WO2014065259A1 - Light-emitting diode and production method therefor - Google Patents

Abstract

This light-emitting diode comprises a light-emitting part including, in order on a support substrate, a metallic reflective layer, a lower DBR layer, and a compound semi-conductor layer which includes, in order, an active layer and an upper DBR layer. Said light-emitting diode is formed by the supporting substrate and the light-emitting part being joined.

Description

Light emitting diode and manufacturing method thereof

The present invention relates to a light emitting diode and a method for manufacturing the same.
This application claims priority based on Japanese Patent Application No. 2012-233768 for which it applied to Japan on October 23, 2012, and uses the content here.

The antinode of the standing wave generated in the resonator composed of two mirrors is located in the light emitting layer disposed in the resonator, and the reflectance of the mirror on the light emitting side (upper DBR layer) is set on the substrate side. The resonator type light emitting diode (RCLED: Resonant-Cavity Light Emitting Diode), which is a high-efficiency light emitting element that operates in the LED mode without causing laser oscillation by setting it lower than the reflectivity of the mirror (lower DBR layer) Known (Patent Documents 1 and 2). Since the resonator type light emitting diode has the resonator structure as described above, the emission spectral line width is narrower, the directivity of emitted light is higher, and the carrier lifetime due to spontaneous emission is shorter than that of a normal light emitting diode. It is possible to enjoy effects such as being able to respond. Therefore, the resonator type light emitting diode is particularly suitable for a sensor or the like.

Japanese Unexamined Patent Publication No. 2002-76433 Japanese Unexamined Patent Publication No. 2007-299949

As described above, the resonator type light emitting diode is configured such that the antinodes of standing waves generated in the resonator composed of two mirrors (the lower DBR layer and the upper DBR layer) are located in the light emitting layer. Of the light incident on the lower DBR, the light other than the vertical direction may not be sufficiently reflected.
Accordingly, there is a need for a light emitting diode having higher output while maintaining high directivity.

This invention is made | formed in view of the said situation, and aims at providing the light emitting diode which has high directivity and high output, and its manufacturing method.

As a result of intensive studies to achieve the above object, the present inventors have completed the present invention shown below.

[1] A light-emitting diode according to an aspect of the present invention includes a light-emitting portion that includes a metal reflective layer and a compound semiconductor layer including a lower DBR layer, an active layer, and an upper DBR layer in order on a support substrate, A support substrate and the light emitting part are joined.
[2] In the light emitting diode according to [1], the support substrate may include any one of a Ge substrate, a metal substrate, a Si substrate, a GaAs substrate, and a GaP substrate.
[3] In the light emitting diode according to [1], the metal reflective layer may be composed of one or more layers of gold, copper, silver, aluminum, Pt, or an alloy thereof.
[4] In the light emitting diode according to [1], the light emitting unit may be bonded to the support substrate via a diffusion prevention layer and / or a bonding layer formed on the metal reflective layer. .
[5] In the light emitting diode according to [1], the lower DBR layer may be configured by alternately stacking 10 to 50 pairs of two types of layers having different refractive indexes.
[6] In the light emitting diode according to [1], the lower DBR layer is formed by alternately stacking two types of layers having different refractive indexes, and the two types of layers having different refractive indexes have different compositions. Two types of (Al _Xh Ga _1-Xh ) _Y3 In _1-Y3 P (0 <Xh ≦ 1, Y3 = 0.5), (Al _Xl Ga _1-Xl ) _Y3 In _1-Y3 P; 0 ≦ Xl < 1, Y3 = 0.5), and a combination of Al composition difference ΔX = xh−xl of both is greater than or equal to 0.5, or a combination of GaInP and AlInP, It is a pair of two different types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _1-xh As (0.1 ≦ xh ≦ 1), and the difference between the two compositions ΔX = xh− whether xl is greater than or equal to 0.5 Less may be selected.
[7] In the light emitting diode according to [1], the upper DBR layer may be configured by alternately stacking 3 to 10 pairs of two types of layers having different refractive indexes.
[8] In the light emitting diode according to [1], the upper DBR layer is formed by alternately stacking two types of layers having different refractive indexes, and the two types of layers having different refractive indexes have different compositions. Two types of (Al _Xh Ga _1-Xh ) _Y3 In _1-Y3 P (0 <Xh ≦ 1, Y3 = 0.5), (Al _Xl Ga _1-Xl ) _Y3 In _1-Y3 P; 0 ≦ Xl < 1, Y3 = 0.5), and a combination of Al composition difference ΔX = xh−xl of both is greater than or equal to 0.5, or a combination of GaInP and AlInP, It is a pair of two different types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _1-xh As (0.1 ≦ xh ≦ 1), and the difference between the two compositions ΔX = xh− Any combination where xl is greater than or equal to 0.5 May be selected.
[9] In the light-emitting diode according to [1], the light-emitting layer included in the active layer has ((Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1), (Al _X2 Ga _1-X2 ) As (0 ≦ X2 ≦ 1), (In _X3 Ga _1-X3 ) As (0 ≦ X3 ≦ 1)).

[10] A method for manufacturing a light-emitting diode according to an aspect of the present invention includes: a light-emitting unit including a metal reflective layer and a compound semiconductor layer including a lower DBR layer, an active layer, and an upper DBR layer in order on a support substrate; A method of manufacturing a light emitting diode comprising: forming a compound semiconductor layer including an upper DBR layer, an active layer, and a lower DBR layer in order on a growth substrate; and forming a metal reflective layer on the compound semiconductor layer Forming a light emitting portion, joining the light emitting portion and the support substrate, and removing the growth substrate.

According to the light emitting diode of the present invention, the resonator structure is constituted by the metal reflection layer, the lower DBR layer, and the upper DBR layer. By providing the resonator type structure, it has high directivity.
Further, in the conventional resonator type structure consisting only of the upper DBR layer and the lower DBR layer, the reflectance directly above the lower DBR layer on the reflection side can be almost 100%. For example, if the rate exceeds 30 degrees, the reflectance is 60% or less. On the other hand, by providing a metal reflection layer further below the lower DBR layer, incident light from an oblique direction can be compensated for by the metal reflection layer and can be sufficiently reflected. In other words, by using a resonator type structure having a metal reflection layer, a lower DBR layer, and an upper DBR layer in order from the substrate side, it can have a reflectance of 90% or more regardless of the incident angle. Therefore, the light emitting diode of the present invention has a higher output than the resonator type light emitting diode having the conventional resonator type structure.
The light emitting diode of the present invention has a structure in which a metal reflective layer is sandwiched between a support substrate and a compound semiconductor layer. This structure removes the growth substrate used for the growth of the compound semiconductor layer. Thus, it is possible to adopt a configuration in which a light emitting portion including the compound semiconductor layer is attached to the support substrate.

It is a cross-sectional schematic diagram of the light emitting diode which is one Embodiment of this invention. It is a cross-sectional schematic diagram of the light emitting diode which is a modification of one Embodiment of this invention. 1B is an enlarged schematic cross-sectional view for explaining in detail the active layer 4 shown in FIG. 1A. FIG. It is a cross-sectional schematic diagram for demonstrating the example which used Ge substrate for the support substrate 1 in the light emitting diode which is one Embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating the example which used the metal substrate for the support substrate 1 in the light emitting diode which is one Embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating the method to manufacture the support substrate which is one Embodiment of this invention using Ge substrate. It is a cross-sectional schematic diagram for demonstrating the method to manufacture the support substrate which is one Embodiment of this invention using a metal substrate. It is a cross-sectional model diagram for demonstrating the manufacturing method of the light emitting diode which is one Embodiment of this invention. It is a cross-sectional model diagram for demonstrating the manufacturing method of the light emitting diode which is one Embodiment of this invention. It is a cross-sectional model diagram for demonstrating the manufacturing method of the light emitting diode which is one Embodiment of this invention. It is a cross-sectional model diagram for demonstrating the manufacturing method of the light emitting diode which is one Embodiment of this invention.

Hereinafter, the configuration of the light emitting diode according to the embodiment to which the present invention is applied and the manufacturing method thereof will be described with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. . In addition, the materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately changed and implemented without changing the gist thereof.

[Light emitting diode]
FIG. 1A is a schematic cross-sectional view showing an example of a light emitting diode according to an embodiment to which the present invention is applied.
The light emitting diode 100 according to the present embodiment includes a light emitting unit 6 including a metal reflective layer 2, a compound semiconductor layer 5 including a lower DBR layer 3b, an active layer 4, and an upper DBR layer 3a in this order on the support substrate 1. And the support substrate 1 and the light emitting unit 6 are joined.
In the example shown in FIG. 1A, a lower current diffusion layer 7 is formed between the metal reflection layer 2 and the lower DBR layer 3b, and an upper current diffusion layer 9 is formed between the upper DBR layer 3a and the contact layer 8. ing. Further, in the example shown in FIG. 1A, a surface electrode 12 is provided on the opposite side of the compound semiconductor layer 5 to the support substrate 1 via a contact layer 8, and on the opposite side of the metal reflection layer 2 of the support substrate 1. Is provided with a back electrode 13. The form of the electrode is not particularly limited. For example, a translucent film (SiO ₂ film) is formed between the metal reflective layer 2 and the lower current diffusion layer 7, and a p-type ohmic electrode is formed on the translucent film. May be formed.

<Metal reflective layer>
The metal reflection layer 2 can reflect light from the light emitting layer 43 (described later) in the front direction f by the metal reflection layer 2 and improve the light extraction efficiency in the front direction f. High brightness can be achieved.
As a material of the metal reflective layer 2, one or more layers of metals such as AgPdCu alloy (APC), gold, copper, silver, aluminum, Pt, or alloys thereof can be used.

<Lower current diffusion layer>
The lower current diffusion layer 7 is disposed for the purpose of suppressing the propagation of junction damage to the active layer along with the current diffusion. As the material, other than GaP, AlGaInP, AlGaAs or the like that is transparent to the emission wavelength is used. be able to.

<Lower DBR layer>
The lower DBR (Distributed Bragg Reflector) layer 3b is of two types having a thickness of λ / (4n) (λ: wavelength of light to be reflected in vacuum, n: refractive index of layer material) and different refractive indexes. It consists of a multilayer film in which layers are alternately stacked. When the difference between the two types of refractive indexes is large, a high reflectance can be obtained with a multilayer film having a relatively small number of layers. Instead of being reflected on a certain surface as in a normal reflective film, the multilayer film as a whole is characterized in that reflection occurs based on the light interference phenomenon.
The material of the lower DBR layer 3b is preferably transparent with respect to the emission wavelength, and is preferably selected so as to be a combination that increases the difference in refractive index between the two types of materials constituting the lower DBR layer.

The lower DBR layer 3b is preferably formed by alternately stacking 10 to 50 pairs of two types of layers 3ba and 3bb having different refractive indexes. This is because when the number of stacked layers is 10 pairs or less, the reflectance is too low to contribute to an increase in output, and even when the number is 50 pairs or more, the increase in reflectance is small.
The two types of layers 3ba and 3bb having different refractive indexes constituting the lower DBR layer 3b are composed of two types of (Al _Xh Ga _1-Xh ) _Y3 In _1-Y3 P (0 <Xh ≦ 1, Y3 = 0) having different compositions. .5), (Al _Xl Ga _1-Xl ) _Y3 In _1-Y3 P; 0 ≦ Xl <1, Y3 = 0.5). Further, the two types of layers 3ba and 3bb having different refractive indexes constituting the lower DBR layer 3b are a combination in which the Al composition difference ΔX = xh−xl is greater than or equal to 0.5, or GaInP and It is a combination of AlInP or a combination of two types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _1-xh As (0.1 ≦ xh ≦ 1) having different compositions. Therefore, it is desirable to select any one of these combinations because a high reflectance can be obtained efficiently.
Particularly, as the two types of layers 3ba and 3bb having different refractive indexes constituting the lower DBR layer 3b, a combination of AlGaInP having different compositions is preferable because it does not contain As which easily causes crystal defects, and GaInP and AlInP are refracted therein. Since the rate difference can be maximized, the number of reflection layers can be reduced, and the composition switching is also simple, which is preferable. Moreover, AlGaAs has an advantage that a large difference in refractive index is easily obtained.

<Active layer>
In the present embodiment, the compound semiconductor layer 5 includes a lower current diffusion layer 7, a lower DBR layer 3 b, an active layer 4, and an upper DBR layer 3 a in this order on the metal reflective layer 2.
As shown in FIG. 2, the active layer 4 includes a lower clad layer 41, a lower guide layer 42, a light emitting layer 43, an upper guide layer 44, and an upper clad layer 45 that are sequentially laminated. That is, the active layer 4 includes a lower clad layer 41 disposed facing the lower side and the upper side of the light emitting layer 43 in order to “confine” the light emitting layer 43 with carriers (carriers) and light emission that cause radiative recombination. A so-called double hetero (English abbreviation: DH) structure including the lower guide layer 42, the upper guide layer 44, and the upper clad layer 45 is preferable for obtaining high-intensity light emission.

As shown in FIG. 2, the light emitting layer 43 can form a quantum well structure in order to control the light emission wavelength of the light emitting diode (LED). That is, the light emitting layer 43 can have a multilayer structure (laminated structure) of the well layer 47 and the barrier layer 48 having a barrier layer (also referred to as a barrier layer) 48 at both ends.

The thickness of the light emitting layer 43 is preferably in the range of 0.02 to 2 μm. The conductivity type of the light emitting layer 43 is not particularly limited, and any of undoped, p-type, and n-type can be selected. In order to increase the light emission efficiency, it is desirable to have an undoped crystallinity with a good crystallinity or a carrier concentration of less than 3 × 10 ¹⁷ cm ⁻³ .

The material of the well layer 47 includes ((Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1), (Al _X2 Ga _1-X2 ) As (0 ≦ X2 ≦ 1), (In _X3 Ga _1-X3 ) As (0 ≦ X3 ≦ 1)) and the like can be used.

The layer thickness of the well layer 47 is preferably in the range of 3 to 30 nm. More preferably, it is in the range of 3 to 10 nm.

As the material of the barrier layer (barrier layer) 48, it is preferable to select a material suitable for the material of the well layer 47. In order to prevent absorption in the barrier layer 48 and increase the light emission efficiency, it is preferable that the composition has a band gap larger than that of the well layer 47.

For example, when AlGaAs or InGaAs is used as the material of the well layer 47, AlGaAs or AlGaInP is preferable as the material of the barrier layer 48. When AlGaInP is used as the material of the barrier layer 48, since it does not contain As which tends to create defects, it has high crystallinity and contributes to high output.
When (Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1) is used as the material of the well layer 47, the Al composition is higher than the material of the barrier layer 48 ( Al _X4 Ga _1-X4 ) _Y1 In _1-Y1 P (0 ≦ X4 ≦ 1, 0 <Y1 ≦ 1, X1 <X4) or (Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P of the well layer 47 AlGaAs whose band gap energy is larger than (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1) can be used.

The layer thickness of the barrier layer 48 is preferably equal to the layer thickness of the well layer 47 or thicker than the layer thickness of the well layer 47. By sufficiently thickening the layer thickness range in which the tunnel effect occurs, spreading between the well layers due to the tunnel effect is suppressed, the carrier confinement effect is increased, the probability of recombination of electrons and holes is increased, and the light emission output Can be improved.

In the multilayer structure of the well layers 47 and the barrier layers 48, the number of pairs in which the well layers 47 and the barrier layers 48 are alternately stacked is not particularly limited, but is preferably 2 or more and 40 or less. . That is, the active layer 4 preferably includes 2 to 40 well layers 47. Here, as a condition that the luminous efficiency of the active layer 4 is suitable, the well layer 47 is preferably five or more layers. On the other hand, since the well layer 47 and the barrier layer 48 have a low carrier concentration, the forward voltage (V _F ) increases when the number of pairs is increased. For this reason, the number of well layers 47 is preferably 40 pairs or less, and more preferably 20 pairs or less.

The lower guide layer 42 and the upper guide layer 44 are provided on the lower surface and the upper surface of the light emitting layer 43, respectively, as shown in FIG. Specifically, the lower guide layer 42 is provided on the lower surface of the light emitting layer 43, and the upper guide layer 44 is provided on the upper surface of the light emitting layer 43.

As the material of the lower guide layer 42 and the upper guide layer 44, a known compound semiconductor material can be used, and it is preferable to select a material suitable for the material of the light emitting layer 43. For example, AlGaAs or AlGaInP can be used.

For example, when AlGaAs or InGaAs is used as the material of the well layer 47 and AlGaAs or AlGaInP is used as the material of the barrier layer 48, the material of the lower guide layer 42 and the upper guide layer 44 is preferably AlGaAs or AlGaInP. When AlGaInP is used as the material of the lower guide layer 42 and the upper guide layer 44, it does not contain As that easily causes defects, so that the crystallinity is high and contributes to high output.
When (Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1) is used as the material of the well layer 47, as the material of the lower guide layer 42 and the upper guide layer 44 (Al _X4 Ga _1-X4 ) _Y1 In _1-Y1 P (0 ≦ X4 ≦ 1, 0 <Y1 ≦ 1, X1 <X4) or the material of the well layer 47 (Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1) AlGaAs whose band gap energy is larger can be used.

The lower guide layer 42 and the upper guide layer 44 are provided in order to reduce the propagation of defects between the lower cladding layer 41 and the upper cladding layer 45 and the active layer 4, respectively. For this reason, the layer thickness of the lower guide layer 42 and the upper guide layer 44 is preferably 10 nm or more, and more preferably 20 nm to 100 nm.

The conductivity types of the lower guide layer 42 and the upper guide layer 44 are not particularly limited, and any of undoped, p-type, and n-type can be selected. In order to increase the light emission efficiency, it is desirable to have an undoped crystallinity with a good crystallinity or a carrier concentration of less than 3 × 10 ¹⁷ cm ⁻³ .

The lower clad layer 41 and the upper clad layer 45 are provided on the lower surface of the lower guide layer 42 and the upper surface of the upper guide layer 44, respectively, as shown in FIG.

As the material of the lower cladding layer 41 and the upper cladding layer 45, a known compound semiconductor material can be used, and it is preferable to select a material suitable for the material of the light emitting layer 43. For example, AlGaAs or AlGaInP can be used.

For example, when AlGaAs or InGaAs is used as the material of the well layer 47 and AlGaAs or AlGaInP is used as the material of the barrier layer 48, the material of the lower cladding layer 41 and the upper cladding layer 45 is preferably AlGaAs or AlGaInP. When AlGaInP is used as the material of the lower clad layer 41 and the upper clad layer 45, it does not contain As that easily causes defects, so that it has high crystallinity and contributes to high output.
When (Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1) is used as the material of the well layer 47, the material of the lower cladding layer 41 and the upper cladding layer 45 is used. (Al _X4 Ga _1-X4 ) _Y1 In _1-Y1 P (0 ≦ X4 ≦ 1, 0 <Y1 ≦ 1, X1 <X4) or the material of the well layer 47 (Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1) AlGaAs whose band gap energy is larger can be used.

The lower cladding layer 41 and the upper cladding layer 45 are configured to have different polarities.
The carrier concentration and thickness of the lower clad layer 41 and the upper clad layer 45 can be in a known suitable range, and the conditions are preferably optimized so that the luminous efficiency of the active layer 41 is increased. The lower and upper clad layers need not be provided.

In the present embodiment, a semiconductor layer such as AlGaAs or AlGaInP may be appropriately provided between the lower DBR layer 3b and the active layer 4.

<Upper DBR layer>
The upper DBR layer 3a can also have the same layer structure as the lower DBR layer 3b. However, since it is necessary to emit light through the upper DBR layer 3a, the reflectance is lower than that of the lower DBR layer 3b. Configure to be Specifically, when it is made of the same material as the lower DBR layer 3b, 3 to 10 pairs of two types of layers having different refractive indexes are alternately stacked so that the number of layers is smaller than that of the lower DBR layer 3b. Is preferred. This is because when the number of stacked layers is 2 pairs or less, the reflectance is too low to contribute to an increase in output, and when the number is 11 pairs or more, the amount of light transmitted through the upper DBR layer 3a is too low.

The two types of layers 3aa and 3ab having different refractive indices constituting the upper DBR layer 3a are similar to the lower DBR layer 3b in that two types of (Al _Xh Ga _1-Xh ) _Y3 In _1-Y3 P ( 0 <Xh ≦ 1, Y3 = 0.5), (Al _Xl Ga _1-Xl ) _Y3 In _1-Y3 P; 0 ≦ Xl <1, Y3 = 0.5). Further, the two types of layers 3aa and 3ab having different refractive indexes constituting the upper DBR layer 3a may be a combination in which the Al composition difference ΔX = xh−xl is greater than or equal to 0.5, or GaInP It is a combination of AlInP or a combination of two types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _1-xh As (0.1 ≦ xh ≦ 1) having different compositions. Therefore, it is desirable to select any one of these combinations because a high reflectance can be obtained efficiently.
Especially for the two types of layers 3aa and 3ab having different refractive indexes constituting the upper DBR layer 3a, a combination of AlGaInP having different compositions is preferable because it does not contain As which easily causes crystal defects, and GaInP and AlInP are refracted therein. Since the rate difference can be maximized, the number of reflection layers can be reduced, and the composition switching is also simple, which is preferable. Moreover, AlGaAs has an advantage that a large difference in refractive index is easily obtained.

<Upper current diffusion layer>
Similar to the lower current diffusion layer 7, the upper current diffusion layer 9 is disposed for the purpose of current diffusion, and as a material, AlGaInP, AlGaAs or the like that is transparent to the emission wavelength can be used in addition to GaP. .

<Contact layer>
The contact layer 8 is provided to reduce the contact resistance with the surface electrode 12. The material of the contact layer 8 is preferably a material having a band gap larger than that of the light emitting layer 43. Further, the lower limit value of the carrier concentration of the contact layer 8 is preferably 5 × 10 ¹⁷ cm ⁻³ or more, more preferably 1 × 10 ¹⁸ cm ⁻³ or more, in order to reduce the contact resistance with the electrode. The upper limit value of the carrier concentration is desirably 2 × 10 ¹⁹ cm ⁻³ or less at which the crystallinity is likely to decrease. The thickness of the contact layer 8 is preferably 0.05 μm or more. The upper limit value of the thickness of the contact layer 8 is not particularly limited, but is desirably 10 μm or less in order to make the cost for epitaxial growth within an appropriate range.

Here, the structure of the metal reflection layer 2 and the compound semiconductor layer 5 (the lower current diffusion layer 7, the lower DBR layer 3b, the active layer 4, the upper DBR layer 3a, the upper current diffusion layer 9, and the contact layer 8) described above is included. A known functional layer can be added in a timely manner. For example, a known layer structure such as a current blocking layer or a current confinement layer for limiting the region through which the element driving current flows can be provided.

Also, for the front electrode 12 and the back electrode 13, known electrode materials can be used, respectively. As the front electrode 12, AuGeNi can be used, and as the back electrode 13, AuBe can be used.

Here, in the semiconductor device shown in FIG. 1A as described above, an example in which the back electrode 13 is provided on the opposite side of the metal reflective layer 2 of the support substrate 1 has been described. However, the front electrode 12 and the back electrode 13 in the present embodiment. The form of is not particularly limited. As an electrode structure, for example, as shown in FIG. 1B, a translucent film (SiO ₂ film) 14 is formed between the metal reflective layer 2 and the lower current diffusion layer 7, and the ohmic electrode 15 is formed on the translucent film 14. May be formed.
In FIG. 1B, the same members as those in the semiconductor device shown in FIG. 1A are denoted by the same reference numerals.

<Support substrate>
As the support substrate 1 in this embodiment, a Ge substrate, a metal substrate, a Si substrate, a GaAs substrate, a GaP substrate, or the like can be used.
Hereinafter, the case where each board | substrate is used is demonstrated.

FIG. 3 is a schematic cross-sectional view of an example in which the Ge substrate 51 is used as the support substrate 1 in the light emitting diode of the present embodiment.
When a Ge substrate 51 is used as the support substrate 1, a layer 52 made of Ti / Au / In is arranged on the front surface of the bonding layer 10 described later, and a layer 53 made of Ti / Au is arranged on the back surface. Therefore, it can be applied to the support substrate 1 according to the present embodiment.
In addition, as a material of the layer 52 and the layer 53, a metal layer having good adhesion to Ge, for example, Pt or Au can be used.

"Metal substrate"
When a metal substrate is used as the support substrate 1, a structure in which a plurality of metal layers (metal plates) are stacked can be employed.
In the case of a structure in which a plurality of metal layers (metal plates) are laminated, it is preferable that two types of metal layers are alternately laminated, and in particular, these two types of metal layers (for example, the first metal layer). The number of layers of the second metal layer is preferably an odd number in total.
For example, when the two types of metal layers are the first metal layer 61b and the second metal layer 61a and the number of layers is three, the structure is as shown in FIG.

As shown in FIG. 4, when the metal substrate has a structure in which the second metal layer 61a is sandwiched between the first metal layers 61b, the compound as the second metal layer 61a is used from the viewpoint of warping and cracking of the metal substrate. When a material having a smaller thermal expansion coefficient than that of the semiconductor layer 5 (not shown in FIG. 4) is used, it is preferable to use the first metal layer 61b made of a material having a larger thermal expansion coefficient than the compound semiconductor layer. Since the thermal expansion coefficient of the entire metal substrate is close to the thermal expansion coefficient of the compound semiconductor layer 5, it is possible to suppress warping and cracking of the metal substrate when the compound semiconductor layer 5 and the metal substrate are joined, This is because the manufacturing yield of the light emitting diode can be improved. Similarly, when a material having a larger thermal expansion coefficient than that of the compound semiconductor layer 5 is used as the second metal layer 61 a, the first metal layer 61 b made of a material having a smaller thermal expansion coefficient than that of the compound semiconductor layer 5 is used. Is preferred. Since the thermal expansion coefficient of the entire metal substrate is close to the thermal expansion coefficient of the compound semiconductor layer 5, warpage and cracking of the metal substrate when the compound semiconductor layer 5 and the metal substrate are joined can be suppressed, and the light emitting diode This is because the manufacturing yield can be improved.

Examples of the two metal layers include silver (thermal expansion coefficient = 18.9 ppm / K), copper (thermal expansion coefficient = 16.5 ppm / K), gold (thermal expansion coefficient = 14.2 ppm / K), and aluminum. (Thermal expansion coefficient = 23.1 ppm / K), nickel (thermal expansion coefficient = 13.4 ppm / K) and a metal layer made of any of these alloys, molybdenum (thermal expansion coefficient = 5.1 ppm / K), Combinations of tungsten (thermal expansion coefficient = 4.3 ppm / K), chromium (thermal expansion coefficient = 4.9 ppm / K), and a metal layer made of any of these alloys can be used.
A preferred example is a metal substrate composed of three layers of Cu / Mo / Cu. From the above viewpoint, the same effect can be obtained with a metal substrate composed of three layers of Mo / Cu / Mo, but the metal substrate composed of three layers of Cu / Mo / Cu is a Cu layer that has high mechanical strength and is easy to process Mo. Therefore, there is an advantage that processing such as cutting is easier than a metal substrate composed of three layers of Mo / Cu / Mo.

The thermal expansion coefficient of the entire metal substrate is, for example, 6.1 ppm / K for a three-layer metal substrate of Cu (30 μm) / Mo (25 μm) / Cu (30 μm), and Mo (25 μm) / Cu (70 μm). In the case of a metal substrate composed of three layers of / Mo (25 μm), it is 5.7 ppm / K.

In order to avoid deterioration due to an etching solution when a compound semiconductor layer or the like is grown on a growth substrate which will be described later, a metal substrate is bonded, and the growth substrate is removed using an etching solution. The upper and lower surfaces of the metal substrate are preferably covered with the metal protective film 61c.
The material of the metal protective film 61c is preferably made of a metal containing at least one of chromium, nickel, chemically stable platinum, and gold having excellent adhesion.
The metal protective film 61c is optimally composed of a layer combining nickel having good adhesion and gold having excellent chemical resistance.

In addition to the Ge substrate or metal substrate as described above, any one of a Si substrate, a GaAs substrate, and a GaP substrate can be used as the support substrate 1 in the present embodiment.
In the case of using a Si substrate, for example, a layer made of Ti / Au / In is arranged on the surface of the silicon substrate on the metal reflective layer side, and a layer made of Ti / Au is further arranged on the back surface of the silicon substrate. Can be applied.

In the present embodiment, the light-emitting portion 6 may be bonded to the support substrate 1 by disposing the diffusion prevention layer 11 and / or the bonding layer 10 on the substrate side of the metal reflection layer 2.

<Diffusion prevention layer>
The diffusion prevention layer 11 can suppress the metal contained in the support substrate 1 from diffusing and reacting with the metal reflection layer 2.
As a material of the diffusion preventing layer 11, nickel, titanium, platinum, chromium, tantalum, tungsten, molybdenum, or the like can be used.
The diffusion prevention layer 11 can improve the performance of diffusion prevention by a combination of two or more kinds of metals, for example, a combination of platinum and titanium.
Even if the diffusion preventing layer 11 is not provided, the bonding layer can have the same function as that of the diffusion preventing layer 11 by adding these materials to the joining layer described later.

<Junction layer>
The bonding layer 10 is a layer for bonding the compound semiconductor layer 5 including the active layer 4 to the support substrate 1.
As a material for the bonding layer 10, an Au-based eutectic metal that is chemically stable and has a low melting point is used. Examples of the Au-based eutectic metal include eutectic compositions of alloys such as AuGe, AuSn, AuSi, and AuIn.

The light emitting diode 100 of the present embodiment has a structure in which the active layer 4 is sandwiched between the metal reflection layer 2, the lower DBR layer 3b, and the upper DBR layer 3a. That is, the light emitted from the active layer 4 resonates between the lower DBR layer 3b and the upper DBR layer 3a so that the antinodes of the standing waves are located in the light emitting layer, and the light emitted from the active layer 4 is incident obliquely. By adopting a configuration in which light is reflected by the metal reflection layer 2 formed below the lower DBR layer 3b, a laser diode does not oscillate and has higher directivity than a conventional light emitting diode, and a highly efficient light emitting diode. It has become.

[Method for manufacturing light-emitting diode]
Next, the manufacturing method of the light emitting diode which is one Embodiment of this invention is demonstrated.
The method of manufacturing a light emitting diode according to the present embodiment includes a step of forming a compound semiconductor layer including an upper DBR layer, an active layer, and a lower DBR layer in order on a growth substrate, and forming a metal reflective layer on the compound semiconductor layer. Forming a light emitting portion, joining the light emitting portion and the supporting substrate, and removing the growth substrate.

<Support Substrate Manufacturing Process> [1] When a Ge Substrate is Used as the Support Substrate 1 As shown in FIG. 5, a layer 52 made of, for example, Ti / Au / In is formed on the front surface 51A of the Ge substrate 51 Then, for example, a layer 53 made of Ti / Au is formed on the back surface of the Ge substrate 51 to produce the support substrate 1.
The materials of the layer 52 and the layer 53 are not limited to these, and may be selected within a range that does not impair the effects of the present invention.

[2] When a metal substrate is used as the support substrate 1 In this embodiment, a structure in which three layers of metals having different thermal expansion coefficients are laminated will be described.
As shown in FIG. 6, when a metal substrate is used as the support substrate 1, a first metal layer (first metal plate) 61b having a thermal expansion coefficient larger than that of the active layer and a material having a thermal expansion coefficient of the active layer. A smaller second metal layer (second metal plate) 61a is employed and hot pressed to form a metal substrate.

Specifically, first, two substantially flat plate-like first metal layers 61b and one substantially flat plate-like second metal layer 61a are prepared. For example, Cu having a thickness of 10 μm is used as the first metal layer 61b, and Mo having a thickness of 75 μm is used as the second metal layer 61a.
Next, the second metal layer 61a is inserted between the two first metal layers 61b, and these are overlapped.

Next, these superimposed metal layers are placed in a predetermined pressure device, and a load is applied to the first metal layer 61b and the second metal layer 61a at a high temperature. Thus, as shown in FIG. 6, the first metal layer 61b is Cu, the second metal layer 61a is Mo, and the three layers of Cu (10 μm) / Mo (75 μm) / Cu (10 μm) are used. Forming a metal substrate.
For example, the metal substrate has a thermal expansion coefficient of 5.7 ppm / K and a thermal conductivity of 220 W / m · K.

Next, as shown in FIG. 6, a metal protective film 61c that covers the entire surface of the metal substrate, that is, the upper surface, the lower surface, and the side surfaces is formed. At this time, since the metal substrate is before being cut into individual light emitting diodes, the side surface covered by the metal protective film 61c is the outer peripheral side surface of the metal substrate.
Therefore, when the side surface of the metal substrate of each light-emitting diode after singulation is covered with the metal protective film 61c, a step of covering the side surface with the metal protective film 61c is performed separately.
FIG. 6 shows a part of the metal substrate that is not on the outer peripheral end side, and the metal protective film on the outer peripheral side surface is not shown in the figure.

A known film forming method can be used for the metal protective film 61c, but a plating method capable of forming a film on the entire surface including the side surfaces is most preferable. For example, in the electroless plating method, nickel is then plated with gold, and a metal substrate in which the upper surface, side surfaces, and lower surface of the metal substrate are covered with a nickel film and a gold film (metal protective film) can be produced.
The plating material is not particularly limited, and known materials such as copper, silver, nickel, chromium, platinum, and gold can be applied. However, a layer that combines nickel having good adhesion and gold having excellent chemical resistance is optimal.
As the plating method, known techniques and chemicals can be used. An electroless plating method that does not require an electrode is simple and desirable.

[3] When Si substrate is used as support substrate 1 For example, a layer made of Au / Pt is formed on the front surface of the Si substrate, and a layer made of Pt / Au is formed on the back surface of the Si substrate, for example. The support substrate 1 is produced.
The material of each layer formed on the front surface or the back surface of the Si substrate is not limited to these, and may be selected within a range not impairing the effects of the present invention.

[4] When a GaP substrate is used as the support substrate 1 For example, a functional substrate made of p-type GaP is prepared, a layer made of, for example, Au / Pt is formed on the front surface, and the back surface of the Si substrate is formed. For example, a support substrate 1 is manufactured by forming a layer made of Pt / Au.
The material of each layer formed on the front surface or the back surface of the Si substrate is not limited to these, and may be selected within a range not impairing the effects of the present invention.

In the present embodiment, in addition to the support substrate as described above, a GaAs substrate can be used as the support substrate 1.

<Step of forming compound semiconductor layer>
Next, a process of forming a compound semiconductor layer including an upper DBR layer, an active layer, and a lower DBR layer in this order on the growth substrate will be described.
First, as shown in FIG. 7, an epitaxial stacked body 30 including the compound semiconductor layer 5 is formed by growing a plurality of epitaxial layers on one surface 21 a of a semiconductor substrate (growth substrate) 21.
The semiconductor substrate 21 is a substrate for forming the epitaxial stacked body 30. For example, the semiconductor substrate 21 is a Si-doped n-type GaAs single crystal substrate in which one surface 21a is inclined by 15 ° from the (100) plane. When an AlGaInP layer or an AlGaAs layer is used as the epitaxial stacked body 30, a gallium arsenide (GaAs) single crystal substrate can be used as a substrate on which the epitaxial stacked body 30 is formed.

As a method for forming the epitaxial layered structure 30, a metal organic chemical vapor deposition (MOCVD) method, a molecular beam epitaxy (MBE) method, or a liquid phase epitaxial (Liquid Phase EpiLex) method is used. Etc. can be used.

In the present embodiment, the low pressure MOCVD method using trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga), and trimethylindium ((CH ₃ ) ₃ In) as group III constituent elements. Each layer is epitaxially grown using
Note that biscyclopentadienyl magnesium ((C ₅ H ₅ ) ₂ Mg) is used as a Mg doping material. Further, disilane (Si ₂ H ₆ ) is used as a Si doping raw material. Further, phosphine (PH ₃ ) or arsine (AsH ₃ ) is used as a raw material for the group V constituent element.

Specifically, first, a buffer layer 22 a made of n-type GaAs doped with Si is formed on one surface 21 a of the semiconductor substrate 21. As the buffer layer 22a, for example, n-type GaAs doped with Si is used, the carrier concentration is 2 × 10 ¹⁸ cm ⁻³ , and the layer thickness is 0.2 μm.

Next, in this embodiment, an etching stop layer 22b made of Si-doped n-type (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P is formed on the buffer layer 22a.
The etching stop layer 22b is a layer for preventing the cladding layer and the light emitting layer from being etched when the semiconductor substrate is removed by etching. For example, Si-doped (Al _0.5 Ga _0.5 ) ₀ It consists _.5 In _0.5 P, the thickness and 0.5 [mu] m.

Next, a contact layer 8 made of Si-doped n-type GaAs is formed on the etching stop layer 22b.

Next, an n-type upper current diffusion layer (n-type semiconductor layer) 9 made of, for example, AlGaInP is formed on the contact layer 8.

Next, the upper DBR layer 3 a is formed on the current spreading layer 9.
Specifically, two types of layers 3aa and 3ab having different refractive indexes are alternately stacked. In the present embodiment, the two types of layers 3aa and 3ab having different refractive indexes are composed of two types of (Al _Xh Ga _1-Xh ) _Y3 In _1-Y3 P (0 <Xh ≦ 1, Y3 = 0.5) having different compositions. ), (Al _Xl Ga _1-Xl ) _Y3 In _1-Y3 P; 0 ≦ Xl <1, Y3 = 0.5). In addition, the two types of layers 3aa and 3ab having different refractive indexes may be a combination in which the Al composition difference ΔX = xh−xl is greater than or equal to 0.5, a combination of GaInP and AlInP, or A combination of two types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _1-xh As (0.1 ≦ xh ≦ 1) having different compositions, and any one of these combinations Is preferably selected.
The upper DBR layer 3a can be formed in the same layer structure as the lower DBR layer 3b described later. However, since it is necessary to transmit light through the upper DBR layer 3a, the upper DBR layer 3a is more than the lower DBR layer 3b. It is formed so that the reflectance is low.
Specifically, when it is made of the same material as the lower DBR layer 3b, 3 to 10 pairs of two types of layers having different refractive indexes are alternately stacked so that the number of layers is smaller than that of the lower DBR layer 3b. Is preferred.

Next, the active layer 4 is formed on the upper DBR layer 3a.
Specifically, first, as shown in FIG. 8, an upper cladding layer 45 made of n-type Al _0.5 In _0.5 P doped with Si is formed.
The upper clad layer 45 may have a two-layer structure of a surface roughened layer for roughening the surface for improving light extraction and a clad layer. In this case, a surface roughened layer may be formed before the upper cladding layer 45 is formed. As the surface roughened layer, an n-type (Al _0.5 Ga _{0. 5} ) _0.5 In _0.5 P can be used.

Next, on the upper cladding layer 45, for example, of an undoped _{(Al 0.1 Ga 0.9) 0.5 In} 0.5 P / (Al 0.7 Ga 0.3) 0.5 In 0.5 A light emitting layer 43 having a 20-pair quantum well structure of P is formed.
Specifically, the light emitting layer 43 can have a multilayer structure (laminated structure) of a well layer 47 and a barrier layer 48 having a barrier layer (also referred to as a barrier layer) 48 at both ends.

The material of the well layer 47 includes ((Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1), (Al _X2 Ga _1-X2 ) As (0 ≦ X2 ≦ 1) or (In _X3 Ga _1-X3 ) As (0 ≦ X3 ≦ 1)) can be used.
As a material of the barrier layer 48, a material suitable for the material of the well layer 47 is preferably selected. In order to prevent the absorption in the barrier layer 48 and increase the light emission efficiency, it is preferable that the composition has a band gap larger than that of the well layer 47.

Next, a lower cladding layer 41 made of p-type Al _0.5 In _0.5 P doped with Mg is formed on the light emitting layer 43.

Next, the lower DBR layer 3 b is formed on the active layer 4.
Specifically, like the upper DBR layer 3a, two types of layers 3ba and 3bb having different refractive indexes are alternately stacked. In the present embodiment, the two types of layers 3ba and 3bb having different refractive indexes are composed of two types of (Al _Xh Ga _1-Xh ) _Y3 In _1-Y3 P (0 <Xh ≦ 1, Y3 = 0.5) having different compositions. ), (Al _Xl Ga _1-Xl ) _Y3 In _1-Y3 P; 0 ≦ Xl <1, Y3 = 0.5). Further, the two types of layers 3ba and 3bb having different refractive indexes may be a combination in which the composition difference ΔX = xh−xl between the two is greater than or equal to 0.5, or a combination of GaInP and AlInP, or A combination of two types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _1-xh As (0.1 ≦ xh ≦ 1) having different compositions, and any one of these combinations Is preferably selected.
The lower DBR layer 3b is preferably formed by alternately stacking 10 to 50 pairs of two types of layers 3ba and 3bb having different refractive indexes. This is because when the number of stacked layers is 10 pairs or less, the reflectance is too low to contribute to an increase in output, and even when the number is 50 pairs or more, the increase in reflectance is small.

Next, an Mg-doped p-type lower current diffusion layer (p-type semiconductor layer) 7 made of, for example, GaP is formed on the lower DBR layer 3b.

An upper guide layer 44 and a lower guide layer 42 may be provided between the upper clad layer 45 and the lower clad layer 41 and the light emitting layer 43, respectively.

<Metal reflective layer formation process>
Next, as shown in FIG. 7, the metal reflection layer 2 is formed on the lower current diffusion layer 7.
Specifically, for example, the metal reflective layer 2 composed of any one layer or two or more layers of gold, copper, silver, aluminum, Pt, or an alloy thereof is formed on the lower current diffusion layer 7 by vapor deposition. .

<Diffusion prevention layer formation process>
In the present embodiment, a diffusion preventing layer and / or a bonding layer may be appropriately formed on the support substrate side surface of the metal reflective layer 2.
Specifically, first, the diffusion prevention layer 11 is formed on the metal reflection layer 2. For example, a barrier layer made of nickel can be formed on the metal reflective layer 2 by vapor deposition. <Joint layer forming step>
Next, the bonding layer 10 is formed on the diffusion preventing layer 11. For example, the bonding layer 10 made of AuGe, which is an Au-based eutectic metal, is formed on the diffusion prevention layer 11 by vapor deposition.

<Support substrate bonding process>
Next, as shown in FIG. 9, the semiconductor substrate 21 on which the epitaxial layered body 30, the metal reflective layer 2, and the like are formed is bonded to the support substrate 1 formed in the support substrate manufacturing process.
Specifically, for example, when a Ge substrate is used as the support substrate 1, first, a Ti / Au / In layer 52 formed on the front surface 51A of the Ge substrate 51 as shown in FIG. The bonding layer 10 of the structure shown in FIG. Thereafter, for example, heating is performed at 320 ° C. and pressure is applied at 500 g / cm ² , and the support substrate 1 is bonded to the structure including the epitaxial multilayer body 30 as illustrated in FIG.
When a metal substrate is used as the support substrate 1, the metal substrate as shown in FIG. 6 and the bonding layer 10 of the structure shown in FIG. 7 are arranged so as to face each other. Next, after evacuating the inside of the decompression device to 3 × 10 ⁻⁵ Pa and heating to 400 ° C., a load of 500 kg is applied to bond the bonding layer 10 of the structure shown in FIG. 7 and the metal substrate. To do.

<Semiconductor substrate and buffer layer removal step>
Next, as shown in FIG. 10, the growth substrate (semiconductor substrate) 21 and the buffer layer 22a are selectively removed from the bonding structure shown in FIG. 9 with an ammonia-based etchant <etching stop layer removal step>
Next, the etching stop layer 22b is selectively removed with a hydrochloric acid-based etchant.

<Formation process of front surface electrode and back surface electrode>
Next, on the contact layer 8, for example, a surface electrode 12 made of a material containing AnGe / Ni is formed, and on the surface opposite to the side on which the metal reflective layer 2 of the support substrate 1 is formed, AuBe A back electrode 13 made of a material containing is formed.
Specifically, for example, a material containing AnGe / Ni is formed on the contact layer 8 and a material containing AuBe is formed on the support substrate 1 by vapor deposition.

As described above, the semiconductor device according to the present embodiment is not limited to the arrangement form of the back electrode 13 as described above.
Hereinafter, a process for forming the electrode structure as shown in FIG. 1B will be described.
First, after forming the lower current diffusion layer 7 by the method described above, a p-type electrode (p-type ohmic electrode) 15 is formed on the lower current diffusion layer (p-type semiconductor layer) 7.
Specifically, a light transmitting film (SiO ₂ film) 14 is formed on the entire surface of the lower current diffusion layer 7 by using, for example, a CVD method. As the material constituting the translucent film _14, may be _{SiO 2, SiN, SiON, Al} 2 O 3, MgF 2, TiO 2, TiN, ZnO, ITO, IZO or the like is used.

Next, a plurality of through holes for embedding a conductive member constituting the p-type ohmic electrode 15 are formed in the light-transmitting film 14 by using a photolithography technique and an etching technique.
Specifically, a photoresist pattern having holes corresponding to the through holes is formed on the light transmitting film 14, and the light transmitting film 14 corresponding to the through holes is removed using a hydrofluoric acid-based etchant. As a result, a plurality of through holes are formed in the translucent film 14.

Next, the p-type ohmic electrode 15 made of a material containing Au, Be, and Ni is formed on the plurality of through holes of the translucent film 14 on the lower current diffusion layer 7 by using, for example, vapor deposition. To do.
The p-type ohmic electrode 15 is preferably made of an AuBeNi alloy, and the Ni content in the alloy is 5 to 40 mol%, and the Be / Au is 0.01 to 0. 3 is preferred.

Next, the metal reflective layer 2 is formed on the p-type ohmic electrode 15 and the translucent film 14, and the subsequent steps can be used to manufacture the semiconductor device as shown in FIG. 1B. .

<Individualization process>
Next, the light emitting diodes on the wafer are separated.
After removing the semiconductor layer in the region to be cut, the structure including the support substrate 1 formed in the above steps is cut with a laser, for example, at intervals of 350 μm to manufacture the light emitting diode 100.

<Metal protective film forming process on side surface of supporting substrate>
In each of the separated light emitting diodes 100, the metal protective film is not formed on the side surface of the substrate 1, but the side surface of the cut substrate 1 is formed under the same conditions as the formation conditions of the upper and lower metal protective films. A metal protective film may be formed on the substrate.

Hereinafter, the present invention will be specifically described based on examples. However, the present invention is not limited only to these examples.

(Example 1)
Example 1 is an example of the embodiment shown in FIGS. 1B and 2. In this example, a light-emitting diode lamp in which a light-emitting diode chip was mounted on a substrate was prepared for characteristic evaluation.
Further, a Ge substrate was used as the support substrate 1.

First, a layer made of Au / Pt with a thickness of 0.5 μm / 0.1 μm was formed on the surface of the Ge substrate. On the back surface of the Ge substrate, a layer made of Pt / Au was formed to a thickness of 0.1 μm / 0.5 μm.

Next, an epitaxial wafer having an emission wavelength of 730 nm was fabricated by sequentially laminating compound semiconductor layers on a GaAs substrate made of n-type GaAs single crystal doped with Si.
In the GaAs substrate, the plane inclined by 15 ° from the (100) plane in the (0-1-1) direction was used as the growth plane, and the carrier concentration was set to 2 × 10 ¹⁸ cm ⁻³ . The layer thickness of the GaAs substrate was about 0.5 μm. As the compound semiconductor layer, an n-type buffer layer made of GaAs doped with Si, an etching stop layer made of Si-doped (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P, Si-doped n Type contact layer made of Al0.1GaAs, upper current diffusion layer made of Al0.3Ga0.7As, upper DBR layer made of Al0.9Ga0.1As / Al0.3Ga0.7As, Si-doped Al _0.5 In _0.5 n-type upper cladding layer composed of _{P, (Al 0.1 Ga 0.9)} 0.5 in 0.5 P / (Al 0.5 Ga 0.5) 20 pairs of 0.5 _{an in 0.5} P emitting layer of the well layer / barrier layer made _of, p-type lower cladding layer made of Al _{0.5 in} 0.5 P, a lower DB consisting of Al0.9Ga0.1As / Al0.3 Ga0.7 Layer, which is the lower current diffusion layer made of Al0.3 Ga0.7.

In this example, a compound semiconductor layer was epitaxially grown on a GaAs substrate having a diameter of 50 mm and a thickness of 350 μm by using a low pressure metal organic chemical vapor deposition apparatus method (MOCVD apparatus) to form an epitaxial wafer. When growing an epitaxial growth layer, trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga) and trimethylindium ((CH ₃ ) ₃ In) are used as the raw material for the group III constituent element did. Further, biscyclopentadienyl magnesium (bis- (C ₅ H ₅ ) ₂ Mg) was used as a Mg doping material. Further, disilane (Si ₂ H ₆ ) was used as a Si doping material. Further, phosphine (PH ₃ ) and arsine (AsH ₃ ) were used as raw materials for the group V constituent elements. The growth temperature of each layer was 700 ° C.

The buffer layer made of GaAs has a carrier concentration of about 1 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 0.5 μm. The etching stop layer had a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 0.5 μm. The contact layer had a carrier concentration of about 1 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 0.05 μm. The upper current diffusion layer was laminated with Al0.3Ga0.7As having a carrier concentration of about 1.0 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 5 μm. Upper DBR layer carrier concentration of about 1 × ¹⁰ 18 ^{cm -3,} and the Al0.9Ga0.1As that were about 57nm thickness, a carrier concentration of about 1 × ¹⁰ 18 ^{cm -3,} a thickness of about 52 nm AlO 8 pairs of 3Ga0.7As were alternately stacked. The upper cladding layer had a carrier concentration of about 2 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 0.5 μm. The well layer is undoped (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P with a thickness of about 5 nm, and the barrier layer is undoped and has a thickness of about 5 nm (Al _0.5 Ga _{0 .5} ) _0.5 In _0.5 P. Further, 20 pairs of well layers and barrier layers were alternately laminated. The lower cladding layer had a carrier concentration of about 8 × 10 ¹⁷ cm ⁻³ and a layer thickness of about 0.5 μm. The lower DBR layer carrier concentration of about 1 × ¹⁰ 18 ^{cm -3,} and Al0.9Ga0.1As that were about 57nm thickness, a carrier concentration of about 1 × ¹⁰ 18 ^{cm -3,} and about 52nm layer thickness 40 pairs of Al0.3Ga0.7As were alternately laminated. The lower current diffusion layer was laminated with Al0.3Ga0.7As having a carrier concentration of about 1 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 3 μm.

Next, a p-type electrode (p-type ohmic electrode) was formed on the lower current diffusion layer.
Specifically, a light-transmitting film (SiO ₂ film) having a thickness of 0.3 μm was formed on the entire surface of the lower current diffusion layer by using, for example, a CVD method.

Next, using a photolithography technique and an etching technique, a plurality of through holes having a diameter of 9 μm for embedding a conductive member constituting the p-type ohmic electrode were formed in the translucent film.
Next, a plurality of cylindrical p-type ohmic electrodes having a height of 0.3 μm and a diameter of 9 μm are formed on the lower current diffusion layer by filling the plurality of through-holes of the light-transmitting film with AuBe alloy by vapor deposition. Formed.

Next, a metal reflective layer made of an Au film having a thickness of 0.7 μm was formed on the lower DBR layer by vapor deposition.
Next, a diffusion preventing layer made of a Ti film having a thickness of 0.5 μm was formed on the metal reflective layer by vapor deposition.
Next, a bonding layer made of AuGe having a thickness of 1.0 μm was formed on the diffusion prevention layer by vapor deposition.

Next, a structure (see FIG. 7) in which a compound semiconductor layer, a metal reflection layer, and the like are formed on a GaAs substrate and a Ge substrate are arranged so as to face each other and are carried into a decompression device, and are brought to 400 ° C. In the state heated by, they were joined with a load of 500 kg to form a joined structure.

Next, the GaAs substrate, which is a growth substrate for the compound semiconductor layer, and the buffer layer were selectively removed from the bonded structure with an ammonia-based etchant, and the etching stop layer was selectively removed with a hydrochloric acid-based etchant.

Next, on the surface of the contact layer opposite to the Ge substrate, a film is formed by vacuum evaporation so that the thickness of AuGe and Ni alloy is 0.5 μm, Pt is 0.2 μm, and Au is 1.0 μm. A surface electrode (n-type electrode) was formed.

Next, wet etching and laser cutting were sequentially performed to obtain individual pieces, thereby manufacturing the light emitting diode of the example.
Next, a light emitting diode lamp was assembled by mounting the light emitting diode chip of Example 1 manufactured as described above on a mounting substrate.

Next, the characteristics of the obtained light emitting diode (light emitting diode lamp) were evaluated.
When a current was passed between the n-type and p-type ohmic electrodes of the light-emitting diode (light-emitting diode lamp), infrared light having a peak wavelength of 730 nm was emitted. The forward voltage (V _F ) when a current of 20 mA (mA) was passed in the forward direction was about 1.9 volts.
The light emission output when the forward current was 20 mA was 13 mW.

(Comparative example)
The light emitting diode of the comparative example is the same as the example except that the lower DBR layer and the upper DBR layer in the light emitting diode of the first embodiment are not provided.
When a current was passed between the n-type and p-type ohmic electrodes of the light emitting diode, infrared light having a peak wavelength of 730 nm was emitted. The forward voltage (V _F ) when a current of 20 mA (mA) was passed in the forward direction was about 1.9 volts, and the light emission output was 10 mW.

The output of the lamp of Example 1 was 30% higher than that of the comparative example, and the light output directly above the lamp was 70% higher. This is presumably because, in Example 1, light from the light emitting part can be efficiently extracted by interference due to reflection between the metal reflection layer and the lower DBR layer and resonance with the upper DBR layer.

1 support substrate 2 metal reflective layer 3a upper DBR layer 3b lower DBR layer 4 active layer 5 compound semiconductor layer 6 light emitting part 7 lower current diffusion layer 8 contact layer 9 upper current diffusion layer 10 bonding layer 11 diffusion prevention layer 12 surface electrode (n Type electrode) 13 back electrode 14 translucent film 15 p type electrode (p type ohmic electrode) 21 semiconductor substrate (growth substrate) 30 epitaxial laminate 41 lower cladding layer 42 lower guide layer 43 light emitting layer 44 upper guide layer 45 upper cladding layer 47 well layer 48 barrier layer (barrier layer) 100 light emitting diode

Claims (10)

1. On the support substrate, a light emitting unit including a metal reflective layer and a compound semiconductor layer including a lower DBR layer, an active layer, and an upper DBR layer in order,
   A light-emitting diode, wherein the support substrate and the light-emitting portion are joined.
2. 2. The light emitting diode according to claim 1, wherein the support substrate includes any one of a Ge substrate, a metal substrate, a Si substrate, a GaAs substrate, and a GaP substrate.
3. 2. The light emitting diode according to claim 1, wherein the metal reflective layer is composed of one or more layers of gold, copper, silver, aluminum, Pt, or an alloy thereof.
4. The light-emitting diode according to claim 1, wherein the light-emitting portion is bonded to the support substrate through a diffusion prevention layer and / or a bonding layer formed on the metal reflective layer.
5. 2. The light emitting diode according to claim 1, wherein the lower DBR layer is formed by alternately stacking 10 to 50 pairs of two kinds of layers having different refractive indexes.
6. The lower DBR layer is formed by alternately stacking two types having different refractive indexes,
   The two types of layers having different refractive indexes are composed of two types of (Al _Xh Ga _1-Xh ) _Y3 In _1-Y3 P (0 <Xh ≦ 1, Y3 = 0.5), (Al _Xl Ga ₁ ) having different compositions. _{-Xl) Y3 in 1-Y3 P} ; 0 ≦ Xl <1, Y3 = 0.5) is a pair of the composition difference of both Al [Delta] X = xh
   -Xl is greater than or equal to 0.5, or a combination of GaInP and AlInP, or two types of different Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1), Al a pair of _xh Ga _1-xh As (0.1 ≦ xh ≦ 1), wherein the composition difference ΔX = xh−xl is selected from any combination that is greater than or equal to 0.5 The light emitting diode according to claim 1.
7. 2. The light emitting diode according to claim 1, wherein the upper DBR layer is formed by alternately stacking 3 to 10 pairs of two kinds of layers having different refractive indexes.
8. The upper DBR layer is formed by alternately stacking two types having different refractive indexes,
   The two types of layers having different refractive indexes are composed of two types of (Al _Xh Ga _1-Xh ) _Y3 In _1-Y3 P (0 <Xh ≦ 1, Y3 = 0.5), (Al _Xl Ga ₁ ) having different compositions. _{-Xl) Y3 in 1-Y3 P} ; 0 ≦ Xl <1, Y3 = 0.5) is a pair of the composition difference of both Al [Delta] X = xh
   -Xl is greater than or equal to 0.5, or a combination of GaInP and AlInP, or two types of different Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1), Al a pair of _xh Ga _1-xh As (0.1 ≦ xh ≦ 1), wherein the composition difference ΔX = xh−xl is selected from any combination that is greater than or equal to 0.5 The light emitting diode according to claim 1.
9. The light emitting layer included in the active layer includes ((Al _X1 Ga _1-X1 ) _Y1 In _1-Y1 P (0 ≦ X1 ≦ 1, 0 <Y1 ≦ 1), (Al _X2 Ga _1-X2 ) As (0 The light-emitting diode according to claim 1, wherein the light-emitting diode is any one of ≦ X2 ≦ 1) and (In _X3 Ga _1-X3 ) As (0 ≦ X3 ≦ 1)).
10. A method of manufacturing a light emitting diode comprising a light emitting unit including a metal reflective layer and a compound semiconductor layer including a lower DBR layer, an active layer, and an upper DBR layer in order on a support substrate,
    Forming a compound semiconductor layer including an upper DBR layer, an active layer, and a lower DBR layer in this order on a growth substrate;
    Forming a light emitting portion by forming a metal reflective layer on the compound semiconductor layer;
    Bonding the light emitting unit and the support substrate;
    And a step of removing the growth substrate.

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