JP2007208048A - Light-emitting element and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element that reduces a poor influence to a semiconductor when etching a transparent conductive film and can extract light generated by an emitter to the outside efficiently. <P>SOLUTION: The light-emitting element comprises a laminate having a first-conductivity-type layer and a second conductivity-type layer via the emitter, and a transparent conductive substrate provided on the laminate. The transparent conductive substrate comprises a transparent base, and a transparent conductive film formed on the transparent base. The transparent conductive substrate is arranged so that the transparent conductive film side opposes the laminate via a transparent conductive polymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device. More specifically, the present invention relates to a semiconductor light emitting device that realizes further higher efficiency by reducing adverse effects on the semiconductor light emitting layer when patterning a transparent conductive film.

  Conventionally, a semiconductor light emitting device (LED) has used a metal tap for an upper electrode (p-type semiconductor electrode side) that extracts light. In this case, light cannot be extracted from the metal tap portion, resulting in a decrease in efficiency. Therefore, it was considered that the light generated from the light emitting part in the semiconductor light emitting element can be efficiently extracted outside by using a transparent conductive film such as ITO on the upper electrode (p-type semiconductor electrode side) and increasing the area. .

FIG. 3 shows a structural diagram of a semiconductor light emitting device with improved extraction efficiency (for example, Patent Document 1).
In the light emitting element 50, an n-type GaN contact layer 53 using Si as a dopant is provided on one surface of a sapphire substrate 51 via a GaN buffer layer 52, and Si is used as a dopant via the n-type GaN contact layer 53. An n-type AlGaN cladding layer 54 (main first conductivity type layer) is provided. A light emitting portion 55 having an InGaN and GaN multiple quantum well (MQW) structure through the n-type AlGaN layer 54, and a p-type AlGaN cladding layer 56 containing Mg as a p-type dopant through the light emitting portion 55 (mainly A transparent conductor formed by sequentially laminating a p-type GaN contact layer 57, a metal thin film layer 58, an ITO film 59, and an FTO film 60, each having Mg as a dopant, through a p-type AlGaN layer 56; 61 is provided. A p-side electrode 62 is provided on a part of the periphery of the surface of the transparent conductor 61, while each layer stacked on a part of the peripheral part of the n-type GaN contact layer 53 is removed and exposed n An n-side electrode 63 is provided on the type GaN contact layer 53.

In order to pattern such a light emitting element, it is necessary to etch the transparent conductive film portion. When the transparent conductive film is etched, an acidic solution is used as an etching solution, which adversely affects the semiconductor light emitting layer and causes a decrease in light emission efficiency.
Japanese Patent No. 3207773

  The present invention has been devised in view of such a conventional situation, and reduces adverse effects on a semiconductor during etching of a transparent conductive film, and efficiently extracts light generated from a light emitting portion to the outside. An object of the present invention is to provide a semiconductor light emitting device capable of achieving the above.

A light-emitting element according to claim 1 of the present invention includes a laminated body in which a first conductive type layer and a second conductive type layer are arranged via a light emitting portion, and a transparent conductive substrate provided on the laminated body. The transparent conductive substrate includes a transparent base material and a transparent conductive film formed on the transparent base material, and the transparent conductive substrate includes a transparent conductive polymer. The transparent conductive film side is disposed so as to face the laminate.
The light emitting device according to claim 2 of the present invention is characterized in that, in claim 1, the transparent conductive film is patterned on the transparent substrate.
The light-emitting device according to claim 3 of the present invention is characterized in that, in claim 1 or 2, the transparent conductive substrate is larger than the laminate, and has a contact region and a non-contact region with the laminate. And
The light-emitting element according to a fourth aspect of the present invention is the light-emitting element according to the third aspect, wherein the transparent conductive substrate includes an electrical connection portion with the outside in the non-contact region.
According to a fifth aspect of the present invention, there is provided a method for manufacturing a light-emitting element, comprising: a laminated body in which a first conductive type layer and a second conductive type layer are arranged via a light emitting part; and a transparent conductive material provided on the laminated body. A light-emitting element manufacturing method comprising a substrate, wherein a transparent conductive film is formed on a transparent base material to form the transparent conductive substrate, and a transparent conductive polymer is used to form the laminate, and the laminate. Is bonded to the transparent conductive substrate, which is a separate body, so that the transparent conductive film side faces the laminated body.
The manufacturing method of the light emitting element which concerns on Claim 6 of this invention is characterized by providing the said transparent conductive film in a pattern on the said transparent base material in Claim 5.

  In the present invention, a transparent conductive substrate composed of a transparent base material and a transparent conductive film formed on the transparent base material is provided as a separate body from the laminate, and bonded together, thereby Damage to the semiconductor light emitting layer during etching can be eliminated. Thereby, the luminous efficiency of the semiconductor light emitting device can be improved.

Hereinafter, a semiconductor light emitting device according to the present invention will be specifically described with reference to the accompanying drawings. In addition, this form is specifically described in order to better understand the gist of the invention, and does not limit the present invention unless otherwise specified.
<First embodiment>

FIG. 1 is a cross-sectional view showing a first embodiment of a light emitting device according to the present invention.
In the light emitting device 1 of the present invention, an n-type GaN contact layer 4 using Si as a dopant is provided on one surface of a sapphire substrate 2 via a GaN buffer layer 3, and Si is added via the n-type GaN contact layer 4. An n-type AlGaN cladding layer 5 (main first conductivity type layer) as a dopant is provided. A light emitting section 6 having an InGaN and GaN multiple quantum well (MQW) structure through the n-type AlGaN layer 5 and a p-type AlGaN cladding layer 7 containing Mg as a p-type dopant through the light emitting section 6 (mainly A second conductivity type layer), a p-type GaN contact layer 8 having Mg as a dopant through a p-type AlGaN layer 7;
A transparent conductive substrate 10 is provided via the transparent conductive polymer film 9. A p-side electrode 13 is provided at a predetermined position of the transparent conductor 10. On the other hand, each layer laminated on a part of the peripheral portion of the n-type GaN contact layer 4 is removed and exposed n-type GaN. An n-side electrode 14 is provided on the contact layer 4.

  Here, in the present invention, the transparent conductive substrate 10 is composed of a transparent base material 11 and a transparent conductive film 12 formed on the transparent base material 11. The transparent conductive substrate 10 is separate from the laminate, and is disposed so that the transparent conductive film 12 side faces the laminate (p-type GaN contact layer 8) with the transparent conductive polymer film 9 interposed therebetween. Has been. The transparent conductive film 12 is patterned on the transparent substrate 11.

A transparent conductive film 12 is formed in advance on a transparent base material 11 to form a transparent conductive substrate 10, and the transparent conductive film 12 is bonded so that the transparent conductive film 12 side faces the laminate (p-type GaN contact layer 8). The etching solution used for patterning 12 by etching can be prevented from touching the semiconductor light emitting layer, and a reduction in light emission efficiency can be prevented.
The transparent conductive substrate 10 and the laminate are bonded together via the transparent conductive polymer film 9. Thereby, the electroconductivity between an electrode and a semiconductor light-emitting element is securable.

The light-emitting element 1 is formed by growing each layer by vapor phase growth methods such as metal-organic chemical vapor deposition (hereinafter referred to as MOCVD method) and halide vapor phase growth (HDCVD). .
In the MOCVD method, for example, trimethylgallium (TMG) as a gallium source, ammonia (NH ₃ ) as a nitrogen source, a compound containing hydrogen atoms such as hydrazine, monosilane (SiH ₄ ) as an Si source, and trimethylaluminum as an Al source. (TMA), trimethylindium (TMI) as the In source, biscyclopentadienylmagnesium (Cp ₂ Mg) as the Mg source, and hydrogen gas, nitrogen gas or the like as the carrier gas.

  The structure of the light-emitting element 1 may be a structure in which at least a first conductive type layer, a second conductive type layer, and a transparent conductor as a current diffusion layer are sequentially laminated on one surface of a substrate. Or a double hetero structure. For example, an n-type contact layer 4 and an n-type cladding layer 5, a light-emitting portion 6, a p-type cladding layer 7, a p-type contact layer 8, and a transparent conductor as a current diffusion layer are provided on the surface of the sapphire substrate 2 via a buffer layer 3. A double hetero structure in which films are sequentially stacked is known as a high light emitting element.

In the following, the case where the light emitting portion 6 forms a layer will be described. In the case of interface light emission, the interface between the n-type cladding layer 5 and the p-type cladding layer 7 functions as the light emitting portion.
The n-type contact layer 4 can be formed of GaN that is non-doped or doped with an n-type dopant such as Si, Ge, S, or C. The n-type cladding layer 5 can be formed of, for example, AlGaN, InAlGaN or the like that is not doped or doped with an n-type dopant.

  The light-emitting portion 6 can be formed of non-doped or n-type dopant and / or InGaN, InAlGaN or the like doped with p-type dopant such as Zn, Mg, Cd, Ba, etc. By forming a light-emitting portion containing indium, purple to red It is possible to change the emission wavelength. When the n-type dopant is doped in the light emitting part, the emission intensity at the peak wavelength is further increased, and when the p-type dopant is doped, the wavelength can be brought to the long wavelength side by about 0.5 eV. When doping is performed, the emission wavelength can be shifted to the longer wavelength side while the emission intensity is kept high.

  The p-type cladding layer 7 can be formed of AlGaN doped with a p-type dopant, InAlGaN, or the like. The p-type contact layer 8 can be formed of GaN doped with a p-type dopant. Like the n-type cladding layer 5, GaN can obtain a preferable ohmic connection with the electrode. Further, the n-type cladding layer 5 and / or the p-type cladding layer 7 can be omitted. If omitted, the contact layer acts as a cladding layer.

As will be described later, the p-side electrode 12 is formed in a non-contact region with the laminate of the transparent conductive substrate 10.
When an insulating substrate such as sapphire is used for the substrate, the n-side electrode 13 cannot be provided on the other surface of the substrate. The electrode 13 must be provided. For this purpose, the p-type contact layer 8, the p-type cladding layer 7, the light emitting portion 6, and the n-type cladding layer 5 are etched to expose the n-type contact layer 4, and the n-side electrode 13 is formed in the exposed portion. To do.

To etch each layer, either wet etching or dry etching may be used. In wet etching, for example, a mixed acid of phosphoric acid and sulfuric acid can be used. In dry etching, for example, reactive ion etching, focused ion beam etching, ion milling, ECR (Electron Cyclotron Resonance) etching, or the like can be used. In reactive ion etching or ECR etching, CF ₄ , CCl ₄ , SiCl are used. ₄ , gas such as CClF ₃ , CClF ₂ , SF ₆ , PCl ₃ can be used, B, Al, Si, Ga, In, etc. can be used as a metal ion source in focused ion beam etching, and in ion milling An inert gas such as Ar, Ne, or N ₂ can be used.

  Etching may be performed by selecting an optimal etching method for each layer and masking each layer, but the emission area decreases with the increase in the number of times of photolithography, so a gas containing chlorine gas, or A method of exposing the n-type contact layer 4 by etching the p-type contact layer 8, the p-type cladding layer 7, the light emitting portion 6, and the n-type cladding layer 5 at a time using a gas containing bromine gas is preferable.

  The transparent conductive substrate 10 is composed of a transparent base material 11 and a transparent conductive film 12 formed on the transparent base material 10. The transparent conductive substrate 10 is disposed such that the transparent conductive polymer film 9 faces the laminated body (p-type contact layer 8) with the transparent conductive polymer film 9 interposed therebetween.

  As the transparent base material 11, a substrate made of a light-transmitting material is used, and any glass, polyethylene terephthalate, polycarbonate, polyethersulfone, or the like that is usually used as a transparent base material for photoelectric conversion elements can be used. Can be used. Moreover, as a transparent base material 11, the board | substrate which is excellent in the light transmittance as much as possible is preferable on a use, and the board | substrate whose transmittance | permeability is 90% or more is more preferable.

  The transparent conductive film 12 is made of tin-doped indium (ITO), indium oxide (IO), zinc oxide (ZO), antimony-doped zinc oxide (AZO), Ga-doped zinc oxide (GZO), aluminum-doped zinc oxide (AlZO) or boron. By using a film made of added zinc oxide (BZO), high conductivity and high translucency are exhibited. Among these, an ITO film is preferably used.

The method for forming the transparent conductive film 12 is not particularly limited, and examples thereof include thin film forming methods such as sputtering, CVD (chemical vapor deposition), spray pyrolysis (SPD), and vapor deposition. Can be mentioned.
Among them, the transparent conductive film 12 is preferably formed by a spray pyrolysis method. By forming the transparent conductive film 12 by spray pyrolysis, the haze rate can be easily controlled. In addition, the spray pyrolysis method is preferable because it does not require a decompression system and can simplify the manufacturing process and reduce costs.

The transparent conductive film 12 is provided in a pattern on the transparent substrate 11.
Conventionally, a transparent conductive film was directly formed on the laminate. However, when patterning the transparent conductive film by etching, an acidic solution is used as an etching solution, which adversely affects the semiconductor light emitting layer and emits light. The efficiency was lowered.

  As in the present invention, a transparent conductive film 12 is previously formed on a transparent base material 11 to form a transparent conductive substrate 10, and the laminate and the transparent conductive substrate 10 that is separate from the laminate are formed. The transparent conductive film 12 is bonded so that the side of the transparent conductive film 12 faces the stacked body (p-type contact layer 8), so that the etching solution for etching the transparent conductive film 12 can be prevented from touching the semiconductor light emitting layer. This makes it possible to prevent a decrease in luminous efficiency.

The transparent conductive substrate 10 and the laminate (p-type contact layer 8) are bonded together via a transparent conductive polymer film 9. Thereby, the electroconductivity between an electrode and a semiconductor light-emitting element is securable.
Examples of the transparent conductive polymer 9 include PEDOT (polyethylene dioxythiophene), polyacetylene, polypyrrole, polythiophene, poly p-phenylene, polyphenylene vinylene, and the like.

  After the laminated body and the transparent conductive substrate 11 are bonded together, the p-side electrode 12 and the n-side electrode 13 are formed. As described above, the n-side electrode 13 is formed on the exposed portion of the n-type contact layer 4 exposed. The p-side electrode 12 is formed at a predetermined portion (non-contact portion with the laminated body) of the transparent conductor film substrate 11;

Here, the transparent conductive substrate 10 is larger than the laminate, and has a contact region 10a and a non-contact region 10b with the laminate. The non-contact region 10b is provided with an external electrical connection (p-side electrode 12).
The transparent conductive substrate 10 has a larger area than the laminated body, and an electrical connection part (p-side electrode 12) with the outside is disposed in a non-contact area with the laminated body, thereby taking out the terminals. It is possible to eliminate the decrease in efficiency due to. As a result, a lot of light can be extracted, and a semiconductor light emitting device with improved extraction efficiency can be obtained.
<Second Embodiment>

  Hereinafter, a second embodiment of the semiconductor light emitting device according to the present invention will be specifically described with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view showing a second embodiment of the light emitting device according to the present invention.
The light-emitting element 20 includes an n-type AlGaInP cladding layer 22 (main first-conductivity-type layer), an AlGaInP light-emitting portion 23, and a p-type AlGaInP cladding layer 24 on one surface of an n-type GaAs substrate 21 serving as a first conductivity-type substrate. (Main second conductivity type layer), p-type AlGaInP current dispersion layer 25, transparent conductive polymer film 26, and transparent conductive substrate 27 are provided in this order, and n-side electrode 30 is provided on the other surface of n-type GaAs substrate 21. A circular p-side electrode 31 is provided at a predetermined position of the transparent conductive substrate 27.

  Also in this case, the transparent conductive substrate 27 includes a transparent base material 28 and a transparent conductive film 29 formed on the transparent base material 28. The transparent conductive substrate 27 is disposed so that the transparent conductive film 29 side faces the stacked body (p-type AlGaInP current dispersion layer 25) with the transparent conductive polymer film 26 interposed therebetween. The transparent conductive film 29 is patterned on the transparent substrate 28.

  A transparent conductive film 29 is formed in advance on a transparent base material 28 to form a transparent conductive substrate 27. The laminate and the transparent conductive substrate 27 that is separate from the laminate are combined with the transparent conductive film 29. By bonding so that the side faces the stacked body (p-type AlGaInP current spreading layer 25), the etching solution for patterning the transparent conductive film 29 by etching can be prevented from touching the semiconductor light emitting layer. It became possible to prevent a decrease in luminous efficiency.

  Further, the transparent conductive substrate 27 has a larger area than that of the multilayer body, and a connection terminal (p-side electrode 30) to the outside is provided in a non-contact region 27b with the multilayer body. Thereby, the efficiency fall by taking out a terminal can be eliminated. As a result, a lot of light can be extracted, and a semiconductor light emitting device with improved extraction efficiency can be obtained.

  The semiconductor light emitting device of the present invention has been described above, but the present invention is not limited to the above example, and can be appropriately changed as necessary.

<Example 1>
A light emitting device having a structure as shown in FIG. 1 was fabricated as follows.
Each GaN-based compound layer was formed on one surface of the sapphire substrate by MOCVD. The source gas is trimethylgallium (TMG) gas, N is ammonia (NH ₃ ) gas, Si is monosilane (SiH ₄ ) gas, Al is trimethylaluminum (TMA) gas, and Mg is biscyclopentadiene. Enilmagnesium (Cp ₂ Mg) gas was used, and hydrogen gas was used as the carrier gas.

First, a sapphire substrate having a diameter of 2 inches and a (0001) plane as a compound deposition surface was placed in an MOCVD apparatus, and heated to 1050 ° C. while supplying hydrogen to perform thermal cleaning. Next, after the sapphire substrate is lowered to 510 ° C. and a GaN buffer layer is deposited, the sapphire substrate provided with the GaN buffer layer is heated to 1035 ° C., and NH ₃ gas, TMG gas, and SiH ₄ gas are allowed to flow. After growing an n-type GaN contact layer using Si as a dopant, an n-type AlGaN cladding layer using Si as a dopant was formed by flowing NH ₃ gas, TMG gas, TMA gas, and SiH ₄ gas.

  Next, the temperature of the sample was set to 750 ° C., and a light emitting portion having a multi-quantum well (MQW) structure of GaN and AlGaN was grown on the n-type AlGaN clad layer while intermittently flowing TMA gas.

Subsequently, NH ₃ gas, TMG gas, TMA gas, and Cp ₂ Mg gas are flowed to form a p-type AlGaN cladding layer using Mg as a dopant on the light emitting portion, and then NH ₃ gas, TMG gas, Cp ₂ Mg gas was flown to form a p-type GaN contact layer using Mg as a dopant.

  Next, a mask is formed on the p-type GaN contact layer to remove the n-type AlGaN clad layer, the light emitting part, the p-type AlGaN clad layer, and the p-type GaN contact layer stacked on the n-side electrode forming part. did. After forming the mask, the sample was transferred to an etching apparatus, and an etching gas was flowed to perform dry etching until the n-type GaN contact layer was exposed.

  On the other hand, an ITO transparent conductive film was formed on a glass substrate by a sputtering method. Thereafter, the ITO transparent conductive film was patterned by etching to produce a transparent conductive substrate that was separate from the laminate.

  Next, a solution of polyethylene dioxythiophene (PEDOT) was applied on the p-type GaN contact layer, and the transparent conductive substrate was bonded thereon with the ITO transparent conductive film side opposed.

  On the n-type GaN contact layer exposed by dry etching, Al was deposited by vapor deposition to form an n-side electrode. Moreover, Al was vapor-deposited by the vapor deposition method in the non-contact part with the laminated body of a transparent conductive substrate, and the p side electrode was formed.

  The sapphire substrate on which this gallium nitride compound layer was formed was diced into 300 μm squares to form bare chips. Then, this bare chip was mounted on the stem by die bonding, and wired by wire bonding to produce a light emitting element.

<Comparative Example 1>
A light emitting device was fabricated in the same manner as in Example 1 except that an ITO film was formed on the p-type GaN contact layer by sputtering and patterned by etching without providing a transparent conductive substrate.
The structure of the light-emitting element manufactured in Comparative Example 1 is shown in FIG.

  The light emission efficiency of the light emitting elements obtained as described above was compared. As a result, compared with Comparative Example 1, Example 1 in which a transparent conductive substrate having a transparent conductive film formed on a transparent base material was bonded via a transparent conductive polymer improved the luminous efficiency by 11%. It was confirmed that This is because in Example 1, only 7% of the glass transmittance was lost, but in the comparative example, the luminous efficiency was lost by 20% due to the metal tap.

<Example 2>
A light emitting device having a structure as shown in FIG. 2 was produced as follows.
First, an n-type AlGaInP clad layer, an AlGaInP light emitting part, a p-type AlGaInP clad layer, and a p-type AlGaInP current distribution layer were sequentially formed on an n-type GaAs substrate by MOCVD.

  On the other hand, an ITO transparent conductive film was formed on a glass substrate by a sputtering method. Thereafter, the ITO transparent conductive film was patterned by etching to produce a transparent conductive substrate separate from the laminate.

  Next, a solution of polyethylene dioxythiophene (PEDOT) was applied on the p-type AlGaInP current dispersion layer, and a transparent conductive substrate was bonded thereon with an ITO transparent conductive film facing each other.

  An Au / Ni p-side electrode is formed by photolithography in a non-contact portion with the laminate of the transparent conductive substrate, and an AuGe / Ni / Au n-side electrode is formed on the other surface of the GaAs substrate. did.

  The wafers thus laminated were diced into 300 μm squares to form bare chips. Then, this bare chip was mounted on the stem by die bonding and wired by wire bonding to produce a light emitting element.

<Comparative example 2>
A light emitting device was fabricated in the same manner as in Example 2 except that an ITO film was formed on the p-type AlGaInP current dispersion layer by sputtering and patterned by etching without providing a transparent conductive substrate.
The structure of the light-emitting element manufactured in Comparative Example 2 is shown in FIG.

  The light emission efficiency of the light emitting elements obtained as described above was compared. As a result, compared with Comparative Example 2, the luminous efficiency of Example 2 in which a transparent conductive substrate having a transparent conductive film formed on a transparent base material was bonded through a transparent conductive polymer film was improved by 13%. It was confirmed that

  The structure of the semiconductor light emitting device, which is a feature of the present invention, is effective for improving the performance of a photoelectric conversion device typified by a liquid crystal display device or a solar cell.

It is sectional drawing which shows one Embodiment of the semiconductor light-emitting device based on this invention. It is sectional drawing which shows other embodiment of the semiconductor light-emitting device based on this invention. It is sectional drawing which shows the structure of the conventional semiconductor light-emitting device. It is sectional drawing which shows the structure of the conventional semiconductor light-emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting element, 5 1st conductivity type layer, 6 Light emission part, 7 2nd conductivity type layer, 9 Transparent conductive polymer film, 10 Transparent conductive substrate, 11 Transparent base material, 12 Transparent conductive film.

Claims (6)

A laminate formed by arranging the first conductivity type layer and the second conductivity type layer via the light emitting part;
A light-emitting element comprising a transparent conductive substrate provided on the laminate,
The transparent conductive substrate is composed of a transparent base material and a transparent conductive film formed on the transparent base material,
The light-emitting element, wherein the transparent conductive substrate is disposed so that the transparent conductive film side faces the laminate through a transparent conductive polymer.   The light emitting device according to claim 1, wherein the transparent conductive film is patterned on the transparent substrate.   The light-emitting element according to claim 1, wherein the transparent conductive substrate is larger than the multilayer body and has a contact region and a non-contact region with the multilayer body.   The light emitting device according to claim 3, wherein the transparent conductive substrate includes an electrical connection portion with the outside in the non-contact region. A manufacturing method of a light emitting device comprising: a laminate formed by arranging a first conductivity type layer and a second conductivity type layer via a light emitting part; and a transparent conductive substrate provided on the laminate,
Forming a transparent conductive film on a transparent substrate to form the transparent conductive substrate;
Using the transparent conductive polymer, the laminate and the transparent conductive substrate that is separate from the laminate are bonded so that the transparent conductive film side faces the laminate. A method for manufacturing a light emitting device. 6. The method for manufacturing a light-emitting element according to claim 5, wherein the transparent conductive film is provided in a pattern on the transparent substrate.

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