KR20040073812A - Waveguide type semiconductor laser diode - Google Patents

Abstract

PURPOSE: A waveguide type semiconductor laser diode is provided to enhance a photoelectric characteristic by increasing and reducing a composition ratio of Al to form a waveguide layer as a dual barrier. CONSTITUTION: A waveguide type semiconductor laser diode includes a first clad layer, a first waveguide layer, an active layer, a second waveguide layer, and a second clad layer. The first waveguide layer is formed on an upper surface of the first clad layer by increasing a composition ratio of Al. The active layer is formed on an upper surface of the first waveguide layer. The second waveguide layer is formed on an upper surface of the active layer by reducing the composition ratio of Al. A second clad layer is formed on an upper surface of the second waveguide layer.

Description

Waveguide type semiconductor laser diode {Waveguide type semiconductor laser diode}

The present invention relates to a wave guide type semiconductor laser diode, and more particularly, to form a wave guide layer with a double barrier in which the aluminum composition is increased or decreased, thereby facilitating the movement of carriers and increasing the binding force on the active layer to improve photoelectric characteristics. The present invention relates to a waveguide semiconductor laser diode.

In the case of a high power semiconductor laser diode (780 nm LD or 650 nm LD), which is generally used for picking up high-capacity high-speed storage devices such as CD-RW or DVD-RAM, semiconductor lasers due to high data storage speeds Diodes are getting higher power.

At the same time, the vertical radiation angle of the device is reduced and the horizontal radiation angle is increased so that the radiation angle is close to the circular beam so that the device can meet the requirements of the system using optics.

In particular, CD-RW or DVD-RAM systems require high output power of semiconductor laser diodes, as well as low vertical and high horizontal radiation angles.

This makes it possible to reduce the light loss from the optical system in the system using the optical system, thereby increasing the system's double speed.

Therefore, in the case of such a high speed system, even with the same output, it is possible to increase the system speed even by improving the radiation angle.

However, in order to increase the vertical emission angle, the optical confinement in the vertical direction must be reduced.

To this end, a waveguide structure using a double barrier (DB) layer in which a near field of a beam does not gather only inside an active layer but spreads to the outside has been recently applied to a semiconductor laser diode.

1 is an energy band diagram and a light distribution diagram of a general wave guide type semiconductor laser diode, wherein the first and second clad layers are formed of Al _0.55 GaAs, and the first and second wave guide layers are formed of Al _0.6 GaAs. The active layer is formed by alternately stacking Al _0.35 GaAs and Al _0.1 GaAs.

Therefore, as shown in FIG. 1, by disposing the first and second wave guide layers of the double barrier layer of Al _0.6 GaAs between the active layer and the clad layer, the light distribution A in which the double barrier wave guide layer is formed is Compared to the light distribution B in which the wave guide layer does not exist, the wave guide layer spreads much outside the active layer, thereby reducing the vertical emission angle.

However, this double barrier wave guide layer acts as a barrier in the movement of the electrical carrier from the clad layer to the active layer, thereby causing a problem of inhibiting electrical characteristics.

Accordingly, the present invention has been made to solve the above problems, to form a wave guide layer with a double barrier to increase or decrease the aluminum composition to facilitate the movement of the carriers, increase the binding force in the active layer to improve the photoelectric characteristics It is an object of the present invention to provide a wave guide type semiconductor laser diode.

A preferred aspect for achieving the above object of the present invention is a first cladding layer;

A first wave guide layer formed on top of the first cladding layer while gradually increasing Al composition;

An active layer formed on the first wave guide layer;

A second wave guide layer formed on the active layer while gradually decreasing Al composition;

A wave guide type semiconductor laser diode configured to include a second clad layer formed on the second wave guide layer is provided.

1 is an energy band diagram and a light distribution diagram of a typical waveguide semiconductor laser diode.

2 is a cross-sectional view of a wave guide type semiconductor laser diode according to the present invention.

3 is an energy band diagram of a waveguide semiconductor laser diode according to the present invention and the prior art.

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

10,14 cladding layer 11,13 wave guide layer

12: active layer

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

2 is a cross-sectional view of a wave guide type semiconductor laser diode according to the present invention, including a first cladding layer 10; A first wave guide layer 11 formed on the first clad layer 10 so that Al composition is gradually increased; An active layer 12 formed on the first wave guide layer 11; A second wave guide layer 13 formed on the active layer 12 to gradually reduce Al composition; It is configured to include a second cladding layer 14 formed on the second wave guide layer 13.

The n-type impurity is doped in the first cladding layer 10 and the first wave guide layer 11, and the p-type impurity is formed in the second waveguide layer 13 and the second cladding layer 14. It is doped.

Therefore, the first cladding layer 10 is preferably formed of n-type Al _0.55 GaAs, and the second cladding layer 14 is preferably formed of p-type Al _0.55 GaAs.

Therefore, Al composition is greater than or equal to 0.55 in the surface of the first wave guide layer 11 in contact with the first cladding layer 10, and Al composition is 0.6 in the surface of the first wave guide layer 11 in contact with the active layer 12. It is preferable to form the first wave guide layer 11 in which Al composition is gradually increased from the first cladding layer 10 to the active layer 12.

The second wave guide layer 13 has an Al composition greater than or equal to 0.55 at the surface in contact with the second cladding layer 14, and an Al composition of 0.6 at the surface in contact with the active layer 12. It is preferable to form the second wave guide layer 13 in which the Al composition is gradually reduced from the second cladding layer 14 to the active layer 12.

In the waveguide semiconductor laser diode configured as described above, an N electrode is formed on the first cladding layer 10, and a P electrode is formed on the second cladding layer 14, and the injected electrons and holes are recombined in the active layer 12. It will emit light.

3 is an energy band diagram of a wave guide type semiconductor laser diode according to the present invention and the prior art, the present invention is a first wave guide layer 11 formed to gradually increase the Al composition and the second formed so that the Al composition is gradually reduced The wave guide layer 13 is formed so that the band offset 'C' from the clad layer to the active layer is increased than the band offset 'D' of the prior art in which the wave guide layer is formed with a constant Al composition.

Therefore, the energy band of the first wave guide layer is inclined from the first cladding layer, so that holes injected into the active layer easily enter the active layer, and the energy band of the second wave guide layer is also inclined from the second cladding layer, thereby injecting electrons into the active layer. Entering smoothly.

In addition, electrons and holes present in the active layer do not leave the clad layer due to the high band offset, and are constrained by the active layer to improve photoelectric characteristics.

As a result, the present invention has the advantage of improving the electrical properties by facilitating the movement of the electrical carrier without changing the average effective refractive index.

As described above, the present invention forms an wave guide layer with a double barrier in which the aluminum composition is increased or decreased, thereby facilitating the movement of carriers, and increasing the restraint force on the active layer, thereby improving photoelectric characteristics.

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 (5)

A first clad layer; A first wave guide layer formed on top of the first cladding layer while gradually increasing Al composition; An active layer formed on the first wave guide layer; A second wave guide layer formed on the active layer while gradually decreasing Al composition; And a second cladding layer formed on the second waveguide layer. The method of claim 1, In the first cladding layer and the first wave guide layer, doped with n-type impurities, In the second wave guide layer and the second clad layer, A wave guide type semiconductor laser diode, wherein the p-type impurity is doped. The method according to claim 1 or 2, The first clad layer is formed of n type Al _0.55 GaAs, The second clad layer is a wave guide type semiconductor laser diode, characterized in that formed of p-type Al _0.55 GaAs. The method of claim 1, Al composition of the first wave guide layer, The portion in contact with the first cladding layer is 0.55 or more, and the portion in contact with the active layer is 0.6, and the wave guide type semiconductor laser diode is gradually increased from the first cladding layer to the active layer. The method of claim 1, Al composition of the second wave guide layer, The area in contact with the active layer is 0.6, and the area in contact with the second clad layer is 0.55 or more, and the wave guide type semiconductor laser diode is gradually reduced from the active layer to the second cladding layer.