Light emitting device

• US 7,476,909 B2
• Filed: 12/20/2005
• Issued: 01/13/2009
• Est. Priority Date: 12/20/2004
• Status: Expired due to Fees

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Kitabayashi, Hiroyuki, Saito, Hirohisa, Ikeda, Ayako, Nagai, Youichi
• Primary Examiner(s): Tran; Minh-Loan T
• Assistant Examiner(s): Yang; Minchul
• Application Number:
  US11/311,638
• Publication Number:
  US 20060157717A1
• Time in Patent Office: 1,120 Days
• Field of Search: 257/95, 257/98, 257/E33.066, 257/74, 257/91, 257/99
• US Class Current: 257/94
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45139 Silver (Ag) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01004 Beryllium [Be]
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01049 Indium [In]
• CPC Class Codes: H01L 2924/10155 being other than a cuboid
• CPC Class Codes: H01L 2924/10158 at the passive surface
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/20752 larger or equal to 20 microns less than 30 microns
• CPC Class Codes: H01L 2924/2076 equal to or larger than 100 microns
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01L 33/22 : Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

A light emitting device having a simple structure that can be easily manufactured, attaining high light emitting efficiency stably for a long time is obtained, which light emitting device includes: a GaN substrate as a nitride semiconductor substrate and, on a first main surface of the nitride semiconductor substrate, an n-type Al_xGa_1-xN layer, a p-type Al_xGa_1-xN layer positioned further than the n-type Al_xGa_1-xN layer viewed from the nitride semiconductor substrate, and a quantum well positioned between the n-type Al_xGa_1-xN layer and the p-type Al_xGa_1-xN layer. In the light emitting device, specific resistance of the nitride semiconductor substrate is at most 0.5 Ω·cm, the side of p-type Al_xGa_1-xN layer is mounted face-down, and the light is emitted from the second main surface 1a that is opposite to the first main surface of the nitride semiconductor substrate. The second main surface 1a of nitride semiconductor substrate has trenches formed therein.

Claims

1. A light emitting device, comprising:

a nitride semiconductor substrate and, on a first main surface of said nitride semiconductor substrate, an n-type nitride semiconductor layer, a p-type nitride semiconductor layer positioned further than said n-type nitride semiconductor layer viewed from said nitride semiconductor substrate, and a light generating layer positioned between said n-type nitride semiconductor layer and said p-type nitride semiconductor layer;

wherein specific resistance of said nitride semiconductor substrate is at most 0.5 Ω

·

cm;

the side of said p-type nitride semiconductor layer is mounted face-down and the light is emitted from a second main surface that is opposite to the first main surface of said nitride semiconductor substrate;

a trench is formed in the second main surface of said nitride semiconductor substrate;

said nitride semiconductor substrate is adapted to have n-type conductivity by oxygen doping, and an oxygen concentration in the range of 2E18/cm³ to 2E19/cm³;

a two-dimensional shape of said nitride semiconductor substrate is a rectangle;

a length of one side of the two-dimensional shape of said nitride semiconductor substrate is at least 1 mm and at most 4 mm;

said trench has a V shaped cross section;

a depth of said trench is at least 0.1 mm and at most 0.3 mm;

a thickness of said nitride semiconductor substrate in the thickness direction where said trench is not formed is at least 0.2 mm and at most 0.4 mm; and

n-electrodes are disposed only at four corners of the second main surface of the nitride semiconductor substrate.

2. The light emitting device according to claim 1, wherein an angle formed by a sidewall of said trench and said second main surface of said nitride semiconductor substrate is at least 40°

and at most 80°

.

3. The light emitting device according to claim 1, wherein on said second main surface of said nitride semiconductor substrate, another trench is formed extended in the same direction as the direction of extension of said trench;

and

pitch between said trench and said another trench in the direction vertical to the direction of extension of the trenches is at most 1 mm.

4. The light emitting device according to claim 1, wherein sidewall of said trench includes a sidewall portion continuous from the bottom of said trench and another sidewall portion positioned on said sidewall portion;

and

an angle formed by the sidewall portion and said second main surface is different from an angle formed by said another sidewall portion and said second main surface.

5. The light emitting device according to claim 1, wherein said nitride semiconductor substrate is a GaN substrate;

on said second main surface of said nitride semiconductor substrate, at least one, another trench extended in the same direction as the direction of extension of said trench and at least one trench of different direction extending in a direction crossing said trench are formed;

pitch between said trench and said another trench in the direction vertical to the direction of extension of the trenches is at most 1 mm; and

a portion of said second main surface of said nitride semiconductor substrate sectioned by said trench, said another trench and said trench of different direction has a shape selected from the group consisting of polygonal cone, a circular cone, and a semi-sphere.

6. The light emitting device according to claim 1, wherein at least a portion of said second main surface of said nitride semiconductor substrate has recesses.