Surface-emitting light-emitting diode

• US 6,420,735 B2
• Filed: 08/03/1999
• Issued: 07/16/2002
• Est. Priority Date: 05/07/1997
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Taek
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): Wille, Douglas A.
• Application Number:
  US09/365,781
• Publication Number:
  US 20010048113A1
• Time in Patent Office: 1,078 Days
• Field of Search: 257/95, 257/98
• US Class Current: 257/95
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape

Abstract

A surface-emitting light-emitting diode having increased light emission is provided. The surface-emitting light-emitting diode includes a substrate, a light generating layer comprising an active layer for generating light, and an upper clad layer and a lower clad layer formed on and below the active layer, respectively, a lower contact layer formed between the light generating layer and the substrate, a buffer layer formed between the lower contact layer and the substrate, a lower ohmic metal layer which ohmically contacts one side of the lower contact layer, an upper contact layer formed on the light generating layer and having a substantially sinusoidal uneven surface portion; and a light transmissive upper ohmic metal layer formed on the upper contact layer, in which the active layer is composed of GaN or AlN, the lower contact layer is composed of doped n-GaN, the upper contact layer is composed doped p-GaN, and the substantially sinusoidal uneven surface portion increases the contact area between the upper contact layer and light transmissive upper ohmic metal layer for reducing the contact resistance therebetween. Therefore, ohmic contact resistance and operating current are reduced, so that durability is improved due to the reduction of hear generated in the device. Also, light is condensed by the substantially sinusoidal uneven surface portion and thus the amount of light which is totally reflected internally is reduced. Accordingly, no additional package device is required and external quantum efficiency is increased.

Claims

1. A surface-emitting light-emitting diode comprising:

a substrate;

a light generating layer comprising an active layer for generating light, and an upper clad layer and a lower clad layer formed on and below said active layer, respectively;

a lower contact layer formed between said light generating layer and said substrate;

a buffer layer formed between said lower contact layer and said substrate;

a lower ohmic metal layer which ohmically contacts one side of said lower contact layer;

an upper contact layer formed on said light generating layer and having a substantially sinusoidal uneven surface portion; and

a light transmissive upper ohmic metal layer formed on said upper contact layer,

wherein said active layer is composed of GaN or AlN, said lower contact layer is composed of doped n-GaN, said upper contact layer is composed of doped p-GaN, and said uneven surface portion increases the contact area between said upper contact layer and light transmissive upper ohmic metal layer for reducing the contact resistance therebetween.

2. The surface-emitting light-emitting diode as claimed in claim 1, wherein said uneven surface portion is formed in accordance with a predetermined pattern.

3. The surface-emitting light-emitting diode as claimed in claim 1, wherein said uneven surface portion is formed to operate as an optical lens for condensing the light passed through from said light generating layer to said transmissive upper ohmic metal layer.

4. The surface-emitting light-emitting diode as claimed in claim 1, wherein said buffer layer consists essentially of GaN or AlN.

5. The surface-emitting light-emitting diode as claimed in claim 1, wherein said lower clad layer is composed of doped n-GaN or n-AlGaN.

6. The surface-emitting light-emitting diode as claimed in claim 1, wherein said upper clad layer is composed of p-GaN or p-AlGaN.