KR100789111B1 - Semiconductor laser diode with improved thermal characteristics and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a semiconductor laser diode having excellent thermal characteristics and a method of manufacturing the same, wherein an n-clad layer, an active layer and a first clad layer are sequentially stacked on an n-GaAs substrate; A second p-clad layer having a ridge shape having a rhombus shape on top of the first p-clad layer, and an n-current blocking layer surrounding both sides of the second p-clad layer; A third p-clad layer having a ridge structure having a rhombus shape is formed on an upper surface of the second clad layer and a portion of the n-current blocking layer; A p-GaAs cap layer is formed on the third p-clad layer; P-GaAs layers are formed on upper surfaces of the n-current blocking layer, both sides of the third p-clad layer, and both sides and upper surfaces of the p-GaAs cap layer; The semiconductor is formed so that a p-metal layer having the same shape as the surface shape of the p-GaAs layer is formed on the p-GaAs layer, and an n-metal layer is formed below the n-GaAs substrate. The heat path emitted near the ridge of the laser diode is shortened to effectively release heat, thereby improving the characteristics of the device.

Semiconductor, laser, heat, pass, ridge, emission

Description

Semiconductor laser diode with improved thermal characteristics and manufacturing method thereof             

1 is a cross-sectional view of a semiconductor laser diode having a conventional ridge waveguide structure.

2A to 2E are manufacturing process diagrams of a semiconductor laser diode having excellent thermal characteristics according to the present invention.

3A and 3B are diagrams showing paths of heat emitted from the semiconductor laser diode of the prior art and the present invention.

<Description of the symbols for the main parts of the drawings>

10, 20: n-GaAs substrate 11, 21: n- clad layer

12, 22: active layer 13, 23: first p-clad layer

14, 24: second p-clad layer 15, 25: n-current prevention layer

16, 26: third p-clad layer 17, 27: p-GaAs cap layer

18, 29: p-metal layer 19, 30: n-metal layer                 

28: p-GaAs layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser diode having excellent thermal characteristics and a method for manufacturing the same. More particularly, the present invention relates to a semiconductor laser diode capable of shortening a heat path emitted near a ridge and to excellent thermal characteristics. It is about.

Recently, in the case of laser diodes used for pick-up of high-capacity high-speed storage devices such as CD-RW or DVD (Digital Versatile Disk) -Random Access Memory (RAM), Diodes are getting higher power.

Reliability can be secured only by effectively dissipating heat generated in the device due to the high output of the laser diode to the outside.

In particular, the CD-RW and DVD-RAM systems require high vertical radiation angles and high horizontal radiation angles as well as high laser power. This makes it possible to reduce the light loss from the optical system in the system using the optical system, thereby bringing up the system's double speed.

Therefore, in the case of a high speed system, even if the same power output can be increased by the improvement of the radiation angle only.

However, in the wave guide structure to reduce the vertical radiation angle, the near field of light is spread far from the active layer.

1 is a cross-sectional view of a laser diode of a conventional ridge waveguide structure, in which an n-clad layer 11 and an active layer 12 are stacked on an n-GaAs substrate 10, and the active layer The first p-clad layer 13, the second p-clad layer 14 and the third p-clad layer 16 having a ridge structure are sequentially stacked on the upper portion of the ridge 12. An n-current blocking layer 15 is formed on both sides of the second p-clad layer 14 of the structure, and the p-GaAs cap layer 17 and the p-metal are formed on the third p-clad layer 16. Layer 18 is formed. An n-metal layer 19 is formed below the n-GaAs substrate 10.

As described above, the laser diode of FIG. 1 adopts a ridge type wave guide structure to reduce the vertical emission angle of light emitted from the active layer 12. In order to prevent absorption of the spread light, The cladding layer 16 is inserted between the P-GaAs cap layer 17 and the second cladding layer 14 of the ridge structure.

However, laser diodes employing such a ridge waveguide structure are designed to emit light and electrical carriers near the ridge, causing a lot of heat generation in the vicinity of the ridge.

At this time, the generated heat is discharged to the outside of the device through the first to third cladding layers 13, 14, 16 and the p-metal layer 18.                         

In other words, the laser diode of the current structure has a problem of dissipating heat through the thick cladding layer, and the path from which the heat is released from the ridge structure becomes longer toward the outer portion of the ridge structure, which does not efficiently dissipate the generated heat. .

Accordingly, the present invention has been made to solve the problems described above, and the semiconductor laser diode having excellent thermal characteristics that can effectively release the heat by optimizing the heat path emitted near the ridge to improve the characteristics of the device and its manufacture The purpose is to provide a method.

According to a preferred aspect of the present invention, an n-clad layer, an active layer and a first clad layer are sequentially stacked on an n-GaAs substrate;

A second p-clad layer having a ridge shape having a rhombus shape on top of the first p-clad layer, and an n-current blocking layer surrounding both sides of the second p-clad layer;

A third p-clad layer having a ridge structure having a rhombus shape is formed on an upper surface of the second p-clad layer and a portion of the n-current blocking layer;

A p-GaAs cap layer is formed on the third p-clad layer;

P-GaAs layers are formed on upper surfaces of the n-current blocking layer, both sides of the third p-clad layer, and both sides and upper surfaces of the p-GaAs cap layer;

A p-metal layer having the same shape as the surface shape of the p-GaAs layer is formed above the p-GaAs layer, and an n-metal layer is formed below the n-GaAs substrate. A semiconductor laser diode having excellent thermal characteristics is provided.

Another preferred aspect for achieving the above object of the present invention is a first step of sequentially forming an n- clad layer, an active layer and a first p- clad layer on top of the n-GaAs substrate;

A second p-clad layer is formed at a central portion of the upper portion of the first p-clad layer in a ridge structure having a narrow top surface and a wide bottom surface, and both sides of the second p-clad layer are formed. Wrapping and forming an n-current blocking layer over the p-clad layer;

A third step of sequentially stacking a third p-clad layer and a p-GaAs cap layer on the second p-clad layer and the n-current blocking layer;

Etching the third p-clad layer and the p-GaAs cap layer to form a ridge structure in a rhombus shape, and exposing a portion of the n-current blocking layer;

Forming a p-GaAs layer on exposed surfaces of the n-current blocking layer, both sides of the third p-clad layer, and both sides and top surfaces of the p-GaAs cap layer;

And a sixth step of forming a p-metal layer having a constant thickness on the top of the p-GaAs layer and an n-metal layer on the bottom of the n-GaAs substrate. Provided is a method of manufacturing a semiconductor laser diode having excellent thermal characteristics.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2A to 2E are process charts for manufacturing a semiconductor laser diode having excellent thermal characteristics according to the present invention. The n-clad layer 21, the active layer 22, and the first p- are formed on an n-GaAs substrate 20. The cladding layer 23 is formed sequentially (FIG. 2A).

A second p-clad layer 24 is formed at a central portion of the upper portion of the first p-clad layer 23 in a ridge structure having a narrow top surface and a wide bottom surface, and the second p-clad layer 24 is formed. The n-current blocking layer 25 is formed on the upper surface of the first p-clad layer 23 while covering both sides of the cladding layer 24 (FIG. 2B).

Then, the third p-clad layer 26 and the p-GaAs cap layer 27 are sequentially stacked on the second p-clad layer 24 and the n-current blocking layer 25. (FIG. 2C) )

The third p-clad layer 26 and the p-GaAs cap layer 27 stacked as described above are etched to form a ridge structure in a rhombus shape, and a portion of the n-current prevention layer 25 is exposed (FIG. 2D). )

In FIG. 2E, the p-GaAs layer 28 is formed on the exposed surface of the n-current blocking layer 25, on both sides of the third p-clad layer, and on both sides and the top surface of the p-GaAs cap layer 27. .

The p-GaAs layer 28 is preferably formed in a thickness of 100 kV to 2000 kPa.

Thereafter, a p-metal layer 29 having a predetermined thickness is formed on the p-GaAs layer 28 from the surface of the p-GaAs layer 29, and n- is formed under the n-GaAs substrate 20. By forming the metal layer 30 (FIG. 2F), the semiconductor laser diode excellent in the thermal characteristics of the present invention is manufactured.

Here, the thickness of the p-metal layer 29 is preferably formed in the range of 0.5 ~ 2 ㎛.

In the semiconductor laser diode of the present invention thus completed, the n-clad layer 21, the active layer 22 and the first p-clad layer 23 are sequentially stacked on the n-GaAs substrate 20; The n-current blocking layer 25 surrounds both sides of the second p-clad layer 24 having a ridge structure on the first p-clad layer 23 and the second p-clad layer 24. ) Is formed; A third p-clad layer (26) having a ridge structure having a rhombus shape is formed on an upper surface of the second p-clad layer (24) and a portion of the n-current blocking layer (25); A p-GaAs cap layer 27 is formed on the third p-clad layer 26; P-GaAs layers 28 are formed on an upper surface of the n-current blocking layer 25, both sides of the third p-clad layer 26, and both sides and an upper surface of the p-GaAs cap layer 27. There is; An n-metal layer below the p-metal layer 29 and the n-GaAs substrate 20 having the same shape as the surface shape of the p-GaAs layer 28 on the p-GaAs layer 28. It is set as the structure in which 30 is formed.

As described above, in the semiconductor laser diode of the present invention, the surface of the p-metal layer 28 has a distance from the surface of the third p-clad layer 26 and the p-GaAs cap layer 27 having a ridge structure. There is an advantage that the heat generated by the laser light emitted from the active layer closer to the structure can be more effectively emitted.

The heat dissipation side described above will be described in more detail with reference to FIGS. 3A and 3B.

3A and 3B illustrate a path of heat emitted from a semiconductor laser diode according to the related art and the present invention. First, in FIG. 3A, a conventional p-clad layer 14 having a ridge structure is used. The heat generated in the path becomes longer as the pass through which heat to the p-metal layer 18 is discharged from the vertical surface (a) of the ridge structure to the outermost surface (f, g) is not effectively released.

On the other hand, as shown in FIG. 3B, the semiconductor laser diode of the present invention has a path through which heat is discharged from the second p-clad layer 24 to the p-metal layer 28 of the ridge structure. From the vertical surface (a) of the ridge structure to the outermost surface (f, g) is almost the same, it is possible to effectively release heat.

As described in detail above, the present invention has the effect of shortening the heat path emitted near the ridge of the semiconductor laser diode to effectively release heat, thereby improving the characteristics of the device.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (4)

an n-clad layer, an active layer and a first p-clad layer are sequentially stacked on the n-GaAs substrate; A second p-clad layer having a ridge shape having a rhombus shape on top of the first p-clad layer, and an n-current blocking layer surrounding both sides of the second p-clad layer; A third p-clad layer having a ridge structure having a rhombus shape is formed on an upper surface of the second p-clad layer and a portion of the n-current blocking layer; A p-GaAs cap layer is formed on the third p-clad layer; P-GaAs layers are formed on upper surfaces of the n-current blocking layer, both sides of the third p-clad layer, and both sides and upper surfaces of the p-GaAs cap layer; A p-metal layer having the same shape as the surface shape of the p-GaAs layer is formed on the p-GaAs layer, and an n-metal layer is formed on the lower part of the n-GaAs substrate. Semiconductor laser diode with excellent thermal characteristics. The method of claim 1, The thickness of the p-GaAs layer is a semiconductor laser diode having excellent thermal characteristics, characterized in that 100 ~ 2000Å. The method of claim 1, The thickness of the p-metal layer is a semiconductor laser diode having excellent thermal characteristics, characterized in that 0.5 ~ 2 ㎛. a first step of sequentially forming an n-clad layer, an active layer and a first p-clad layer on top of the n-GaAs substrate; A second p-clad layer is formed at a central portion of the upper portion of the first p-clad layer in a ridge structure having a narrow top surface and a wide bottom surface, and both sides of the second p-clad layer are formed. Wrapping and forming an n-current blocking layer over the p-clad layer; A third step of sequentially stacking a third p-clad layer and a p-GaAs cap layer on the second p-clad layer and the n-current blocking layer; Etching the third p-clad layer and the p-GaAs cap layer to form a ridge structure in a rhombus shape, and exposing a portion of the n-current blocking layer; Forming a p-GaAs layer on exposed surfaces of the n-current blocking layer, both sides of the third p-clad layer, and both sides and top surfaces of the p-GaAs cap layer; And a sixth step of forming a p-metal layer having a constant thickness on the top of the p-GaAs layer and an n-metal layer on the bottom of the n-GaAs substrate. A method of manufacturing a semiconductor laser diode having excellent thermal characteristics.

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