KR100552333B1 - White light emitting device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white light emitting device, and in particular, the white light emitting device of the present invention comprises a light emitting diode chip having a multilayer light emitting layer emitting light of different wavelengths (for example, blue and green), and a mixture of light emitting diode chips. It includes a fluorescent material that emits light of a color that is complementary to the color of light (red) and mixes with the light emitted from the light emitting diode chip to realize white color. Therefore, the present invention mixes red-based fluorescent materials having complementary colors with the mixed color on a light emitting diode chip that emits light made by mixing two or more different colors of light that can be made of a nitride semiconductor to make white. By configuring the package, it is possible to realize a white light emitting device having excellent color rendering with low power consumption.

White light emitting device, LED chip, fluorescent material

Description

White light emitting device {WHITE LIGHT EMITTING DEVICE}

1 is a vertical cross-sectional view showing the structure of a light emitting diode device according to an embodiment of the present invention;

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

Explanation of symbols on the main parts of the drawings

b: multi-quantum well emitting layer 40: substrate

42 buffer layer 44 cathode doping layer

46: first well wall 48: first green quantum well light emitting layer

50: second well wall 52: second green quantum well light emitting layer

54: third well wall 56: first blue quantum well light emitting layer

58: fourth well wall 60: second blue quantum well light emitting layer

62: fifth well wall 64: anode doped layer

70: red fluorescent substance

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white light emitting device, and more particularly, to a white light emitting device capable of emitting white light by combining a fluorescent material with a light emitting diode chip emitting two or more mixed lights vertically.

Currently, researches on light emitting diodes using optical semiconductors are mainly focused on white light emitting devices that have many marketability in lighting fields such as home fluorescent lamps, LCD backlights, and the like. In addition, as nitride-based semiconductor light emitting diodes are commercially available, a single light emitting diode chip white light emitting device that emits white light using a blue or ultraviolet light emitting diode chip having the highest energy level as an excitation light source for a fluorescent material is being used.

As a representative method of implementing a white light emitting device, a light emitting diode chip emitting three primary colors of light, red, green, and blue, is assembled in one place. This method has excellent advantages such as excellent color rendering and long life time inherent to the light emitting diode chip, but it is expensive and almost impossible to implement in a backlight side view ultra small package of a small liquid crystal display. Therefore, due to the fluorescent material, the lifespan is short and color rendering is inferior, but it is the first design in Nichia in consideration of the economic aspect, and there is a method of excitation of yellow fluorescent material with a blue light emitting diode chip to produce white color by combining two colors. In addition to this method, the white, green, blue, and three primary fluorescent materials devised by Toyota Kosei are excited by an ultraviolet light emitting diode chip. However, this method also has a disadvantage in that the color rendering is good but the brightness characteristics are poor. In order to compensate for the problem of brightness, several chips are put in, but considering that most of the white light emitting diode products using fluorescent materials are used in small liquid crystal display devices, it is not very effective due to difficulties in the assembly process.

Therefore, there is an urgent need for research and development of technology that can further develop excellent color rendition and white brightness characteristics while maintaining the characteristics of white light emitting diodes using fluorescent materials that can be realized in a compact package, while being economical. have.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting diode chip capable of emitting two or more different wavelengths of light that can be produced by a nitride based semiconductor in order to solve the problems of the prior art. The present invention is to provide a white light emitting device that has excellent color rendering and high brightness characteristics and is suitable for an ultra-small package by combining a fluorescent material having a complementary color relationship with the emitted light.

In order to achieve the above object, the present invention provides a white light emitting device having a light emitting diode chip comprising: a light emitting diode chip having a plurality of green quantum well light emitting layers emitting green light, and a plurality of blue quantum well emitting layers emitting blue light; And a fluorescent material that emits red light having a complementary color to the mixed light emitted from the light emitting diode chip and is mixed with the light emitted from the light emitting diode chip to realize white color. The blue quantum well light emitting layer is formed on top of the green quantum well light emitting layer. Characterized in that formed.

In order to achieve the above object, another device of the present invention is a white light emitting device having a light emitting diode chip, a plurality of green quantum well light emitting layer for emitting green light, a plurality of blue quantum well light emitting layer for emitting blue light, A light emitting diode chip having well walls between the quantum well emitting layers, and a fluorescent material that emits red light having a complementary color to that of the mixed light emitted from the light emitting diode chip and is mixed with the light emitted from the light emitting diode chip to produce white light. Including, but the blue quantum well light emitting layer is characterized in that formed on the green quantum well light emitting layer.

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

1 is a vertical cross-sectional view showing the structure of a light emitting diode device according to an embodiment of the present invention.

Referring to FIG. 1, a white light emitting device according to an exemplary embodiment of the present invention has a maximum wavelength in a 620 nm to 660 nm wavelength region of a multi-light source LED chip 40 to 64 having a multi-quantum well structure that emits blue and green light. A red fluorescent substance (for example, zinc selenium, etc.) 70 showing luminescence intensity is blended to form a package. The red phosphor 70 is formed on the entire surface of the multi-light emitting LED chip 40 to 64 or on one surface of the chip.

In the white light emitting device according to the embodiment of the present invention, the blue and green light emitted from the multi-light emitting diode chips 40 to 64 of the package and the red light emitted from the red fluorescent material 70 excited by some of the lights In the end, mix, giving off a white glow.

Here, the multi-light emitting LED chips 40 to 64 are made of a nitride-based semiconductor layer on a substrate 40 made of sapphire (Al ₂ O ₃ ), silicon carbide (SiC), gallium nitride (GaN), or the like. First, a nitride layer such as gallium nitride (GaN), aluminum nitride (AlN), or a combination of aluminum gallium nitride (AlGaN), which is a buffer layer 42 for obtaining good thin film quality on the substrate 40, is obtained. The material layer is laminated to a thickness of 1 μm or less. On the buffer layer 42, a gallium nitride cathode doping layer (N-type GaN) 44 doped with an n-type dopant for electron injection is stacked to a thickness of about 3 to 5 um. A gallium nitride anode doped layer (P-type GaN) 64 doped with a p-type dopant for hole injection with a light emitting layer (b) having a multi-quantum well structure interposed therebetween is stacked to a thickness of about 0.2 μm.

Between the cathode doping layer 44 and the anode doping layer 64 of the multi-light emitting LED chip, a light emitting layer (b) having a multi quantum well structure is provided to simultaneously emit blue and green light.

In the present invention, it is preferable to use a multi-quantum well structure having at least two or more quantum well emitting layers emitting blue and green light, respectively, in order to increase luminous efficiency of the multi-light emitting LED chip. At this time, by adjusting the number of quantum well emitting layer for emitting light of each color so that the desired intensity ratio (color intensity ratio) for each color.

Accordingly, the light emitting layer (b) having the multi-quantum well structure is sequentially formed on the cathode doping layer 44 by the first well wall 46, the first green quantum well light emitting layer 48, the second well wall 50, and the second green quantum. Well emitting layer 52, third well wall 54, first blue quantum well light emitting layer 56, fourth well wall 58, second blue quantum well light emitting layer 60, fifth well wall 62, etc. The quantum well light emitting layer and the well wall are alternately stacked in order so that the quantum well light emitting layer is between the well walls.

In the light emitting layer (b) of the multi-quantum well structure, each of the quantum well light emitting layers 48, 52, 56, and 60 forms indium gallium nitride (InGaN) in a thickness of about 20 kV, and controls the indium ratio of indium gallium nitride (InGaN). To emit blue light in the wavelength range of 465 nm to 475 nm and emit green light in the wavelength range of 520 nm to 530 nm. In the light emitting layer (b) of the multi-quantum well structure, each of the well walls 46, 50, 54, 58, and 62 is formed of gallium nitride (GaN) or aluminum gallium nitride (AlGaN) having a higher energy band gap than the light emitting layer. Make it 100Å ~ 1000 층 thick so that there is no interaction between well emitting layers.

On the other hand, the multi-light emitting diode chip of the present invention is a quantum well light emitting layer (56, 60) that emits blue light with a relatively high energy level of the quantum well light emitting layer (48, 52) that emits green light having a low energy level in the light emitting layer (b) It is preferable to place it below. The reason is that when the green quantum well light emitting layers 48 and 52 are located on the path where blue light exits, green light having a high energy level is incident on the green quantum well light emitting layers 48 and 52, so that the green quantum having a low energy band gap is present. It acts as a kind of optical pumping to excite the electrons in the well emitting layer, which causes blue light to not escape all, resulting in a significant decrease in blue luminous efficiency.

Therefore, the white light emitting device according to the present invention supplies current through the electrode and metal wire (not shown) connected to the cathode doping layer 44 and the anode doping layer 64 in the above-described multi-light emitting LED chip 40 to 64. The green light in the wavelength range of 520 nm to 530 nm and the blue light in the wavelength range of 465 nm to 475 nm are emitted from the first and second green and blue quantum well light emitting layers 48, 52, 56, and 60, respectively. Some of the blue and green light emitted from the multi-light emitting LED chips 40 to 64 are mixed with all the red of the fluorescent material 70 while exiting the red fluorescent material 70 surrounding the whole or one side of the LED chip. , White light comes out.

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

2, a white light emitting device according to another embodiment of the present invention is a 620nm ~ 660 in a multi-light source light emitting diode chip (80 ~ 104) of a super lattice multi quantum well structure that emits blue and green light A red fluorescent substance (eg, zinc selenium, etc.) 110 exhibiting the maximum light emission intensity in the nm wavelength region is blended to form a package. The red phosphor 110 is formed on one surface of the entire surface of the multi-light emitting LED chip 80 to 104 or on the chip.

According to another embodiment of the present invention, a white light emitting device includes a blue and green light emitted from a superlattice multi-light emitting diode chip 80 to 104 in a package, and a red light emitted from a red fluorescent material 110 excited by some of these lights. The light mixes, eventually giving off a white glow.

Here, the multi-light emitting LED chips 80 to 104 are buffer layers 82 for obtaining a good thin film on a substrate 80 made of sapphire (Al ₂ O ₃ ), silicon carbide (SiC), gallium nitride (GaN), or the like. ), A nitride semiconductor layer such as gallium nitride (GaN), aluminum nitride (AlN), or aluminum gallium nitride (AlGaN), which is a combination thereof, is laminated to a thickness of 1 탆 or less. On the buffer layer 82, a gallium nitride anode doped layer (N-type GaN) 84 doped with an n-type dopant for electron injection is stacked to a thickness of about 3 to 5 um. A gallium nitride anode doped layer (P-type GaN) 104 doped with a p-type dopant for hole injection with the light emitting layer c of the superlattice multi-quantum well structure interposed therebetween is stacked to a thickness of about 0.2 μm.

Between the cathode doping layer 84 and the anode doping layer 104 of the multi-light emitting LED chip, a light emitting layer (c) having a multi quantum well structure is provided to simultaneously emit blue and green light.

Furthermore, in another embodiment of the present invention, it is preferable to use a superlattice multi-quantum well structure having at least two or more quantum well emitting layers emitting blue and green light, respectively, in order to increase luminous efficiency of the multi-light emitting LED chip. In addition, the number of quantum well emitting layers that emit light of each color is adjusted to obtain the desired light ratio by color. The superlattice refers to a structure in which the well wall is also the same thickness as the quantum well light emitting layer so that electrons and holes can freely pass through the well wall by tunneling in any quantum well light emitting layer. The light emitting diode chip having the superlattice quantum well structure has a large number of charge carriers such as electrons or holes because electrons or holes are present in all quantum well light emitting layers freely when driving at high current. Carrier overflow can be prevented from overflowing to other layers.

The light emitting layer (c) of the multi-quantum well structure in the multi-light emitting LED chip according to another embodiment of the present invention may be sequentially formed on the cathode doping layer 84 by the first well wall 86, the first green quantum well light emitting layer 88, Second well wall 90, first blue quantum well light emitting layer 92, third well wall 94, second green quantum well light emitting layer 96, fourth well wall 98, second blue quantum well light emitting layer 100, the fifth well wall 102 is included. The quantum well light emitting layer and the well wall are alternately stacked in order so that each quantum well light emitting layer 88, 92, 96, 100 is between the well walls 86, 90, 94, 98, and 102.

In the light emitting layer (c) of the superlattice multi-quantum well structure, each quantum well light emitting layer (88, 92, 96, 100) forms indium gallium nitride (InGaN) in a thickness of about 20 kW, and an indium ratio of indium gallium nitride (InGaN). By adjusting the blue light in the wavelength range of 465nm ~ 475nm and green light in the wavelength range of 520nm ~ 530nm.

In the light emitting layer (c) of the superlattice multi-quantum well structure, each well wall (86, 90, 94, 98, 102) is made of gallium nitride (GaN) or aluminum gallium nitride (AlGaN) having a higher energy band gap than the light emitting layer. Form and about 20 mm thick for superlattice structure.

On the other hand, the multi-light emitting LED chip of the present embodiment has a relatively high energy level in the quantum well light emitting layers 88 and 96 that emit green light having a low energy level in the light emitting layer c when the horizontal plane mainly extracting light is placed on the top. All electrons in the green quantum well light emitting layers 88 and 96 are placed below the high blue quantum well light emitting layers 92 and 100 so that all of the electrons in the blue quantum well light emitting layers 92 and 100 are blue. All of them come out to prevent the blue luminous efficiency from falling.

Therefore, the white light emitting device according to another embodiment of the present invention uses the electrodes and metal wires (not shown) connected to the cathode doping layer 84 and the anode doping layer 104 in the above-described multi-light emitting LED chips 80 to 104. When current is supplied through the first and second green and blue quantum well light emitting layers 88, 92, 96 and 100, green light in the wavelength range of 520 nm to 530 nm and blue light in the 465 nm to 475 nm wavelength range are respectively obtained. Part of the light excites the red fluorescent material (70) surrounding the entire light emitting diode chip or at least one surface to emit red light, and the remaining green and blue light exits the red fluorescent material (70). Mix with 70 red lights to create white light.

As described above, the present invention comprises a package by combining a red-based fluorescent material on a light emitting diode chip having a light emitting layer having a plurality of different wavelengths including green and blue, excellent color rendering properties and high brightness characteristics It is possible to implement a white light emitting device having a.

Meanwhile, in the above-described embodiment, the green and blue quantum well light emitting layers are separately stacked on the light emitting layer of the light emitting diode chip, and the light emitting layers may be alternately stacked. That is, the present invention is not limited to the above embodiments, but various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims below.

Claims (16)

In a white light emitting device having a light emitting diode chip, A light emitting diode chip having a plurality of green quantum well emitting layers emitting green light and a plurality of blue quantum well emitting layers emitting blue light; And It includes a fluorescent material that emits a red light having a complementary color and the color of the mixed light emitted from the light emitting diode chip to be mixed with the light emitted from the light emitting diode chip to implement white, And the blue quantum well light emitting layer is formed on the green quantum well light emitting layer. delete delete In a white light emitting device having a light emitting diode chip, A light emitting diode chip having a plurality of green quantum well emitting layers emitting green light and a plurality of blue quantum well emitting layers emitting blue light; And It includes a fluorescent material that emits a red light having a complementary color and the color of the mixed light emitted from the light emitting diode chip to be mixed with the light emitted from the light emitting diode chip to implement white, Wherein the plurality of green quantum well light emitting layers and the blue quantum well light emitting layers are alternately stacked. delete delete In a white light emitting device having a light emitting diode chip, A light emitting diode chip having a plurality of green quantum well emitting layers emitting green light, a plurality of blue quantum well emitting layers emitting blue light, and well walls between the quantum well emitting layers; And It includes a fluorescent material that emits a red light having a complementary color and the color of the mixed light emitted from the light emitting diode chip to be mixed with the light emitted from the light emitting diode chip to implement white, And the blue quantum well light emitting layer is formed on the green quantum well light emitting layer. delete delete In a white light emitting device having a light emitting diode chip, A light emitting diode chip having a plurality of green quantum well emitting layers emitting green light, a plurality of blue quantum well emitting layers emitting blue light, and well walls between the quantum well emitting layers; And It includes a fluorescent material that emits a red light having a complementary color and the color of the mixed light emitted from the light emitting diode chip to be mixed with the light emitted from the light emitting diode chip to implement white, Wherein the plurality of green quantum well light emitting layers and the blue quantum well light emitting layers are alternately stacked. delete delete The method according to any one of claims 7 and 10, And the quantum well light emitting layer has a thickness greater than that of the well wall. delete The method according to any one of claims 7 and 10, And the thickness of the quantum well light emitting layer is the same as that of the well wall. delete

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