Semiconductor light-emitting diode

• US 6,936,858 B1
• Filed: 08/13/1999
• Issued: 08/30/2005
• Est. Priority Date: 08/21/1998
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Nakatsu, Hiroshi, Yamamoto, Osamu
• Primary Examiner(s): Lee, Eddie
• Assistant Examiner(s): Kang, Donghee
• Application Number:
  US09/373,544
• Time in Patent Office: 2,209 Days
• Field of Search: 257/94, 257/96, 257/97, 257/103, 438/22, 438/46, 438/47
• US Class Current: 257/94
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous

Abstract

A light-emitting diode includes: a semiconductor substrate; and a layered structure, made of an AlGaInP type compound semiconductor material and provided on the semiconductor substrate. The layered structure includes: a light-emitting structure composed of a pair of cladding layers and an active layer for emitting light provided between the pair of cladding layers; and a current diffusion layer which is lattice-mismatched with the light-emitting structure. A lattice mismatch Δa/a of the current diffusion layer with respect to the light-emitting structure defined by the following expression is −1% or smaller:
Δa/a=(a_d−a_e)/a_e
where a_d is a lattice constant of the current diffusion layer, and a_e is a lattice constant of the light-emitting structure.

Claims

1. A light-emitting diode comprising:

a semiconductor substrate; and

a layered structure comprising an AlGaInP type compound semiconductor material and provided on the semiconductor substrate,

wherein the layered structure comprises;

a light-emitting structure composed of a pair of cladding layers and an active layer for emitting light provided between the pair of cladding layers; and

a current diffusion layer comprising an AlGaInP type material which is lattice-mismatched with the light-emitting structure, wherein a lattice mismatch Δ

a/a of the current diffusion layer with respect to the light-emitting structure defined by the following expression is −

1% or smaller;

Δ

a/a=(a_d−

a_e)/a_e

where a_d is a lattice constant of the current diffusion layer, and a_e is a lattice constant of the light-emitting structure, and

wherein crystal of the semiconductor substrate is inclined by 8°

(degrees) to 20°

(20 degrees) in a 011 direction with respect to a (100) plane thereof.

2. A light-emitting diode according to claim 1, wherein a composition of the current diffusion layer is selected in such a manner that the current diffusion layer becomes transparent with respect to a wavelength of light emitted from the light-emitting structure.

3. A light-emitting diode according to claim 1, wherein a composition of the current diffusion layer is expressed as (Al_xGa₁₋

x)_yIn<sub>1−

y</sub>P, and x is set in the range of 0.01to 0.05 and 1−

y is set in the range of 0.01 to 0.30in the composition.

4. A light-emitting diode comprising:

a semiconductor substrate, and

a layered structure comprising an AlGaInP type compound semiconductor material and provided on the semiconductor substrate,

wherein the layered structure comprises;

a light-emitting structure composed of a pair of cladding layers and an active layer for emitting light provided between the pair of cladding layers; and

a current diffusion layer comprising an AlGaInP type material which is lattice-mismatched with the light-emitting structure, wherein a lattice mismatch Δ

a/a of the current diffusion layer with respect to the light-emitting structure defined by the following expression is −

1% or smaller;

Δ

a/a=(a_d−

a_e)a_e

where a_d is a lattice constant of the current diffusion layer, and a_e is a lattice constant of the light-emitting structure, and

wherein a composition of the current diffusion layer is expressed as (Al_xGa<sub>1−

x</sub>)_yIn<sub>1−

y</sub>P, and at least one of a value of x and a value of 1−

y in the composition varies along a thickness direction of the layered structure.

5. A light-emitting diode according to claim 4, wherein both the values of x and 1−

y in the composition of the current diffusion layer vary, independent of each other.

6. A light-emitting diode comprising

a semiconductor substrate;

and

a layered structure comprising an AlGaInP type compound semiconductor material and provided on the semiconductor substrate,

wherein the layered structure comprises;

a light-emitting structure composed of a pair of cladding layers and an active layer for emitting light provided between the pair of cladding layers; and

a current diffusion layer comprising an AlGaInP type material which is lattice-mismatched with the light-emitting structure, wherein a lattice mismatch Δ

a/a of the current diffusion layer with respect to the light-emitting structure defined by the following expression is −

1% or smaller;

Δ

a/a=(a_d−

a_e)a_e

where a_d is a lattice constant of the current diffusion layer, and a_e is a lattice constant of the light-emitting structure, and

wherein a composition of the current diffusion layer is expressed as (Al_xGa<sub>1−

x</sub>)_yIn<sub>1−

y</sub>P, and at least one of a value of x and a value of 1−

y in the composition decreases in a step-like manner along a thickness direction of the layered structure from an interface with the light-emitting structure toward opposite end of the current diffusion layer.

7. A light-emitting diode according to claim 6, wherein both the values of x and 1−

y in the composition of the current diffusion layer decrease, independent of each other.

8. A light-emitting diode comprising:

a semiconductor substrate; and

a layered structure comprising an AlGaInP type compound semiconductor material and provided on the semiconductor substrate,

wherein the layered structure comprises;

a light-emitting structure composed of a pair of cladding layers and an active layer for emitting light provided between the pair of cladding layers; and

a current diffusion layer comprising an AlGaInP type material which is lattice-mismatched with the light-emitting structure, wherein a lattice mismatch Δ

a/a of the current diffusion layer with respect to the light-emitting structure defined by the following expression is −

1% or smaller;

Δ

a/a=(a_d−

a_e)/a_e

where a_d is a lattice constant of the current diffusion layer, and a_e is a lattice constant of the light-emitting structure, and

wherein a composition of the current diffusion layer is expressed as (Al_xGa<sub>1−

x</sub>)_yIn<sub>1−

y</sub>P, and at least one of a value of x and a value of 1−

y in the composition varies in a step-like manner along a thickness direction of the layered structure from an interface with the light-emitting structure toward opposite end of the current diffusion layer, thereby controlling a resistivity of the current diffusion layer in the thickness direction.

9. A light-emitting diode according to claim 8, wherein both the values of x and 1−

y in the composition of the current diffusion layer vary, independent of each other.