JP2013038450A - Semiconductor light-emitting element and light device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light extraction efficiency of a semiconductor light-emitting element in which an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer are laminated on a translucent growth substrate.SOLUTION: A semiconductor light-emitting element in which a translucent n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer are laminated, comprises a reflection film provided on a side opposite to a surface for light extraction from the light-emitting layer. The reflection film includes a transparent layer, and a metal layer laminated on the transparent layer on a side opposite to the light-emitting layer, for reflecting light. A layer provided on the light-emitting layer side in relation to the transparent layer is either of the n-type semiconductor layer or the p-type semiconductor layer. A first transparent electrode layer ohmic contacting a layer provided on a side of the light-emitting layer in relation to the transparent layer is laminated between the layer provided on the light-emitting layer side between the n-type semiconductor layer and the p-type semiconductor layer in relation to the transparent layer, and the transparent layer. A metal part penetrating the transparent layer for electrically connecting the first electrode layer and the metal layer is provided in a part of the transparent layer. The metal layer is used as a second electrode layer.

Description

  The present invention relates to a semiconductor light-emitting element that emits light by combining electrons and holes in a semiconductor and a lighting device using the same, and more particularly, the light extraction efficiency of a semiconductor light-emitting element having a light emission peak on a shorter wavelength side than red. It is related with the technique for improvement.

  2. Description of the Related Art Conventionally, in a semiconductor light-emitting device in which an n-type semiconductor layer, the light-emitting layer, and a p-type semiconductor layer are stacked on a growth substrate that is transparent at the light emission wavelength of the light-emitting layer, light extraction efficiency (or external quantum efficiency) In order to improve the above, a method of forming a reflective film having a high reflectance on the surface opposite to the light extraction surface from the light emitting layer is used. This is because the light generated in the semiconductor light-emitting layer is directed in all directions, and as shown in FIG. 8, it is directed obliquely (the emission angle is large) than the light that exits directly above the emission point (the emission angle is small). This is because most of the light emitted from the light emitting layer is multiple-reflected inside the device and becomes a loss because there is more light.

  FIG. 9 shows changes in light extraction efficiency with respect to changes in the reflectance of the reflective film. As apparent from FIG. 9, in order to increase the light extraction efficiency to 70% or more, the reflectivity needs to be 95% or more, and in the region of 95% or more, the reflectivity is improved only by 1%. The extraction efficiency is improved by about 6%. Here, in the case of a GaAs semiconductor, by using Au as an electrode material that also serves as the reflection film, a high reflectance can be obtained and light extraction efficiency can be improved.

  However, the reflectance of the metal greatly depends on the wavelength, and such a method cannot be used for an oxide or nitride-based compound semiconductor light-emitting element having an emission peak shorter than the red color. For example, ohmic contact cannot be ensured between a GaN-based material and a highly reflective metal such as silver or aluminum. For this reason, a laminated electrode of a metal such as Ni, Pt, or Rh, a metal oxide such as ITO (Indium Tin Oxide), and the highly reflective metal is used, and the reflection is higher than the intrinsic reflectance of the highly reflective metal. Getting rates is getting harder.

Therefore, Non-Patent Document 1 has been proposed as a prior art that can solve such a problem. In the prior art, in order to ensure reflectivity higher than the reflectivity inherent to the highly reflective metal, between the silver as the highly reflective metal and the pGaN layer, which is a semiconductor layer, a 1/4 optical wavelength of SiO. _Two films are laminated, and a higher reflectance than that of a single silver film is obtained for all incident angles. As a result, an ODR (omni-directional reflector: omnidirectional reflector electrode structure) is formed, and the average reflectance is 98% at a calculated value of a wavelength of 450 nm. In addition, the ohmic contact forms a RuO ₂ (ruthenium oxide) film between the pGaN layer and the SiO ₂ film, and the silver layer passes from the RuO ₂ film to the pGaN layer through the opening formed in the SiO ₂ film. Secured by electrically connected microcontacts.

GaInN light-emitting diodes with RuO2 OSiO2 OAg omni-directional reflector (Jong Kyu Kim, Thomas Gesmann, Hong Luo, and E. Fred Schubert. Applied Physics Letters 84, 4508 (2004) Rensselaer Polytechnic Institute)

In the above prior art, although a high reflectance is obtained for all angles of incidence, where the present inventors have carried out the same calculation, as shown in Figure 10, the film thickness of the SiO ₂ film In the 1/8 optical wavelength film thickness (0.5Q), the reflectance is reduced by about 20% in a wide angle range centered at about 55 degrees, and in the 1/4 optical wavelength film thickness (1Q), about 45 degrees is centered. It was found that the reflectance was reduced by about 30%. This is because, when a single layer SiO ₂ film is formed on a metal as a reflective film, when the incident angle is small, good reflection can be obtained with the 1/4 optical wavelength film thickness (1Q). It is considered that light that oozes from the semiconductor layer into the SiO ₂ film, so-called near-field or evanescent wave, as shown by the broken line in FIG. In FIG. 10, 1/4 optical wavelength film thickness = λ / (4n) = 1Q, and n is a refractive index. Further, in FIG. 10, when it is attempted to obtain the data characteristics described in Non-Patent Document 1, that is, the reflectance of 98% by the average value of each reflectance at an incident angle of 0 to 90 °, the thickness of the reflecting film is obtained. It can be seen that the thickness must be increased to 5Q or 6Q.

  As shown in FIG. 12, the amount of the oozing is 0 until the incident angle θ reaches the critical angle θc, oozes to a depth of about the wavelength λ at the critical angle θc, and then decreases exponentially. Go. θc = 30 to 40 °.

  The objective of this invention is providing the semiconductor light-emitting device which can improve light extraction efficiency, and an illuminating device using the same.

  The semiconductor light-emitting device according to one aspect of the present invention includes a light-transmitting n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer stacked at a light emission wavelength of the light-emitting layer, and a light extraction surface from the light-emitting layer. A reflective film is provided on the opposite side, and the reflective film is a transparent layer having translucency at the emission wavelength of the light emitting layer, and a metal material that is laminated on the opposite side of the transparent layer from the light emitting layer and reflects light A layer provided on the light emitting layer side when viewed from the transparent layer is one of the n-type semiconductor layer and the p-type semiconductor layer, and the n-type semiconductor layer and Between the p-type semiconductor layer, the layer provided on the light emitting layer side when viewed from the transparent layer, and the transparent layer, the layer provided on the light emitting layer side when viewed from the transparent layer and the ohmic layer are provided. A first electrode layer that contacts and is transparent at the emission wavelength The transparent layer is partially provided with a metal portion that penetrates the transparent layer and electrically connects the first electrode layer and the metal layer. Used as an electrode layer.

  According to this configuration, since the first electrode layer and the metal layer are electrically connected through the transparent layer by the metal portion provided in a part of the transparent layer, the n-type semiconductor layer and the p-type Of the semiconductor layers, the layer provided on the light emitting layer side of the transparent layer and the highly reflective metal layer used as the second electrode layer are electrically connected via the first electrode layer and the metal portion. Is done. As a result, a sufficient current can be injected from the second electrode layer to the light emitting layer, so that it is possible to improve the light emission efficiency by emitting light from the light emitting layer while increasing the reflectance by the transparent layer. It becomes.

  Moreover, it is preferable that the said metal part is formed in several island shape.

  According to this configuration, since the metal portion is formed into a plurality of islands, the current supplied from the metal portion to the first electrode layer is converted into a transparent insulating material portion in the transparent layer in the first electrode layer. As a result, the current supplied to the light emitting layer is made uniform, and uneven light emission is reduced.

  The metal part may be formed in a mesh shape.

  According to this configuration, since the metal portion is formed in a mesh shape, the current supplied from the metal portion to the first electrode layer is transferred to the transparent insulating material portion in the transparent layer in the first electrode layer. As a result, the current supplied to the light emitting layer is made uniform, and uneven light emission is reduced.

  The first electrode layer is preferably formed using at least one material of ITO, GZO, ZnO, IZO, and AZO.

  ITO, GZO, ZnO, IZO, and AZO are suitable for the first electrode layer because they are transparent conductive materials.

  The first electrode layer is a highly reflective metal that is one of silver, Pt, Rh, Pt, Al, and any alloy of Pt, Rh, silver, and Al, and has a thickness of 0. It is preferably 1 nm to 5 nm.

  According to the above configuration, when the first electrode layer is made of a highly reflective metal with little absorption and has a thickness of 0.1 nm to 5 nm, the absorption can be 1% or less.

  The highly reflective metal is silver, and the thickness of the first electrode layer is preferably 0.1 nm to 2 nm.

  According to said structure, there is very little absorption and it is especially suitable.

  Further, the layer provided on the light emitting layer side when viewed from the transparent layer is the p-type semiconductor layer, and the first electrode layer is formed of any one of Pt, Rh, and an alloy thereof being 0.00. It is preferably formed as a mesh or a microregion group having a thickness of 1 nm to 2 nm and an area occupation ratio of 10% to 50%.

  According to said structure, as said 1st electrode layer, Pt or Rh, or those alloys can be ohmic-connected with a GaN-type p-type semiconductor layer, and a reflectance is 60% or more. Therefore, by forming them in a mesh or minute region group having a thickness of 0.1 nm to 2 nm and an area occupation ratio of 10% to 50%, the forward voltage can be reduced without sacrificing high reflection. It is possible and suitable.

  The semiconductor light-emitting device according to one aspect of the present invention includes an n-type semiconductor layer having a light-transmitting property at the emission wavelength of the light-emitting layer, the light-emitting layer, and the p-type semiconductor layer, and a light extraction surface from the light-emitting layer. A reflective film on the opposite side of the light-emitting layer, and the reflective film is laminated on the side of the transparent layer opposite to the light-emitting layer, and reflects light, and has a light-transmitting property at the emission wavelength of the light-emitting layer. A metal layer made of a metal material, wherein the n-type semiconductor layer, the light emitting layer, and the p-type semiconductor layer are stacked on a light-transmitting growth substrate, and the reflective film is formed on the growth substrate. It is provided on the surface opposite to the light emitting layer, and the layer provided on the light emitting layer side when viewed from the transparent layer is the growth substrate.

  According to this configuration, it is possible to realize a structure in which light emitted from the light emitting layer is extracted to the side opposite to the growth substrate.

The transparent layer may be formed using at least one material of SiO ₂ , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , MgF, CaF, and Si ₃ N _4. preferable.

According to the above configuration, as the transparent layer to issue a total reflection effect, SiO ₂ (refractive index = 1.43) is preferred. Not only is the semiconductor layer suitable for the group III-V, but particularly when the semiconductor layer is made of a group II-VI ZnO-based material, the refractive index of ZnO is about 2.0, so that the total reflection effect is reduced. It is suitable for use. Similarly to SiO ₂ , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , MgF, CaF, and Si ₃ N ₄ are also suitable as the transparent layer.

  The metal layer is preferably configured using at least one material of silver, Al, and alloys thereof.

  Silver, Al, and alloys thereof are suitable as a metal layer because of high light reflectance.

  In addition, it is preferable that any one layer of Al and Al alloy is formed by laminating one of the layers and the silver layer so that the layer is in contact with the transparent layer.

  Since Al and Al alloy have higher adhesiveness to the transparent layer than silver, any one of Al and Al alloy is laminated with the silver layer so that either layer is in contact with the transparent layer. And if a metal layer is comprised, a possibility that a metal layer and a transparent layer may peel will reduce.

  Moreover, it is preferable that the said metal layer is silver and the thickness of the said metal layer is 80 nm or more.

  According to the above configuration, by laminating the transparent layer and silver, a reflectance of 98% to 99% on average is obtained, and high light extraction efficiency is possible. Further, when the refractive index (n, k) of silver is (0.066, 2.5), the reflectivity (R) is changed when the film thickness is 80 nm, although it varies depending on the film forming method and film forming conditions. Is 93% or more and the transmittance (T) is 3% or less, so that a film thickness of 80 nm or more is desirable to obtain a high reflectance. Here, k of the refractive index is “absorption coefficient” or “attenuation coefficient”. However, as the film thickness increases, peeling due to film stress is likely to occur, and therefore, about 100 nm is particularly preferable.

  The metal layer may be Al, and the thickness of the metal layer may be 50 nm or more.

  According to this configuration, by laminating the transparent layer and Al, a reflectance of 97% or more can be obtained, and high light extraction efficiency is possible.

  A Pt layer is preferably formed between the first electrode layer and the metal part.

  According to this configuration, the adhesion between the first electrode layer and the metal part can be further enhanced.

  In addition, the lighting device according to the present invention uses the above-described semiconductor light emitting element.

  According to said structure, the light extraction efficiency can be improved and, therefore, the illuminating device which can achieve low power consumption and high brightness | luminance is realizable.

  The semiconductor light emitting element and the lighting device having such a configuration can improve the light extraction efficiency.

It is sectional drawing which shows the structure of the light emitting diode which is a semiconductor light emitting element concerning one Embodiment of this invention. It is sectional drawing which shows the structure of the light emitting diode which is a semiconductor light emitting element concerning one Embodiment of this invention. It is sectional drawing which shows the structure of the light emitting diode which is a semiconductor light emitting element concerning one Embodiment of this invention. It is sectional drawing which shows the structure of the light emitting diode which is a semiconductor light emitting element concerning one Embodiment of this invention. It is a graph which shows the change of the reflectance with respect to the change of the thickness of a transparent layer at the time of using silver for the metal layer in the metal layer and transparent layer which comprise the reflecting film in each said light emitting diode. It is a graph which shows the change of the reflectance (R), the transmittance | permeability (T), and the absorptivity (A) with respect to the film thickness change of the reflective film of silver. It is a graph which expands and shows the one part area | region of FIG. It is a graph for demonstrating the change of the light beam with respect to each output direction from a light emitting layer. It is a graph which shows the change of the light extraction efficiency with respect to the change of the reflectance of the said reflecting film. It is a graph which shows the change of the actual reflectance with respect to the incident angle change of the light to the reflecting film by a prior art. It is a figure for demonstrating an evanescent wave (near field). It is a graph for demonstrating the change with respect to the incident angle of the amount of light leaching by the said evanescent wave. The thickness of the transparent layer (SiO _2), is a graph showing the relationship between the reflectance of the reflective film. It is explanatory drawing for demonstrating the calculation conditions and calculation method of the graph shown in FIG. It is a graph which shows the relationship between the thickness t of a metal layer, and the weighted average reflectance <R> of a reflecting film. It is explanatory drawing for demonstrating the calculation conditions of the graph shown in FIG. It is a graph which shows the relationship between the thickness t of an Al layer at the time of comprising a metal layer by providing Al layer between Ag layer and a transparent layer, and the weighted average reflectance <R> of a reflecting film. It is explanatory drawing for demonstrating the calculation conditions of the graph shown in FIG. It is a top view which shows an example of the transparent layer shown in FIG. 1, FIG. FIG. 19A shows an overall view, and FIG. 19B shows an enlarged view of a part of the transparent layer. It is a top view which shows another example of the transparent layer shown in FIG. 1, FIG. FIG. 20A shows an overall view, and FIG. 20B shows an enlarged view of a part of the transparent layer. The relationship between the Pt area occupancy, the forward voltage Vf of the light emitting diode, and the weighted average reflectance <R> when the transparent conductive layer is formed in a mesh shape or an island shape using Pt having a thickness of 1 nm is shown. It is a graph. It is a table | surface which shows the experimental result which investigated the relationship between the thickness of Pt layer, and adhesiveness (tensile strength).

  1 to 4 are sectional views showing structures of light emitting diodes 1 to 4 which are semiconductor light emitting elements according to an embodiment of the present invention. The structure of FIGS. 1 to 4 shows a typical structure example of a semiconductor light emitting device to which the present invention is applied. The light emitting diode 1 of FIG. 1 is a flip chip type, and the light emission of FIGS. The diodes 2 to 4 are wire bond types.

  The light-emitting diode 1 of FIG. 1 has an n-type semiconductor layer 11, a light-emitting layer 12, and a p-type semiconductor layer 13 stacked on a growth substrate (not shown), and a surface opposite to the light extraction surface 14 from the light-emitting layer 12. Has a reflective film. Here, it should be noted that the p-type electrode is the reflective film A according to the present invention. The reflective film A has a refractive index lower than the refractive index of the p-type semiconductor layer 13 in contact with the reflective film at the light emission wavelength of the light emitting layer 12, and has a thickness of 3/4 optical wavelength (3Q) or more. And a transparent metal layer 16 formed on the transparent layer 15 and made of a metal material having a high reflectance.

  Further, as will be described later, a part of the transparent layer 15 has a mesh shape or a plurality of island shapes that penetrate the transparent layer 15 and electrically connect the p-type semiconductor layer 13 and the metal layer 16. A metal portion 15b is provided. As shown in FIG. 1, a transparent conductive layer 19 (first electrode layer) may be laminated between the p-type semiconductor layer 13 and the transparent layer 15.

Each of the layers 11 to 13 is made of a III-V group semiconductor or a II-VI group semiconductor. For example, in the case of GaN, the wavelength is about λ = 455 nm and the refractive index is about 2.5. The transparent layer 15 is made of, for example, SiO ₂ , and the refractive index in that case is about 1.43. The metal layer 16 is made of silver, for example. After the metal layer 16 is formed, a corner is engraved to form an n-type electrode 17 connected to the n-type semiconductor layer 11, and after the growth substrate is peeled off, the light extraction surface 14 is formed. Concavities and convexities are formed on the peeled surface, and the structure shown in FIG. 1 is obtained.

2, an n-type semiconductor layer 21, a light-emitting layer 22, and a p-type semiconductor layer 23 are stacked on a growth substrate (not shown), and is opposite to the light extraction surface 24 from the light-emitting layer 22. A reflective film on the surface. Here, it should be noted that the p-type electrode is the reflective film B according to the present invention. The reflective film B has a refractive index lower than the refractive index of the p-type semiconductor layer 23 in contact with the reflective film B at the light emission wavelength of the light-emitting layer 22, and has a thickness of 3/4 optical wavelength (3Q) or more. And a metal layer 26 made of a metal material that is laminated on the transparent layer 25 and has a high reflectance. Each of the layers 21 to 23 is made of a III-V group semiconductor or a II-VI group semiconductor such as GaN, the transparent layer 25 is made of SiO ₂ , and the metal layer 26 is made of silver, for example. Then, after the metal layer 26 is formed, the growth substrate is peeled off, and unevenness is formed on the peeled surface that becomes the light extraction surface 24, and an n-type electrode 27 is formed on the unevenness. The metal layer 26 becomes a p-type contact and has the configuration shown in FIG.

  Further, as will be described later, a part of the transparent layer 25 has a mesh shape or a plurality of island shapes that penetrate the transparent layer 25 to electrically connect the p-type semiconductor layer 23 and the metal layer 26. A metal part 25b is provided. As shown in FIG. 2, a transparent conductive layer 29 (first electrode layer) may be laminated between the p-type semiconductor layer 23 and the transparent layer 25.

On the other hand, in the light emitting diode 3 of FIG. 3, the n-type semiconductor layer 31, the light emitting layer 32, and p are formed on the growth substrate (or bonded substrate) 30 having irregularities at the interface 30 a and transparent at the light emission wavelength of the light emitting layer 32. A type semiconductor layer 33 is laminated, and a reflective film is provided on the surface opposite to the light extraction surface 34 from the light emitting layer 32. Here, it should be noted that the back surface of the growth substrate 30 is the reflective film C according to the present invention. The reflective film C has a refractive index lower than the refractive index of the growth substrate 30 in contact with the reflective film at the emission wavelength of the light emitting layer 32, and has a thickness of 3/4 optical wavelength (3Q) or more. A layer 35 and a metal layer 36 which is laminated on the transparent layer 35 and made of a metal material having a high reflectance are configured. The growth substrate 30 is made of GaN, ZnO, or Al ₂ O ₃ . Each of the layers 31 to 33 is made of a III-V group semiconductor or a II-VI group semiconductor. For example, in the case of GaN, the wavelength is about λ = 455 nm and the refractive index is about 2.5. The transparent layer 35 is made of, for example, SiO ₂ , and the refractive index in that case is about 1.43. The metal layer 36 is made of, for example, silver. Then, after the transparent conductive layer 38 is formed on the p-type semiconductor layer 33 and the transparent layer 35 and the metal layer 36 are formed on the back side, the corner is engraved on the transparent conductive layer 38 and the transparent conductive layer 38. An n-type electrode 37 and a p-type electrode 39 are formed to have the configuration shown in FIG. Note that the n-type semiconductor layer 31 and the p-type semiconductor layer 33 may be interchanged. In that case, the electrode 37 is p-type and the electrode 39 is n-type.

  Furthermore, in the light-emitting diode 4 of FIG. 4, an n-type semiconductor layer 41, a light-emitting layer 42, and a p-type semiconductor layer 43 are stacked on a growth substrate (or a bonded substrate) 40 that is transparent at the emission wavelength of the light-emitting layer 42. A reflection film is provided on the surface opposite to the light extraction surface 44 from the light emitting layer 42. The back surface of the growth substrate 40 is a reflective film D in which a transparent layer 45 and a metal layer 46 similar to the transparent layer 35 and the metal layer 36 are laminated. The difference from FIG. 3 is that the unevenness is formed on the upper surface of the p-type semiconductor layer 43 which is the light extraction surface 44. Also in the light emitting diode 4, the n-type semiconductor layer 41 and the p-type semiconductor layer 43 may be interchanged, and the n-type electrode 47 and the p-type electrode 49 may be p-type and n-type, respectively.

As described above, in the present embodiment, the reflectance is not improved by ¼ optical wavelength thin film interference as in Non-Patent Document 1, but a medium having a high refractive index (for example, GaN material: refractive index = 2.5). ) To make use of the total reflection effect when light is incident on a medium having a low refractive index (for example, SiO ₂ : refractive index = about 1.43). 25, 35, 45 and a reflection layer made of metal layers 16, 26, 36, 46 of silver, silver alloy, Al, Al alloy laminated thereon, and light extraction surfaces 14, 24, 44, or An uneven structure that disturbs the regular reflection angle is disposed on the interface 30a. As a result, in the region where the incident angle θ is small, an improvement in the reflectance that is higher than the case where the quarter optical wavelength film according to Non-Patent Document 1 is laminated cannot be expected, but the actual light-emitting layers 12, 22, shown in FIG. Considering the radiation angle distribution of the light from 32 and 42, a higher average reflectance can be obtained.

  Specifically, light incident at a relatively deep angle exceeding the critical angle θc is a near-field or evanescent wave at the interface between the growth substrate 30 or 40 or the semiconductor layers 13 and 23 having a high refractive index and the reflective film. The light oozes into the transparent layers 15, 25, 35, 45 from the interface referred to as the light, but the transparent layers 15, 25, 35, 45 have a thickness of 3/4 optical wavelength or more, The possibility of passing through the transparent layers 15, 25, 35, 45 and being absorbed by the metal layers 16, 26, 36, 46 is reduced, and most of the transparent layers 15, 25, 35, 45 go to the interface. It returns (bounces back) and re-enters the growth substrate 30, 40 or the semiconductor layers 13, 23 from the interface toward the light extraction surfaces 14, 24, 34, 44.

  Also, the light that cannot be extracted by one transmission and is re-reflected in this way also has an angle conversion function depending on the incident angle, the refractive index, and the shape at the uneven light extraction surfaces 14, 24, 44 or the interface 30a. Statistically, it is considered to have a distribution similar to the first emission. Therefore, when weighting these radiation angle distributions and considering the weighted average reflectance for all the incident angles, it is more than that in the case where the quarter optical wavelength film according to Non-Patent Document 1 is laminated. Can be obtained. In this way, light incident on the reflection film at any incident angle can be efficiently extracted, and when the same light is extracted, the power consumption can be reduced, and when the same power is injected, the brightness is increased. Can do. Further, with such a film configuration, precise film thickness control is unnecessary and the number of film layers is small, so that the process is easy.

  1 to 4 exemplify minute irregularities as shapes that disturb the regular reflection angle, the purpose is to eliminate repeated multiple reflections of regular reflection in a rectangular parallelepiped, and the shape is not limited to this. By changing the macro structure of the element, the side surface of the element may be inclined, or the element itself may be a pyramid structure having a truncated pyramid shape.

  Here, FIG. 5 shows a change in reflectance with respect to a change in thickness of the transparent layers 15, 25, 35, 45 when silver is used as the metal layers 16, 26, 36, 46. The horizontal axis indicates the film thickness N, and the film thickness N is expressed as a multiple of ¼ optical wavelength (1Q). As shown in FIGS. 11 and 12, the transparent layers 15, 25, 35, and 45 utilizing the total reflection effect need to have a film thickness of about one optical wavelength or more. FIG. FIG. 5 shows the weighted average reflectance in consideration of the radiant flux distribution shown. From FIG. 5, the thickness of the transparent layers 15, 25, 35, and 45 is such that the reflectance is 99% or more. It will be appreciated that there may be more than about 4 optical wavelengths.

The transparent layers 15 and 25 (transparent portions 15c and 25c described later) and the transparent layers 35 and 45 are not limited to the SiO ₂ but may be ZrO ₂ , and their refractive indexes are 1.43, 1.95, and Al ₂ O ₃ or the like having a refractive index between these may be used. However, when the light emitting semiconductor element is made of a II-VI group ZnO-based material, the refractive index of ZnO is about 2.0. Therefore, in order to utilize the total reflection effect, the transparent layers 15, 25, 35, 45 are used. Is preferably SiO ₂ (Al ₂ O ₃ and ZrO ₂ have a small difference in refractive index and a small total reflection effect). FIG. 5 also shows the reflectance characteristics of ZrO ₂ .

Further, (transparent portion 15c to be described later, 25c) transparent layers 15 and 25, and the transparent layer 35 or 45, for _{example, SiO 2, ZrO 2, Al} 2 O 3, TiO 2, Ta 2 O 5, MgF, CaF , And Si ₃ N ₄ can be used. Moreover, you may comprise these transparent layers or transparent parts by the multilayered structure which laminated | stacked the several layer. Furthermore, each layer laminated in this way may be composed of the same material selected from the above materials, or layers of different materials may be laminated.

  On the other hand, if the transparent layers 15, 25, 35, and 45 have a thickness of 3/4 optical wavelength or more as described above, a total reflection effect can be obtained. However, the film actually formed depends on the film formation method, but has a film stress. The thicker the film, the stronger the film stress becomes, and the film peels off during the process or while using the device. Resulting in. Therefore, by setting the thickness of the transparent layers 15, 25, 35, and 45 to 5/4 optical wavelength or less, both optical characteristics and film stability can be achieved. In addition, when laminating the transparent layers 15, 25, 35, and 45, it is easy to weaken the film stress by using sputtering, but the semiconductor layer may be damaged. When EB (electron beam) vapor deposition having a small thickness is used, it is easy to increase the film stress as described above.

FIG. 13 is a graph showing the relationship between the thickness of the transparent layers 15, 25, 35, 45 (SiO ₂ ) and the reflectivity of the reflective films A, B, C, and D. In FIG. 13, the weighted average reflectance <R> on the vertical axis is a reflectance considering the solid angle distribution. 14A and 14B are explanatory diagrams for explaining the calculation conditions of the weighted average reflectance <R> in FIG. FIG. 14C is an explanatory diagram for explaining a method of calculating the weighted average reflectance <R> in consideration of the solid angle distribution.

14A and 14B, the refractive index n = 1.43 of the transparent layer (SiO ₂ ), the refractive index n of the semiconductor layer (GaN) n = 2.4, and the light wavelength λ = 450 nm. Then, in FIG. 13, the optical wavelength film thickness Q = 450 / (4 × 1.43) = 78.7 nm. The weighted average reflectance <R> is the reflectance at the interface of the transparent layer (SiO ₂ ).

  In FIG. 14C, weighting according to the incident angle of light comes to be performed by convolution integration by multiplying the term of sin φ on the right side of the equation of weighted average reflectance <R>. ing.

Referring to FIG. 13, whether Ag is used as the metal layer or Al is used, the thickness t of the transparent layer (SiO ₂ ) is 3Q (3/4 of the emission wavelength is the transparent layer). The weighted average reflectance <R> is 96% or more, and the weighted average reflectance <R> increases greatly even if the thickness t is further increased. do not do. Therefore, the thickness t of the transparent layers 15, 25, 35, 45 is desirably 3Q or more.

Furthermore, when the thickness t of the transparent layer (SiO ₂ ) is 5Q (a value obtained by dividing 5/4 of the emission wavelength by the refractive index of the transparent layer), the weighted average reflectance <R> is substantially constant. Even if the thickness t is further increased, the effect of improving the reflectance cannot be obtained. Therefore, the thickness t of the transparent layers 15, 25, 35, 45 is preferably 3Q to 5Q.

  Further, when the metal layers 16, 26, 36, 46 are made of silver or a silver alloy, they are laminated with the transparent layers 15, 25, 35, 45, so that an average of 98% to 99% as shown in FIG. % Or more can be obtained, and high light extraction efficiency can be obtained. However, the highly reflective metal is not limited to a silver-based material, and Al is desirable for a light emitting element in the ultraviolet region. Even when the transparent layers 15, 25, 35, 45 are laminated on Al, the radiation flux is small in the incident angle region where the reflectance of Al contributes, and the total reflection effect contributes in the region where the incident angle is large. As an average, an effect higher than the reflectance of Al itself can be obtained.

  Furthermore, although the film forming method and the film forming conditions are changed, when the refractive index (n, k) of silver is (0.066, 2.5), the film thickness, the reflectance (R), and the transmittance. (T) and the absorption rate (A) are as shown in FIG. Therefore, in order to obtain a high reflectance, a film thickness of 80 nm or more that can obtain a reflectance of 90% or more is desirable. Moreover, since peeling due to film stress tends to occur as the film thickness increases, the thickness is desirably 200 nm or less. In particular, about 100 nm is preferable in terms of both reflectance and film stability.

  As the metal layers 16, 26, 36, and 46, for example, Al and an Al alloy can be used in addition to silver and a silver alloy.

  FIG. 15 is a graph showing the relationship between the thickness t of the metal layers 16, 26, 36, and 46 (Ag or Al) and the weighted average reflectance <R> of the reflective films A, B, C, and D. . FIGS. 16A and 16B are explanatory diagrams for explaining the calculation conditions of the weighted average reflectance <R> in FIG.

  Referring to FIG. 15, when Ag is used as the metal layer, the graph becomes almost flat when the thickness t of the metal layer is 80 nm or more, and the weighted average reflectance <R> even if the thickness t is further increased. Does not increase. Further, when Al is used as the metal layer, the graph becomes almost flat when the thickness t of the metal layer is 50 nm or more, and the weighted average reflectance <R> does not increase even if the thickness t is increased further.

  Therefore, when Ag is used as the metal layer, the thickness t of the metal layer is preferably 80 nm or more, more preferably about 80 nm at which a substantially maximum reflectance can be obtained with a minimum thickness.

  Further, when Al is used as the metal layer, the thickness t of the metal layer is preferably 50 nm or more, more preferably about 50 nm at which a substantially maximum reflectance can be obtained with a minimum thickness.

  Further, the metal layers 16, 26, 36, and 46 may be configured in a multilayer structure in which a plurality of layers are stacked. Furthermore, each layer laminated in this way may be composed of the same material selected from the above materials, or layers of different materials may be laminated.

Moreover, when the metal layers 16, 26, 36, 46 are Ag or an Ag alloy, the adhesion with the transparent layers 15, 25, 35, 45 (SiO ₂ ) is poor, and the metal layers 16, 26, 36, 46 There is a possibility that the transparent layers 15, 25, 35, 45 are easily peeled off. On the other hand, Al and an Al alloy have better adhesion to the transparent layers 15, 25, 35, and 45 than Ag and an Ag alloy. Therefore, by forming an Al or Al alloy layer and further forming an Ag or Ag alloy layer thereon, the transparent layers 15, 25, 35, 45 (SiO ₂ ) and the Ag or Ag alloy layer are formed. By sandwiching an Al or Al alloy layer between them, the metal layers 16, 26, 36, 46 and the transparent layers 15, 25, 35, 45 can be made difficult to peel off.

  FIG. 17 shows the thickness t of the Al layer and the weighted average reflectance of the reflection films A, B, C, and D when the metal layer is configured by providing an Al layer between the Ag layer and the transparent layer. It is a graph which shows the relationship with R>. FIG. 18 is an explanatory diagram for explaining the calculation condition of the weighted average reflectance <R> in FIG.

Referring to FIG. 17, when the thickness t of the Al layer is 1 nm, the weighted average reflectance <R> is 99.0%, and a very good weighted average reflectance <R> is obtained. Therefore, the thickness t of the Al layer is desirably 1 nm or less. When the thickness t of the Al layer is 3 nm, the weighted average reflectance <R> is 98.3%, which is the same reflectance as that of bulk aluminum. Then, since Al has a light reflectance lower than that of Ag, if the thickness t of the Al layer is 3 nm or more, there is no Ag layer, which is the same as the case where the metal layer is configured by only the Al layer. Therefore, the thickness t of the Al layer needs to be thinner than 3 nm.

  By the way, in the light emitting diodes 3 and 4 of FIGS. 3 and 4, the transparent layers 35 and 45 and the metal layers 36 and 46 are formed on the growth substrates 30 and 40 and are provided in a portion unrelated to the path of the diode current. In contrast, in the light-emitting diodes 1 and 2 of FIGS. 1 and 2, the metal layers 16 and 26 are p-type electrodes, and the transparent layers 15 and 25 are formed on the p-type semiconductor layers 13 and 23. It is provided in the path of the diode current. When the reflection films A and B are thus formed on the p-type semiconductor layers 13 and 23 and also serve as the p-type electrodes, as shown in FIGS. 1 and 2, the p-type semiconductor layers 13 and 23 and the transparent films A and B are transparent. Transparent conductive layers 19 and 29 are laminated between the layers 15 and 25.

  The transparent conductive layers 19 and 29 are first electrode layers that are conductive (ohmically contacted) with the p-type semiconductor layers 13 and 23 and are transparent at the emission wavelengths of the light-emitting layers 12 and 22. Then, the transparent layers 15 and 25 having openings (through holes) 15a and 25a are formed on the transparent conductive layers 19 and 29. Further, when the metal layers 16 and 26 are laminated on the transparent layers 15 and 25, the metal material of the metal layers 16 and 26 is laminated on the transparent layers 15 and 25 from the openings 15a and 25a, and the openings 15a and 25a The metal portions 15b and 25b are formed by the metal material laminated on the substrate.

  The transparent conductive layers 19 and 29 and the metal layers 16 and 26 are electrically connected by the metal portions 15b and 25b. Thereby, the metal layers 16 and 26 are electrically connected to the p-type semiconductor layers 13 and 23 via the metal portions 15b and 25b and the transparent conductive layers 19 and 29, and a p-type electrode (second electrode layer). Used as

  The transparent conductive layers 19 and 29 are formed by forming a Pt layer having a thickness of 0.1 nm to 0.3 nm between the transparent conductive layers 19 and 29 (for example, ITO) and the metal portions 15b and 25b (for example, Ag). The adhesion between (for example, ITO) and the metal portions 15b, 25b (for example, Ag) can be further enhanced.

  In this way, when the reflective film also serves as an electrode and requires ohmic junction, a micro contact hole is formed in the transparent layers 15 and 25 utilizing the total reflection effect, or the transparent layers 15 and 25 are formed in a mesh shape or the like. The openings 15a and 25a are formed, for example, by dividing the region into portions, and the openings 15a and 25a are covered with the metal layers 16 and 26 having high reflectivity to form the metal portions 15b and 25b. Thereby, ohmic contact between the metal layers 16 and 26 and the transparent conductive layers 19 and 29 is possible. As a result, the semiconductor layers 13 and 23 and the highly reflective metal layers 16 and 26 are electrically connected without sacrificing the high reflectivity by the transparent layers 15 and 25, and sufficient current is supplied to the light emitting layers 12 and 22. Can be injected.

  19 and 20 are plan views showing examples of the transparent layers 15 and 25 shown in FIGS. 19 (a) and 20 (a) show an overall view, and FIGS. 19 (b) and 20 (b) show enlarged views of a part of the transparent layer.

  In the transparent layers 15 and 25 shown in FIG. 19A, a plurality of transparent portions 15c and 25c are arranged in a hexagonal island shape, for example. And the metal parts 15b and 25b are formed in mesh shape so that the clearance gap between each transparent part 15c and 25c may be filled. The transparent portions 15c and 25c are not limited to hexagons, and may be, for example, circular or other shapes.

  In addition, a plurality of transparent layers 15 and 25 shown in FIG. 20A are arranged such that the metal portions 15b and 25b are formed into, for example, a circular island shape. And the transparent parts 15c and 25c are formed in mesh shape so that the clearance gap between each metal part 15b and 25b may be filled. The transparent portions 15c and 25c are not limited to hexagons, and may be, for example, circular or other shapes.

  In the transparent layers 15 and 25, no current flows through the transparent portions 15c and 25c. Therefore, the current for causing the LED to emit light reaches the transparent conductive layers 19 and 29 from the metal layers 16 and 26, which are p-type electrodes, through the respective metal portions 15b and 25b, and p from the transparent conductive layers 19 and 29. The light emitting layers 12 and 22 emit light by flowing to the type semiconductor layers 13 and 23, the light emitting layers 12 and 22, and the n type semiconductor layer 11.

  At this time, in order to cause the light emitting layers 12 and 22 to emit light uniformly, the current reaching the transparent conductive layers 19 and 29 is below the transparent portions 15c and 25c (the transparent portions 15c and 25c and the p-type semiconductor layers 13 and 23 and ). The smaller the size of the transparent portions 15c and 25c, the easier it is for the current to flow under the transparent portions 15c and 25c.

  Therefore, the smaller the size of the transparent portions 15c and 25c, the easier it is for the light emitting layers 12 and 22 to emit light uniformly. The size of the transparent portions 15c and 25c is, for example, as shown in FIG. 19B, the distance d from the center of the island-like transparent portions 15c and 25c to the farthest outer edge portion, for example, as shown in FIG. And the shortest distance d between the adjacent metal portions 15b and 25b.

The transparent conductive layers 19 and 29 as the first electrode layers are formed by laminating, for example, metal oxide ITO with a thickness of 30 nm or less, for example. In this case, a transmittance of 98% or more can be secured, and the total reflection effect on the transparent layers 15 and 25 is not hindered. Especially preferably, it is 10 nm or less. In addition to ITO, magnesium hydroxide (Mg (OH) ₂ ) can also be used.

  The transparent conductive layers 19 and 29 do not necessarily have a thickness of 30 nm or less, and may have a thickness exceeding 30 nm.

Further, as the transparent conductive layers 19 and 29, in addition to ITO and magnesium hydroxide, for example, ZnO, GZO in which ZnO is doped with gallium, ZnO is doped with indium, and In ₂ O ₃ is doped with indium. IZO obtained and AZO doped with aluminum in ZnO can be used. Further, the transparent conductive layers 19 and 29 may have a multilayer structure in which a plurality of layers are stacked. Furthermore, each layer laminated in this way may be composed of the same material selected from the above materials, or layers of different materials may be laminated.

  In addition, when sputtering is used to form the transparent conductive layers 19 and 29, there is a possibility that the contact resistance between the semiconductor layer and the adjacent layer increases because damage to the semiconductor layer as a base material is large. On the other hand, when EB vapor deposition is used for forming the transparent conductive layers 19 and 29, the damage to the semiconductor layer is smaller than that of sputtering, so that the increase in the resistance value of the semiconductor layer is less than that of sputtering. On the other hand, when EB vapor deposition is used, the flatness of the film formation is inferior to that of sputtering, so that irregularities occur at the interfaces between the transparent conductive layers 19 and 29 and the metal layers 16 and 26, and the light reflectance is reduced.

  Therefore, when the transparent conductive layers 19 and 29 are formed by laminating a layer formed by EB vapor deposition (first film formation method) and a layer formed by sputtering (second film formation method), reflection is achieved. It is possible to reduce the increase in the resistance value of the semiconductor layer while reducing the decrease in the rate. In particular, the surfaces of the transparent conductive layers 19 and 29 that are in contact with the transparent layers 15 and 25 are preferably formed by sputtering in order to reduce a decrease in reflectance.

  Further, the transparent conductive layers 19 and 29 as the first electrode layers may be formed of a highly reflective metal with little absorption, such as silver, and the thickness thereof is laminated to 5 nm or less. In this case, as shown in the enlarged view of FIG. 7 where the film thickness is 20 nm or less in FIG. 6, the absorption can be 1% or less. In particular, from FIG. 7, it is preferable that the thickness is 2 nm or less because the absorption is extremely reduced.

  Furthermore, the transparent conductive layers 19 and 29 which are the first electrode layers and are in contact with the p-type semiconductor layers 13 and 23 can be ohmic-connected to the GaN-based p-type semiconductor layers 13 and 23 and have a reflectivity. It is made of Pt or Rh that is 60% or more, or an alloy thereof. Then, by forming the openings 19a and 29a by dividing them into meshes or island-like microregion groups having a thickness of about 2 nm or less and an occupation ratio of 50% or less, preferably 25% or less, a high The forward voltage of the light emitting diodes 1 and 2 can be reduced without sacrificing reflection, which is preferable.

  FIG. 21 shows the area occupancy of Pt, the forward voltage Vf of the light emitting diodes 1 and 2, and the weight when the transparent conductive layers 19 and 29 are formed in a mesh shape or an island shape using Pt having a thickness of 1 nm. It is a graph which shows the relationship of average reflectance <R>.

  The light emission efficiency of the light emitting diodes 1 and 2 is higher as the forward voltage Vf is lower, and is higher as the weighted average reflectance <R> is higher.

  As shown in FIG. 21, when the area occupancy of Pt falls below 10%, the forward voltage Vf rapidly increases. Therefore, the area occupancy of Pt is preferably 10 or more. Further, if the Pt area occupancy exceeds 50%, the weighted average reflectance <R> is 93% or less, which is not desirable. Accordingly, the area occupation ratio of Pt is desirably 50% or less. Further, if the area occupation ratio of Pt is 25% or less, the weighted average reflectance <R> is 95% or more, which is more desirable.

  FIG. 22 is a table showing the experimental results of examining the relationship between the thickness of the Pt layer and adhesion (tensile strength). Sample 1 shown in FIG. 22 does not include a Pt layer, and a GaN layer and an Ag layer are in close contact with each other. Samples 2 to 4 include a Pt layer between the GaN layer and the Ag layer. is there.

In sample 1, delamination occurred at a tensile strength of 10 N / mm ² . On the other hand, in sample 2 having a Pt layer thickness of 0.1 nm, peeling did not occur even at a tensile strength of 44.0 N / mm ² . Further, in Samples 3 and 4 having a Pt layer thickness of 0.3 nm and 1.0 nm, peeling did not occur even at a tensile strength of 44.7 N / mm ² or more (measurement limit or more).

  For this reason, the thickness of the Pt layer is preferably 0.1 nm or more. Further, it is estimated that the same result as that of the Rt layer can be obtained even in a layer using an alloy of Rh, Pt, and Rh, and the thickness of the layer is preferably 0.1 nm or more.

  By using the light emitting diodes 1 to 4 as described above for the lighting device, it is possible to improve the light extraction efficiency, and thus it is possible to realize a lighting device that can achieve low power consumption and high luminance.

  The semiconductor light-emitting device according to one aspect of the present invention includes an n-type semiconductor layer having a light-transmitting property at the emission wavelength of the light-emitting layer, the light-emitting layer, and the p-type semiconductor layer, and a light extraction surface from the light-emitting layer. A reflective film on the opposite side of the light-emitting layer, and the reflective film is laminated on the side of the transparent layer opposite to the light-emitting layer, and reflects light, and has a light-transmitting property at the emission wavelength of the light-emitting layer. A metal layer made of a metal material; and a layer provided between the transparent layer and the metal layer for making the transparent layer and the metal layer difficult to peel, wherein the transparent layer is the light emitting element. It has a refractive index lower than the refractive index of the layer provided on the light emitting layer side when viewed from the transparent layer, and the thickness of the transparent layer is 3/4 of the light emitting wavelength. Is equal to or greater than the value obtained by dividing the refractive index of the transparent layer by 5/4 of the emission wavelength. Or less divided by the value in the refractive index.

  According to the above configuration, a substrate or a semiconductor layer that has translucency at the emission wavelength of the light-emitting layer and becomes conductive by appropriately including a conductive buffer layer on a conductive substrate or an insulating substrate. Semiconductor light-emitting device in which at least an n-type semiconductor layer, the light-emitting layer, and a p-type semiconductor layer are stacked in this order or the reverse order on a growth substrate such as an insulating substrate that is appropriately separated after the growth of In the above, a reflective film is provided on the side opposite to the light extraction surface from the light emitting layer. Further, the reflective film has a refractive index lower than the refractive index of the layer provided on the light emitting layer side at the light emitting wavelength of the light emitting layer, and 3/4 of the light emitting wavelength is the refractive index of the transparent layer. A transparent layer having a thickness equal to or greater than the divided value and a metal layer formed on the transparent layer and made of a metal material having a high reflectivity are provided.

  Therefore, light incident at a relatively shallow angle (incident angle is small) up to the critical angle θc is reflected by the transparent layer or metal layer. In addition, light incident at a relatively deep angle (incident angle is large) exceeding the critical angle θc is a near field or an interface between a growth substrate such as GaN having a high refractive index or a semiconductor layer and the reflective film. Light oozes from the interface, called evanescent wave, into the transparent layer. However, if the transparent layer has a thickness equal to or greater than 3/4 of the emission wavelength divided by the refractive index of the transparent layer, there is a possibility that the transparent layer will be absorbed by the metal layer through the transparent layer. Most of the light returns from the transparent layer to the interface (bounces back), reenters the growth substrate or the semiconductor layer from the interface, and travels toward the light extraction surface.

  Therefore, it is possible to efficiently extract light incident on the reflection film at all incident angles, to reduce power consumption when extracting the same light, and to increase brightness when injecting the same power. Can do.

  And according to said structure, if the thickness of a transparent layer is 3/4 optical wavelength or more as mentioned above, a total reflection effect will be acquired. However, although the film actually formed depends on the film forming method, it has a film stress. The thicker the transparent layer, the stronger the film stress becomes, and the film or the element is in use. The possibility that the film peels increases.

  Therefore, by setting the thickness of the transparent layer to be equal to or less than 5/4 of the emission wavelength divided by the refractive index of the transparent layer, both optical characteristics and film stability can be achieved.

  Further, the metal layer is made of either Ag or an Ag alloy, and the layer for making it difficult to peel is made of a material having higher adhesion to the transparent layer than the Ag and Ag alloy. Preferably it is.

  Moreover, it is preferable that the layer for making it hard to peel is comprised by either Al or Al alloy.

  Moreover, it is preferable that the thickness of the layer for making it difficult to peel off exceeds 0 nm and is less than 3 nm.

  Moreover, it is preferable that the layer provided on the light emitting layer side as viewed from the transparent layer is one of the n-type semiconductor layer and the p-type semiconductor layer.

  According to this configuration, the refractive index of the transparent layer is lower than the refractive index of the n-type semiconductor layer and the p-type semiconductor layer provided on the light emitting layer side of the transparent layer. Light is reflected on the light emitting layer side.

  Further, between the n-type semiconductor layer and the p-type semiconductor layer provided on the light emitting layer side when viewed from the transparent layer and the transparent layer, the light emitting layer is viewed from the transparent layer. A first electrode layer that is in ohmic contact with a layer provided on the side and transparent at the emission wavelength is laminated, and a part of the transparent layer penetrates the transparent layer and the first electrode layer and the It is preferable that a metal portion for electrically conducting the metal layer is provided, and the metal layer is used as the second electrode layer.

  According to this configuration, since the first electrode layer and the metal layer are electrically connected through the transparent layer by the metal portion provided in a part of the transparent layer, the n-type semiconductor layer and the p-type Of the semiconductor layers, the layer provided on the light emitting layer side of the transparent layer and the highly reflective metal layer used as the second electrode layer are electrically connected via the first electrode layer and the metal portion. Is done. As a result, a sufficient current can be injected from the second electrode layer to the light emitting layer, so that it is possible to improve the light emission efficiency by emitting light from the light emitting layer while increasing the reflectance by the transparent layer. It becomes.

  The first electrode layer is formed by stacking a layer formed by a first film formation method and a layer formed by a second film formation method different from the first film formation method. It is preferable that

  The first electrode layer has different characteristics depending on the type of film formation method used for film formation. Therefore, by stacking layers formed by different types of film formation methods, it becomes easy to combine the characteristics of each film formation method to form the first electrode layer having desired characteristics.

  In addition, the first film formation method is EB vapor deposition, the second film formation method is sputtering, and the layer in contact with the transparent layer in the first electrode layer is formed by the sputtering. Preferably it is.

  The EB vapor deposition causes less damage to the semiconductor layer that is a base material than the sputtering, and the contact resistance between the semiconductor layer and the adjacent layer is less likely to increase. Also, since sputtering is more flat than EB vapor deposition, by forming a layer in contact with the transparent layer in the first electrode layer by sputtering, the interface between the transparent layer and the first electrode layer uses EB vapor deposition. It becomes flatter than the case, and the reflectance increases. Therefore, when a layer formed by EB vapor deposition and a layer formed by sputtering are stacked, and the first electrode layer is formed so that the layer formed by sputtering contacts the transparent layer, the resistance value of the semiconductor layer is increased. It is possible to increase the reflectance of light while reducing the risk of increase.

  The n-type semiconductor layer, the light-emitting layer, and the p-type semiconductor layer are stacked on a light-transmitting growth substrate, and the reflective film is on the opposite side of the growth substrate from the light-emitting layer. The layer provided on the surface and provided on the light emitting layer side when viewed from the transparent layer may be the growth substrate.

  According to this configuration, it is possible to realize a structure in which light emitted from the light emitting layer is extracted to the side opposite to the growth substrate.

1, 2, 3, 4 Light emitting diodes 11, 21, 31, 41 n-type semiconductor layers 12, 22, 32, 42 Light-emitting layers 13, 23, 33, 43 p-type semiconductor layers 14, 24, 34, 44 Light extraction surface 15, 25, 35, 45 Transparent layers 15a, 25a; 19a, 29a Openings 15b, 25b Metal portions 15c, 25c Transparent portions 16, 26, 36, 46 Metal layers 17, 27, 37, 47 n-type electrodes 30, 40 Growth Substrate 30a Interface 19, 29, 38 Transparent conductive layer 39, 49 p-type electrode

Claims (15)

An n-type semiconductor layer having translucency at the emission wavelength of the light-emitting layer, the light-emitting layer and the p-type semiconductor layer are laminated, and a reflective film is provided on the side opposite to the light extraction surface from the light-emitting layer;
The reflective film is
A transparent layer having translucency at the emission wavelength of the light emitting layer;
A layer of the transparent layer opposite to the light-emitting layer, and a metal layer made of a metal material that reflects light,
The layer provided on the light emitting layer side when viewed from the transparent layer is
One of the n-type semiconductor layer and the p-type semiconductor layer;
Between the n-type semiconductor layer and the p-type semiconductor layer provided on the light emitting layer side when viewed from the transparent layer, and between the transparent layer, the light emitting layer side when viewed from the transparent layer. A first electrode layer that is in ohmic contact with the provided layer and is transparent at the emission wavelength is laminated,
A part of the transparent layer is provided with a metal portion that penetrates the transparent layer and electrically connects the first electrode layer and the metal layer,
The semiconductor light emitting element, wherein the metal layer is used as a second electrode layer. The semiconductor light emitting element according to claim 1, wherein the metal portion is formed in a plurality of island shapes. The semiconductor light emitting element according to claim 1, wherein the metal part is formed in a mesh shape. 4. The semiconductor according to claim 1, wherein the first electrode layer is formed using at least one material of ITO, GZO, ZnO, IZO, and AZO. Light emitting element. The first electrode layer is a highly reflective metal that is one of silver, Pt, Rh, Al, and an alloy of Pt, Rh, silver, and Al, and has a thickness of 0.1 nm to 5 nm. The semiconductor light-emitting element according to claim 1, wherein The semiconductor light emitting element according to claim 5, wherein the highly reflective metal is silver, and the thickness of the first electrode layer is 0.1 nm to 2 nm. The layer provided on the light emitting layer side when viewed from the transparent layer is the p-type semiconductor layer,
The first electrode layer is a mesh-like or microregion group in which any one of Pt, Rh, and an alloy thereof is laminated with a thickness of 0.1 nm to 2 nm, and an area occupation ratio is 10% to 50%. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is formed as follows. An n-type semiconductor layer having translucency at the emission wavelength of the light-emitting layer, the light-emitting layer and the p-type semiconductor layer are laminated, and a reflective film is provided on the side opposite to the light extraction surface from the light-emitting layer;
The reflective film is
A transparent layer having translucency at the emission wavelength of the light emitting layer;
A layer of the transparent layer opposite to the light-emitting layer, and a metal layer made of a metal material that reflects light,
The n-type semiconductor layer, the light emitting layer, and the p-type semiconductor layer are stacked on a light-transmitting growth substrate,
The reflective film is provided on a surface of the growth substrate opposite to the light emitting layer;
The layer provided on the light emitting layer side when viewed from the transparent layer is
A semiconductor light emitting device, which is the growth substrate. The transparent layer is formed using at least one material of SiO ₂ , ZrO ₂ , Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , MgF, CaF, and Si ₃ N _4. The semiconductor light-emitting device according to claim 1. The semiconductor light emitting element according to claim 1, wherein the metal layer is configured using at least one material of silver, Al, and an alloy thereof. The metal layer is
The semiconductor light emitting element according to claim 10, wherein any one of Al and an Al alloy is formed by laminating one of the layers and a silver layer so that the layer is in contact with the transparent layer. . The metal layer is silver;
The thickness of the said metal layer is 80 nm or more. The semiconductor light-emitting device of Claim 10 characterized by the above-mentioned. The metal layer is Al;
The thickness of the said metal layer is 50 nm or more. The semiconductor light-emitting device of Claim 10 characterized by the above-mentioned. The semiconductor light emitting element according to claim 1, wherein a Pt layer is formed between the first electrode layer and the metal part.   An illumination device using the semiconductor light emitting element according to claim 1.

Images