KR20070035306A - Light emitting diode and manufacturing method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device, and in particular, by manufacturing a light emitting diode in which active layers emitting different wavelengths of light are stacked on top of a substrate, the light emitted from each active layer is mixed to provide light of various wavelengths in the visible region. A light emitting diode that emits light and a method of manufacturing the same. The light emitting device according to the present invention is a semiconductor light emitting device in which a first conductive cladding layer, an active layer, and a second conductive cladding layer are sequentially stacked on a substrate, wherein the active layer has an xy, z active layer having a different composition of In. This is a sequentially stacked structure.

Light Emitting Device, Quantum Well (QW)

Description

Light emitting diode and manufacturing method thereof

1 is a cross-sectional view showing a conventional light emitting diode structure

2 is a cross-sectional view showing a light emitting diode structure according to the present invention.

* Explanation of symbols for main parts of drawings *

100 substrate 200 first conductive clad layer

300: active layer 400: second conductivity type clad layer

500: contact layer 600: first electrode

700: second electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device, and in particular, by manufacturing a light emitting diode in which active layers emitting different wavelengths of light are stacked on top of a substrate, the light emitted from each active layer is mixed to provide light of various wavelengths in the visible region. A light emitting diode that emits light and a method of manufacturing the same.

Currently, research trends on optical devices using compound semiconductors have recently had considerable marketability in lighting fields such as home fluorescent lamps and liquid crystal display (LCD) backlights, and attention has been focused on white light emitting diodes.

In general, a light emitting diode (Light Emitting Diode) is a kind of semiconductor used to send and receive signals by converting electricity into infrared or light by using the characteristics of compound semiconductors, such as home appliances, remote control, display boards, display devices, various automation devices, etc. Used.

The operation principle of the light emitting diode is to apply a forward voltage to a semiconductor of a specific element and recombine with each other while electrons and holes are moved through a junction of a positive and a negative electrode. The energy level drops and light is emitted.

In addition, the light emitting diode is generally manufactured in a very small size of 0.23 square millimeters, and has an epoxy mold, a lead frame and a PCB mounted structure. Currently, the most commonly used light emitting diodes are either 5mm plastic packages or new types of packages depending on the specific application. The color of light emitted from the light emitting diodes creates wavelengths depending on the composition of the semiconductor chip components, and these wavelengths determine the color of the light.

In addition to the development of red and green LEDs using AlGaAs or AlGaInP materials, the development of ultraviolet and white LEDs as well as the wavelengths of various visible light areas such as blue and green using III-V nitride semiconductors are underway. .

The white light emitting diode includes a YAG-GaN white light emitting diode, a white light emitting diode based on ZnSe heteroepitaxy, and a white light emitting diode using three color (red, green, blue) light emitting diodes.

Herein, the YAG-GaN white light emitting diode uses an InGaN blue light emitting diode and YAG (Yittrium Aluminum Garnet) phosphor in accordance with the development and commercialization of a white light emitting diode device and an ultraviolet light emitting diode device started with the development of a light emitting device using an InGaN-based material. It is composed in combination.

In addition, attention has been focused on light emitting diode devices that emit light from ultraviolet to red using group III nitride compound semiconductors. InGaN-based light emitting diodes emitting ultraviolet / blue / blue / yellow / white regions have been put to practical use. When used, it is difficult to fabricate a light emitting device having high efficiency.

Hereinafter, a light emitting device according to the prior art will be described with reference to the accompanying drawings.

1 is a cross-sectional view showing the structure of a general light emitting device.

In the following, the light emitting element described below uses a nitride semiconductor, and gallium nitride is used.

Referring to FIG. 1, a conventional light emitting device includes an n-type first conductive cladding layer 20, an active layer 30, a p-type second conductive cladding layer 40, which are sequentially formed on a sapphire substrate 10. It consists of the p-type contact layer 50, the n-type electrode 50, and the p-type electrode 70.

The active layer 30 has an InGaN well layer (QW) / GaN barrier structure, and the wavelength of light emitted from the InGaN well layer may be determined by the composition of In and the thickness of the InGaN well layer.

That is, there is a method of adjusting the content of In in the method of implementing all wavelength bands in the visible light region using the light emitting device configured as described above, and it is difficult to accurately implement light in all wavelength bands.

Another method is to adjust the wavelength by combining blue, green and red light emitting diodes.

In other words, in order to create a yellow light wavelength, blue and green are combined to make a yellow light wavelength.

Finally, there is a method of using phosphors of various colors to be expressed in ultraviolet light emitting diodes.

In other words, if you want to create an orange color, the corresponding orange phosphor is covered on top of the ultraviolet light emitting diode to make a light emitting diode.

However, in the case of using a single light emitting diode of such a conventional method, it is not easy to implement the correct wavelength, and the method of using a mixture of red, green and blue light emitting diodes is difficult to assemble and costly compared with other methods. There is this.

In addition, the white light emitting diode manufactured by mixing the light emitting diode has a problem that is difficult to arrange in space.

It is an object of the present invention to provide a light emitting diode having a direct structure without mixing red, green, and blue light emitting diodes, and a method of manufacturing the same. have.

According to an aspect of the present invention for achieving the above object, in a semiconductor light emitting device in which a first conductive type cladding layer, an active layer, and a second conductive type cladding layer are sequentially stacked on a substrate, the active layer may have a different composition of In. The xy, z active layers are stacked in this order.

Preferably, the x, y and z active layers emit red, blue and green wavelengths, respectively.

In addition, the composition value of In of the x, y, and z active layers is 0 <x <y <z <1.

In addition, the quantum wells QW of the x, y, and z active layers are 10 or less.

According to another aspect of the present invention, there is provided a method of forming a first conductive cladding layer on a substrate, and sequentially forming x, y, and z active layers on the first conductive cladding layer. forming a second conductive cladding layer on the x, y, z active layer, etching to expose a portion of the first conductive cladding layer to form a first electrode, and the second conductive cladding layer Forming a second electrode on the substrate.

Preferably, each of the x, y, z active layers has a different composition of In.

The composition value of In is 0 <x <y <z <1.

2 is a cross-sectional view showing the structure of a light emitting device according to the present invention.

First, in describing the embodiments of the present invention, the light emitting device according to the present invention is used by nitride semiconductors using Group 3 and 5 compounds such as GaN (gallium nitride), AlN (aluminum nitride), InN (indium nitride), and the like. The gallium nitride is applied to it.

As shown in FIG. 2, the light emitting device according to the present invention includes a first conductive cladding layer 200, an active layer 300, a second conductive cladding layer 400, and a contact layer sequentially formed on the substrate 100. Form 500.

The substrate 100 may be formed of the same material or different materials as the first conductive cladding layer 200.

For example, when the first conductivity type cladding layer 200 is Si-GaN, the dissimilar material substrate is a sapphire substrate or a silicon carbide (SiC) substrate, and the homogeneous material substrate is a GaN substrate.

Thereafter, the active layer 300 is formed on the first conductive cladding layer 200.

Here, the active layer 300 is formed of an InGaN quantum well (QW) / GaN barrier (Barrier) structure, the hole flowing through the p-type electrode 700 to be formed later and flows through the n-type electrode 600 The electrons are bonded to each other to generate light.

The active layer 300 implements red, blue, and green light emitting diodes by varying the composition of In in x, y, and z in InGaN QW, respectively.

For example, the composition of x, y, and z values is composed of 0 <x <y <z <1, and QW having In composition of x, QW having In composition of y, and QW having In composition of z. The number is less than ten.

In other words, a white light emitting diode is implemented by using QW having a composition of In different in xy, z in InGaN QW of the active layer 300, and grows QW on the first conductive cladding layer 200, and then Grow QWs with the same composition.

More efficient light output can be obtained by placing InGaN QW with a small In composition in the direction where light output mainly occurs during QW growth.

Subsequently, a second conductive cladding layer 400 is formed on the active layer 300.

In the above configuration, the first conductive cladding layer 200 is n-type and the second conductive cladding layer 400 is p-type. This is the most common light emitting diode configuration.

On the contrary, the first conductive cladding layer 200 may be a p-type, and the second conductive cladding layer 400 may be an n-type light emitting diode.

In addition, a first electrode 600 is formed on the first conductive cladding layer 200 etched to expose a portion of the first conductive cladding layer 200, and on the second conductive cladding layer 400. The second electrode 700 is formed on the contact layer 500 formed on the contact layer 500.

When a voltage is applied to the second electrode 700 and the first electrode 600 in the light emitting device configured as described above, electrons are injected from the first conductive cladding layer 200 to the active layer 300, and the second conductive Holes are injected into the active layer 300 from the type cladding layer 400.

At this time, electrons and holes injected into the active layer 300 region are recombined to generate light.

The present invention has been described above with reference to the preferred embodiments, which are merely examples and are not intended to limit the invention, and those of ordinary skill in the art do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not possible.

For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

As described in detail above, the present invention can achieve a more efficient light output by implementing a white light emitting diode using InGaN QW having a different composition in the well layer (QW) region, unlike the conventional general light emitting diode structure, By mixing red, green and blue light emitting diodes, there is an effect of solving the difficulty of spatial arrangement that occurs during the production of white light emitting diodes.

Claims (7)

In a semiconductor light emitting device in which a first conductive cladding layer, an active layer, and a second conductive cladding layer are sequentially stacked on a substrate, The active layer is a light emitting device, characterized in that the x y, z active layer having a different composition of In is laminated sequentially. The method of claim 1, And the x, y, and z active layers emit red, blue, and green wavelengths, respectively. The method of claim 1, The composition value of In of the x, y, z active layers is 0 <x <y <z <1. The method of claim 1, The quantum wells (QW) of the x, y, z active layer is 10 or less light emitting device. Forming a first conductivity type clad layer on the substrate; Sequentially forming an x, y, z active layer on the first conductivity type clad layer; Forming a second conductive cladding layer on the x, y, z active layer; Etching a portion of the first conductive clad layer to form a first electrode; And forming a second electrode on the second conductive cladding layer. The method of claim 5, The x, y, z active layer is a light emitting diode manufacturing method, characterized in that the composition of In different. The method of claim 6, The composition value of In is 0 <x <y <z <1.

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