Nitride Semiconductor Light Emitting Device

• US 20090278144A1
• Filed: 11/28/2006
• Published: 11/12/2009
• Est. Priority Date: 11/29/2005
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Ito, Norikazu, Sakai, Mitsuhiko, Sonobe, Masayuki
• Granted Patent: US 8,093,606 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 33/105 with a resonant cavity structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 5/18358 containing spacer layers to adjust the phase of the light wave in the cavity
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

There is provided a nitride semiconductor light emitting device having a light reflection layer capable of preventing reflectivity from lowering and luminance from lowering due to deterioration of quality of an active layer. A nitride semiconductor laser includes at least a light emitting layer forming portion (3) provided on a first light reflection layer (2) provided on a substrate (1). The first light reflection layer (2) is formed with laminating a low refractivity layer (21) and a high refractivity layer (22) which have a different refractivity from each other, and the low refractivity layer (21) of the first light reflection layer is formed with a single layer structure of an Al_xGa_1-xN layer (0≦x≦1), and the high refractivity layer (22) of the first light reflection layer is formed with a multi layer structure formed by laminating alternately an Al_yGa_1-yN layer (0≦y≦0.5 and y<x) or an In_tGa_1-tN layer (0<t≦0.5) and an In_uGa_1-uN layer (0<u≦1 and t<u).

Claims

1. A nitride semiconductor light emitting device comprising:

a substrate;

a light reflection layer provided on the substrate, the light reflection layer being formed by laminating alternately a low refractivity layer and a high refractivity layer which has a higher refractivity than that of the low refractivity layer; and

a light emitting layer forming portion provided on the light reflection layer,

wherein the low refractivity layer of the light reflection layer is formed with a single layer structure of an Al_xGa_1-xN (0<

x<

1) layer, and the high refractivity layer of the light reflection layer is formed with a multi layer structure formed by laminating alternately an Al_yGa_1-yN (0≦

y≦

0.5 and y<

x) layer or an In_tGa_1-tN (0<

t≦

0.5) layer and an In_uGa_1-uN (0<

u≦

1 and t<

u) layer.

2. The nitride semiconductor light emitting device according to claim 1, wherein the high refractivity layer of the light reflection layer is formed with a multi layer structure formed by laminating alternately an Al_yGa_1-yN (0≦

y≦

0.5 and y<

x) layer and an In_uGa_1-uN (0<

u≦

1) layer.

3. The nitride semiconductor light emitting device according to claim 2, wherein a relaxation layer made of the Al_yGa_1-yN (0≦

y≦

0.5 and y<

x) is formed with a thickness of 1 to 3 nm, and an adjustment layer made of the In_uGa_1-uN (0<

u≦

1) is formed with a thickness of 0.5 to 2 nm.

4. The nitride semiconductor light emitting device according to claim 1, wherein a second light reflection layer formed by laminating alternately a low refractivity layer and a high refractivity layer which has a higher refractivity than that of the low refractivity layer is further provided at an upper surface side of the light emitting layer forming portion.

5. The nitride semiconductor light emitting device according to claim 4, wherein the light emitting layer forming portion is formed with a lamination structure of an n-type layer, an active layer and a p-type layer so that light emitted in the active layer resonates between the light reflection layer and the second light reflection layer.

6. The nitride semiconductor light emitting device according to claim 4, wherein a reflection coefficient of the second light reflection layer is formed smaller than that of the light emitting reflection layer, and light is taken out from a second light reflection layer side.

7. The nitride semiconductor light emitting device according to claim 4, wherein at least one of the low refractivity layer and the high refractivity layer of the second light reflection layer is formed with a multi layer structure.

8. The nitride semiconductor light emitting device according to claim 7, wherein the high refractivity layer of the second light reflection layer is formed with a lamination structure of an adjustment layer made of an InGaN based compound and a relaxation layer made of GaN, and the low refractivity layer of the second light reflection layer is formed with a lamination structure of an adjustment layer made of an AlGaN based compound and a relaxation layer made of GaN.