JP2012004297A - Light-emitting diode, light emitting device, illumination device, and display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting diode capable of actualizing a large amount of light emission, high light emission efficiency and uniform surface light emission, and is low-cost, and a light emitting device, an illumination device and a display using the same.SOLUTION: An n-type semiconductor layer 21 and a p-type semiconductor layer 23 are laminated on one surface of a support layer 1. A p-side electrode 4 penetrates the n-type semiconductor layer 21 positioned on the side of the support layer 1 from the side of the support layer 1, and a tip thereof reaches the p-type semiconductor layer 23. An n-side electrode is a thin-film electrode 3 of the n-type semiconductor layer 21 formed on a surface positioned on the side of the support layer 1.

Description

  The present invention relates to a light emitting diode, a light emitting device using the same, a lighting device, and a display.

  Light emitting diodes have the advantages of energy saving and long life, and are attracting attention as light sources such as lighting devices, color image display devices, liquid crystal panel backlights, or traffic signal lights.

  For example, when the light emitting diode is a blue light emitting diode, as disclosed in Patent Document 1, a buffer layer, an N-type GaN layer, an active layer, P, and the like are formed on the surface of a support layer (substrate) made of sapphire. A type GaN layer and a transparent electrode layer are sequentially laminated.

  A P-side electrode is formed on a part of the surface of the transparent electrode layer, and the transparent electrode layer, the P-type GaN layer and a part of the active layer are dry-etched to expose a part of the N-type GaN layer, An N-side electrode is formed on the exposed N-type GaN layer. Patent Documents 2 and 3 also disclose similar laminated structures and electrode structures.

  As described above, in the conventional light emitting diode, the P-side electrode is formed on the surface of the transparent electrode layer serving as the light emitting surface, while the transparent electrode layer, the P-type GaN layer, and a part of the active layer are dry-etched, and N Since a part of the p-type GaN layer is exposed and the n-side electrode is formed on the exposed n-type GaN layer, the light emission area is reduced by the occupied area of the p-side electrode and the n-side electrode. End up. For this reason, as a natural result, the amount of light emission decreases and the light emission efficiency also decreases.

  In addition, since the N-side electrode is provided in a limited and concentrated manner on the exposed portion of the N-type GaN layer, current tends to concentrate on this portion, thereby preventing uniform surface light emission.

  Furthermore, an ICP type RIE apparatus must be used for dry etching for forming the N-side electrode. ICP-type RIE equipment is used for various Si micromachining (MEMS) applications, high-frequency device processing by compound semiconductor etching, thin film magnetic head processing by Altic etching, etc., but it is extremely expensive. . The expensive equipment cost is reflected in the cost increase of the light emitting diode.

JP 2001-210867 A JP 2009-71337 A JP 2008-153634 A

  An object of the present invention is to provide a light emitting diode having a large light emission amount and high light emission efficiency, and a light emitting device, a lighting device, and a display using the light emitting diode.

  Another object of the present invention is to provide a light emitting diode capable of realizing uniform surface light emission, a light emitting device using the same, a lighting device, and a display.

  Still another object of the present invention is to provide an inexpensive light emitting diode, a light emitting device using the same, a lighting device, and a display.

  In order to solve at least one of the above-described problems, a light emitting diode according to the present invention includes an n-type semiconductor layer, a p-type semiconductor layer, a support layer, and an electrode. The type semiconductor layer is laminated on one surface of the support layer.

  The electrode includes an n-side electrode and a p-side electrode, and one of the n-side electrode and the p-side electrode is located on the support layer side of the p-type semiconductor layer and the n-type semiconductor layer. One semiconductor layer penetrates from the support layer side, and the tip reaches the other semiconductor layer.

  The other of the n-side electrode and the p-side electrode is a thin film electrode formed on the surface on the support layer side of the one semiconductor layer located on the support layer side. The thin film electrode is a metal film.

  With respect to electrodes for supplying electric energy to the p-type semiconductor layer and the n-type semiconductor layer, conventionally, a P-side electrode is formed on a part of the surface of the transparent electrode layer, and an N-type GaN layer exposed by dry etching is formed on an N-type GaN layer. The side electrode was formed. For this reason, the problem mentioned above has arisen.

  In the present invention, as a means for solving this problem, one of the n-side electrode and the p-side electrode is one of the p-type semiconductor layer and the n-type semiconductor layer, and one of the semiconductor layers located on the support layer side is replaced with the support layer. It penetrates from the side and the tip reaches the other semiconductor layer.

  The other of the n-side electrode and the p-side electrode is a thin film electrode formed on the surface of one semiconductor layer located on the support layer side. According to this configuration, the following operational effects can be obtained.

 (A) One of the n-side electrode and the p-side electrode is one of the p-type semiconductor layer and the n-type semiconductor layer, which penetrates one semiconductor layer located on the support layer side from the support layer side, and the tip is the other semiconductor The thin film electrode formed on the surface of the semiconductor layer located on the support layer side is formed on the other side, so that the p-side electrode or the n-side electrode appears on the light emitting surface. There is nothing. Therefore, since the light emitting area is not reduced by the electrode, it is possible to realize a surface emitting light emitting diode having a large light emission amount and high light emission efficiency.

 (B) For one of the electrodes, the surface density of the current in the semiconductor layer depends on the surface density of the micropores. Therefore, by increasing the surface density of the micropores with respect to the surface of the semiconductor layer, the surface diffusion of current to the semiconductor layer is promoted without having a transparent electrode layer, and uniform surface emission is realized. obtain. For this reason, a transparent electrode layer is abbreviate | omitted and the simplification of a manufacturing process, the improvement of the production efficiency accompanying it, and a cost reduction can be achieved. In addition, since the loss of light energy due to the transparent electrode layer is eliminated, the light emission amount and the light emission efficiency are improved. However, the transparent electrode layer is not excluded.

 (C) The fine holes can be easily opened by applying a known drilling technique such as laser drilling or chemical drilling. In addition, since the electrode is composed of the conductor filled in the fine holes thus drilled, a method of filling and pressurizing the molten metal into the fine holes is adopted when manufacturing the electrode. be able to. According to this method, it is possible to form a dense electrode without a cavity in the micropore. Even better results can be obtained by curing while maintaining the pressurized state.

  Moreover, the manufacturing method described above belongs to the press method, and the equipment cost is significantly lower and the processing time is shorter than the dry etching method using a conventional ICP type RIE apparatus. Therefore, an inexpensive light emitting diode can be realized.

  The micropores are preferably distributed with a predetermined surface density. Thereby, the surface diffusion of the current with respect to the semiconductor light emitting layer can be promoted, and uniform surface light emission can be realized. The micropore has a pore size on the order of μm.

 (D) Since the other electrode is a thin film electrode, it is easy to manufacture and the current is efficiently diffused into the surface.

  A transparent electrode layer may be provided on the light emitting side surface, and a part of the electrode, for example, one end of the P-side electrode may be connected to the transparent electrode layer. Accordingly, it is possible to obtain both the surface diffusion of the current by the electrode distribution and the promotion of the surface diffusion of the current by the transparent electrode layer.

  The light emitting diode may be a red light emitting diode, a green light emitting diode or a blue light emitting diode, or a white light emitting diode.

  The present invention further discloses a light emitting device, a lighting device display (display device), and a signal lamp using the above-described light emitting diode.

As described above, according to the present invention, the following effects can be obtained.
(A) It is possible to provide a light emitting diode having a large light emission amount and high luminous efficiency, and a light emitting device, a lighting device and a display using the light emitting diode.
(B) It is possible to provide a light emitting diode that can promote surface diffusion of current and realize uniform surface light emission, and a light emitting device, a lighting device, and a display using the light emitting diode.
(C) A low-cost light-emitting diode, a light-emitting device using the light-emitting diode, a lighting device, and a display can be provided.

  Other objects, configurations and advantages of the present invention will be described in more detail with reference to the accompanying drawings. The accompanying drawings are merely examples.

It is a fragmentary sectional view showing an embodiment of a light emitting diode concerning the present invention. It is a fragmentary sectional view which shows another embodiment of the light emitting diode which concerns on this invention. It is a fragmentary sectional view which shows another embodiment of the light emitting diode which concerns on this invention. It is a fragmentary sectional view which shows another embodiment of the light emitting diode which concerns on this invention. It is a fragmentary sectional view which shows embodiment of the light-emitting device using the light emitting diode which concerns on this invention. It is a fragmentary sectional view which shows another embodiment of the light-emitting device using the light emitting diode which concerns on this invention. It is a fragmentary sectional view which shows embodiment of the light-emitting device using the light emitting diode which concerns on this invention. FIG. 8 is a plan view of the light emitting device illustrated in FIG. 7. It is a fragmentary sectional view which shows another embodiment of the light-emitting device using the light emitting diode which concerns on this invention. It is a fragmentary sectional view which shows the structure of the liquid crystal display using the light emitting diode which concerns on this invention.

1. Light-Emitting Diode Referring to FIG. 1, a light-emitting diode according to the present invention includes a support layer 1, a semiconductor light-emitting layer 2, a p-side electrode 4, and an n-side electrode 3. The support layer 1 can be composed of a semiconductor layer. Typically, a semiconductor layer such as Si or SiC. A semiconductor light emitting layer 2 is mounted on one surface of the support layer 1.

  Various types of semiconductor light emitting layers 2 have been proposed so far. Basically, a pn junction is used, and a group III-V compound semiconductor is typically used. However, not only a known technique but also a compound semiconductor that may be proposed in the future may be used. The same applies to the layer structure of the semiconductor light emitting layer 2.

  In the present invention, the light emitting diode may be any of a red light emitting diode, a green light emitting diode, a blue light emitting diode, and an orange light emitting diode, or a white light emitting diode. In these light emitting diodes, an example of a semiconductor material constituting the semiconductor light emitting layer 2 is shown below.

(A) Red light emitting diode (a) Using an arsenic (As) compound semiconductor Example: AlGaAs red light emitting diode (A) Using an arsenic (As) or phosphorus (P) compound semiconductor Example: GaAsP-based red light emitting diode (b) Green light-emitting diode (a) Using phosphorus (P) compound semiconductor Example: GaP green light-emitting diode (A) Using nitrogen (N) compound semiconductor Example: GaN-based green light-emitting diode (c) Blue light-emitting diode Using nitrogen (N) -based compound semiconductor Example: GaN-based blue light-emitting diode (d) White light-emitting diode Using nitrogen (N) -based compound semiconductor Example: GaN based white light emitting diode (e) Orange light emitting diode Phosphorus (P) based quaternary mixed crystal compound semiconductor Example: AlGaInP based orange light emitting diode

  1 and 2 show an example of a GaN blue light emitting diode using a nitrogen (N) compound semiconductor. Referring to the figure, the semiconductor light emitting layer 2 has a structure in which an n-type semiconductor layer 21, an active layer 22, a p-type semiconductor layer 23, and a top layer 24 are stacked in this order on one surface of the support layer 1. For example, the n-type semiconductor layer 21 is composed of a Si-doped GaN layer, and the p-type semiconductor layer 23 is composed of a Mg-doped GaN layer. Unlike the illustrated example, the p-type semiconductor layer 23 and the n-type semiconductor layer 21 may have a stacked structure.

  The active layer 22 has a multiple quantum well (MQW) structure made of GaN—InGaN or the like, and may include an Al—GaN superlattice cap layer on the side in contact with the p-type semiconductor layer 23. The top layer 24 may be an optical layer that is optically transparent, and need not be a transparent electrode. In other words, the light emitting surface of the semiconductor light emitting layer 21 may not have a transparent electrode. However, it is not intended to exclude the transparent electrode.

  Conventionally, the electrode has a structure in which a P-side electrode is formed on a part of the surface of the transparent electrode layer, and the n-side electrode is formed on the n-type GaN layer exposed by dry etching. For this reason, the problem already pointed out has arisen.

  In the present invention, as a means for solving this problem, the p-side electrode 4 for the p-type semiconductor layer 23 penetrates through the support layer 1, the n-type semiconductor layer 21 and the active layer 22, and is formed into the p-type semiconductor layer 23. The n-side electrode for the n-type semiconductor layer 21 located on the support layer 1 side was constituted by the thin film electrode 3 while being constituted by the conductor filled in the reaching micropores 5. The thin film electrode 3 can also serve as a light reflecting film. The periphery of the p-side electrode 4 is covered with an insulating film 6 as necessary.

  The micro holes 5 for the p-side electrode 4 are arranged in a matrix of m rows and n columns at a predetermined pitch interval. The number of rows m and the number of columns n are arbitrary. The fine holes 5 have a hole diameter on the order of μm, and the pitch interval may be in such an order. As a result, the p-side electrode 4 filled in the micropores 5 can function as an electrode that replaces the conventional transparent electrode layer, promotes current surface diffusion with respect to the semiconductor light emitting layer 2, and can realize uniform surface light emission. . Therefore, while improving the light emission amount and the light emission efficiency, the transparent electrode layer, which has been essential in the past, can be omitted, the manufacturing process can be simplified, and the cost can be reduced.

  The n-side thin film electrode 3 is formed on almost the entire surface of the n-type semiconductor layer 21 facing the support layer 1. The support layer 1 is provided with vertical conductors 71 and 72. The vertical conductors 71 and 72 are filled in fine holes provided penetrating in the thickness direction of the support layer 1 and can be formed by the same means as the p-side electrode 4.

  Of the vertical conductors 71 and 72, the vertical conductor 71 serves as an extraction electrode of the n-side thin film electrode 3, and the vertical conductor 72 is a heat sink. Similarly to the p-side electrode 4, the set of the vertical conductors 71 and 72 can also be arranged in a matrix of m rows and n columns.

  The number, distribution density, and the like of the vertical conductors 71 serving as extraction electrodes are determined in consideration of the current capacity. The vertical conductors 72 serving as heat sinks are preferably distributed with a uniform surface density in order to promote efficient surface heat dissipation. However, instead of dividing the vertical conductors 71 and 72, vertical conductors having the same configuration may be used as heat sinks or extraction electrodes. The heat sink vertical conductor 72 may be connected to the n-side thin film electrode 3 as shown in FIG. 1, or may be separated from the n-side thin film electrode 3 as shown in FIG. Further, as shown in FIG. 3, the tip side of the p-side electrode 4 may be brought into contact with the top layer 24. This structure is useful when the top layer 24 is a transparent electrode. According to the light emitting diode described above, the following operational effects can be obtained.

(A) The p-side electrode 4 is formed so as to penetrate the n-type semiconductor layer 21 located on the support layer 1 side from the support layer 1 side, and the tip reaches the p-type semiconductor layer 23. The n-side electrode is constituted by the thin-film electrode 3 formed on the surface of the n-type semiconductor layer 21 located on the support layer 1 side. Therefore, whether it is a p-side electrode or an n-side electrode, It does not appear on the light emitting surface. Therefore, since the light emitting area is not reduced by the electrode, it is possible to realize a surface emitting light emitting diode having a large light emission amount and high light emission efficiency.

(B) The current distribution depends on the distribution of the fine holes 5. Accordingly, the surface distribution of the micropores 5 with respect to the surface of the semiconductor light emitting layer 2 is increased in density and uniform, thereby facilitating the surface diffusion of the current to the semiconductor light emitting layer 2, uniformizing the current distribution, and achieving uniform surface light emission. It can be realized.

(C) The fine holes for the p-side electrode 4 and the vertical conductors 71 and 72 can be easily opened by applying a known drilling technique such as a laser drilling method or a chemical drilling method. In addition, since the p-side electrode 4 and the vertical conductors 71 and 72 can be constituted by the conductor filled in the fine holes thus drilled, the molten metal is filled in the fine holes when manufacturing the electrodes, and A method of applying pressure can be employed. According to this method, it is possible to form the dense p-side electrode 4 and the vertical conductors 71 and 72 having no cavities in the fine holes. Even better results can be obtained by curing while maintaining the pressurized state.

  The pressure filling manufacturing method described above belongs to the press method, and the equipment cost is significantly lower and the processing time is shorter than the dry etching method using a conventional ICP type RIE apparatus. Therefore, an inexpensive light emitting diode can be realized.

(D) Since the n-side electrode for the n-type semiconductor layer 21 is the thin film electrode 3, the n-side electrode is easy to manufacture and the current is diffused efficiently.

  The p-side electrode 4 and the vertical conductors 71 and 72 are preferably formed using molten metal from the viewpoint of improving electrical characteristics and improving the quality of the electrode itself. Examples of the main metal material used in this case include bismuth (Bi), tin (Sn), copper (Cu), aluminum (Al), and zinc (Zn). In particular, when bismuth (Bi) is contained, the dense p-side electrode 4 and the vertical conductor 71 that do not generate cavities or voids inside the micropores 5 due to the volume expansion characteristics of bismuth (Bi) during solidification. , 72 can be formed.

  Next, referring to FIG. 4, a light emitting diode having a large light emitting area is illustrated. In the figure, components corresponding to those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted.

  In the embodiment of FIGS. 5 and 6, the micropores 5 are arranged in a matrix at a predetermined pitch interval on the surface of the support layer 1. Therefore, the p-side electrode 4 formed inside the micro hole 5 is also arranged in a matrix of M rows and N columns, and a large light emission area and light emission amount almost proportional to the number of rows M and the number of columns N can be secured. .

2. Light Emitting Device The present invention discloses a light emitting device according to two embodiments.
(1) Light Emitting Device According to First Aspect Referring to FIG. 5, the light emitting device according to the first aspect includes a light emitting diode LED and a phosphor 8. The light emitting diode LED is a light emitting diode according to the present invention described with reference to FIGS. The phosphor 8 is provided on the light emitting side of the light emitting diode LED, and emits color light different from the light emission of the light emitting diode LED.

  For example, when a blue light emitting diode is used as the light emitting diode LED and a phosphor 8 that emits complementary color light with respect to the blue light emitted from the blue light emitting diode is used, white light (visible light) is obtained. . When a GaN compound semiconductor is used as the blue light emitting diode, a YAG phosphor 8 is used as the corresponding phosphor 8.

  However, the color light as the light emitting device can be set in a wide range depending on the type of the light emitting diode LED and the optical property of the phosphor 8, and is not limited to white light.

  The light-emitting diode LED is mounted on one surface of the mother board 9, and terminals 10 and 11 for supplying power to the n-side electrode 3, the p-side electrode 5, and the like are provided on the other surface side of the mother board 9. The phosphor 8 covers the light emitting diode LED on one surface of the mother board 9 in a so-called “bullet shape”.

  Further, referring to FIG. 6, a light emitting device having a very large light emitting area is shown. This light emitting device is suitable as a surface emitting device. As described with reference to FIG. 4 and the like, the light emitting diode LED has the micro holes 5 and the electrodes 4 arranged in M rows and N columns, and can secure a light emitting surface with a large area. On the light emitting side (light emitting surface side) of the large-area light emitting diode LED, a phosphor 8 that emits color light different from the light emission of the light emitting diode LED is provided.

  When a blue light emitting diode is used as the light emitting diode LED and a phosphor 8 that emits complementary color light with respect to the blue light emitted from the blue light emitting diode is used, it is extremely useful for an illumination device or a liquid crystal backlight. A large-area white light (visible light) light-emitting device can be obtained.

(2) Light Emitting Device According to Second Aspect The light emitting device according to the second aspect is illustrated in FIGS. 7 to 9. First, referring to FIGS. 7 and 8, a combination of a red light emitting diode R, a green light emitting diode G, and a blue light emitting diode B is included. In this light emitting device, red, green, and blue light emitting diodes R, G, and B, which are the three primary colors of light, are combined (as one cell) to obtain white light.

  The red light emitting diode R, the green light emitting diode G, and the blue light emitting diode B are all light emitting diodes according to the present invention.

  Next, referring to FIG. 9, the red, green, and blue light emitting diodes R, G, and B are combined into one cell, and the light emitting diode cells (C11 to CMN) are arranged in M rows and N columns. Thus, a white light emitting device having a large area light emitting surface is obtained.

3. Lighting Device The lighting device according to the present invention can be configured using the light emitting device illustrated in FIGS. When the light emitting device shown in FIG. 5 is used, a plurality of the light emitting devices are arranged to generate intermediate color light and white light. The light emitting devices are preferably arranged in a matrix (vertical and horizontal) at a narrow pitch.

  Next, when the light-emitting device shown in FIG. 6 is used, since the light-emitting device itself has a large area, it can be used as it is to generate intermediate color light and white light. In order to further increase the area, a plurality of light emitting devices shown in FIG. 8 may be arranged horizontally or vertically.

  When the light-emitting devices shown in FIGS. 7 and 8 are used, a plurality of the light-emitting devices are arranged to generate intermediate color light and white light. The light emitting devices are preferably arranged in a matrix (vertical and horizontal) at a narrow pitch.

  In the case of using the light emitting device shown in FIG. 9, since the light emitting device itself has a large area, it can be used as it is and can generate intermediate color light and white light. In order to further increase the area, a plurality of light emitting devices shown in FIG. 9 may be arranged horizontally or vertically.

4). Display The display (display device) according to the present invention includes a liquid crystal display and a light emitting diode display.
(1) Liquid Crystal Display Referring to FIG. 10, the liquid crystal display includes a liquid crystal panel 12 and a backlight 13. The backlight 12 is an illuminating device according to the present invention using the light emitting device shown in FIGS. 5 to 9, and illuminates the liquid crystal panel 12 from the back surface. FIG. 10 illustrates a case where the light emitting device illustrated in FIG. 6 is used.

(2) Light-emitting diode display The light-emitting diode display according to the present invention comprises a plurality of light-emitting devices arranged. The light emitting device is preferably the light emitting device illustrated in FIG. That is, a combination (as one cell) of a red light emitting diode R, a green light emitting diode G, and a blue light emitting diode B is included. The red light emitting diode R, the green light emitting diode G, and the blue light emitting diode B are all light emitting diodes according to the present invention. The red, green, and blue light emitting diodes R, G, and B arranged in a cell and individually arranged in one cell are individually driven to display a desired color image.

  A traffic signal lamp can also be constituted by the light emitting diode according to the present invention. The necessary signal lamp color light can be realized by the type of the light emitting diode and the combination thereof with the phosphor 8.

  Although the contents of the present invention have been specifically described above with reference to the preferred embodiments, it is obvious that those skilled in the art can adopt various modifications based on the basic technical idea and teachings of the present invention. It is.

1 Support layer
2 Semiconductor light emitting layer
21 n-type semiconductor layer
23 p-type semiconductor layer
3 Thin film electrodes
4 electrodes
5 micropores

Claims (7)

a light-emitting diode including an n-type semiconductor layer, a p-type semiconductor layer, a support layer, and an electrode;
The n-type semiconductor layer and the p-type semiconductor layer are stacked on one surface of the support layer,
The electrode includes an n-side electrode and a p-side electrode,
One of the n-side electrode and the p-side electrode penetrates one of the p-type semiconductor layer and the n-type semiconductor layer located on the support layer side from the support layer side, and the tip is Reaching the other semiconductor layer,
The other of the n-side electrode and the p-side electrode is a thin-film electrode formed on the surface of the one semiconductor layer located on the support layer side on the support layer side,
Light emitting diode.   2. The light emitting diode according to claim 1, wherein the support layer has a vertical conductor provided in a thickness direction thereof, and the vertical conductor constitutes an extraction electrode or a heat sink of the thin film electrode. A light emitting diode. A light emitting device including a light emitting diode and a phosphor,
The light emitting diode is the one described in claim 1 or 2,
The phosphor is provided on the light emitting side of the light emitting diode, and emits color light different from the light emission of the light emitting diode.
Light emitting device. A light emitting device including a combination of a red light emitting diode, a green light emitting diode, and a blue light emitting diode,
The red light-emitting diode, the green light-emitting diode, and the blue light-emitting diode are those described in any one of claims 1 to 3.
Light emitting device.   A lighting device in which a plurality of light emitting devices are arranged, wherein the light emitting device is the lighting device according to claim 3 or 4. A liquid crystal display having a liquid crystal panel and a backlight,
The said backlight is a illuminating device described in Claim 5, The liquid crystal display which illuminates the said liquid crystal panel from the back surface.   A light emitting diode display in which a plurality of light emitting devices are arranged, wherein the light emitting device is the one described in claim 3 or 4.

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