KR100287202B1 - Semiconductor laser device and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A semiconductor laser device and a manufacturing method thereof are provided to enhance the reproductivity of an activation layer by employing double channels. CONSTITUTION: A V-shape first channel stripe(24b) is formed on a center of a first conductive type GaAs first contact layer(22) which is formed on a first conductive type GaAs substrate(21). A stepwise second channel stripe(24a) is formed on the center of a second conductive type GaAs current shield layer(23) which is formed on the first contact layer. A first conductive type AlGaInP first clad layer(25) is formed on the current shield layer and the first channel stripe, and has a flat surface of the center of the first channel stripe and inclined surfaces corresponding to the inclined surfaces of the first channel stripe. An InGaP activation layer(26) is formed on the first clad layer, and has a central flat surface and inclined surfaces of both sides of the central flat surface. A second conductive type AlGaInP second clad layer(27) is formed on the activation layer.

Description

Semiconductor laser device and manufacturing method thereof

1 (a), (b) and (c) are cross-sectional views showing a manufacturing process of a conventional visible light laser diode.

2 (a), (b) and (c) are sectional views showing an example of a method of manufacturing a laser diode according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device and a method of manufacturing the same. In particular, an AlGaInP system having a wavelength range of 630-670 nm used as a light source for optical information processing such as an optical disk or a magneto-optical disk (MOD) The present invention relates to a refractive index waveguide semiconductor laser diode device and a method of manufacturing the same.

In general, in the thermal equilibrium state of the material, the absorption of photons in a state where the energy level is higher than that of induction emission occurs, but it can be brought to a negative temperature state in which natural emission exceeds absorption by a certain method.

The laser generates light and oscillates using this negative temperature state, and is characterized by coherence, unipolarity, directivity, and high intensity. Helium (He-Ne) There are various kinds of lasers, gas lasers such as argon (Ar) lasers, and solid state lasers such as lasers and ruby lasers, ranging from small size and high-frequency semiconductor lasers that are easily modulated by modulating bias current at high frequencies.

In particular, the semiconductor laser diode is a semiconductor device that includes the concept of quantum electrons based on PN junctions, and artificially induces electron-hole recombination by injecting a current into a thin film made of a semiconductor material, that is, an active layer. By doing so, the principle is to emit light corresponding to the reduced energy of recombination. Due to the above characteristics, as an information processing device such as a compact disc player (CDP), an optical memory, a high-speed laser printer, and an optical communication device, the application range has been expanded by replacing the conventional gas laser such as helium-neon.

In recent years, the performance of semiconductor lasers has been developed through the development of materials that determine the wavelength and epitaxial growth technology that determines the characteristics and reliability of critical current values, light output, efficiency, single wavelength, and spectral line width (especially conventional liquid phase growth). Instead of the Liquid Phase Epitaxy (LPE) method, the control of atomic layer level has been made possible by the Organic Organic Chemical Vapor Deposition (MOCVD) and Molecular Beam Epitaxy (MBE) methods, and microfabrication technology. Remarkable progress is being made by the advancement of.

In particular, as a material for semiconductor lasers, AlGaInP-based lasers are red lasers having a wavelength of 0.6 μm, which is the shortest among III-V compound semiconductor lasers, as a semiconductor laser by injection of a carrier capable of continuous oscillation at room temperature. It is the material with the largest band gap energy among group III-V compounds, and has been widely used as a light source such as a high density optical recording device.

1 (a), (b) and (c) are sectional views showing a conventional method for manufacturing a visible light laser diode, and are disclosed in Japanese Patent Laid-Open No. 5-129716.

The technique described in Japanese Patent Laid-Open No. 716 is to produce a laser diode structure in which a visible light laser diode structure can be formed by two crystal growths, and the light emitting portion of the active layer is composed of a refractive index guide type structure. In other words, when an AlGaInP-based double-hetero structure is grown on a GaAs substrate on which a mesa-type channel is formed in the <011> direction, a convexly curved active layer is obtained. The band gap energy of this portion changes in accordance with the difference in orientation so that light is confined to the center portion of the curved active layer.

Hereinafter, a method of manufacturing a conventional visible light laser diode will be described with reference to FIGS. 1 (a), (b) and (c). In the drawings, reference numeral 11 denotes a p-type GaAs substrate, 12 denotes a p-type GaAs contact layer, 13 denotes an n-type GaAs blocking layer, and 14 denotes a pure mesa-type channel. Indicates a p-type AlGaInP cladding layer, "16" indicates an InGaP active layer, "17" indicates an n-type AlGaInP cladding layer, and "18" indicates an n-type GaAs contact layer. In the following description, the symbol which shows the component of each part is abbreviate | omitted, and only a function is used (for example, the active layer 16).

First, as shown in FIG. 1 (a), the contact layer 12 and the blocking layer 13 are formed on the substrate 11 by primary crystal growth.

Next, as shown in FIG. 1 (b), a pure mesa-shaped channel 14 is formed in the <011> direction. The pure mesa-type channel 14 is in contact with the contact layer 12 and the p-type cladding layer 15 at this portion, the width (t) is appropriately controlled according to the etching conditions.

Thereafter, as shown in FIG. 1 (C), the AlGaInP-based double heterostructure, i.e., the p-type cladding layer 15, the active layer 16, the n-type cladding layer 17 and the contact layer 18 is divided into two. Formed by crystal growth of tea. Accordingly, the active layer 16 is convexly curved, and a flat portion 16A at the center of the curved portion becomes a light emitting portion.

As described above, according to the technique of the conventional Japanese Patent Application Laid-Open No. 716, the refractive index guide type visible light laser diode can be manufactured only by the second crystal growth, so that the process is easy, and the threshold of laser oscillation is lowered and the aspect ratio is low. Laser light approximating a small circular beam can be obtained.

However, in the prior art, it is very difficult to reproducibly obtain a curved active layer having a predetermined step when forming a double heterostructure by secondary crystal growth on the channel 14.

Accordingly, an object of the present invention is to provide a semiconductor laser device having improved reproducibility of an active layer by applying a dual channel in order to solve the problems of the prior art.

Another object of the present invention is to provide an easy and suitable method for manufacturing the semiconductor laser device of the present invention.

In order to achieve the above object, the semiconductor laser device of the present invention,

A GaAs substrate of a first conductivity type;

A first conductive GaAs first contact layer formed on the substrate and having a V-shaped first channel stripe formed on the center thereof;

It is formed on the first contact layer, the inclined portion of the first channel stripe is formed in a form extending in a central length by a predetermined length and extending in a horizontal direction from both ends of the inclined portion by a predetermined length and has a stepped shape A second conductive GaAs current blocking layer formed with a second channel stripe;

A first layer formed on the current blocking layer and the first channel stripe, the surface having a flat surface at a central portion above the first channel stripe, and having a sloped surface corresponding to the inclined portion of the second channel stripe from both ends; A conductive AlGaInP first cladding layer;

An InGaP active layer formed on the first cladding layer and having a flat surface at a central portion corresponding to the surface shape thereof, and having an inclined surface from both ends thereof; And

And a second clad AlGaInP second cladding layer formed on the active layer.

As a specific type of the semiconductor laser device of the present invention, a second conductive GaInP conductive layer and a second conductive GaAs second contact layer may be formed on the second clad layer. The first conductive metal electrode may be connected to the substrate, and the second conductive metal electrode may be connected to the second contact layer to complete the diode structure.

On the other hand, in order to achieve the above another object of the present invention, the manufacturing method of the semiconductor laser device of the present invention,

Sequentially forming a first conductive GaAs first contact layer and a second conductive GaAs current blocking layer on the first conductive GaAs substrate;

Etching a portion of the current blocking layer and the first contact layer in a central portion of the resultant to form a V-shaped first channel stripe exposing a portion of the first contact layer;

Etching a portion of the current blocking layer to form a stepped second channel stripe having an inclined portion extending from the opposite ends of the first channel stripe inclined portion by a predetermined length in a horizontal direction; And

After forming the AlGaInP first cladding layer of the first conductivity type on the resultant, and has a flat surface in the center portion on the first channel stripe, and has an inclined surface corresponding to the inclined portion of the second channel stripe from both ends And a step of forming an InGaP active layer continuously.

According to the present invention, due to the effect of the dual channel consisting of the first channel stripe and the second channel stripe, the flat active layer formed in the center portion on the first channel stripe becomes a light emitting region, and the inclination of the second channel stripe from both ends thereof. The inclined active layer formed corresponding to the negative portion effectively performs light control by an energy band gap effect. In addition, by forming the second channel stripe, the inclined surface of the active layer can be formed reproducibly.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 (c) is a cross-sectional view showing an example of a semiconductor laser device according to the present invention. Specifically, the first conductive GaAs first contact layer 22 having the V-shaped first channel stripe 24b formed thereon is formed on the GaAs substrate 21 of the first conductive type. The inclined portion of the first channel stripe 24b is formed on the center of the first contact layer 22 so as to extend by a predetermined length, and extends in the horizontal direction from both ends of the inclined portion by a predetermined length. A second conductive GaAs current blocking layer 23 in which a stepped second channel stripe 24a having an inclined portion is formed is formed.

In addition, an AlGaInP-based double heterostructure is formed on the current blocking layer 23 and the first channel stripe 24b. That is, the AlGaInP first cladding layer of the first conductivity type having a flat surface at the center portion above the first channel stripe 24b and having an inclined surface corresponding to the inclined portion of the second channel stripe 24a from both ends thereof. 25 is formed, and on the first cladding layer 25, an InGaP active layer 26 having a flat surface in the center and an inclined surface from both ends thereof is formed corresponding to the surface shape of the first cladding layer 25. The second conductive AlGaInP second cladding layer 27 is formed on the active layer 26.

On the second cladding layer 27, a second conductive GaInP conductive layer 29 and a second conductive GaAs second contact layer 28 are sequentially formed. Although not shown, a second conductive metal electrode is connected to the second contact layer 28, a first conductive metal electrode is connected to the first conductive substrate 21, and the first conductive type is connected to the second conductive layer 28. The first conductive metal electrode is connected to the substrate 21 to complete the diode structure.

In the structure of an example of the present invention, the first conductive type represents a constituent means in which p-type impurities are injected, and the second conductive type represents a constitutional means in which n-type impurities are injected. In addition, the active layer 26 formed on the outside of the second channel stripe 24a has a flat surface.

In addition, it demonstrates below with reference to 2nd (a), (b), and (c) which attached an example of the manufacturing method of the semiconductor laser element by this invention.

FIG. 2 (a) illustrates sequentially forming a first conductive GaAs first contact layer 22 and a second conductive GaAs current blocking layer 23 on the GaAs substrate 21 of the first conductive type. Indicates. The step is performed by primary crystal growth by a conventional organometallic vapor phase growth method.

FIG. 2 (b) shows forming a first channel stripe 24b and a second channel stripe 24a on the resultant. To be more specific, first, a part of the current blocking layer 23 and the first contact layer 22 is etched by the conventional visual vision technique in the center of the resultant shown in FIG. A V-shaped first channel stripe 24b exposing a portion of the contact layer 22 is formed. Subsequently, a part of the current blocking layer 23 is etched by a conventional photolithography technique to extend a predetermined length in a horizontal direction from both ends of the inclined portion of the first channel stripe 24b, and then have a stepped second shape having a inclined portion. The channel stripe 24a is formed. Therefore, a dual channel stripe structure is formed including the first channel stripe 24b therein and surrounding the second channel stripe 24b.

FIG. 2 (c) shows a step of forming an AlGaInP-based double hetero structure on the resultant material shown in FIG. 2 (b) to complete the device. That is, the AlGaInP first cladding layer 25 of the first conductivity type, the InGaP active layer 26, the AlGaInP second cladding layer 27 of the second conductivity type, and the GaInP conduction facilitating layer of the second conductivity type are formed on the resultant. (29) and the second conductive GaAs second contact layer 28 are sequentially formed.

At this time, the width and depth of the first and second channel stripes 24a and 24b are precisely controlled by an etching process, so that the first cladding layer 25 is formed at the center thereof on the first channel stripe 24b. It has a flat surface, and has an inclined surface corresponding to the inclined portion of the second channel stripe 24a from both ends thereof, and on the first clad layer 25 on the surface shape of the first clad layer 25. Correspondingly, an InGaP active layer 26 having a flat surface in the center portion and an inclined surface from both ends thereof is formed.

The step is performed by secondary crystal growth by a conventional organometallic vapor phase growth method.

As shown in the above embodiment, according to the present invention, a flat active layer formed in the center portion on the first channel stripe by the effect of the dual channel consisting of the first channel stripe 24b and the second channel stripe 24a. Is a light emitting region, and the inclined active layer formed corresponding to the inclined portion of the second channel stripe from both ends thereof can realize a refractive index guide type laser element which effectively performs light control by an energy band gap effect.

In addition, by forming the second channel stripe, the inclined surface of the active layer having a predetermined step can be formed reproducibly, so that a circular beam capable of low threshold current value, low astigmatism distance and high output operation can be obtained.

Claims (4)

A GaAs substrate of a first conductivity type; A first conductive GaAs first contact layer formed on the substrate and having a V-shaped first channel stripe formed at a center thereof; A staircase formed on the first contact layer, the inclined portion of the first channel stripe extending in a central portion by a predetermined length, and extending in the horizontal direction from both ends of the inclined portion by a predetermined length and then having a sloped portion A second conductive GaAs current difference layer on which a second channel stripe of a type is formed; A first layer formed on the current blocking layer and the first channel stripe, the surface having a flat surface at a central portion above the first channel stripe, and having a sloped surface corresponding to the inclined portion of the second channel stripe from both ends; A conductive AlGaInP first cladding layer; An InGaP active layer formed on the first cladding layer and having a flat surface at a central portion corresponding to the surface shape thereof, and having an inclined surface from both ends thereof; And And a second clad AlGaInP second cladding layer formed on the active layer. The semiconductor laser device according to claim 1, wherein the first channel stripe is formed so that the substrate is not exposed. The semiconductor laser device according to claim 1, further comprising a second conductive GlInP conducting layer and a second conductive GaAs second contact layer formed on the second cladding layer. The semiconductor laser device according to claim 1, wherein the first conductive type is formed by implanting p-type impurities and the second conductive type is implanted by n-type impurities.