitride semiconductor light emitting element characterized in that

an undoped InGaN layer is included in an intermediate semiconductor layer formed between the p-type nitride semiconductor layer and the well layer of the active layer disposed at a position closest to the p-type side, and

the intermediate semiconductor layer has a film thickness of 20 nm or less.

2. The nitride semiconductor light emitting element according to claim 1, characterized in that

the intermediate semiconductor layer is made up only of the undoped InGaN layer.

3. The nitride semiconductor light emitting element according to claim 2, characterized in that

the undoped InGaN layer has an In composition ratio of 2.5% or less.

4. The nitride semiconductor light emitting element according to claim 1, characterized in that

the intermediate semiconductor layer is made up of a barrier layer of the active layer and the undoped InGaN layer.

5. The nitride semiconductor light emitting element according to claim 4, characterized in that

the undoped InGaN layer is an In composition gradient layer whose In content decreases toward the p-type nitride semiconductor layer.

6. The nitride semiconductor light emitting element according to claim 5, characterized in that

In gradient of the In composition gradient layer is formed during a process of increasing a temperature to a growth temperature for forming the p-type nitride semiconductor layer.

7. The nitride semiconductor light emitting element according to claim 1, characterized in that

a p-type contact layer is formed as a part of the p-type nitride semiconductor layer, and is in contact with a p-electrode, and

the p-type contact layer is made up of any one of Mg-doped InGaN and Mg-doped GaN.

8. The nitride semiconductor light emitting element according to claim 7, characterized in that

Mg-doped p-type Al_xGaN (0.02≦

x≦

0.15) is formed as a part of the p-type nitride semiconductor layer between the undoped InGaN layer and the p-type contact layer.

9. The nitride semiconductor light emitting element according to claim 8, characterized in that

the p-type AlGaN (0.02≦

x≦

0.15) has a hole carrier concentration in a range of 2×

10¹⁷ cm<sup>−

3</sup> or more.

10. The nitride semiconductor light emitting element according to claim 8, characterized in that

the p-type Al_xGaN (0.02≦

x≦

0.15) is grown at a temperature of 1000°

C. or above.

11. The nitride semiconductor light emitting element according to claim 1, characterized in that

the well layer has an In composition ratio of 10% or more, and

a total time when a growth temperature is 950°

C. or above is within 30 minutes from the time of completion of the formation of the well layer of the active layer disposed at the position closest to the p-type side to the time of completion of the formation of the p-type nitride semiconductor layer.