Light emitting device

• US 6,608,330 B1
• Filed: 09/21/1999
• Issued: 08/19/2003
• Est. Priority Date: 09/21/1998
• Status: Expired due to Term

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Yamada, Motokazu
• Primary Examiner(s): Baumeister, Bradley W.
• Application Number:
  US09/400,432
• Time in Patent Office: 1,428 Days
• Field of Search: 257/94, 257/96, 257/97, 257/79, 257/88, 257/89, 257/90, 257/103, 257/190, 257/201, 257/613, 257/615, 257/12-15, 257/17, 257/18, 257/22
• US Class Current: 257/90
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

First and second well layers of a light emitting device emit light of different peak wavelengths so as to produce a mixed light, such as white light having high luminous intensity and high luminous efficiency. A color rendering property of the device can be controlled by adjusting the ratio of the growth numbers of the first and second well layers, and/or the thickness of the barrier layers sandwiching the well layers. The color rendering property can also be controlled by forming the second well layer so as to have a degree of asperity greater than that of the first well layer, or so that a degree of area occupied by dished portions having a thickness which is less than half of an average thickness over a total surface is not less than 10%.

Claims

1. A light emitting device comprising:

an active layer of a multiple quantum well structure, sandwiched between an n-type semiconductor layer and a p-type semiconductor layer;

said active layer including,

at least one of first well layers made of nitride compound semiconductor containing In, and

at least one of second well layers made of nitride compound semiconductor containing In, said second well layer emitting light having a principal peak wavelength longer than that of said first well layer;

wherein each of growth surfaces of said second well layers is rougher than that of each of said first well layer.

2. A light emitting device according to claim 1,

wherein each of said second well layers has dished portions having thickness less than a half of an average thickness thereof, and an area of the dished portions is not less than 10% thereof.

3. A light emitting device according to claim 2,

wherein said second well layer is disposed between said first well layer and said p-type semiconductor layer.

4. A light emitting device according to claim 3,

wherein the growth number of said first well layer is more than that of said second well layer.

5. A light emitting device according to claim 1,

wherein said second well layer is disposed between said first well layer and said p-type semiconductor layer.

6. A light emitting device according to claim 5,

wherein the growth number of said first well layer is more than that of said second well layer.

7. A light emitting device comprising:

an active layer of a multiple quantum well structure, sandwiched between an n-type semiconductor layer and a p-type semiconductor layer;

said active layer including,

at least one of first well layers made of nitride compound semiconductor containing In, and

at least one of second well layers made of nitride compound semiconductor containing In, said second well layer emitting light having a principal peak wavelength longer than that of said first well layer;

wherein each of said second well layers has dished portions having thickness less than a half of an average thickness thereof, and an area of the dished portions is not less than 10% thereof.

8. A light emitting device according to claim 7,

wherein said second well layer is disposed between said first well layer and said p-type semiconductor layer.

9. A light emitting device according to claim 8,

wherein the growth number of said first well layer is more than that of said second well layer.