JP2004319671A - Light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode structure capable of solving a problem that a pad electrode formed on a transparent conductive film is stripped in an LED having a structure employing a transparent conductive film of a metal oxide as a current dispersion layer. <P>SOLUTION: In a light emitting diode where a pn junction single heterostructure or double heterostructure becoming a light emitting part 11 is formed on a semiconductor substrate 1, a transparent conductive film 7 of a metal oxide is formed thereon as a current dispersion layer, and metal electrodes 8 and 9 are formed for conduction on the surface side and the rear surface side, the surface side electrode on the metal oxide film has a multilayer structure including a lowermost layer 8a of Al, In or Ti, and an uppermost layer 8b of Au. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light emitting diode having a structure using a metal oxide transparent conductive film as a current dispersion layer, and more particularly to a technique for preventing peeling of a pad electrode on the transparent conductive film.
[0002]
[Prior art]
Conventionally, light emitting diodes (Light Emitting Diodes: LEDs) have been mostly GaP green and AlGaAs red. However, recently, since a GaN-based or AlGaInP-based crystal layer can be grown by metal organic chemical vapor deposition (MOVPE), orange, yellow, green, and blue high-brightness LEDs can be manufactured. Was.
[0003]
The epitaxial wafer for LED formed by the MOVPE method has made it possible to produce an LED exhibiting short-wavelength light emission and high luminance, which has never been seen before.
[0004]
In the conventional high-brightness LED, the light is reflected by the surface-side electrode (pad electrode) in the light extraction surface, and the light emission immediately below the light cannot be extracted to the outside. A current distribution layer (window layer) is provided on the upper side, and the current supplied from the upper electrode is spread in the lateral direction of the chip in the current distribution layer to increase the light emission ratio in a region other than immediately below the upper electrode. However, when trying to grow the thickness of the current dispersion layer to obtain high luminance, there is a problem that the cost of the epitaxial wafer for LED increases.
[0005]
As a method of solving these problems, there is a method of using a material capable of obtaining a value of resistance as low as possible as the current dispersion layer. For example, in the case of an AlGaInP quaternary system, GaP or AlGaAs is used as a current dispersion layer. However, even with the use of these low resistivity materials, it is necessary to increase the film thickness to 8 μm or more in order to improve the current dispersion.
[0006]
Therefore, in order to make the current spreading layer thinner, it is conceivable to lower the resistivity of the current spreading layer. Since it is difficult to significantly change the mobility, attempts have been made to increase the carrier concentration. However, at this stage, the carrier concentration cannot be so high as to make the current dispersion layer thinner.
[0007]
As a solution to this, a method has been proposed in which a transparent conductive film made of a metal oxide such as indium tin oxide (abbreviated as ITO) is used for the current distribution layer instead of the current distribution layer of the semiconductor. The transparent conductive film using this metal oxide has a very high carrier concentration and can obtain a sufficient current dispersion with a thin film thickness.
[0008]
This transparent conductive film is formed on the surface of the semiconductor epitaxial layer, and a metal electrode (pad electrode) for wire bonding is formed thereon. However, at this time, when the transparent conductive film is a metal oxide, there is a serious problem that the upper electrode (pad electrode) formed thereon is peeled off during a process such as etching or dicing or during wire bonding.
[0009]
As a technique for solving this problem, it is known that an electrode on an oxide window layer (current distribution layer) containing n-type zinc oxide has a multilayer structure (for example, see Patent Document 1). In this method, the lowermost layer of the electrode is composed of a layer containing a metal oxide of a transition metal. Specifically, nickel oxide (NiO) (lowest layer) / Au (top layer) or titanium oxide (TiO2) ₂ ) An electrode having a multilayer structure of / Al or the like.
[0010]
This multilayer electrode has a laminated structure of a single film of Ni or titanium (Ti), which is a metal element constituting the lowermost oxide layer, and a metal film of the uppermost layer, that is, a Ni / Au or Ti / Al multilayer structure. Construct as a base. With the heat treatment (alloying) for imparting ohmic properties to the electrodes or the heat treatment in the LED manufacturing process, the lowermost Ni layer or Ti layer is oxidized on the underlayer in the single-layer metal-structured electrode configured as described above. It is oxidized by oxygen invading from the object window layer and becomes a layer containing an oxide, resulting in an electrode having a NiO / Au or TiO ₂ / Al multilayer structure.
[0011]
Patent Literature 1 also discloses a configuration example in which a multilayer electrode in which the uppermost layer is Au and a layer made of molybdenum (Mo) or Pt is provided between the lowermost layer and the uppermost layer. As described above, when the intermediate layer made of the high melting point metal is inserted, oxygen atoms are prevented from being concentrated in the region near the bonding interface with the Au electrode layer, and the multilayer electrodes which are firmly adhered to each other are formed. There are benefits brought.
[0012]
[Patent Document 1]
JP 2001-44503 A
[Problems to be solved by the invention]
However, Patent Literature 1 discloses that a multilayer structure of Ni / Au or Ti / Al is used when the surface-side electrode has a two-layer structure, but does not disclose other combinations of multilayer structures. Further, even when the surface-side electrode has a three-layer structure, there is a description of a multilayer structure of Ti / Pt (or Mo) / Au, but there is no disclosure of other combinations of multilayer structures.
[0014]
The present inventors have found that peeling can be effectively prevented in other multilayer structures of the surface-side electrode and other combinations of the materials of the layers, and have reached the present invention.
[0015]
That is, an object of the present invention is to solve the problem of peeling of a pad electrode formed on a transparent conductive film in an LED having a structure in which a metal oxide transparent conductive film is used as a current distribution layer on the surface of an epitaxial wafer. It is an object of the present invention to provide a possible electrode structure.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0017]
In the light emitting diode according to the first aspect of the present invention, a pn junction single hetero structure or a double hetero structure serving as a light emitting portion is formed on a semiconductor substrate, and a transparent conductive film made of a metal oxide is formed thereon as a current distribution layer. In a light-emitting diode having a metal electrode for conducting electricity on the front side and the back side, the front side electrode on the transparent conductive film has a multilayer structure, the lowermost layer being Al and the uppermost layer being Au. Features.
[0018]
This is a light emitting diode in which the surface electrode (pad electrode) on the transparent conductive film has a multilayer structure of Al / Au.
[0019]
In the light emitting diode according to the second aspect of the present invention, a pn junction single hetero structure or double hetero structure serving as a light emitting portion is formed on a semiconductor substrate, and a transparent conductive film made of a metal oxide is formed thereon as a current distribution layer. In a light-emitting diode having a metal electrode for conducting electricity on the front side and the back side, the front side electrode on the transparent conductive film has a multilayer structure, the lowermost layer being In, and the uppermost layer being Au. Features.
[0020]
This is a light emitting diode in which a pad electrode metal on a transparent conductive film has a multilayer structure of In / Au.
[0021]
In the light emitting diode according to the third aspect of the present invention, a pn junction single hetero structure or a double hetero structure serving as a light emitting portion is formed on a semiconductor substrate, and a transparent conductive film made of a metal oxide is formed thereon as a current distribution layer. In a light emitting diode having a metal electrode for conducting electricity on the front side and the back side, the front side electrode on the transparent conductive film has a multilayer structure, the lowermost layer is Ti, and the uppermost layer is Au. Features.
[0022]
This is a light emitting diode in which a pad electrode metal on a transparent conductive film has a multilayer structure of Ti / Au.
[0023]
According to a fourth aspect of the present invention, in the light emitting diode according to any one of the first to third aspects, an intermediate layer having a multilayer structure of any one of AuZn, AuBe or AuGe and Ni is provided between the lowermost layer and the uppermost layer. Is provided.
[0024]
This is a light emitting diode having a four-layer structure in which a pad electrode metal on a transparent conductive film has a four-layer structure.
[0025]
In the light emitting diode according to the fifth aspect of the present invention, a single hetero structure or a double hetero structure of a pn junction serving as a light emitting portion is formed on a semiconductor substrate, and a transparent conductive film made of a metal oxide is formed thereon as a current distribution layer. In a light-emitting diode in which metal electrodes for energization are formed on the front side and the back side, the front side electrode on the transparent conductive film has a multilayer structure, the lowermost layer is Ni, and the uppermost layer is Au. The intermediate layer between them has a multilayer structure of any one of AuZn, AuBe or AuGe and Ni.
[0026]
This is a combination in which the lowermost layer of the pad electrode metal on the transparent conductive film is Ni and the uppermost layer is Au, but has an intermediate layer having a multilayer structure of Ni and any one of AuZn, AuBe or AuGe. It is different from that of Reference 1.
[0027]
<The gist of the invention>
In order to achieve the above object, in the present invention, a surface-side electrode has a two-layer structure as an electrode structure that is difficult to peel off and is formed on a metal oxide transparent conductive film. That is, on the surface of a transparent conductive film made of a metal oxide acting as a current dispersion layer, for example, an ITO film, first, Al, In, or Ti is formed as a lowermost layer, and Au is stacked thereon as an uppermost layer. The problem of electrode peeling was solved.
[0028]
The transparent conductive film may be an oxide such as tin oxide (SnO ₂ ), zinc oxide (ZnO), indium oxide (In ₂ O ₃ ), indium tin oxide (ITO), and magnesium oxide (MgO). It is preferably made of indium tin oxide (ITO). Since the specific resistance of ITO is about 3 × 10 ⁻⁶ Ωm, which is about one-hundredth of the specific resistance of p-type GaP, the thickness of the transparent conductive film is greatly increased by forming the transparent conductive film of ITO. Can be reduced.
[0029]
The front-side electrode is easy to connect (good bonding characteristics), stably obtains a low ohmic contact resistance with the lower layer (good ohmic characteristics), and has good adhesion to the lower layer. Is required. In order to satisfy these requirements, in the present invention, the surface-side electrode (pad electrode) has a two-layer structure in which the lowermost layer is made of Al, In or Ti, and the uppermost layer is made of Au. Strong adhesion can be obtained by the lowermost layer of Al, In or Ti, and the bonding characteristics are also better because the uppermost layer is made of Au.
[0030]
Further, a mode in which an intermediate layer having a multilayer structure of any one of AuZn, AuBe or AuGe and Ni is provided between the lowermost layer (Al, In or Ti) and the uppermost layer (Au), or Even in the case where an intermediate layer having a multilayer structure of any one of AuZn, AuBe or AuGe is provided between Ni and Au as the uppermost layer, a surface-side electrode with no peeling and good bonding characteristics can be obtained.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiments.
[0032]
FIG. 1 shows a structure of a light-emitting diode for describing an embodiment of the present invention. This light emitting diode has a structure in which an n-type GaAs buffer layer as a first conductivity type buffer layer and an n-type AlGaInP cladding layer as a first conductivity type cladding layer are formed on an n-type GaAs substrate 1 as a first conductivity type substrate. 2, an AlGaInP active layer 3 and a p-type AlGaInP cladding layer 4 serving as a second conductivity type cladding layer, on which a light emitting unit 11 is provided, on which a p-type GaP current spreading layer (second conductivity type current spreading layer) is provided. 5. An AlInP surface semiconductor layer 6 is further formed thereon, and a Sn-doped In ₂ O ₃ (Indium Tin) is further formed thereon as a transparent conductive film having a sufficient light-transmitting property and electric characteristics capable of obtaining current dispersion. There is an ITO film 7 made of Oxide (abbreviation: ITO). A surface-side electrode 8 composed of a circular pad electrode (partial electrode) is provided at the center of the front surface side of the chip, that is, at the center of the ITO film (transparent conductive film) 7, and the n-side metal is provided on the back surface of the chip. A substrate-side electrode 9 made of an electrode is provided.
[0033]
The structure up to this point is the same as that of a light-emitting diode having a structure using a conventional transparent conductive film. The light-emitting diode of this embodiment has a transparent conductive film (ITO) made of a metal oxide serving as a current distribution layer in the above structure. The surface-side electrode 8 provided on the film 7) has a double-layer structure, in which the lowermost layer 8a is made of Al, In or Ti, and the uppermost layer 8b is made of Au.
[0034]
In order to confirm the operation and effect of the present invention having such a surface-side electrode having a multilayer structure, a conventional example and an example of an epitaxial wafer for a red light emitting diode having an emission wavelength of about 630 nm were prepared.
[0035]
[Conventional example]
As a conventional example, an epitaxial wafer for a red light emitting diode having a laminated structure of the epitaxial layers shown in FIG. 1 and having a light emitting wavelength of about 630 nm, which is different only in the material of the multilayer structure of the front electrode 8 was manufactured.
[0036]
An n-type (Se-doped) GaAs buffer layer 10 and an n-type (Se-doped) (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding layer 2 are formed on an n-type GaAs substrate 1 by MOVPE. , Undoped (Al _0.15 Ga _0.85 ) _0.5 In _0.5 P active layer 3, p-type (zinc-doped) (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding layer 4. A p-type GaP current dispersion layer 5 was grown, and an AlInP surface semiconductor layer 6 was grown thereon by MOVPE growth.
[0037]
An ITO film 7 was formed on this epitaxial wafer by a sputtering method. An n-type electrode (substrate-side electrode 9) is formed on the entire surface of the epitaxial wafer on the substrate side, and a p-type electrode (surface-side electrode 8) comprising a circular pad electrode having a diameter of 130 μm is formed on the ITO film side. , And an LED chip.
[0038]
Three samples of the conventional example were produced. First, for these n-side electrodes (substrate-side electrodes 9), AuGe, Ni, and Au were vapor-deposited by 60 nm, 10 nm, and 500 nm, respectively, from the substrate side by a vacuum evaporation method. For the p-side electrode (surface-side electrode 8) on the upper surface of the chip, the first sample is AuZn, Ni, Au, the second sample is AuBe, Ni, Au, the third sample is AuGe, Ni, Au, and the vacuum is By a vapor deposition method, 60 nm, 10 nm, and 1000 nm were vapor-deposited on the ITO film, respectively.
[0039]
In order to make the three types of ITO films and the epitaxial wafer with electrodes into light emitting diodes having a chip size of 300 μm square, process processing such as etching and dicing and wire bonding were performed. As a result, the pad electrode (surface-side electrode 8) was peeled off by about 50% or more during processing such as etching and dicing. When the wire bonding step was further performed, 98% or more of the electrode pads (surface-side electrodes 8) were peeled off.
[0040]
[Examples 1 to 3]
An epitaxial wafer for a red light emitting diode having a light emission wavelength of about 630 nm having the structure shown in FIG. 1 was produced. The method of growing the epitaxial layer by the MOVPE method, the laminated structure of the epitaxial layers 1 to 6, and 10 were basically the same as those in the above-described conventional example. The method of forming the ITO film 7 by the sputtering method, the method of forming the electrodes by the vacuum evaporation method, and the electrode shape were basically the same as those of the above-mentioned conventional example. Further, the processing and the wire bonding step were the same as those in the above-mentioned conventional example.
[0041]
That is, an n-type (Se-doped) GaAs buffer layer and an n-type (Se-doped) (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding layer are formed on the n-type GaAs substrate 1 by MOVPE. 2, undoped (Al _0.15 Ga _0.85 ) _0.5 In _0.5 P active layer 3, p-type (zinc-doped) (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding The layer 4 and the p-type GaP current dispersion layer 5 were grown, and the AlInP surface semiconductor layer 6 was grown thereon by MOVPE growth. An ITO film 7 was formed on this epitaxial wafer by a sputtering method.
[0042]
An n-type electrode (substrate-side electrode 9) is formed on the entire surface of the epitaxial wafer on the substrate side, and a p-type electrode (surface-side electrode 8) comprising a circular pad electrode having a diameter of 130 μm is formed on the ITO film side. , And an LED chip.
[0043]
The n-type electrode (substrate-side electrode 9) has a multilayer structure of AuGe / Ni / Au, and AuGe was deposited to 60 nm, Ni was deposited to 10 nm, and Au was deposited to 500 nm by vacuum deposition.
[0044]
For the surface-side electrode 8 on the ITO film 7, the multilayer structure of the lowermost layer 8a / the uppermost layer 8b is set to Al / Au (Example 1), In / Au (Example 2), Ti / Au (Example). Example 3) and three types of Ni / Au (Comparative Example 1) were prototyped as comparative examples.
[0045]
In the surface-side electrodes 8 of Examples 1 to 3, Al, In, or Ti was 20 nm as the lowermost layer 8a, and Au was 1000 nm as the uppermost layer 8b, and each was deposited by a vacuum deposition method. Also in Comparative Example 1, the metal film of the upper electrode of the chip had a lower layer of 20 nm and an upper layer of 1000 nm.
[0046]
Processes such as etching and dicing and wire bonding (connection by an ultrasonic bonding method) similar to the above-described conventional example in order to make the ITO film and the epitaxial wafer with the electrodes of the above Examples 1 to 3 into a light emitting diode having a chip size of 300 μm square. Was performed. As a result, the electrode pad peeling during the process processing such as etching and dicing was as small as 0 to 1%, and the electrode pad peeling during the wire bonding step could be reduced to 0 to 1%. Further, the peeling of only the Au layer in the wire bonding step could be reduced to 0 to 1%. Similar results were obtained for Comparative Example 1.
[0047]
Here, in order to examine the optimum conditions of the multilayer structure of the chip upper surface electrode (surface side electrode 8), Al / Au (Example 1), In / Au (Example 2), Ti / Au (Example 3) ) And Ni / Au (Comparative Example 1), the electrode pad peeling during the processing and the electrode pad peeling during the wire bonding step were all low values of 0 to 1%. However, of these four types, the electrodes of Al / Au (Example 1) and In / Au (Example 2) had the best wire bondability. The reason why wire bondability is good is that softer electrodes have better wire bondability. For this reason, it is desirable to use an Al / Au structure or an In / Au structure among the four types of electrodes.
[0048]
[Modification 1]
Regarding the chip upper surface electrode, that is, the surface side electrode 8, four types of Al / Au (Example 1), In / Au (Example 2), Ti / Au (Example 3), and Ni / Au (Comparative Example 1) are used. In the multilayer structure, the uppermost layer Au was made to have a constant thickness of 1000 nm, and the lowermost layers Al, In, Ti, and Ni were changed in thickness to 5 to 500 nm.
[0049]
Also in the epitaxial wafer having the surface-side electrode 8 having this structure, the peeling of the electrode pad during the process such as etching and dicing is set to 0 to 1%, and the peeling of the electrode pad in the wire bonding step is set to 0 to 1%. I was able to do it.
[0050]
[Examples 4 to 15]
In this embodiment, as shown in FIG. 2, the surface-side electrode 8 on the metal oxide transparent conductive film has a multilayer structure of four layers 8a, 8c, 8d, and 8b, and the lowermost layer 8a is Ni, The upper layer 8b is made of Au, and the intermediate layer between them has a multilayer structure of any one of AuZn, AuBe or AuGe and Ni. That is, two intermediate layers 8c and 8d are provided between Ni of the lowermost layer 8a and Au of the uppermost layer 8b, and the intermediate layer 8c on the lowermost (Ni) side is made of AuZn, AuBe or AuGe. The intermediate layer 8d on the side of the uppermost layer 8b (surface side) is made of Ni.
[0051]
Specifically, the chip upper surface electrode 8 is formed of Al / AuZn / Ni / Au (Example 4), Al / AuBe / Ni / Au (Example 5), Al / AuGe / Ni / Au (Example 6), In / AuZn / Ni / Au (Example 7), In / AuBe / Ni / Au (Example 8), In / AuGe / Ni / Au (Example 9), Ti / AuZn / Ni / Au (Example 10) ), Ti / AuBe / Ni / Au (Example 11), Ti / AuGe / Ni / Au (Example 12), Ni / AuZn / Ni / Au (Example 13), Ni / AuBe / Ni / Au (Example) Example 14) and a multilayer structure of Ni / AuGe / Ni / Au (Example 15).
[0052]
When such a multilayer structure is formed, electrode pad peeling during process processing such as etching and dicing is as low as 0 to 1%, and electrode pad peeling during the wire bonding step is as low as 0 to 1%. Was.
[0053]
[Modification 2]
In the above embodiment, a hetero structure is provided on both sides of the active layer to emit light more efficiently by a pn junction, and a double hetero (DH) structure in which electrons and holes are confined in the active layer is employed. However, the present invention is not limited to this, and can be applied to a light emitting diode having a single hetero (SH) structure with a pn junction. In the above embodiment, the method for forming the transparent conductive film (ITO film 7), which is a metal oxide, is a sputtering method. However, the method for forming the transparent conductive film (ITO film 7) is limited to the sputtering method. Instead, the transparent conductive film (ITO film 7) may be formed by a coating method, a spray pyrolysis method, or a vacuum evaporation method.
[0054]
The present invention essentially eliminates peeling of a pad electrode provided on a transparent conductive film made of a metal oxide acting as a current dispersion layer. Is not limited, and can be of any structure. For example, in the above embodiment, an AlGaInP-based DH-type LED has been described. However, the present invention is naturally applicable to other DH-type LEDs such as a GaAs-based, an AlGaAs-based, an InAlGaAs-based, and a ZnSe-based. Further, in the above description of the embodiment, p and n may be completely reversed. Furthermore, a light reflecting layer (DBR layer) is provided between the substrate 1 and the lower cladding layer 2, a structure in which the surface semiconductor layer 6 and the buffer layer 10 are omitted, or a single hetero (SH) structure. Can be.
[0055]
The present invention can also be applied to an electrode structure of a blue light emitting diode using a gallium nitride-based compound semiconductor such as GaN, GaAlN, and InGaN.
[0056]
FIG. 3 shows an example in which the electrode structure of the present invention is applied to a homojunction light emitting diode (LED) made of GaN. 21 is a sapphire substrate, 22 is an n-type GaN layer, 23 is a very high-resistance p-type GaN (i-type GaN) layer, 24 is a transparent conductive film, 25 is a p-type electrode (surface-side electrode), and 26 is n-type Electrodes. As shown in FIG. 3, the n-type electrode 26 is provided on the side surface of the n-type GaN layer 22. In this specification, the n-type electrode 26 is also a metal electrode formed on the back side of the chip for conducting electricity. Therefore, it is included in the concept of the substrate-side electrode.
[0057]
The p-type electrode (surface-side electrode) 25 is provided on the transparent conductive film 24 formed on the p-type GaN layer 23, and a gold wire is wire-bonded to these electrodes to energize the LED. It has a structure to extract emitted light. The structure of the front surface side electrode 25 is formed as the multilayer structure described above as the first to third embodiments or the fourth to fifteenth embodiments, that is, an electrode that does not peel off. FIG. 3 shows a surface-side electrode 25 having a multilayer structure typically including a lowermost layer 25a and an uppermost layer 25b.
[0058]
【The invention's effect】
As described above, according to the present invention, the following excellent effects can be obtained.
[0059]
In the present invention, the pad electrode which is an electrode on the metal oxide film has a multilayer structure of Al / Au, In / Au, or Ti / Au. That is, the present invention has a structure in which Al, In, or Ti is first formed on the surface of a transparent conductive film made of a metal oxide as a layer that is hardly peeled off, and Au is laminated thereon, so that the entire pad electrode is made of a metal oxide. The electrode does not peel off from the transparent conductive film. Since the uppermost layer is made of Au, the wire bonding property with respect thereto is also good.
[0060]
Further, in the present invention, a mode in which an intermediate layer having a multilayer structure of any one of AuZn, AuBe or AuGe and Ni is provided between the lowermost layer (Al, In or Ti) and the uppermost layer (Au), or And a mode in which an intermediate layer having a multilayer structure of any of AuZn, AuBe, or AuGe and Ni is provided between the lowermost layer Ni and the uppermost layer Au. A surface-side electrode can be obtained.
[0061]
Therefore, by using the electrode structure of the present invention, it is possible to realize an LED using a metal oxide transparent conductive film such as an ITO film.
[0062]
The light-emitting diode to which the present invention is applied has a configuration in which a current is dispersed using a transparent conductive film made of a metal oxide such as an ITO film as a current dispersion layer, and it is not necessary to make the current dispersion layer thick. With this technique, the thickness of the epitaxial layer for the LED can be reduced from one fifth to several tenths. This is because the current dispersion film is the thickest among the epitaxial layers constituting the LED. Thereby, the price of the epitaxial wafer for LED can be significantly reduced.
[0063]
In the past, a semiconductor epitaxial layer was used, and sufficient current dispersion characteristics could not be obtained even if the epitaxial layer was thickened. , The brightness of the LED can be increased by about 30%.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a structure of a light emitting diode according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a structure of a light emitting diode according to another embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating a structure of a light emitting diode according to another embodiment of the present invention.
[Explanation of symbols]
1 GaAs substrate (first conductivity type substrate)
2 AlGaInP cladding layer (first conductivity type cladding layer)
3 AlGaInP active layer 4 AlGaInP cladding layer (second conductivity type cladding layer)
5 GaP current spreading layer (second conductivity type current spreading layer)
6 AlInP surface semiconductor layer 7 ITO film (transparent conductive film)
Reference Signs List 8 front surface electrode 8a bottom layer 8b top layer 8c, 8d intermediate layer 9 substrate side electrode 10 GaAs buffer layer (first conductivity type)

Claims (5)

A pn junction single hetero structure or double hetero structure serving as a light emitting portion is formed on a semiconductor substrate, and a transparent conductive film made of a metal oxide is formed thereon as a current distribution layer. In the light emitting diode formed with a metal electrode for
A light-emitting diode, wherein a surface-side electrode on a transparent conductive film has a multilayer structure, the lowermost layer being Al and the uppermost layer being Au. A pn junction single hetero structure or double hetero structure serving as a light emitting portion is formed on a semiconductor substrate, and a transparent conductive film made of a metal oxide is formed thereon as a current distribution layer. In the light emitting diode formed with a metal electrode for
A light-emitting diode, wherein a surface-side electrode on a transparent conductive film has a multilayer structure, the lowermost layer being In and the uppermost layer being Au. A pn junction single hetero structure or double hetero structure serving as a light emitting portion is formed on a semiconductor substrate, and a transparent conductive film made of a metal oxide is formed thereon as a current distribution layer. In the light emitting diode formed with a metal electrode for
A light-emitting diode, wherein a surface-side electrode on a transparent conductive film has a multilayer structure, the lowermost layer being Ti and the uppermost layer being Au. The light-emitting diode according to any one of claims 1 to 3,
A light-emitting diode comprising an intermediate layer having a multilayer structure of any one of AuZn, AuBe or AuGe and Ni is provided between the lowermost layer and the uppermost layer. A pn junction single hetero structure or double hetero structure serving as a light emitting portion is formed on a semiconductor substrate, and a transparent conductive film made of a metal oxide is formed thereon as a current distribution layer. In the light emitting diode formed with a metal electrode for
The surface side electrode on the transparent conductive film has a multilayer structure, the lowermost layer is Ni, the uppermost layer is Au, and the intermediate layer between the two has a multilayer structure of any one of AuZn, AuBe or AuGe and Ni. A light emitting diode characterized by the above-mentioned.

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