Semiconductor light emitting element with improved light extraction efficiency

• US 6,956,241 B2
• Filed: 04/04/2003
• Issued: 10/18/2005
• Est. Priority Date: 04/05/2002
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Abe, Hirohisa, Konno, Kuniaki, Sugawara, Hideto, Watanabe, Yukio
• Primary Examiner(s): Wilczewski, Mary
• Assistant Examiner(s): Lewis, Monica
• Application Number:
  US10/407,867
• Publication Number:
  US 20030218172A1
• Time in Patent Office: 928 Days
• Field of Search: 257/79, 257/94, 257/95, 257/98, 257/103
• US Class Current: 257/79
• CPC Class Codes: H01L 2224/32245 the item being metallic
• 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 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 2924/00012 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 2924/10155 being other than a cuboid
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

A high-luminance light emitting element is manufactured by a method comprising: forming a light emitting layer on a first surface of a GaP substrate including the first surface and a second surface opposed to the first surface and having an area smaller than the first area, the light emitting layer emitting light of a wavelength λ permitted to pass through the GaP substrate; forming a plurality of side surfaces on the GaP substrate to be respectively aslant by substantially the same angle to become narrower toward the second surface; and forming a plurality of depressions and protrusions as high as 0.1 λ to 3 λ on the side surfaces.

Claims

1. A semiconductor light emitting element comprising:

a light emitting layer for emitting light of a wavelength λ

by current injection; and

a GaP substrate transparent to light of the wavelength λ

, the GaP substrate being an off-axis (100) GaP substrate with an off-axis angle of θ

(5°

≦

θ

≦

20°

) along the direction, and having;

a first surface on which the light emitting layer is formed;

a second surface opposed to the first surface and having an area smaller than the first surface; and

first to fourth side surfaces, the first and the third side surfaces being opposed to each other, the second and the fourth side surfaces being opposed to each other, the first side surface being (1-11) oriented, the second side surface being slanted from a (111) orientation, the third side surface being (11-1) oriented, the fourth side surface being slanted from a (1-1-1) orientation, the first to fourth side surfaces individually being aslant to become narrower toward the second surface and permitting part of light from the light emitting layer to be extracted externally therethrough, the first to fourth side surfaces having a plurality of depressions and protrusions along outer surfaces thereof,

wherein the depressions and protrusions have a height in a range from a lower limit equal to or higher than 0.1 λ

to an upper limit equal to or lower than 3 λ

.

2. A semiconductor light emitting element according to claim 1 wherein the first to fourth side surfaces are respectively aslant by substantially a same angle to become narrower toward the second surface.

3. A semiconductor light emitting element according to claim 1 wherein the light emitting layer includes an InGaAlP layer.

4. A semiconductor light emitting element according to claim 1 wherein the wavelength λ

is 650 nm.

5. A semiconductor light emitting element comprising:

a light emitting layer for emitting light of a wavelength λ

by current injection; and

a GaP substrate transparent to light of wavelength λ

, the GaP substrate is a just substrate having no inclination in surface orientation and having;

a first surface on which the light emitting layer is formed;

a second surface opposed to the first surface and having an area smaller than the first surface; and

first to fourth side surfaces, the first and the third side surfaces being opposed to each other, the second and the fourth side surfaces being opposed to each other, the first side surface being (1-11) oriented, the second side surface being (111) orientated, the third side surface being (11-1) oriented, the fourth side surface being (1-1-1) orientated, said first to fourth side surfaces individually being aslant to become narrower toward the second surface and permitting part of light from the light emitting layer to be extracted externally therethrough, the first to fourth side surfaces having a plurality of depressions and protrusions along outer surfaces thereof for enhancing light extraction efficiency and optical output,

wherein the depressions and protrusions have a height in a range from a lower limit equal to or higher than 0.1 λ

to an upper limit equal to or lower than 3 λ

.

6. A semiconductor light emitting element according to claim 5 wherein the side surfaces are respectively aslant by substantially a same angle to become narrower toward the second surface.

7. A semiconductor light emitting element according to claim 5 wherein the light emitting layer includes an InGaAlP layer.

8. A semiconductor light emitting element according to claim 5 wherein the wavelength λ

is 650 nm.