High-brightness blue-light emitting crystalline structure

• US 20020117672A1
• Filed: 02/23/2001
• Published: 08/29/2002
• Est. Priority Date: 02/23/2001
• Status: Abandoned Application

• Current Assignee: Huga Optotech Incorporated (Epistar Corporation)
• Original Assignee: Huga Optotech Incorporated (Epistar Corporation)
• Inventors: Sung, Chun-Yung, Chang, Liang-Tung, Chu, Ming-Sung, Chen, Shi-Kun
• Application Number:
  US09/792,446
• Publication Number:
  US 20020117672A1
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

A high-brightness blue-light emitting crystalline structure is provided for enhancing illuminating intensity of a blue-light emitting diode by taking advantage of a sapphire substrate, which is provided with a multi-layer distributed Bragg reflector (DBR) or a plated mirror layer on its surface for reflecting a part of the light created from a P-GaN surface so as to supplement the other part of light, which penetrates a transparent conductive layer directly. And, indium tin oxide is adopted for serving as a transparent conductive layer of blue-light emitting diode, or an extraordinarily thin nickel/aurum layer is plated on the P-GaN surface precedently before forming the ITO conductive layer to thereby care both the light-permeability and the ohmic contact resistance. A plurality of anti-reflection coatings (ARC) is formed on the ITO conductive layer for the enhancement of blue-light emissivity.

Claims

1. A high-brightness blue-light emitting crystalline structure, comprising:

a transparent substrate having a first and a second surface;

a semiconductor stack layer formed on the first surface of the transparent substrate being provided at least with an N-GaN series semiconductor layer of group III-V compounds and a P-GaN series semiconductor layer of group III-V compounds, wherein a multiple-quantum-well structured illuminating layer is formed between those two N-GaN series and P-GaN series semiconductor layers;

a plated mirror layer formed and plated on the second surface of the transparent substrate;

a first electrode provided for connection with the N-GaN series semiconductor layer of group III-V compounds; and

a second electrode made of a light-permeable material being provided for connection with the P-GaN series semiconductor layer of group III-V compounds.

2. The structure according to claim 1, wherein the plated mirror layer is made of any of the following materials including:

aluminum, nickel, silver, titanium, copper, aurum, beryllium-aurum, germanium-aurum, nickel-aurum-germanium, etc, or their alloys, and the thickness of the plated mirror layer is 1 nm˜

10 μ

m.

11. A high-brightness blue-light emitting crystalline structure according to claim 1, claim 3, or claim 5, wherein the light permeable second electrode is substantially an electrically conductive transparent electrode made of Indium tin oxide (ITO).

12. The structure according to claim 11, wherein an extraordinarily thin Ni/Au layer is predeterminately arranged under the ITO transparent conductive layer and between the same and the semiconductor stack layer, and the thickness of the Ni/Au layer is 0.1˜

10 nm.

13. The structure according to claim 11, wherein a plurality of anti-reflection coatings (ARC) are formed on the ITO transparent conductive layer;

the ARC are made in SiO₂/TiO₂ or AlN/AlGaN with n-pair layers (n=5˜

50); and

the thickness of each layer is about one half of the blue-light wavelength.

14. The structure according to claim 12, wherein a plurality of anti-reflection coatings (ARC) are formed on the ITO transparent conductive layer;

the ARC are made in SiO₂/TiO₂ or AlN/AlGaN with n-pair layers (n=5˜

50); and

the thickness of each layer is about one half of the blue-light wavelength.

3. A high-brightness blue-light emitting crystalline structure, comprising:

a transparent substrate having a first and a coarsened second surface;

a semiconductor stack layer formed on the first surface of the transparent substrate being provided at least with an N-GaN series semiconductor layer of group III-V compounds and a P-GaN series semiconductor layer of group III-V compounds;

a coarsened mirror layer formed to cover the coarsened second surface of the transparent substrate;

a first electrode provided for connection with the N-GaN series semiconductor layer of group III-V compounds; and

a second electrode made of a light-permeable material being provided for connection with the P-GaN series semiconductor layer of group III-V compounds.

4. The structure according to claim 3, wherein the coarse index of the coarsened second surface is about 5˜

20 μ

m.

5. A high-brightness blue-light emitting crystalline structure, comprising:

a transparent substrate having a first and a coarsened second surface;

a plurality of multi-layer distributed Bragg reflectors (DBR) formed on the first surface of the transparent substrate;

a semiconductor stack layer formed on the first surface of the transparent substrate being provided at least with an N-GaN series semiconductor layer of group III-V compounds and a P-GaN series semiconductor layer of group III-V compounds;

a first electrode provided for connection with the N-GaN series semiconductor layer of group III-V compounds; and

a second electrode made of a light-permeable material being provided for connection with the P-GaN series semiconductor layer of group III-V compounds.

6. The structure according to claim 5, wherein the material of the multi-layer distributed Bragg reflector is (Al_xGa₁₋

x)<sub>1−

y</sub>In_yN/(Al_aGa<sub>1−

a</sub>)<sub>1−

b</sub>In_bN (where x>

a) with epitaxial layer in n pairs (where n=5˜

50), wherein the thickness of each epitaxial layer is correspondent to one-fourth of blue-light wavelength.

7. A high-brightness blue-light emitting crystalline structure, comprising:

a transparent substrate having a first and a coarsened second surface;

a semiconductor stack layer formed on the first surface of the transparent substrate being provided at least with an N-GaN series semiconductor layer of group III-V compounds and a P-GaN series semiconductor layer of group III-V compounds;

a first electrode provided for connection with the N-GaN series semiconductor layer of group III-V compounds; and

a second electrode provided for connection with the P-GaN series semiconductor layer of group III-V compounds being a transparent conductive layer made of light permeable indium tin oxide (ITO).

8. The structure according to claim 7, wherein an extraordinarily thin Ni/Au layer is predeterminately arranged under the ITO transparent conductive layer and between the same and the semiconductor stack layer, and the thickness of the Ni/Au layer is 0.1˜

10 nm.

9. The structure according to claim 7, wherein a plurality of anti-reflection coatings (ARC) are formed on the ITO transparent conductive layer;

the ARC are made in SiO₂/TiO₂ or AlN/AlGaN with n-pair layers (n=5˜

50); and

the thickness of each layer is about one half of the blue-light wavelength.

10. The structure according to claim 8, wherein a plurality of anti-reflection coatings (ARC) are formed on the ITO transparent conductive layer;

the ARC are made in SiO₂/TiO₂ or AlN/AlGaN with n-pair layers (n=5˜

50); and

the thickness of each layer is about one half of the blue-light wavelength.