JP2007073789A - Electrodes for semiconductor light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electrodes capable of obtaining intense light emission with a low driving voltage without degrading crystallinity. <P>SOLUTION: In the structure of the electrodes for a semiconductor light emitting device, one electrode of n-type or p-type and the other electrode of p-type or n-type opposed thereto are provided on the same surface of the light emitting device. Both of the electrodes consist of a bonding pad and a transparent conductive layer. The light emitting device is a GaN-based semiconductor light emitting device etc. For the transparent conductive layer, an oxide such as ITO etc., and/or a metal such as Al, Ni etc. are used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrode for a semiconductor light emitting device, and more particularly to an electrode for a semiconductor light emitting device suitable for a gallium nitride compound semiconductor light emitting device and capable of obtaining strong light emission at a low driving voltage.

  In recent years, GaN-based compound semiconductor materials have attracted attention as semiconductor materials for short wavelength light emitting devices. GaN-based compound semiconductors include sapphire single crystals, various oxides and III-V compounds as substrates, and metalorganic vapor phase chemical reaction method (MOCVD method) or molecular beam epitaxy method (MBE method). And so on.

  A characteristic of the GaN-based compound semiconductor material is that current diffusion in the lateral direction is small. The cause is thought to be the presence of dislocations penetrating from the substrate present in the epitaxial crystal to the surface, but the details are not known. Furthermore, the p-type GaN-based compound semiconductor has a higher resistivity than the n-type GaN-based compound semiconductor, and the lateral current spread in the p-layer can be increased by simply laminating a metal on a part of the surface. When there is almost no LED structure having a pn junction, light is emitted only directly below the positive electrode.

  For this reason, a translucent positive electrode is often used that emits light emitted directly under the positive electrode through the positive electrode. In particular, as a technique used in the market, a technique is generally used in which Ni and Au are stacked on the p layer as a positive electrode on the order of several tens of nanometers, and then heated in an oxygen atmosphere to perform alloying treatment (Patent Document). 1). In addition, a conductive transparent oxide such as ITO may be used. The conductive transparent oxide can be formed by sputtering or vapor deposition.

  However, even with these transparent electrodes, the problem of current diffusion has not been completely solved. One of the causes is insufficient current diffusion in the n layer. As a method of increasing the diffusion of the current in the n layer, one must reduce the resistivity of the n layer or increase the film thickness to decrease the resistance value. However, these measures for reducing the resistance value lower the crystallinity. The decrease in crystallinity causes deterioration of characteristics such as generation of leakage due to aging and decrease in electrostatic resistance.

  On the other hand, a method has been proposed in which the distance between the n electrode and the p electrode is reduced by surrounding the periphery of the electrode located at the transparent center with the other electrode (see Patent Documents 2 and 3). However, in such a structure in which the central transparent electrode is surrounded by the n electrode, there is a problem that light emission cannot be sufficiently extracted to the outside due to being blocked by the surrounding electrode.

Further, as an electrode arrangement used for a chip having a relatively large area or the like, a technique in which a negative electrode and a positive electrode are alternately arranged in a comb shape has been disclosed (see Patent Documents 4 and 5). However, when such an arrangement is adopted for the semiconductor having a problem in the current spread in the lateral direction of the p-layer and the n-layer described above, the light is not sufficiently extracted to the outside because it is eventually blocked by the electrode. There was a problem.
Japanese Patent No. 2803742 JP-A-9-97922 JP-A-8-340131 JP-A-5-335622 JP 2003-133589 A

An object of the present invention is to provide an electrode capable of obtaining strong light emission with a low driving voltage without reducing crystallinity in order to solve the above-mentioned problems.
In the present invention, translucency means translucency with respect to light in the emission wavelength region. In the case of a gallium nitride compound semiconductor light emitting device, the emission wavelength region is usually in the range of 300 to 700 nm.

The present invention has been made to achieve the above object, and comprises the following inventions.
(1) An electrode for a semiconductor light emitting device having a structure having one n-type or p-type electrode on the same surface of the light-emitting device and the other p-type or n-type electrode opposed to the electrode. An electrode for a semiconductor light emitting device comprising a bonding pad and a transparent conductive layer.
(2) An electrode for a semiconductor light emitting device having a structure having one n-type or p-type electrode on the same surface of the light-emitting device and the other p-type or n-type electrode opposed to the electrode. An electrode for a semiconductor light emitting device, wherein a bonding pad is formed on a transparent conductive layer.
(3) The transparent conductive layer of the one electrode is disposed in a central region of the light emitting element, and the transparent conductive layer of the other electrode facing the transparent conductive layer is part or all of the periphery of the transparent conductive layer of the one electrode The electrode for a semiconductor light-emitting element according to the above (1) or (2), wherein the electrode for a semiconductor light-emitting element has a planar shape surrounding the substrate.
(4) The electrode for a semiconductor light-emitting element according to (1) or (2), wherein the transparent conductive layer of the one electrode and the transparent conductive layer of the other electrode are in a planar shape.
(5) The electrode for a semiconductor light-emitting element according to any one of (1) to (4), wherein the area of the transparent conductive layer of the n-type electrode is smaller than the area of the transparent conductive layer of the p-type electrode.

(6) The material of the transparent conductive layer of the n-type electrode is at least one selected from the group consisting of ITO, aluminum oxide, zinc, fluorine-doped tin oxide, titanium oxide, zinc sulfide, bismuth oxide, and magnesium oxide. The electrode for a semiconductor light-emitting device according to any one of (1) to (5) above.
(7) The electrode for a semiconductor light-emitting element according to (6) above, wherein the transparent conductive layer of the n-type electrode has a thickness of 10 to 100 nm.
(8) The material of the transparent conductive layer of the n-type electrode is at least one selected from the group consisting of aluminum, nickel, titanium, gold, silver, and chromium, (1) to (5) above The electrode for semiconductor light-emitting devices in any one of.
(9) The electrode for a semiconductor light-emitting element according to (8) above, wherein the transparent conductive layer of the n-type electrode has a thickness of 1 to 100 nm.
(10) The electrode for a semiconductor light-emitting element according to any one of (1) to (9), wherein the transparent conductive layer of the n-type electrode transmits 70% or more of the emitted light.
(11) The electrode for a semiconductor light-emitting element according to any one of (1) to (10) above, wherein the area of the transparent conductive layer of the n-type electrode is 5 to 50% of the light-emitting element chip area.

(12) The n-type electrode is composed of a bonding pad and a transparent conductive layer extending from the pad along the periphery of the light-emitting element chip, according to any one of (1) to (11) above Electrode for semiconductor light emitting device.
(13) The electrode for a semiconductor light-emitting element according to any one of (1) to (12) above, wherein the transparent conductive layer of the p-type electrode has a thickness of 5 to 1000 nm.
(14) The semiconductor light-emitting device as described in any one of (1) to (13) above, wherein bonding pads for the n-type electrode and the p-type electrode are provided to face the sides or corners of the light-emitting element. Element electrode.
(15) The bonding pad has a multilayer structure, and the lowermost layer (side in contact with the transparent conductive layer) is selected from the group consisting of Cr, Al, Ti, platinum group metals such as Pt, Rh, Ru, Ir, and Ag. The electrode for a semiconductor light-emitting device according to any one of the above (1) to (14), wherein the electrode is a metal that has been removed.

(16) Any of the above (1) to (15), wherein the bonding pad has a multilayer structure, and the upper layer on the lowermost layer is a metal selected from the group consisting of Ti, Cr, and Al. The electrode for semiconductor light-emitting elements as described in 2.
(17) The electrode for a semiconductor light-emitting element according to any one of (1) to (16), wherein the bonding pad has a multilayer structure, and the uppermost layer is Au or Al.
(18) The electrode for a semiconductor light-emitting device according to any one of (1) to (17), wherein the light-emitting device chip has a size of 500 μm square or more.
(19) The electrode for a semiconductor light-emitting element according to any one of (1) to (18), wherein the light-emitting element is a GaN-based semiconductor light-emitting element.
(20) A light emitting device using the electrode according to any one of (1) to (19).
(21) A light emitting device in which the light emitting device according to (20) and a phosphor are combined.
(22) A lamp using the light emitting device according to (20) or (21).

  In an element having a structure in which electrodes are formed on the same surface of a light emitting element, both electrodes are formed of a bonding pad and a transparent electrode, thereby solving the problem of current spreading and increasing the electrode contact area. Even if the electrode structure for lowering the driving voltage is adopted, the emission intensity can be increased without lowering the efficiency of extracting emitted light.

Hereinafter, the present invention will be described in detail with reference to the drawings.
In the present invention, translucency and transparency mean translucency and transparency to light in the emission wavelength region. In the case of a gallium nitride compound semiconductor light emitting device, the emission wavelength region is usually in the range of 300 to 700 nm. The light transmittance also means the transmittance for light of these wavelengths.
FIG. 1 is a schematic view showing a plane of an example of a light emitting device having the electrode arrangement of the present invention. Reference numeral 10 denotes an n-type electrode (negative electrode), which includes a negative electrode transparent conductive layer (11) and a bonding pad (12). Reference numeral 20 denotes a p-type electrode (positive electrode), which includes a positive electrode transparent conductive layer (21) and a bonding pad (22). The negative electrode is formed in the exposed n-type semiconductor by etching the semiconductor layer from the upper surface until the n-type semiconductor layer is exposed. A part of the negative bonding pad is formed on the transparent conductive layer 11 and the remaining part is formed on the n-type semiconductor layer. The bonding pad may not be on the n-type semiconductor layer. The bonding pad for the positive electrode is formed so as to partially overlap the transparent conductive layer.

FIG. 2 is also a schematic view showing a plane of another example of the light emitting device having the electrode arrangement of the present invention. The numbering in the figure is the same as in FIG.
When the electrode of the present invention in which the conductive layers constituting the n-type electrode (also referred to as n-electrode) and p-type electrode (also referred to as p-electrode) are both transparent is used, each transparent conductive layer can be formed without reducing light extraction. The area can be increased. As a result, the contact area between the transparent conductive layer and the semiconductor layer can be increased to lower the driving voltage, and the transparent conductive layer of the p electrode and the transparent conductive layer of the n electrode can be arranged close to each other. The adverse effect of reducing the light emission area due to the small current spread can also be avoided.

The transparent conductive layer of the electrode of the present invention may be arranged such that one (p-type layer in FIG. 1) is located at the center of the element and the other (n-type layer in FIG. 1) surrounds the periphery. it can. In this case, it is not necessary for the other transparent conductive layer to completely surround one transparent conductive layer, and it is sufficient to surround at least half the length of two sides. However, it goes without saying that a completely enclosed arrangement is most effective for the problem of current diffusion. Further, an effect of increasing the area of the transparent conductive layer of the n electrode can be obtained.
The bonding pad may be located anywhere on the transparent conductive layer, but it is desirable that the bonding pad be located as far away as possible from the opposite corner (corner) or side.
In many cases, since the p-type layer has a problem that current spread is not good, it is desirable to make the area of the transparent conductive layer of the p electrode larger than the area of the transparent conductive layer of the n-electrode. In this case, it is more effective to use the transparent conductive layer located at the center for the p-electrode.

The transparent conductive layer of the electrode of the present invention can be arranged in a comb shape or a lattice shape as shown in FIG. For the above reasons, it is desirable that the area of the transparent conductive layer of the p electrode is larger than the area of the transparent conductive layer of the n electrode even in the case of a comb shape.
This arrangement is suitable for a light-emitting element chip called a large one having a side of 500 μm or more. The bonding pad may be located anywhere on the electrode, but it is desirable that the bonding pad be located as far away as possible from the opposite corners and sides.
The material of the transparent conductive layer of the positive electrode is widely known and can be used freely. For example, it is also possible to use a metal layer structure such as a two-layer structure of Au and NiO, a two-layer structure of Pt and Au, or a conductive oxide such as ITO from the semiconductor side.

As a material for the transparent conductive layer of the negative electrode, a metal thin film or a conductive oxide can be used. For example, ITO, aluminum oxide zinc, fluorine-doped tin oxide, titanium oxide, zinc sulfide, bismuth oxide, magnesium oxide, or a thin film such as aluminum, nickel, titanium, gold, silver, or chromium can be used.
The transparent conductive layer of these negative electrodes desirably has a light transmittance of 70% or more.
For this reason, when a metal thin film is used, it is necessary to make the film thickness very thin. The film thickness is preferably 1 to 100 nm. If it is less than 1 nm, the current diffusion effect is not sufficiently exhibited. If it exceeds 100 nm, the light transmittance is remarkably lowered, and the light emission output is likely to be lowered. 1-50 nm is more preferable. Furthermore, when the thickness is in the range of 3 to 20 nm, the balance between light transmittance and current diffusion effect is the best, and light is emitted uniformly over the entire surface, and high-output light emission can be obtained.
In the case of using a conductive oxide, the thickness is preferably 10 nm to 100 μm. If it is less than 10 nm, current spread in the lateral direction cannot be obtained in the transparent electrode. When the thickness exceeds 100 μm, the light transmittance is remarkably lowered, and the light emission output may be lowered. More preferably, it is 50 nm-1 micrometer. These also have a light transmittance of 70% or more.

The area of the transparent conductive layer of the negative electrode is desirably 5% to 50% of the area of the light emitting element chip (semiconductor layer of the light emitting element). As described above, since current diffusion cannot be expected in the p-type layer, it is better to distribute the current vertically in the p-type layer. Therefore, in many cases, a structure having light emission under the p-layer is used.
Therefore, if the area of the transparent conductive layer of the negative electrode is too large, the light emitting area is reduced. The limit is 50% of the light emitting element chip area. On the other hand, if this area is smaller than 50%, the contact area becomes small and the drive voltage rises.

Known materials and structures can be used as the negative electrode bonding pads.
The negative electrode bonding pad is often formed in multiple layers, but the lowermost material is made of Cr, Al, Ti, platinum group metals such as Pt, Rh, Ru, Ir, Ag, and a small amount of these metals. Is also a kind of alloy. Among them, Cr, Al, Ag, Pt and alloys containing at least one of these metals are common as electrode materials, and are excellent in terms of easy availability and handling. Yes.
Further, the layer formed on the lowermost layer of the bonding pad electrode has a role of enhancing the strength of the entire bonding pad electrode. For this reason, it is necessary to use a relatively strong metal material or to sufficiently increase the film thickness. Desirable materials are Ti, Cr or Al. Among these, Ti is desirable in terms of material strength. When such a function is given, this layer is called a barrier layer.
The uppermost layer of the bonding pad electrode is preferably made of a material having good adhesion to the bonding ball. Gold is often used for the bonding balls, and Au and Al are known as metals having good adhesion to the gold balls. Of these, gold is particularly desirable. The thickness of the uppermost layer is desirably 50 to 1000 nm, and more desirably 100 to 500 nm. If it is too thin, the adhesion to the bonding ball will be poor, and if it is too thick, no particular advantage will be produced, and only the cost will increase.

The n-electrode bonding pad can have any shape. However, since the bonding pad is an opaque region, the area is preferably as small as possible, and the area can be reduced by taking a circular shape. For the purpose of assisting current diffusion, it is also effective to match the shape of the exposed region of the n layer formed for forming the n electrode.
As the area of the n-electrode bonding pad is smaller, the opaque region can be reduced. However, if the area is too small, bonding becomes difficult. It is desirable that the diameter is about 50 μm to about 200 μm.
The method for forming the transparent region of the p-side electrode, the bonding pad, the transparent region of the n-side electrode, and the bonding pad is not particularly limited, and a known vacuum deposition method or sputtering method can be used.

The positive electrode of the present invention includes a conventionally known gallium nitride compound semiconductor light emitting device in which a gallium nitride compound semiconductor is stacked on a substrate via a buffer layer to form an n-type semiconductor layer, a light emitting layer, and a p type semiconductor layer. It can be used for a semiconductor light emitting device without any limitation.
For the substrate, sapphire single crystal (Al ₂ O ₃ ; A plane, C plane, M plane, R plane), spinel single crystal (MgAl ₂ O ₄ ), ZnO single crystal, LiAlO ₂ single crystal, LiGaO ₂ single crystal, Substrate materials such as oxide single crystals such as MgO single crystals, Si single crystals, SiC single crystals, GaAs single crystals, AlN single crystals, GaN single crystals, and boride single crystals such as ZrB ₂ can be used without any limitation. . The plane orientation of the substrate is not particularly limited. Moreover, a just board | substrate may be sufficient and the board | substrate which provided the off angle may be sufficient.

The n-type semiconductor layer, the light emitting layer, and the p-type semiconductor layer can be used without any limitation including those of various known structures. In particular, the carrier concentration of the p-type semiconductor layer may be a general concentration, but the light-transmitting property of the present invention is also applied to a p-type semiconductor layer having a relatively low carrier concentration, for example, about 1 × 10 ¹⁷ cm ^−3. A sex electrode is applicable.
The carrier concentration of the n-type semiconductor layer is preferably about 1 × 10 ¹⁷ cm ⁻³ to 2 × 10 ¹⁹ cm ⁻³ , for example. Below this, the contact resistance becomes too high, and above this, the crystallinity and flatness are lowered. More desirably, it is 1 × 10 ¹⁸ cm ⁻³ to 1 × 10 ¹⁹ cm ⁻³ , and 5 × 10 ¹⁸ cm ⁻³ to 8 × 10 ¹⁸ cm ⁻³ is optimal.
As the gallium nitride compound semiconductor constituting the n-type semiconductor layer, the light emitting layer, and the p-type semiconductor layer in the present invention, the general formula Al _x In _y Ga _1-xy N (0 ≦ x <1, 0 ≦ y <1,0) Semiconductors having various compositions represented by ≦ x + y <1) can be used without any limitation.

The growth method of these gallium nitride-based compound semiconductors is not particularly limited, and Group III nitride semiconductors such as MOCVD (metal organic chemical vapor deposition), HVPE (hydride vapor deposition), MBE (molecular beam epitaxy), etc. All methods known to grow can be applied. A preferred growth method is the MOCVD method from the viewpoint of film thickness controllability and mass productivity. In the MOCVD method, hydrogen (H ₂ ) or nitrogen (N ₂ ) as a carrier gas, trimethyl gallium (TMG) or triethyl gallium (TEG) as a Ga source which is a group III source, trimethyl aluminum (TMA) or triethyl aluminum as an Al source (TEA), trimethylindium (TMI) or triethylindium (TEI) as an In source, ammonia (NH ₃ ), hydrazine (N ₂ H ₄ ), or the like as an N source that is a group V source. In addition, as a dopant, monosilane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is used as an Si raw material for n-type, germane (GeH ₄ ) or an organic germanium compound is used as a Ge raw material, and Mg raw material is used for a p-type. For example, biscyclopentadienyl magnesium (Cp ₂ Mg) or bisethylcyclopentadienyl magnesium ((EtCp) ₂ Mg) is used.

  When the electrode arrangement for a semiconductor light emitting device of the present invention is used, a gallium nitride compound semiconductor light emitting device having high light emission intensity can be obtained. In other words, since this technology can produce a high-intensity LED lamp, electronic devices such as mobile phones, displays, and panels incorporating a chip produced by this technology, automobiles, computers incorporating such electronic devices, Machine devices such as game machines can be driven with low power and can achieve high characteristics. In particular, the battery-powered devices such as mobile phones, game machines, toys, and automobile parts exhibit power saving effects.

FIG. 1 shows a cross section of a gallium nitride compound semiconductor light emitting device manufactured in this example.
EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited only to these Examples.

Example 1
It is a schematic diagram.
In Example 1, an epitaxial substrate having the following laminated structure was used. That is, an n-doped GaN contact layer having a thickness of 6 μm, a Ge-doped n-type GaN contact layer having a thickness of 4 μm, and Si having a thickness of 180 nm are formed on a substrate made of sapphire via a buffer layer made of AlN. A multi-quantum well structure in which a type In _0.1 Ga _0.9 N cladding layer, a 16 nm thick Si-doped GaN barrier layer, and a 2.5 nm thick In _0.2 Ga _0.8 N well layer are stacked five times, and finally a barrier layer is provided. A light emitting layer, an Mg-doped p-type Al _0.07 Ga _0.93 N cladding layer having a thickness of 0.01 μm, and an Mg-doped p-type Al _0.02 Ga _0.98 N contact layer having a thickness of 0.175 μm were sequentially laminated. On the p-type Al _0.02 Ga _0.98 N contact layer, a light-transmitting electrode (11) made of ITO having a thickness of 250 nm and a 50 nm Al layer, 20 nm Ti layer, 10 nm Al layer, 100 nm Ti layer, 200 nm A positive electrode (10) of the present invention comprising a bonding pad electrode (12) having a five-layer structure composed of an Au layer was formed.
Next, a transparent region (21) made of Al with a thickness of 5 nm and a Ti / Au double-layer bonding pad (22) are formed on the n-type GaN contact layer, and the light-emitting element having the light extraction surface as the semiconductor side It is. The shapes of the positive electrode and the negative electrode are as shown in FIG.

In this structure, the carrier concentration of the n-type GaN contact layer was 7 × 10 ¹⁹ cm ⁻³ , and the carrier concentration of the p-type Al _0.02 Ga _0.98 N contact layer was 5 × 10 ¹⁸ cm ⁻³ .
Lamination of the gallium nitride compound semiconductor layers was performed by MOCVD under normal conditions well known in the art. Moreover, the positive electrode and the negative electrode were formed in the following procedure.
First, the n-type GaN contact layer for forming the negative electrode by the reactive ion etching method was exposed by the following procedure.
First, an etching mask was formed on the p-type semiconductor layer. The formation procedure is as follows. After uniformly applying the resist over the entire surface, the resist was removed from a region that was slightly larger than the positive electrode region using a known lithography technique. It was set in a vacuum deposition apparatus, and ITO was laminated by an electron beam method at a pressure of 4 × 10 ⁻⁴ Pa or less so that the film thickness was about 500 nm. Thereafter, the metal film other than the positive electrode region was removed together with the resist by a lift-off technique.

Next, the semiconductor laminated substrate is placed on the electrode in the etching chamber of the reactive ion etching apparatus, the pressure in the etching chamber is reduced to 10 ⁻⁴ Pa, and then Cl ₂ is supplied as an etching gas to expose the n-type GaN contact layer. Etched until After the etching, it was taken out from the reactive ion etching apparatus, and the etching mask was removed with nitric acid and hydrofluoric acid.
Next, after taking out from the vacuum chamber, it is processed in accordance with a well-known procedure called “normally lift-off”, and further, a lower layer made of Pt, a barrier layer made of Ti, A barrier layer made of Ti, a barrier layer made of Ti, and an uppermost layer made of Au were laminated in order to form a bonding pad electrode (12). Thus, the positive electrode of the present invention was formed on the p-type GaN contact layer.

  Next, a negative electrode was formed on the exposed n-type GaN contact layer by the following procedure. After the resist is uniformly applied to the entire surface, the resist is removed from the negative electrode forming portion on the exposed n-type GaN contact layer using a known lithography technique, and further, a portion other than the region where the transparent electrode is to be formed is covered with the resist. In a protected state, an Al thin film having a thickness of 5 nm was formed by vacuum deposition, and the Al film (21) other than the portion to be formed was removed according to the lift-off method. Further, a negative side bonding pad (22) having Ti of 100 nm and Au of 200 nm was formed in this order from the semiconductor side by a commonly used vacuum deposition method. Thereafter, the resist was removed by a known method.

The wafer in which the positive electrode and the negative electrode were formed in this way was thinned and polished to a substrate thickness of 80 μm by grinding and polishing the back surface of the substrate, and a ruled line was entered from the semiconductor lamination side using a laser scriber. It was cut and cut into 350 μm square chips. Subsequently, when these chips were energized with a probe needle and the forward voltage was measured at a current application value of 20 mA, it was 3.0 V.
After that, when mounted on a TO-18 can package and measured for light output by a tester, the light output at an applied current of 20 mA was 12.5 mW. Moreover, it was confirmed that the light emission distribution on the light emitting surface emitted light on the entire surface under the positive electrode.
Further, the reflectance of the reflective layer produced in this example was 92% in the wavelength region of 470 nm. This value was measured with a spectrophotometer using a glass dummy substrate placed in the same chamber when the bonding pad electrode was formed.

(Comparative Example 1)
A light-emitting element was fabricated in the same manner as in Example 1 except that the n-electrode was made the same region as in FIG.
When the obtained light emitting device was evaluated in the same manner as in Example 1, the forward voltage was 3.0 V as in Example 1, but the light emission output was 11 mW.

(Example 2)
In Example 2, a large chip having a side of 1 mm as shown in FIG. 2 was produced. The structure of the electrode material and the like were the same as in Example 1 except that the pattern was different.
When the obtained light emitting device was evaluated, when a current of 350 mA was passed, the forward voltage was 3.2 V and the light emission output was 200 mW.

(Comparative Example 2)
A light-emitting element was fabricated in the same manner as in Example 2 except that the n-electrode was made the same region as in FIG.
When the obtained light emitting device was evaluated in the same manner as in Example 2, the forward voltage was 3.2 V, which was the same as that in Example 1, but the light emission output was 150 mW.

  The semiconductor light-emitting device provided by the positive electrode of the present invention is extremely useful as a material for a lamp or the like because of low driving voltage and high emission intensity.

1 is a schematic view showing a cross section of a gallium nitride-based compound semiconductor light-emitting element having a positive electrode of the present invention produced in Example 1. FIG. 6 is a schematic view showing a plane of a gallium nitride-based compound semiconductor light-emitting element having a positive electrode according to the present invention produced in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Positive electrode 11 Transparent conductive layer 12 Bonding pad 20 Negative electrode 21 Transparent conductive layer 22 Bonding pad

Claims (22)

  An electrode for a semiconductor light emitting device having a structure having one electrode of n-type or p-type on the same surface of the light-emitting device and the other electrode of p-type or n-type opposed to the electrode, both electrodes being bonded pads And an electrode for a semiconductor light emitting device, comprising: a transparent conductive layer.   An electrode for a semiconductor light emitting device having a structure having one n-type or p-type electrode on the same surface of the light-emitting device and the other p-type or n-type electrode opposed thereto, both of which are transparent conductive An electrode for a semiconductor light emitting device, wherein a bonding pad is formed on the layer.   The transparent conductive layer of the one electrode is disposed in the center region of the light emitting element, and the transparent conductive layer of the other electrode facing the one surrounds part or all of the periphery of the transparent conductive layer of the one electrode. The electrode for a semiconductor light-emitting element according to claim 1, wherein the electrode is a planar shape.   3. The electrode for a semiconductor light-emitting element according to claim 1, wherein the transparent conductive layer of the one electrode and the transparent conductive layer of the other electrode are in a planar shape.   The area for the transparent conductive layer of the n-type electrode is smaller than the area of the transparent conductive layer for the p-type electrode.   The material of the transparent conductive layer of the n-type electrode is at least one selected from the group consisting of ITO, aluminum oxide, zinc, fluorine-doped tin oxide, titanium oxide, zinc sulfide, bismuth oxide, and magnesium oxide. The electrode for a semiconductor light-emitting element according to claim 1.   The electrode for a semiconductor light-emitting element according to claim 6, wherein the transparent conductive layer of the n-type electrode has a thickness of 10 to 100 nm.   The material for the transparent conductive layer of the n-type electrode is at least one selected from the group consisting of aluminum, nickel, titanium, gold, silver, and chromium. Electrode for semiconductor light emitting device.   The electrode for a semiconductor light-emitting element according to claim 8, wherein the transparent conductive layer of the n-type electrode has a thickness of 1 to 100 nm.   10. The electrode for a semiconductor light emitting device according to claim 1, wherein the transparent conductive layer of the n-type electrode transmits 70% or more of the emitted light.   The area for the transparent conductive layer of the n-type electrode is 5 to 50% of the area of the light emitting element chip, and the electrode for a semiconductor light emitting element according to any one of claims 1 to 10.   12. The electrode for a semiconductor light-emitting element according to claim 1, wherein the n-type electrode is composed of a bonding pad and a transparent conductive layer extending from the pad along the periphery of the light-emitting element chip.   The electrode for a semiconductor light-emitting element according to any one of claims 1 to 12, wherein the transparent conductive layer of the p-type electrode has a thickness of 5 to 1000 nm.   14. The electrode for a semiconductor light emitting device according to claim 1, wherein a bonding pad for the n-type electrode and the p-type electrode is provided to face a side or a corner of the light emitting device.   The bonding pad has a multilayer structure, and the lowermost layer (the side in contact with the transparent conductive layer) is a metal selected from the group consisting of Cr, Al, Ti, platinum group metals such as Pt, Rh, Ru, Ir, and Ag. The electrode for a semiconductor light emitting device according to claim 1, wherein the electrode is a semiconductor light emitting device.   The semiconductor light emitting element according to claim 1, wherein the bonding pad has a multilayer structure, and the upper layer on the lowermost layer is a metal selected from the group consisting of Ti, Cr, and Al. Electrode.   The electrode for a semiconductor light-emitting element according to claim 1, wherein the bonding pad has a multilayer structure, and the uppermost layer is Au or Al.   The electrode for a semiconductor light-emitting element according to claim 1, wherein the light-emitting element chip has a size of 500 μm square or more.   The electrode for a semiconductor light-emitting element according to claim 1, wherein the light-emitting element is a GaN-based semiconductor light-emitting element.   The light emitting element using the electrode in any one of Claims 1-19.   A light emitting device comprising a combination of the light emitting device according to claim 20 and a phosphor. A lamp using the light emitting device according to claim 20 or 21.