Semiconductor light-emitting element having transparent electrode and current blocking layer, and semiconductor light-emitting including the same

• US 6,121,635 A
• Filed: 04/15/1998
• Issued: 09/19/2000
• Est. Priority Date: 04/15/1997
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nozaki, Hideki, Watanabe, Yukio, Saeki, Ryo
• Primary Examiner(s): Tran, Minh Loan
• Application Number:
  US09/060,549
• Time in Patent Office: 888 Days
• Field of Search: 257/94, 257/96, 257/101, 257/102, 257/103, 257/91, 257/99, 257/100, 372/45, 372/46
• US Class Current: 257/91
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/32257 the layer connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• 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 2924/181 Encapsulation
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

A current blocking layer (7) formed immediately below a transparent electrode (9) is formed of a semiconductor layer containing Al, and a bandgap equal to or longer than the emission wavelength. Since the current blocking layer (7) is formed of such semiconductor layer, an oxide film forms on or near the surface of the current blocking layer (7) in a process of forming the transparent electrode (9) such as an ITO film containing oxygen, and the current blocking layer functions effectively. The diameter of a bonding electrode (20) is set to be smaller than that of the current blocking layer (7), thus effectively outputting the light emitted. Furthermore, the oxidized current blocking layer can have a high breakdown voltage and, hence, can be formed to have a small thickness, thus improving step coverage upon forming the transparent electrode on the current blocking layer. By inserting a thin Zn layer (8) between the transparent electrode (9) and an ohmic layer (6), the adhesion therebetween can be improved.

Claims

1. A semiconductor light-emitting element comprising:

a semiconductor substrate;

a light-emitting region grown on said semiconductor substrate and including an active layer having a p-n junction;

a transparent electrode formed to cover the entire light-emitting surface of said light-emitting region and containing oxygen for a light output side electrode;

a bonding electrode formed on said transparent electrode; and

a current blocking layer formed under said transparent electrode and located immediately below said bonding electrode,

wherein said current blocking layer consists of a semiconductor having a bandgap not less than an emission wavelength and containing Al, and

said current blocking layer is located immediately below said bonding electrode with the center thereof matching the center of said bonding electrode, and a difference between diameters of said current blocking layer and bonding electrode is not less than three times a distance from said current blocking layer to said active layer.

2. An element according to claim 1, wherein at least a portion of said current blocking layer is oxidized.

3. An element according to claim 1, wherein a p-type impurity is doped in said active layer at a concentration of 5E16 to 2E17 cm^-3.

4. An element according to claim 1, wherein said current blocking layer consists of In₀.5 (Ga_1-x Al_x)₀.5 P (for 1≧

x>

0.5).

5. An element according to claim 1, wherein said transparent electrode consists of a mixture of indium oxide and tin oxide.

6. A semiconductor light-emitting device comprising:

a semiconductor light-emitting element of claim 1;

a bed portion for supporting and fixing said semiconductor light-emitting element;

a dish-shaped reflection plate formed around said bed portion to surround said semiconductor light-emitting element;

a first lead connected to said bed portion;

a second lead;

a bonding wire for electrically connecting said transparent electrode of said semiconductor light-emitting device element and said second lead; and

a resin capsule for encapsulating said semiconductor light-emitting element, portions of said first and second leads, and said bonding wire.

7. A semiconductor light-emitting element comprising:

a semiconductor substrate;

a light-emitting region grown on said semiconductor substrate and including an active layer having a p-n junction;

a transparent electrode formed to cover the entire light-emitting surface of said light-emitting region and containing oxygen for a light output side electrode;

a bonding electrode formed on said transparent electrode;

an ohmic-contact layer formed on said light-emitting region and under said transparent electrode;

a zinc layer or zinc layer containing gold, which is formed between said transparent electrode and said ohmic-contact layer; and

a current blocking layer formed under said transparent electrode and located immediately below said bonding electrode,

wherein said current blocking layer consists of a semiconductor having a bandgap not less than an emission wavelength and containing Al, and

said current blocking layer is located immediately below said bonding electrode with the center thereof matching the center of said bonding electrode, and a difference between diameters of said current blocking layer and bonding electrode is not less than three times a distance from said current blocking layer to said active layer.

8. An element according to claim 7, wherein said zinc layer or zinc layer containing gold has a thickness of 1 to 5 nm.

9. A semiconductor light-emitting element comprising:

a semiconductor substrate;

a light-emitting region grown on said semiconductor substrate and including an InGaAlP-based active region having a p-n junction;

a transparent electrode formed to cover the entire light-emitting surface of said light-emitting region and containing oxygen for a light output side electrode;

a bonding electrode formed on said transparent electrode;

an ohmic-contact layer formed on said light-emitting region and under said transparent electrode; and

a current blocking layer formed under said transparent electrode and said ohmic-contact layer, and located immediately below said bonding electrode,

wherein said current blocking layer consists of a semiconductor having a bandgap not less than an emission wavelength and containing aluminum, and zinc as a p-type impurity is doped in said active layer at a concentration of 5e16 to 2e17 cm^-3, and

said current blocking layer is located immediately below said bonding electrode with the center thereof matching the center of said bonding electrode, and a difference between diameters of said current blocking layer and bonding electrode is not less than three times a distance from said current blocking layer to said active layer.

10. A semiconductor light-emitting element comprising:

a semiconductor substrate;

a light-emitting region formed on said semiconductor substrate, and having a double heterostructure including a cladding layer and active layer to form a p-n junction;

a current blocking layer formed on said light-emitting region; and

a transparent electrode formed on said light emitting region,

wherein a distance between said active layer and said current blocking layer falls within a range from 0.3 μ

m to 3 μ

m, wherein an edge portion of said transparent electrode is located inside a chip edge portion of said semiconductor light-emitting element.

11. An element according to claim 10, wherein a current diffusion layer having a crystal structure different from said light-emitting region is formed between said light-emitting region and said current blocking layer.

12. An element according to claim 10, wherein a thickness of said semiconductor light-emitting element is not more than 150 μ

m.

13. An element according to claim 10, wherein a chip size of said semiconductor light-emitting element is not more than 250 μ

m.

14. An element according to claim 10, wherein said transparent electrode has a circular or polygonal shape.

15. A semiconductor light-emitting device comprising:

a semiconductor light-emitting element of claim 10;

a bed portion for supporting and fixing said semiconductor light-emitting element;

a dish-shaped reflection plate formed around said bed portion to surround said semiconductor light-emitting element;

a first lead connected to said bed portion;

a second lead;

a bonding wire for electrically connecting said transparent electrode of said semiconductor light-emitting device element and said second lead; and

a resin capsule for encapsulating said semiconductor light-emitting element, portions of said first and second leads, and said bonding wire.