JP4918245B2 - Light emitting diode and manufacturing method thereof - Google Patents

Description

  The present invention relates to a high-intensity light emitting diode, a method for manufacturing the same, and a light emitting diode package.

  AlGaInP-based compound semiconductor light-emitting elements can emit light with high efficiency in the wavelength region from red to yellow-green, and are being used more widely for in-vehicle use and traffic signals. Further, it is used together with a GaN-based compound semiconductor light-emitting device, and is also used for a white light-emitting device that emits three primary colors of blue, green, and red.

In an AlGaInP-based compound semiconductor light emitting device, a transparent substrate is desirable in order to efficiently extract emitted light from the device. However, a transparent GaP substrate, for example, has a problem of lattice mismatch with a semiconductor layer grown thereon. A GaAs substrate does not cause a lattice mismatch problem, but GaAs has a problem of being opaque. Therefore, a method has been developed in which the opaque GaAs substrate used for AlGaInP crystal growth is removed and a transparent GaP substrate is bonded (see Patent Documents 1 and 2).
Further, when the GaP substrate used in the high-intensity light-emitting element has a (100) plane or a (100) plane inclined in the <011> direction within 20 ° as a principal plane, the thickness is 100 to 150 μm. The problem is that the mechanical strength is weak and the process yield decreases due to “cracking” during the manufacturing process.

In order to ensure mechanical strength, when the thickness of the GaP substrate exceeds 200 μm, the yield drop due to “cracking” can be reduced, but it becomes difficult for the heat inside the chip to escape, causing problems such as lowering of brightness and deterioration of reliability. cause. In addition, a white light emitting device used with a GaN light emitting device has a chip height that is twice or more that of a general GaN light emitting device. Therefore, inconvenience occurs when packaging together with the GaN-based light emitting device.
Patent Document 2 also discloses that the main surface (bonding surface) of the GaP substrate is (111), but the substrate is thick and still has the above-described problems.
Japanese Patent No. 3230638 JP 2001-57441 A

In view of the above-described problems in the prior art, the present invention reduces the light emitting element chip height to a GaN-based light emitting element without lowering the process yield, and is a transparent substrate type AlGaInP having high brightness and good heat dissipation. It is an object of the present invention to provide a system light emitting device and a forming method capable of producing the same at a low cost.

As a result of diligent research to achieve the above object, the present invention shows that GaP has a (111) principal surface with a higher mechanical strength than a (100) surface, and thus the substrate can be made thinner. This is based on the fact that it is possible, and that it is possible to easily form irregularities on the substrate by etching.
That is, this invention consists of the following invention.

(1) Light emitted from the light emitting portion on the semiconductor layer having the light emitting portion having the composition formula (Al _X Ga _1-X ) _Y In _1-YP (0 ≦ X ≦ 1, 0 <Y ≦ 1) A light emitting diode having an optically transparent substrate, the transparent substrate having a principal surface inclined within 20 ° from (111) or (111) and having a thickness of 200 μm or less A light emitting diode comprising gallium (GaP).
(2) The light-emitting diode according to (1), wherein the transparent substrate has a thickness of 150 μm or less.
(3) The light-emitting diode according to (1) or (2) above, wherein the thickness of the transparent substrate is 50 μm or more.

(4) Light emission emitted from the light emitting portion on the semiconductor layer having the light emitting portion having the composition formula (Al _X Ga _1-X ) _Y In _1-YP (0 ≦ X ≦ 1, 0 <Y ≦ 1) A light-emitting diode provided with a substrate optically transparent to the substrate, the transparent substrate being made of gallium phosphide (GaP) whose main surface is inclined within 20 ° from (111) or (111). A light emitting diode, wherein unevenness having a height difference of 1 to 10 μm is formed on the back and side surfaces of the GaP.
(5) Light emitted from the light emitting portion on the semiconductor layer having the light emitting portion having the composition formula (Al _X Ga _1-X ) _Y In _1-YP (0 ≦ X ≦ 1, 0 <Y ≦ 1) A light-emitting diode comprising an optically transparent substrate, the transparent substrate being made of n-type gallium phosphide (GaP) whose principal surface is inclined within 20 ° from (111) or (111). A light-emitting diode configured and disposed on a p-type semiconductor layer of the semiconductor layer.
(6) The light-emitting diode according to (5), wherein the n-type GaP is doped with Si, S, or Te or is undoped.

(7) The light-emitting diode according to any one of (1) to (6), wherein the carrier concentration of GaP is 1 × 10 ¹⁸ cm ⁻³ or less.
(8) The light-emitting diode according to any one of (1) to (7), wherein the transparent substrate is bonded to the semiconductor layer.
(9) The light-emitting diode according to any one of (1) to (8) above, wherein the transmittance is 50% or more for light having a wavelength of GaP of 560 nm or more.
(10) forming a semiconductor layer including a light emitting portion composed of a composition formula in an opaque substrate _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1), the Light emission characterized in that a gallium phosphide (GaP) substrate having a thickness of 200 μm or less is bonded onto a semiconductor layer with its main surface being (111) or inclined within 20 ° from (111). Diode manufacturing method.

(11) forming a semiconductor layer including a light emitting portion composed of a composition formula in an opaque substrate _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1), the A gallium phosphide (GaP) substrate is bonded on the semiconductor layer with the main surface thereof set to (111) or inclined within 20 ° from (111), and the height difference of 1 to 10 μm on the back and side surfaces of the substrate. A method for manufacturing a light emitting diode, characterized by forming irregularities on the substrate.
(12) forming a semiconductor layer including a light emitting portion composed of a composition formula in an opaque substrate _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1), the An n-type gallium phosphide (GaP) substrate is bonded to a p-type semiconductor layer of a semiconductor layer with a principal surface of (111) or inclined within 20 ° from (111). Manufacturing method of light emitting diode.
(13) The method for producing a light-emitting diode according to any one of (10) to (12), wherein the bonding of the GaP substrate is performed in a vacuum of 1 × 10 ⁻² Pa or less.

(14) The bonding surface of the GaP substrate and / or the bonding surface of the semiconductor layer has been irradiated with an atomic beam or an ion beam before bonding, according to any one of the above (10) to (13) The manufacturing method of the light emitting diode of description.
(15) forming a semiconductor layer including a light emitting portion made of an opaque substrate in the composition formula _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1), the A non-transparent substrate is removed by bonding a gallium phosphide (GaP) substrate on a semiconductor layer with its main surface being (111) or inclined within 20 ° from (111). The manufacturing method of the light emitting diode in any one of said (10)-(14).
(16) A light-emitting diode package in which the light-emitting diode according to any one of (1) to (9) is combined with a GaN-based light-emitting diode.

Compounds in the present invention, including a light emitting layer made of the substrate, the formed composition formula of the substrates _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1) In an LED comprising a semiconductor layer and a GaP substrate that is optically transparent to light emitted from a light emitting part provided on the light emitting part, a GaN-based material can be used without causing a decrease in yield. It is possible to provide an AlGaInP-based compound semiconductor light emitting device having a height similar to that of the compound semiconductor light emitting device.

In the present invention, since a GaP substrate having a main surface with a plane orientation inclined within 20 ° from (111) or (111) is used, it is easy to form irregularities on the substrate by wet etching, thereby The extraction efficiency can be increased.
In addition, since the GaP with the above-mentioned plane orientation has higher mechanical strength than GaP with the (100) plane orientation, the substrate can be made thin.
Further, as a substrate for growing a compound semiconductor layer including a light emitting layer having the composition formula _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1) (100) or (100 ), The resistance at the bonding interface with the GaP substrate can be increased.
In the present invention, since thin GaP of 200 μm or less is used, the thermal resistance between the light emitting layer and the stem is small. Therefore, an increase in the temperature of the light emitting layer can be suppressed, and an AlGaInP-based compound semiconductor light emitting element that can operate more stably at high current and high temperature can be provided.

The present invention is a semiconductor layer having a light emitting portion having the composition formula _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1), luminescence emitted from the light emitting portion A light emitting diode provided with an optically transparent substrate. The transparent substrate is made of gallium phosphide (GaP) whose principal surface is inclined within 20 ° from (111) or (111).
Emitting unit according to the present invention is a portion having a light-emitting including a light emitting layer made of _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1). Emitting layer may be constructed from n-type or p-type one conductivity type _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1).

  The light-emitting portion is a so-called double heterogeneous structure composed of a carrier that brings about radiative recombination and a clad layer disposed opposite to both sides of the light-emitting layer in order to “confine” light emission in the light-emitting layer. A (English abbreviation: DH) structure is preferable. The light-emitting layer may have a single quantum well structure (abbreviation: SQW) or a multiple quantum well (abbreviation: MQW) structure in order to obtain light emission excellent in monochromaticity. Examples of the means for forming the constituent layers of the light emitting part include metal organic chemical vapor deposition (abbreviation: MOCVD), molecular beam epitaxy (abbreviation: MBE), and liquid phase epitaxy (abbreviation: LPE). .

Clad layer constituting the light emitting layer _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1) wider band gap than, and a high refractive index It is preferably made of a semiconductor material. For example, for a light-emitting layer composed of (Al _0.4 Ga _0.6 ) _0.5 In _0.5 P emitting yellow-green with a wavelength of about 570 nm, the cladding layer is composed of (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P (Y. Hosakawa et al. al., J. Crystal Growth, 221 (2000), 652-656.). An intermediate layer for gently changing the band discontinuity between the two layers may be provided between the light emitting layer and the cladding layer. In this case, the intermediate layer is composed of the light emitting layer and the cladding layer. It is desirable that it is made of a semiconductor material having an intermediate band gap.

  In the middle of the substrate and the light emitting portion, there is a buffer layer that acts to alleviate the lattice mismatch between the substrate material and the constituent layers of the light emitting portion, and a Bragg (for reflecting light emitted from the light emitting layer to the outside of the device). Bragg) A reflection layer, an etching stop layer used for selective etching, and the like are provided. Further, above the constituent layers of the light emitting part, a contact layer for lowering the contact resistance of the ohmic electrode, a current diffusion layer for planarly diffusing the element driving current throughout the light emitting part, and conversely, the element A current blocking layer, a current constricting layer, or the like for limiting the region through which the drive current flows can be provided.

In the present invention, a transparent GaP substrate is provided on a light emitting portion or a semiconductor layer such as a contact layer on the light emitting portion. Here, the term “transparent” means that the transmittance is 50% or more for light having a wavelength of GaP of 560 nm or more. This GaP substrate can be provided by bonding to the semiconductor layer. The semiconductor layers to be joined can be either p-type or n-type, but are usually p-type.
The transparent substrate to be bonded to the semiconductor layer including the light emitting portion has sufficient strength to mechanically support the light emitting portion, and has a wide forbidden bandwidth capable of transmitting the light emitted from the light emitting portion, and is optically It is made of a transparent material.

In a compound semiconductor LED having a light emitting layer made of (Al _X Ga _1-X ) _Y In _1-YP (0 ≦ X ≦ 1, 0 <Y ≦ 1), as a more inexpensive transparent substrate material, GaP is preferred.
GaP has stronger mechanical strength when the main surface is set to (111) than (100), so that the substrate can be thinned to 200 μm or less, preferably 150 μm or less. The lower limit is 50 μm from the viewpoint of strength.
The light emitting layer (AlGaInP) usually has a main surface that is inclined within 20 ° from (100) or (100). The closer the plane orientation is, the smaller the electrical resistance is. Therefore, it is considered that the electrical resistance at the bonding surface increases when the (111) main surface substrate is used.
Both n-type and p-type GaP substrates can be used. However, when an n-type GaP substrate is disposed on the p-type semiconductor layer by bonding or the like, the resistance at the bonding interface can be increased, and the current passing through the bonding interface can be reduced. There is. In the LED as shown in the embodiment, it is preferable that the resistance of the bonding interface is large.
The n-type GaP is doped with Si, S, Te or undoped, and its carrier concentration is 1 × 10 ^{18 in} order to suppress internal absorption of light generated in the light emitting layer and increase light extraction efficiency. It is preferable that it is cm ⁻³ or less.
Moreover, it is preferable that the unevenness | corrugation with a height difference of about 1-10 micrometers is formed in the back surface and side surface of a GaP board | substrate. When the main surface of the GaP substrate is tilted within 20 ° from (111) or (111), the light emitting element removes the opaque GaAs substrate used for the growth of the semiconductor layer in order to increase the light extraction rate. It is desirable.

The light emitting device of the present invention can be obtained as follows.
A light emitting part made of a semiconductor layer in which an n-type cladding layer, a light-emitting layer, and a p-type cladding layer are laminated on an opaque substrate, for example, a GaAs substrate, if necessary, via a buffer layer, and if necessary, p-type is formed thereon. Semiconductor layers such as a contact layer and a p-type current diffusion layer are formed. A known method such as MOCVD is used for forming the semiconductor layer. The GaP substrate is bonded onto these semiconductor layers.
The surface of the GaP substrate to be bonded or the semiconductor layer to which it is bonded depends on chemical mechanical polishing (English abbreviation: CMP) means using an abrasive containing silicon carbide (SiC) fine powder or cerium (element symbol: Ce) fine powder. It can be flat. After chemical mechanical polishing, if the polished surface is further treated with an acid solution or ant potassium solution, the smoothness of the surface can be further improved, and foreign matters and contaminants on the surface in the polishing process can be removed. Can contribute to obtaining a clean surface.

The GaP and the semiconductor layer are bonded in a vacuum of 1 × 10 ⁻² Pascal (pressure unit: Pa) or less, preferably 1 × 10 ⁻³ Pa or less. In particular, as described above, when the polished smooth surfaces are bonded to each other, a strong bond can be formed. When bonding both, the surface to be bonded is irradiated with a beam of an atom such as He or Ar having an energy of 100 electron volts (unit: eV) or ion, or an ion beam, and the surface to be bonded is activated. It is preferable to do so. Activation means creation of a clean surface from which an oxide film, an impurity layer containing carbon or the like, a contamination layer, and the like existing on the surfaces to be bonded are removed. If this irradiation is performed on the surface of either the transparent substrate or the semiconductor layer including the light emitting portion, both can be firmly and reliably bonded. Moreover, if it performs on both surfaces, both can be combined with stronger strength. The joining is preferably performed by applying mechanical pressure.

After GaP is bonded to the semiconductor layer including the light emitting portion so that the semiconductor layer can be mechanically supported, the substrate used to form the light emitting portion is removed, thereby improving the efficiency of taking out light emission to the outside. Therefore, a high-brightness compound semiconductor LED can be constructed. In particular, utilizing the _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1) an optically opaque material that absorbs light emitted from the light emitting layer as the substrate In this case, the means for removing the substrate in this way can contribute to stable production of high-brightness LEDs. If a layer made of a material that absorbs light emitted from the light-emitting layer, for example, a buffer layer, is present at a position intermediate between the substrate and the light-emitting portion, removing it together with the substrate is advantageous for increasing the brightness of the LED. It becomes. The substrate can be removed by mechanical cutting, polishing, physical dry or chemical wet etching, or a combination thereof. In particular, according to the selective etching means using the difference in etching rate depending on the material, it is possible to selectively remove only the substrate, and the substrate can be removed uniformly with good reproducibility.
The GaP substrate can form irregularities by etching the back surface and side surfaces thereof. For etching, hydrochloric acid or hydrofluoric acid is used. As a result, irregularities with a height difference of about 1 to 10 μm can be formed.

  A first electrode (n-type) is formed on the surface from which the substrate has been removed. Further, the epitaxial layer is removed to the layer where the second electrode (p-type) is formed by etching, and the second electrode is formed. In addition, when a metal layer that reflects light emitted from the light emitting layer is provided on the back surface of the GaP substrate (the surface opposite to the bonding surface with the semiconductor layer), a high-brightness LED can be obtained. The metal film may be a single layer film made of a metal such as aluminum (Al), gold (Au), silver (Ag) or the like having a high reflectivity with respect to visible light, or a multilayer film in which films of different metals are laminated in multiple layers. Can be configured preferably

  In the first embodiment, the present invention will be specifically described with reference to an example in which a light emitting diode is manufactured by bonding an epitaxial multilayer structure (epiwafer) provided on a GaAs substrate and a GaP substrate.

  1 and 2 are schematic views showing a semiconductor light emitting diode manufactured in this example, FIG. 1 is a plan view thereof, and FIG. 2 is a cross-sectional view taken along the line II of FIG. FIG. 3 is a schematic diagram of a layer structure of a semiconductor epiwafer used for a semiconductor light emitting diode. In this example, an AlGaInP red light emitting diode (LED) was produced.

The LED 10 is manufactured using an epitaxial wafer including a semiconductor layer 13 sequentially stacked on a semiconductor substrate 11 made of a GaAs single crystal having a plane inclined by 15 ° from an n-type (100) plane doped with Si. . The stacked semiconductor layers are a buffer layer 130 made of n-type GaAs doped with Si, a contact layer 131 made of n-type (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P doped with Si, and an n-type doped with Si. of _{(Al 0.7 Ga 0.3) 0.5 in} 0.5 the lower cladding layer 132 composed of P, undoped _{(Al 0.2 Ga 0.8) 0.5 in} 0.5 P / Al 0.7 Ga 0.3) 0.5 in 0.5 emitting layer 133 composed of P of 20 pairs, and The upper cladding layer made of p-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P doped with Mg, the intermediate layer 134 made of thin film (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P, and the p-type GaP layer 135 doped with Mg. . The light emitting unit 12 of the LED 10 has a pn junction type double heterojunction structure including a lower cladding layer 132, a light emitting layer 133, and an upper cladding layer + intermediate layer 134.

In this embodiment, each of the semiconductor layers 130 to 135 is made of trimethylaluminum ((CH ₃ ) ₃ Al), trimethyl gallium ((CH ₃ ) ₃ Ga), and trimethylindium ((CH ₃ ) ₃ In) as a group III. An epitaxial wafer was formed by laminating on the GaAs substrate 11 by a low pressure metal organic chemical vapor deposition method (MOCVD method) used as a constituent element material. Biscyclopentadiethyl magnesium (bis- (C ₅ H ₅ ) ₂ Mg) was used as the Mg doping material. Disilane (Si ₂ H ₆ ) was used as a Si doping material. Further, phosphine (PH ₃ ) or arsine (AsH ₃ ) was used as a raw material for the group V constituent elements. The GaP layer 135 was grown at 750 ° C., and the other semiconductor layers 130 to 134 forming the semiconductor layer 13 were grown at 730 ° C.

The carrier concentration of the GaAs buffer layer 130 was about 2 × 10 ¹⁸ cm ⁻³ and the layer thickness was about 0.2 μm. The contact layer 131 is made of (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P, has a carrier concentration of about 2 × 10 ¹⁸ cm ⁻³ , and a layer thickness of about 1.5 μm. The n-cladding layer 132 has a carrier concentration of about 8 × 10 ¹⁷ cm ⁻³ and a layer thickness of about 1 μm. The light emitting layer 133 was undoped 0.8 μm. The carrier concentration of the p-cladding layer 134 was about 2 × 10 ¹⁷ cm ⁻³ and the layer thickness was 1 μm. The carrier concentration of the GaP layer 135 was about 3 × 10 ¹⁸ cm ⁻³ and the layer thickness was 9 μm.
The p-type GaP layer 135 was polished and mirror-finished in a region reaching a depth of about 1 μm from the surface. Depending on the mirror finish, the surface roughness of the p-type GaP layer 135 was set to 0.18 nm. On the other hand, an n-type GaP substrate 14 to be bonded to the mirror-polished surface of the p-type GaP layer 135 was prepared. For this bonding GaP substrate 14, a single crystal having a plane orientation of (111) to which Si and Te were added so that the carrier concentration was about 2 × 10 ¹⁷ cm ⁻³ was used. The bonding GaP substrate 14 had a diameter of 50 millimeters (mm) and a thickness of 100 μm. The surface of the GaP substrate 14 was polished to a mirror surface before being bonded to the p-type GaP layer 135, and finished to a square average square root value (rms) of 0.12 nm.

The GaP substrate 14 and the epitaxial wafer were carried into a general semiconductor material pasting apparatus, and the inside of the apparatus was evacuated to 3 × 10 ⁻⁵ Pa. Then, the energy of 800 eV is heated while heating the temperature of the GaP substrate 14 placed in the apparatus excluding the member made of carbon (carbon) material in order to avoid contamination of carbon or the like to a temperature of about 800 ° C. in a vacuum. The surface of the GaP substrate 14 was irradiated with Ar ions that were accelerated to 1 nm. Thus, a bonding layer 141 having a non-stoichiometric composition was formed on the surface of the GaP substrate 14. After forming the bonding layer 141, the irradiation of the Ar ions was stopped, and the temperature of the GaP substrate 14 was lowered to room temperature.

Next, neutral Ar that is neutralized by colliding electrons with the surface of both the GaP substrate 14 having the bonding layer 141 having a non-stoichiometric composition in the surface region and the GaP layer 135. The beam was irradiated for 3 minutes. Thereafter, the surfaces of both 135 and 14 were superposed in a sticking apparatus maintained in vacuum, a load was applied so that the pressure on each surface was 20 g / cm ^2, and both were joined at room temperature. The bonded wafer was taken out from the vacuum chamber of the sticking apparatus, and the bonded interface was analyzed. As a result, a bonding layer 141 made of Ga _0.6 P _0.4 having a non-stoichiometric composition was present in the bonding portion. The thickness of the bonding layer 141 is about 3 nm, the concentration of oxygen atoms in the bonding layer 141 is 7 × 10 ¹⁸ cm ⁻³ according to a general SIMS analysis method, and the atomic concentration of carbon is 9 × 10 9. ¹⁸ cm ⁻³ .

  Next, the GaAs substrate 11 and the GaAs buffer layer 130 were selectively removed with an ammonia-based etchant. On the exposed surface of the contact layer 131, an AuGe / Ni alloy film having a thickness of 0.2 μm and an Au film having a thickness of 0.1 μm were deposited by vacuum evaporation. Patterning was performed using general photolithography means to form an n-type ohmic electrode 15. Next, the surface of the contact layer 131 and the surface of the n-type ohmic electrode 15 were covered with an indium / tin composite oxide (ITO) film 17 having a thickness of 0.5 μm formed using a general sputtering apparatus. Further, a 0.03 μm-thick chromium (Cr) thin film and a 1 μm-thick gold (Au) thin film were sequentially stacked on the ITO surface by sputtering, and a bonding pad having a diameter of 110 μm was formed.

Next, the epi layers 131 to 134 in the region for forming the p electrode were selectively removed to expose the GaP layer 135. A p-type ohmic electrode 16 was formed on the surface of the GaP layer by vacuum deposition so that AuBe was 0.2 μm, Pt was 0.2 μm, and Au was 1 μm.
Heat treatment was performed at 450 ° C. for 10 minutes, and alloyed to form low resistance p-type and n-type ohmic electrodes.

  Next, using a general dicing saw, cutting was performed at an interval of 250 mμ, and was cut into a substantially square shape in plan view, whereby the LED chip 10 was obtained. After dicing, in order to remove the crushed layer generated on the cut side surface of the semiconductor layer forming the epitaxial wafer due to the cutting, the side surface portion was etched with a sulfuric acid / hydrogen peroxide mixed solution. Further, by using hydrochloric acid, irregularities having a height difference of about 2 μm were formed on the back and side surfaces of the GaP substrate of the chip.

  The LED chip 10 produced as described above was assembled into a light emitting diode lamp. This LED lamp is fixed and supported (mounted) with a silver (Ag) paste on a mounting base, and an n-type ohmic electrode 15 of the LED chip 10 and an n-electrode terminal provided on the surface of the mounting base are also p-type. The ohmic electrode 16 and the p-electrode terminal were wire-bonded with a gold wire and then sealed with a general epoxy resin. The shear strength related to the bonding surface between the substrate and the LED chip 10 was about 300 g or more. Since the fracture mode was a crack of the LED chip 10, the joint strength of the joint surface was interpreted to be greater than or equal to the fracture strength of the crystal layer constituting the epitaxial wafer.

  When a current was passed between the n-type and p-type ohmic electrodes 15 and 16 via the n-electrode terminal and the p-electrode terminal provided on the surface of the mounting base, red light having a main wavelength of 620 nm was emitted. . The forward voltage (Vf) when a current of 20 milliamperes (mA) flows in the forward direction is low in resistance at the junction interface between the GaP layer 135 and the GaP substrate 14 and the ohmic electrodes 15 and 16. Reflecting good ohmic characteristics, it was about 2.2 volts (V). In addition, the emission intensity when the forward current is 20 mA reflects the configuration of the light emitting part with high emission efficiency and the improvement of the extraction efficiency to the outside, such as the removal of the crushing layer generated when cutting into chips. As a result, the brightness became 520 mcd.

  In the present embodiment, for example, the ohmic electrode 15 is configured from the simple configuration illustrated in FIG. 1, but the shape of the electrode is, for example, a point (dot), a grid, a circle, a square shape, Even if an electrode pattern suitable for current diffusion, such as a combined shape thereof, is selected, it can contribute to obtaining an LED having the characteristics described in this embodiment.

  The light-emitting element of the present invention has high luminance and low element height. Since the height of the GaN-based light emitting element is also low, it is convenient to combine it with this GaN-based light emitting element to form, for example, a white light emitting element.

It is a plane schematic diagram of the semiconductor light emitting diode concerning the Example of this invention. It is a schematic diagram which shows the cross section along the II line | wire of FIG. 1 of the semiconductor light-emitting diode concerning the Example of this invention. It is a schematic diagram which shows the cross-section of the epi wafer concerning the Example of this invention. It is a schematic diagram which shows the cross-section of the epi wafer concerning Example of this invention, and GaP to join.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor light emitting diode 11 Semiconductor substrate 12 Light emission part 13 Semiconductor layer 14 GaP single crystal substrate for junction 15 N type ohmic electrode 16 P type ohmic electrode 130 Buffer layer 131 Contact layer 132 Lower clad layer 133 Light emitting layer
134 Upper cladding layer 135 GaP layer 141 Junction layer

Claims (14)

With respect to light emitted from the light emitting portion on the semiconductor layer having the light emitting portion having the composition formula (Al _X Ga _1-X ) _Y In _1-YP (0 ≦ X ≦ 1, 0 <Y ≦ 1) A light-emitting diode comprising an optically transparent substrate, the transparent substrate being composed of n-type gallium phosphide (GaP) whose main surface is inclined within 20 ° from (111) or (111), A light-emitting diode, which is disposed on a p-type semiconductor layer of the semiconductor layer via a bonding layer .   The light-emitting diode according to claim 1, wherein the transparent substrate has a thickness of 200 μm or less.   The light-emitting diode according to claim 1, wherein the transparent substrate has a thickness of 150 μm or less.   The light-emitting diode according to claim 1, wherein the transparent substrate has a thickness of 50 μm or less.   The light emitting diode according to any one of claims 1 to 4, wherein the transparent substrate has irregularities with a height difference of 1 to 10 µm formed on the back surface and side surfaces thereof.   The light emitting diode according to any one of claims 1 to 5, wherein the n-type GaP is doped with Si, S, or Te or is undoped. The light-emitting diode according to claim 1, wherein a carrier concentration of GaP is 1 × 10 ¹⁸ cm ⁻³ or less.   The light-emitting diode according to any one of claims 1 to 7, wherein the transmittance is 50% or more for light having a wavelength of GaP of 560 nm or more. Forming a semiconductor layer including a light emitting portion composed of a composition formula in an opaque substrate _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1), the semiconductor layer In addition, a gallium phosphide (GaP) substrate having a thickness of 200 μm or less is bonded through a bonding layer with the main surface thereof set to (111) or inclined within 20 ° from (111), and then opaque. A method of manufacturing a light emitting diode, comprising removing a substrate, forming an electrode, and forming a light emitting diode chip by dicing .   10. The method for manufacturing a light emitting diode according to claim 9, wherein unevenness having a height difference of 1 to 10 [mu] m is formed on the back and side surfaces of the GaP substrate.   The method for manufacturing a light-emitting diode according to claim 9 or 10, wherein an n-type GaP substrate is bonded on the p-type semiconductor layer. The method for producing a light-emitting diode according to claim 9, wherein the bonding of the GaP substrate is performed in a vacuum of 1 × 10 ⁻² Pa or less.   13. The light-emitting diode according to claim 9, wherein the bonding surface of the GaP substrate and / or the bonding surface of the semiconductor layer is irradiated with an atomic beam or an ion beam before bonding. Method. The light emitting diode package which combined the light emitting diode in any one of Claims 1-8, and a GaN-type light emitting diode.

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