Semiconductor laser with mesa stripe waveguide structure

• US 4,910,743 A
• Filed: 12/13/1988
• Issued: 03/20/1990
• Est. Priority Date: 02/28/1986
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ohba, Yasuo, Ishikawa, Masayuki, Sugawara, Hideto, Watanabe, Yukio, Yamamoto, Motoyuki
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Epps, Georgia Y.
• Application Number:
  US07/283,796
• Time in Patent Office: 462 Days
• Field of Search: 372/43, 372/44, 372/45, 372/46, 357/17
• US Class Current: 372/45.01
• CPC Class Codes: H01S 5/0421 characterised by the semiconducting contacting layers electrodes H01S5/0425
• CPC Class Codes: H01S 5/2231 with inner confining structure only between the active layer and the upper electrode
• CPC Class Codes: H01S 5/3054 p-doping
• CPC Class Codes: H01S 5/32325 red laser based on InGaP
• CPC Class Codes: Y10S 148/095 Laser devices

Abstract

There is disclosed a semiconductor layer which can emit a continuous laser beam in a visible wavelength range. The laser has an n-GaAs substrate. On this substrate, an n-InGaAlP cladding layer, an active layer, and p-InGaAlP cladding layers are sequentially formed, thus forming a double hetero-structure. A mesa-shaped, upper cladding layer is provided, defining a laser beam-guiding channel. A thin p-InGaAlP contact layer and a mesa-shaped, p-GaAs contact layer are formed on the top surface of the upper cladding layer. Two n-type semiconductive, current-blocking layers cover the slanted sides of the upper, mesa-shaped cladding layer and also the contact layer. They are made of the same n-GaAs compound semiconductor material as the substrate.

Claims

1. A semiconductor laser for emitting a laser light, comprising:

a semiconductor substrate of a first conductivity type made of a III-V compound semiconductor material;

a first semiconductor cladding layer section of the first conductivity type provided above said substrate;

an active layer of semiconductor material formed on said cladding layer section;

a second semiconductor cladding layer section of a second conductivity type formed on said active layer so as to form a double hetero-structure, said second cladding layer section including a mesa-shaped layer portion which is formed on or above said active layer and has side surfaces, said layer portion serving as a waveguide channel, said first and second cladding layer sections and said layer portion being made of a specific III-V compound semiconductor material comprising indium, aluminum and phosphorus;

conductive layer means for serving as one of terminal electrodes of said laser;

a semiconductive contact layer provided between said second cladding layer section and said conductive layer means, having a band gap width of a value between those of said layer portion of said second cladding layer section and of said conductive layer means being different from each other, for reducing the rate of band gap variation therebetween; and

a semiconductive current-blocking layer covering said side surfaces of said layer portion of said second cladding layer section, said current-blocking layer being made of III-V compound semiconductor material.

2. The semiconductor laser according to claim 1, wherein said double hetero-structure is made of one material selected from the group consisting of In_x Ga_1-x-y Al_y P (0≦

y≦

1); and

In_x Ga_1-x-y Al_y As (1≦

y≦

1).

3. The semiconductor laser according to claim 2, wherein said substrate is made of GaAs, and said current-blocking layer is made of Ga_1-z Al_z As (1≦

z≦

1).

4. The semiconductor laser according to claim 3, wherein said substrate and said current-blocking layer are made of GaAs.

5. The semiconductor laser according to claim 2, wherein said substrate and said current-blocking layer are made of InP.

6. The semiconductor laser according to claim 5, wherein the band gap width of said contact layer is smaller than that of said layer portion of said second cladding layer section and yet greater than that of said conductive layer means.

7. The semiconductor laser according to claim 1, wherein said second cladding layer section includes a plurality of semiconductor layers of the same conductivity type.

8. A semiconductor laser for emitting a laser light, comprising:

a semiconductor substrate of a first conductivity type made of a III-V compound semiconductor material;

a first semiconductor cladding layer section of the first conductivity type provided above said substrate;

an active layer of semiconductor material formed on said cladding layer section;

a second semiconductor cladding layer section of a second conductivity type formed on said active layer so as to form a double hetero-structure, said second cladding layer section including a mesa-shaped layer portion which is formed on or above said active layer and has side surfaces defining a waveguide channel, said first and second cladding layer sections and said layer portion being made of a specific III-V compound semiconductor material comprising indium, aluminum and phosphorus;

conductive layer means for serving as one of terminal electrodes of said laser;

a first semiconductive contact layer sandwiched between said layer portion of said second cladding layer section and said conductive layer means, having a band gap width of a value between those of said layer portion of said second cladding layer section and of said conductive layer means being different from each other, for reducing the rate of band gap variation therebetween;

a semiconductive current-blocking layer covering said side surfaces of said layer portion of said second cladding layer section, said current-blocking layer being made of III-V compound semiconductor material; and

a second semiconductive contact layer of the second conductivity type covering the top surfaces of said first contact layer and said current-blocking layer, said second semiconductor contact layer having a flat top surface.

9. The semiconductor laser according to claim 8, wherein said first and second cladding layer sections are made of a material selected from the group consisting of In_x Ga_1-x-y Al_y P (0<

y<

1) and In_x Ga_1-x-y Al_y As (0<

y<

1).

10. The semiconductor laser according to claim 9, wherein said substrate is made of GaAs, and said current-blocking layer is made of Ga_1-z Al_z As (0<

z<

1).

11. The semiconductor laser according to claim 10, wherein said current-blocking layer is made of GaAs.

12. The semiconductor laser according to claim 9, wherein said substrate and said current-blocking layer are made of InP.

13. The semiconductor laser according to claim 9, wherein the band gap width of said first contact layer is smaller than that of said layer portion of said second cladding layer and yet greater than that of said conductive layer means.

14. The semiconductor laser according to claim 8, wherein said second cladding layer section includes a plurality of semiconductor layers of the same conductivity type.

15. A semiconductor laser for emitting a continuous laser light, comprising:

a semiconductor substrate of a first conductivity type made of III-V semiconductor cladding material;

a first semiconductor cladding layer section of the first conductivity type provided above said substrate;

an active layer of semiconductor material formed on said cladding layer section;

a second semiconductor cladding layer section of a second conductivity type formed on said active layer so as to form a double hetero-structure, said second cladding layer section including a mesa-shaped layer portion which is formed on or above said active layer and has side surfaces defining a waveguide channel, and first and second cladding layer sections and said layer portion being made of a specific III-V compound semiconductor material comprising indium, aluminum and phosphorus;

conductive layer means for serving as one of terminal electrodes of said laser;

a semiconductive contact layer provided between said second cladding layer section and said conductive layer means, having a band gap width which is smaller than that of said layer portion of said second cladding layer section and yet greater than that of said conductive layer means being different from each other, for reducing the rate of band gap variation between said second cladding layer section and said first contact layer so that an electrical resistance therebetween is lowered, said contact layer comprising III-V compound semiconductor material containing at least indium, gallium and phosphorus; and

a semiconductive current-blocking layer covering said side surfaces of said layer portion of said second cladding layer section, said current-blocking layer being made of III-V compound semiconductor material which contains at least one of gallium and aluminum as its III semiconductor element, and arsenide as its V semiconductor element.

16. The semiconductor laser according to claim 15, wherein said second cladding layer section includes a plurality of semiconductor layers of the same conductivity type.

17. A semiconductor laser for emitting a laser light, comprising:

a substrate;

a first semiconductor cladding layer section of a first conductivity type provided above said substrate;

an active layer of semiconductor material formed on said cladding layer section;

a second semiconductor cladding layer section of a second conductivity type formed on said active layer so as to form a double hetero-structure, said second cladding layer including a mesa-shaped layer portion which is formed on or above said active layer and serves as a mesa waveguide structure, said first and second cladding layer sections and said mesa-shaped layer portion being made of a specific III-V compound semiconductor material comprising indium, aluminum and phosphorus;

conductive layer means for serving as one of terminal electrodes of said laser;

a semiconductive contact layer provided between said second cladding layer section and said conductive layer means, having a band gap width of a value between those of said layer portion of said second cladding layer and of said conductive layer means being different from each other, for reducing the rate of band gap variation therebetween; and

a semiconductive current-blocking layer covering said side surface of said layer portion of said second cladding layer, said current-blocking layer being made of III-V compound semiconductor material.

18. The semiconductor laser according to claim 17, wherein said second cladding layer section includes a plurality of semiconductor layers of the same conductivity type.