JP2006237071A - Light-emitting device and display apparatus employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device emitting brighter light by preventing an emitted light from being shielded by electrodes or wires, and also to provide a display apparatus employing the same. <P>SOLUTION: In this LED chip 1a, an n-type semiconductor layer 121a on an insulating substrate 11a is provided with a step so that its external periphery may have a thickness thinner than that of center portion, and a light-emitting layer 122a and a p-type semiconductor layer 123a are laminated only on the center portion. A translucent negative pole electrode pad 13a is stacked on the external periphery of the n-type semiconductor layer 121a and a translucent negative pole electrode pad 14a is stacked on the top surface of the p-type semiconductor layer 123a so as to cover the entire top surface, and each of the electrode pads is connected to transparent electrodes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting element and a display device using the same, and more particularly to a light emitting element capable of emitting more emitted light without being blocked by electrodes or wires, and a display device using the same.

  In recent years, LED (Light-Emitting Diode) elements have been put into practical use, and LEDs are used in various applications. LEDs are superior to conventional incandescent lamps and fluorescent lamps in terms of power saving, low heat generation, long life, space saving, etc. Downsizing of products seen in recent technological trends And a light source suitable for environmental compatibility.

  There are roughly two types of basic structures of LED chips. One is a structure in which a semiconductor layer is laminated on an insulating substrate as shown in FIG. 9 (see, for example, Patent Document 1), and both electrodes of the positive electrode and the negative electrode are arranged on a surface facing the substrate. It is what. The other is a structure in which a semiconductor layer is laminated on a conductive substrate as shown in FIG. 10 (see, for example, Patent Document 2), in which only the positive electrode is disposed on the surface facing the substrate. It is.

  9A, a semiconductor chip 100a includes an n-type semiconductor layer 102a, a light-emitting layer 103a, and a p-type semiconductor layer 104a stacked on an insulating substrate 101a, and the light-emitting layer 103a and the p-type semiconductor layer 104a. Is partially cut out to expose a part of the surface of the n-type semiconductor layer 102a. A negative electrode 105a is provided on the exposed portion, and a positive electrode 106a is provided on the surface of the p-type semiconductor layer 104a.

  As shown in FIG. 9B, the LED chip 100a having such a structure is installed on a substrate 107, and the negative electrode 105a and the positive electrode 106a are connected to the wiring pattern 109 through wires 108, respectively.

  In FIG. 10A, an LED chip 100b includes an n-type semiconductor layer 102b, a light emitting layer 103b, and a p-type semiconductor layer 104b stacked on a conductive substrate 101b. A negative electrode pad 105b is provided on the surface of the conductive substrate 101b facing the n-type semiconductor layer 102b, and a positive electrode 106b is provided on the surface of the p-type semiconductor layer 104b.

  As shown in FIG. 10B, the LED chip 100b having such a structure is installed on a substrate 107, the negative electrode pad 105b is directly connected to the wiring pattern 109, and the positive electrode 106b is connected to the wiring pattern 109 via the wire. The

With respect to the LED chip, various improvements and developments have been made with the basic structure as described above in order to achieve higher performance.
In addition, a display device is proposed in which LED chips of the type shown in FIG. 10 are arranged in a grid and sandwiched between two glass substrates and electrically connected to wiring formed on both glass substrates. (For example, refer to Patent Document 3).
JP-A-9-298313 JP 2004-31945 A JP-A-8-18105

  However, in each of the LED chips shown in FIGS. 9 and 10, since the electrodes and wires are located on the upper surface of the LED chip serving as the light emitting surface, a part of the emitted light is blocked. Furthermore, as LED chips are further miniaturized, the area of the light emitting surface is reduced, but the size of the electrodes and wires cannot be reduced proportionally. In a more compact LED chip, The electrodes and wires are relatively large, and the emitted light is blocked at a higher rate. Moreover, in the display device which consists of the above-mentioned LED chip, since the light emitting both sides of the LED chip are connected to the wiring on the glass substrate through the solder, the emitted light is blocked by the solder portion.

  Accordingly, an object of the present invention is to provide a light emitting element capable of emitting more emitted light without being blocked by electrodes and wires, and a display device using the light emitting element.

  In order to achieve the above object, the present invention provides a light emitting device in which a semiconductor layer is formed on one main surface of an insulating substrate, and includes first and second electrodes on the semiconductor layer, Provided is a light-emitting element in which an electrode close to the insulating substrate among the first and second electrodes has a shape surrounding an outer periphery of the electrode far from the insulating substrate.

  In order to achieve the above object, the present invention provides a conductive substrate, a first conductive layer in contact with at least one main surface of the conductive substrate, and a layer farthest from the one main surface. Provided is a light-emitting element having a semiconductor layer having a second conductive layer of a conductivity type different from that of the first conductive layer, and a second conductive electrode formed on the second conductive layer To do.

  In order to achieve the above object, according to the present invention, a semiconductor layer is formed on one main surface of an insulating substrate, and the first and second electrodes are provided on the semiconductor layer. Provided is a display device using, as a light source, a light emitting element having a shape in which an electrode close to the insulating substrate among the second electrodes surrounds an outer periphery of an electrode far from the insulating substrate.

  According to the present invention, since the emitted light emitted from the light emitting layer is not blocked by the electrode or the like, the light emitting efficiency of the light emitting element and the display device using the light emitting element can be improved.

[Configuration of LED chip]
FIG. 1 shows an LED chip according to the present invention, wherein (a) shows an upper plan view and a cross-sectional view when an insulating material is used for the substrate, and (b) shows an upper view when a conductive material is used for the substrate. The top view and sectional drawing are shown.

  In FIG. 1A, a semiconductor layer 12a is provided on an insulating substrate 11a, and the semiconductor layer 12a is formed in order from the insulating substrate 11a side, an n-type semiconductor layer 121a, a light emitting layer 122a, and a p-type semiconductor layer. 123a is formed. Further, the n-type semiconductor layer 121a is provided with a step so that the thickness of the outer peripheral portion is thinner than that of the central portion, and the light emitting layer 122a is laminated at the central portion. A negative electrode pad 13a is provided on the outer periphery of the n-type semiconductor layer 121a. A positive electrode pad 14a is stacked on the upper surface of the p-type semiconductor layer 123a so as to cover the entire surface.

  The insulating substrate 11a is used as a base substrate for generating a semiconductor layer and for maintaining the strength of the semiconductor layer 12a. Specifically, a sapphire substrate is used.

  The semiconductor layer 12a emits light of a target color when a voltage is applied, and is formed by stacking an n-type semiconductor layer 121a, a light-emitting layer 122a, and a p-type semiconductor layer 123a.

  The negative electrode pad 13a is used for electrical connection to the n-type semiconductor layer 121a. By providing along the outer periphery of the n-type semiconductor layer 121a, there is less risk of disconnection than the connection at a single point, and the current is distributed uniformly throughout the n-type semiconductor layer 121a, increasing the amount of current diffusion. As a result, the resistance loss is reduced and the luminous efficiency can be increased.

  The positive electrode pad 14a is used for electrical connection to the p-type semiconductor layer 123a. By providing so as to cover the upper surface of the p-type semiconductor layer 123a, the current spreads uniformly throughout the p-type semiconductor layer 123a. Further, a translucent material is used for the positive electrode pad 14a. Thereby, the emitted light emitted in the light emitting layer 122a is irradiated upward without being blocked. For example, ITO (Indium Tin 0xide) is used as a material of the negative electrode pad 13a and the positive electrode pad 14a.

  On the other hand, in FIG. 1B, the semiconductor layer 12b is provided on the conductive substrate 11b, and the semiconductor layer 12b is formed in order from the conductive substrate 11b side, the n-type semiconductor layer 121b, the light emitting layer 122b, and the p-type. A semiconductor layer 123b is formed. A negative electrode pad 13b is provided on the surface of the conductive substrate 11b facing the semiconductor layer 12b so as to cover the entire surface. Further, a positive electrode pad 14b is laminated on the upper surface of the p-type semiconductor layer 123b so as to cover the whole.

  The conductive substrate 11b is used for maintaining the strength of the semiconductor layer 12b. When the conductive substrate 11b is made of a translucent material, the negative electrode pad 13b is also made of a translucent material. Thereby, the emitted light emitted from the light emitting layer 122b can be emitted to both surfaces of the LED chip 1b. Moreover, the use of each other part is common to the example of the LED chip 1a using the conductive substrate 11a.

  Next, a mounting example when the LED chip in FIG. 1 is mounted on a glass substrate will be described.

[First Embodiment]
FIG. 2 is a schematic view showing a first embodiment in which a semiconductor chip 1a of a type using an insulating substrate among the semiconductor chips according to the present invention is mounted on a glass substrate. (A) is an upper top view in 1st Embodiment, (b) is a sectional side view in the AA cut surface of (a).

  In the first embodiment shown in FIG. 2, a glass side negative electrode 15a and a glass side positive electrode 16a are connected to the LED chip 1a, and each of the glass side negative electrode 15a and the glass side positive electrode 16a is connected to the LED chip 1a. The LED chip 1a is fixed to the glass substrate 17a by being attached to the lower surface of the glass substrate 17a. The glass side negative electrode 15a and the glass side positive electrode 16a are both positioned on the side where the LED chip 1a is provided with respect to the glass substrate.

  FIGS. 3A and 3B are partial enlarged views showing a detailed configuration according to the first embodiment shown in FIGS. 2A and 2B. FIG. 3A is an upper plan view, and FIG. The side sectional view in an AA cut surface, (c) is a side sectional view in the BB cut surface of (a). In FIG. 3A, the description of the glass substrate 17a is omitted.

  The glass-side negative electrode 15a has a shape in which one side of a rectangular shape is cut into a concave shape, and the glass-side positive electrode 16a has a shape in which one side of the rectangular shape has a convex shape so that the concave portions are not in contact with each other. The shape part and the convex part are arranged so as to mesh with each other. Moreover, both the glass side negative electrode 15a and the glass side positive electrode 16a are sheet-like, and it arrange | positions so that the one surface may affix on the glass substrate 17a.

  In the LED chip 1a, the positive electrode pad 14a is in contact with the convex portion of the glass-side positive electrode 16a and the negative electrode pad 13a is in contact with the concave portion of the glass-side negative electrode 15a. While being electrically connected with the side positive electrode 16a, it is fixed to the glass substrate 17a. At this time, since the height of each upper surface portion of the negative electrode pad 13a and the positive electrode pad 14a with respect to the insulating substrate 11a does not necessarily match, the glass side negative electrode 15a and the glass side positive electrode 16a are at least connected to the LED chip 1a. The contact portions have different thicknesses. In FIG. 3, since the height position of the upper surface of the negative electrode pad 13a is lower than the height position of the upper surface of the positive electrode pad 14a, the glass side negative electrode 15a is configured to be thicker than the glass side positive electrode 16a.

  The glass side negative electrode 15a and the glass side positive electrode 16a are comprised with a translucent material. Thereby, the electrode located in the light emission surface of LED chip 1a does not block light emission, and the light emission efficiency can be improved. Further, even if the light emitting device is further downsized, the light emission efficiency does not deteriorate. The glass substrate 17a is not limited to glass as long as it is a substrate using a translucent material.

  For example, when the electrode pads 13a and 14a and the electrodes 15a and 16a are formed of ITO, the connection structure of the glass substrate electrodes 15a and 16a and the LED chip electrodes 13a and 14a is set to 2-00 ° C. After pre-sintering, it is formed by main sintering at 700 ° C. in a state where pressure is applied so that the positive electrodes 15a, 13a and the negative electrodes 16a, 14a are in contact with each other. Further, in the LED chip 1a shown in FIG. 1, without forming the electrodes 13a and 14a of the LED chip, the p-type and n-type semiconductor layers 123a of the LED chip directly with the electrodes 16a and 15a of the temporarily sintered glass substrate, You may form by carrying out a main sintering at 700 degreeC in the state which applied the pressure so that it may contact 121a.

  Moreover, since the thickness of the light-emitting device can be suppressed by configuring electrical connection using all thin-film members, space can be saved not only in the horizontal direction but also in the height direction.

[Second Embodiment]
FIG. 4 is a schematic view showing a second embodiment in which a semiconductor chip 1a which is a type using an insulating substrate among the semiconductor chips according to the present invention is mounted on a glass substrate. The figure and (b) are side sectional views in the AA section of (a).

  In the second embodiment shown in FIG. 4, the LED chip 1a is directly connected to the glass-side negative electrode 15a located on the same surface side as the glass substrate 17a, and is located on the opposite surface side to the glass substrate 17a. The glass-side positive electrode 16a is connected to the glass substrate 17a through a current-carrying wiring 18a penetrating the glass substrate 17a, and the LED chip 1a is attached to the lower surface of the glass substrate 17a so that the LED chip 1a is attached to the glass substrate 17a. It is fixed to.

  FIGS. 5A and 5B are partial enlarged views showing a detailed configuration according to the second embodiment shown in FIGS. 4A and 4B. FIG. 5A is an upper plan view, and FIG. 5B is a plan view of FIG. The side sectional view in an AA cut surface, (c) is a side sectional view in the BB cut surface of (a). In FIG. 5A, the description of the glass substrate 17a is omitted.

  The glass-side negative electrode 15a has a shape in which one side of a rectangular shape is cut into a concave shape, and the glass-side positive electrode 16a has a substantially rectangular shape and is disposed so as to be located on opposite surfaces of the glass substrate 17a. ing. Moreover, both the glass side negative electrode 15a and the glass side positive electrode 16a are sheet-like, and it arrange | positions so that the one surface may affix on the glass substrate 17a.

  The glass substrate 17a has a hole penetrating from one surface to the opposite surface at a substantially central portion thereof, and a conductive wiring 18a is provided in the hole.

  In the LED chip 1a, the positive electrode pad 14a is in contact with the energizing wiring 18a and the negative electrode pad 13a is in contact with the concave portion of the glass-side negative electrode 15a, whereby the glass-side negative electrode 15a and the glass-side positive electrode 16a are electrically connected. And is fixed to the glass substrate 17a.

  The glass-side negative electrode 15a and the glass-side positive electrode 16a are made of a light-transmitting material as in the first embodiment. Thereby, the electrode located in the light emission surface of LED chip 1a does not block light emission, and the light emission efficiency can be improved. Further, even if the light emitting device is further downsized, the light emission efficiency does not deteriorate. The glass substrate 17a is not limited to glass as long as it is a substrate using a translucent material.

  Moreover, since the thickness of the light-emitting device can be suppressed by configuring all the electrical connection members except the energization wiring 18a using thin-film members, the space can be saved not only in the horizontal direction but also in the height direction. Is possible.

[Third Embodiment]
FIG. 6 is a partially enlarged view showing a third embodiment in which a semiconductor chip 1b, which is a type using a conductive substrate, of a semiconductor chip according to the present invention is mounted on a glass substrate. An upper top view and (b) are side sectional views in an AA section of (a).

  In the third embodiment shown in FIG. 6, the glass-side negative electrode 15b and the glass-side positive electrode 16b are in contact with the LED chip 1b on both sides, and the glass-side positive electrode 16b is in contact with the glass substrate 17b. The side negative electrode 15b is affixed to the glass substrate 18b, whereby the LED chip 1b is fixed so as to be sandwiched between the glass substrates 17b and 18b.

  The LED chip 1b can emit light by passing a current between the glass side positive electrode 16b on the glass substrate 17b side and the glass side negative electrode 15b on the glass substrate 18b side.

  Here, when the conductive substrate 11b is made of a light-transmitting material, there is no light blocking material on both surfaces of the light emitting layer 122b. Therefore, the two glass substrates and the LED chip sandwiched between them are used. A light source that emits emitted light on both sides can be obtained from the plate-shaped light source.

[Fourth Embodiment]
FIG. 7 is a schematic view showing a fourth embodiment in which a semiconductor chip 1b which is a type using a conductive substrate among the semiconductor chips according to the present invention is mounted on a glass substrate, and FIG. The figure and (b) are side sectional views in the AA section of (a).

  In the fourth embodiment, the glass chip negative electrode 15b is in contact with the LED chip 1b on one side, the other side is in contact with the glass substrate 17b, and the glass side negative electrode 15b is on the glass substrate 18b. By being affixed, the LED chip 1b is fixed so as to be sandwiched between the glass substrates 17b and 18b. Further, the glass side positive electrode 16b is in contact with the glass substrate 17b, and the positive electrode side electrode pad 14b of the LED chip 1b and the glass side positive electrode 16b are electrically connected. The glass side positive electrode 16b is fixed by a spacer 19b provided on the glass substrate 18b.

  In the LED chip 1b shown in FIG. 1, the positive electrode pad 14b has substantially the same size as the p-type semiconductor layer 123b. However, in the present embodiment, the positive electrode pad 14b is a p-type semiconductor layer. It is larger than the size of 123b and substantially the same size as the glass substrate 17b. Thereby, it can contact | connect with the glass side positive electrode 16b provided on the spacer 19b. The size of the positive electrode pad 14b remains substantially the same size as that of the p-type semiconductor layer 123b, and the light-transmitting conductive material having substantially the same size as the glass substrate 17b between the positive electrode pad 14b and the glass substrate 17b. A thin film may be provided.

  In the fourth embodiment shown in FIG. 7, unlike the third embodiment shown in FIG. 6, the glass-side negative electrode 15b and the glass-side positive electrode 16b face the same direction. The design when arranging the wiring on the substrate 18b becomes easy.

  In any of the above-described embodiments, the conventional type of electrode or wire is not used for the LED chip, so that the ratio of the light emitting area in one LED chip can be kept large, and the emitted light is blocked. Since there is nothing, issuance efficiency can be increased compared to conventional LEDs.

  In any of the above-described embodiments, the electrode pad and the glass side electrode are provided in both the positive electrode and the negative electrode. Both the electrode pad and the glass side electrode are made of a light-transmitting conductive thin film, and Au / Co, ITO, or the like is used. Therefore, in the present invention, it is not always necessary to use both members, and a single sheet-like member in which both members are integrated may be used.

[Fifth Embodiment]
8A and 8B show a display device as a light emitting device according to a fifth embodiment of the present invention, in which FIG. 8A is a plan view and FIG. 8B is a cross-sectional view taken along line AA in FIG. . In the fifth embodiment, the LED chip 1b described in the third embodiment is used as the light source.

The display device 200 includes a substrate 201 formed of an insulating material such as Al ₂ O _3, a wiring layer 201A formed on the surface of the substrate 201 so as to have a predetermined wiring pattern using copper foil, The LED chip 1b mounted on the LED chip 1b, the transparent substrate 202 provided on the upper surface of the LED chip 1b and having a wiring layer 202A made of ITO, and the mask member 203 provided on the surface of the transparent substrate 202. The light extraction window 203A for externally radiating light reaching from the LED chip 1b through the transparent substrate 202 is provided according to the arrangement of the LED chip 1b.

  The LED chip 1b has a configuration sandwiched between a substrate 201 and a transparent substrate 203, and a plurality of LED chips 1b are arranged in a 5 × 5 matrix. In addition, about arrangement | positioning of LED chip 1b, it is not limited to the number of arrangement | positioning mentioned above, Other numbers and arrangement | sequences may be sufficient.

  The wiring layers 201 </ b> A and 202 </ b> A are formed to have a wiring pattern that can individually supply power to each LED chip 1 b.

  In the display device 200, the LED chip 1 b emits light by connecting the wiring layers 201 </ b> A and 202 </ b> A and a power supply unit (not shown) and supplying power. Here, a desired display is performed by controlling energization to the LED chip 1b according to a pattern such as a character or a pattern to be displayed on the display device 200.

According to the fifth embodiment, in addition to the preferable effect of the third embodiment, the display device 200 having excellent luminance can be obtained. In the fifth embodiment, the structure in which the substrate 201 made of Al ₂ O ₃ having no light transmittance is provided on the substrate 201 is described. However, the present invention is not limited to this, and any substrate having light transmittance can be used. It can also be set as the structure which can extract light from the board | substrate side.

It is the top view and side sectional view of an LED chip concerning the present invention. It is the schematic of the light-emitting device which concerns on the 1st Embodiment of this invention, (a) is a top view, (b) is a sectional side view in the AA cross section of (a). It is the elements on larger scale of the light-emitting device concerning the 1st Embodiment of this invention, (a) is a top view, (b) is a cross-sectional view in the AA cross section of (a), (c) is (a) It is a cross-sectional view in the BB cross section. It is the schematic of the light-emitting device which concerns on the 2nd Embodiment of this invention, (a) is a top view, (b) is a sectional side view in the AA cross section of (a). It is the elements on larger scale of the light-emitting device concerning the 2nd Embodiment of this invention, (a) is a top view, (b) is a cross-sectional view in the AA cross section of (a), (c) is (a) It is a cross-sectional view in the BB cross section. It is the elements on larger scale of the light-emitting device which concerns on the 3rd Embodiment of this invention, (a) is a top view, (b) is a cross-sectional view in the AA cross section of (a). It is the elements on larger scale of the light-emitting device which concerns on the 4th Embodiment of this invention, (a) is a top view, (b) is a cross-sectional view in the AA cross section of (a). The display apparatus as a light-emitting device concerning the 5th Embodiment of this invention is shown, (a) is a top view, (b) is sectional drawing cut | disconnected by the AA part of (a). (A) is a top view and a side sectional view of a conventional LED chip, and (b) is a configuration example in which the LED chip of (a) is mounted on a substrate. FIG. 8A is a plan view and a side sectional view of an LED chip of a type different from that of FIG. 8 according to the prior art, and FIG. 8B is a configuration example in which the LED chip of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b ... LED chip, 11a ... Insulating substrate, 11b ... Conductive substrate, 12a, 12b ... Semiconductor layer, 13a, 13b ... Negative electrode pad, 14a, 14b ... Positive electrode pad, 15a, 15b ... Glass side negative electrode , 16a, 16b ... glass side positive electrode, 17a, 17b, 18b ... glass substrate, 18a ... energization wiring, 19b ... spacer, 100a, 100b ... LED chip, 101a ... insulating substrate, 101b ... conductive substrate, 102a, 102b ... n-type semiconductor layer, 103a, 103b ... light emitting layer, 104a, 104b ... p-type semiconductor layer, 105a ... negative electrode, 105b ... negative electrode pad, 106a, 106b ... positive electrode, 107a, 107b ... substrate, 108 ... wire, 109: wiring pattern, 121a, 121b ... n-type semiconductor layer, 122a, 122b ... Layers, 123a, 123b ... p-type semiconductor layer, 200 ... display unit, 201 ... substrate, 201A ... wiring layer, 202 ... transparent substrate, 202A ... wiring layer, 203 ... mask member, 203A ... light extraction window

Claims (8)

In a light emitting device in which a semiconductor layer is formed on one main surface of an insulating substrate,
The first and second electrodes are formed on the semiconductor layer, and the electrode close to the insulating substrate of the first and second electrodes surrounds the outer periphery of the electrode far from the insulating substrate. A light emitting element characterized by that.   The light-emitting element according to claim 1, wherein the electrode far from the insulating substrate is formed of a light-transmitting material.   The light emitting element according to claim 1, wherein the electrode far from the insulating substrate is electrically connected to the outside over the entire surface. A conductive substrate;
A semiconductor having at least a first conductive layer in contact with one main surface of the conductive substrate, and a second conductive layer having a conductivity type different from the first conductive layer in a layer farthest from the one main surface Layers,
A light-emitting element having a second conductive electrode formed on the second conductive layer.   The light emitting element according to claim 4, wherein the second conductive electrode is formed of a light transmissive material.   The light-emitting element according to claim 4, wherein the conductive substrate, the semiconductor layer, and the second electrode have substantially the same cross-sectional area.   The light emitting element according to claim 4, wherein the second conductive electrode is electrically connected to the outside over the entire surface.   A semiconductor layer is formed on one main surface of the insulating substrate, has a first electrode and a second electrode on the semiconductor layer, and is close to the insulating substrate among the first electrode and the second electrode. A display device using a light emitting element having a shape in which an electrode surrounds an outer periphery of an electrode far from the insulating substrate.

Images