TWI446580B - Light-emitting diode, light-emitting diode lamp and lighting device - Google Patents

Description

Light-emitting diode, light-emitting diode lamp and lighting device

The present invention relates to a light-emitting diode, a light-emitting diode lamp using the same, and an illumination device having an emission peak wavelength of 850 nm or more, particularly 900 nm or more.

The application of the present invention claims priority based on Japanese Patent Application No. 2010-013530, filed on Jan. 25, 2010, and the Japanese Patent Application No. 2010-183205, filed on August 18, 2010. The content is used here.

Infrared light-emitting diodes have been widely used in infrared communication, infrared remote control devices, various sensor light sources, and night illumination.

In the vicinity of such a peak wavelength, a compound semiconductor layer containing an AlGaAs active layer is grown on a light-emitting diode of a GaAs substrate by an epitaxial method (for example, Patent Documents 1 to 3); and a GaAs substrate used as a growth substrate is removed. A so-called substrate-removing type light-emitting diode which constitutes a compound semiconductor layer of a compound layer which is transparent to a light-emitting wavelength is an infrared light-emitting diode which is the highest output at present (for example, Patent Document 4).

On the other hand, in the case of infrared communication used for transmitting or receiving messages between machines, for example, using infrared rays of 850 to 900 nm, in the case of infrared remote control operation, a wavelength band having a high sensitivity of the light receiving portion, for example, 880 is used. Infrared light up to 940 nm. As an infrared light-emitting diode that can be used for both infrared communication and infrared remote control operation of a terminal such as a mobile phone having both infrared communication and infrared remote control operation communication, it is known that the wavelength of the illuminating peak is 880. An AlGaAs active layer containing Ge in a substantial impurity of 890 nm (Patent Document 4).

Further, as an infrared light-emitting diode which can have an emission peak wavelength of 900 nm or more, an InGaAs active layer is conventionally used (Patent Documents 5 to 7).

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Publication No. 6-21507

Patent Document 2: Japanese Laid-Open Patent Publication No. 2001-274454

Patent Document 3: Japanese Patent Laid-Open No. Hei 7-38148

Patent Document 4: Japanese Laid-Open Patent Publication No. 2006-190792

Patent Document 5: Japanese Patent Laid-Open Publication No. 2002-26377

Patent Document 6: Japanese Patent Laid-Open Publication No. 2002-111048

Patent Document 7: Japanese Laid-Open Patent Publication No. 2002-344013

However, within the scope of the patent applicant, for the infrared light-emitting diodes of 850 nm or more, especially 900 nm or more, the epitaxial wafer is not attached to the functional substrate (joining) in order to improve the output. The so-called bonding type of the GaAs substrate for growth is removed.

Further, in the case where an AlGaAs active layer containing Ge in an actual impurity is used, it is difficult to set the emission peak wavelength to 900 nm or more (Patent Document 4, FIG. 3).

Further, in the case of an infrared light-emitting diode using an InGaAs active layer having an emission peak wavelength of 900 nm or more, development of a higher luminous efficiency is desired from the viewpoint of further improving performance, energy saving, and cost.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an infrared light emitting diode of high-output/high-efficiency emission of infrared light having an emission peak wavelength of 850 nm or more, particularly 900 nm or more, and a light-emitting diode using the same Polar body lights and lighting fixtures.

The inventors of the present invention have been made to solve the above problems, and as a result of continuous research, a multi-quantum well structure made of a well layer made of InGaAs and a barrier layer made of AlGaInP is used as an active layer, and is composed of AlGaInP. The guiding layer is sandwiched between the active layers, and the cladding layer is made of a 4-component mixed AlGaInP, and the compound semiconductor layer including the active layer, the guiding layer and the cladding layer is epitaxially grown on the growth substrate, and again The compound semiconductor layer is attached to a transparent substrate (joined) to form a structure for removing the grown substrate, and an infrared light-emitting diode of high-output/high-efficiency emission of infrared light having an emission peak wavelength of 850 nm or more, particularly 900 nm or more is obtained. carry out.

First, the present inventors have used a well layer made of InGaAs to form a multi-quantum well structure for improving monochromaticity and output by using a light-emitting peak wavelength of 850 nm or more, particularly 900 nm or more, used for infrared communication or the like. The active layer.

In addition, a 4-component mixed crystal AlGaInP is used, which is attached to the barrier layer of the well layer sandwiching the ternary mixed crystal, and the well layer and the barrier layer containing the barrier layer. In the guiding layer and the coating layer of the weight sub-well structure, the band gap is large and transparent to the emission wavelength, and the crystallinity is good because it does not contain As which is liable to cause defects.

Moreover, compared with GsAs used as a growth substrate, a multiple quantum well structure having an InGaAs layer as a well layer has a large lattice constant and a skewed quantum well structure. In such a skewed quantum well structure, the influence on the composition and thickness of the InGaAs composition and the monochromaticity is also large, and the selection of the appropriate composition, thickness, and number of pairs becomes important. Therefore, it has been found that by adding the skew opposite to the InGaAs well layer to the AlGaInP of the barrier layer, the quantum well structure is used as a whole to alleviate the lattice irregularity caused by the logarithm increase of InGaAs, and the light-emitting output characteristics in the high current region are improved. .

Further, as described above, in the infrared light-emitting diode using the InGaAs-based active layer, the compound semiconductor layer containing the active layer is not attached to the transparent substrate (bonding) type, but is used in the original state. A GaAs substrate in which a compound semiconductor layer is grown. However, the GaAs substrate is highly doped in order to improve conductivity, and absorption of light by a carrier cannot be avoided. Therefore, it is possible to avoid the absorption of light by the carrier and attach it to a transparent substrate (joining) type capable of expecting high output and high efficiency.

In particular, in the case of the bonding type, there is also an influence from the stress of the functional substrate, and it is important to design the element structure of the skewed quantum well which is optimized.

The inventors of the present invention conducted further studies based on such findings, and thus completed the present invention shown in the following structures.

The present invention provides the following structure:

(1) A light-emitting diode comprising: a light-emitting portion having: an alternating layer consisting of a composition formula (In _X1 Ga _1-X1 ) As (0) X1 1) The well layer formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The active layer of the quantum well structure of the barrier layer formed, and the composition formula (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P(0) sandwiching the active layer X3 1, 0 < Y2 1) a first guiding layer and a second guiding layer, and a first cladding layer and a second cladding layer sandwiching the active layer via the respective layers of the first guiding layer and the second guiding layer; a diffusion layer formed on the light-emitting portion; and a functional substrate bonded to the current diffusion layer; and the first and second cladding layers are composed of a composition formula (Al _X4 Ga _1-X4 ) _Y3 In _1-Y3 P(0 X4 1, 0 < Y3 1) constitutes.

(2) The light-emitting diode disclosed in the item (1), wherein the In composition (X1) of the well layer is 0 X1 0.3.

(3) The light-emitting diode disclosed in the item (2), wherein the In composition (X1) of the well layer is 0.1 X1 0.3.

(4) The light-emitting diode disclosed in any one of (1) to (3), wherein the composition of the barrier layer X2 and Y1 are 0, respectively. X2 0.2, 0.5 < Y1 0.7, the composition of the first and second guiding layers X3 and Y2 are respectively 0.2 X3 0.5, 0.4 < Y2 0.6, the composition of the first and second cladding layers X4 and Y3 are respectively 0.3 X4 0.7, 0.4 < Y3 0.6.

(5) The light-emitting diode of any one of (1) to (4), wherein the functional substrate is transparent to an emission wavelength.

(6) The light-emitting diode disclosed in any one of (1) to (5), wherein the functional substrate is composed of GaP or SiC.

(7) The light emitting diode according to any one of (1) to (6), wherein a side of the functional substrate has a vertical vertical to the main light extraction surface on a side close to the light emitting portion. The surface has an inclined surface that is inclined toward the inner side of the main light extraction surface on a side away from the light emitting portion.

(8) The light-emitting diode disclosed in the item (7), wherein the inclined surface contains a rough surface.

(9) A light-emitting diode characterized by comprising: a light-emitting portion having an alternating layer consisting of a composition formula (In _X1 Ga _1-X1 ) As (0) X1 1) The well layer formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The active layer of the quantum well structure of the barrier layer formed, and the composition formula (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P(0) sandwiching the active layer X3 1, 0 < Y2 1) a first guiding layer and a second guiding layer, and a first cladding layer and a second cladding layer sandwiching the active layer via the respective layers of the first guiding layer and the second guiding layer; a diffusion layer formed on the light-emitting portion; and a functional substrate disposed opposite to the light-emitting portion and including a reflective layer having a reflectance of 90% or more with respect to an emission wavelength, and bonded to the current diffusion layer And the first and second cladding layers are composed of a composition formula (Al _X4 Ga _1-X4 ) _Y3 In _1-Y3 P(0 X4 1, 0 < Y3 1) constitutes.

Here, the "joining" further includes bonding a layer between the current diffusion layer and the functional substrate.

(10) The light-emitting diode disclosed in the item (9), wherein the In composition (X1) of the well layer is 0 X1 0.3.

(11) The light-emitting diode disclosed in the item (10), wherein the In composition (X1) of the well layer is 0.1 X1 0.3.

(12) The light-emitting diode disclosed in any one of (9) to (11), wherein the composition of the barrier layer X2 and Y1 are 0, respectively. X2 0.2, 0.5 < Y1 0.7, the composition of the first and second guiding layers X3 and Y2 are respectively 0.2 X3 0.5, 0.4 < Y2 0.6, the composition of the first and second cladding layers X4 and Y3 are respectively 0.3 X4 0.7, 0.4 < Y3 0.6.

(13) The light-emitting diode according to any one of (9) to (12), wherein the functional substrate contains a layer composed of ruthenium or osmium.

(14) The light-emitting diode according to any one of (9) to (12), wherein the functional substrate contains a metal substrate.

(15) The light-emitting diode disclosed in the item (14), wherein the metal substrate is composed of a plurality of metal layers.

(16) The light-emitting diode disclosed in any one of (1) to (15), wherein the current diffusion layer is composed of GaP or GaInP.

(17) The light-emitting diode disclosed in any one of (1) to (16), wherein the current diffusion layer has a thickness in a range of 0.5 to 20 μm.

(18) The light-emitting diode according to any one of (1) to (17), wherein the first electrode and the second electrode are provided on the main light extraction surface side of the light emitting diode.

(19) The light-emitting diode according to (18), wherein the first electrode and the second electrode are ohmic electrodes.

(20) The light-emitting diode disclosed in any one of (18) or (19), which is on the opposite side of the main light extraction surface side of the functional substrate It also has a third electrode.

(21) A light-emitting diode lamp characterized by comprising the light-emitting diode disclosed in any one of the items (1) to (20).

(22) A light-emitting diode lamp comprising the light-emitting diode disclosed in the item (20), wherein the first electrode or the second electrode is connected to the third electrode at approximately the same potential.

(23) A lighting device that mounts a plurality of light-emitting diodes disclosed in any one of (1) to (20), and/or at least one of (21) or (22) The item discloses a light-emitting diode lamp.

In the present invention, the term "functional substrate" refers to a substrate in which a compound semiconductor layer is grown on a growth substrate, the growth substrate is removed, and the current diffusion layer is interposed and bonded to the compound semiconductor layer to support the compound semiconductor layer. However, in the case where a predetermined layer is formed in the current diffusion layer and a predetermined substrate is bonded to a predetermined layer, a predetermined layer is referred to as a "functional substrate".

According to the above configuration, the following effects are obtained.

Infrared light having an emission peak wavelength of 850 nm or more, particularly 900 nm or more, can be emitted with high output/high efficiency.

Because the active layer has alternating layers as the composition formula (In _X1 Ga _1-X1 ) As (0 X1 1) The well layer formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The structure of the multiple quantum well structure of the barrier layer formed by the structure has superior monochromaticity.

By making the functional substrate transparent to the light-emitting wavelength, it is possible to display high output/high efficiency without absorbing light emitted from the light-emitting portion.

Because the barrier layer, the guiding layer and the cladding layer are composed of the composition formula (Al _X Ga _1-X ) _Y In _1-Y P(0 X1 1, 0 < Y 1) Since the structure is constituted, it does not contain As which is easy to form defects, and contributes to high crystallinity and high output.

Because the barrier layer, the guiding layer and the cladding layer are composed of the composition formula (Al _X Ga _1-X ) _Y In _1-Y P (0 X1 1, 0 < Y 1) Since the structure is such that the barrier layer, the guiding layer, and the cladding layer are infrared light-emitting diodes composed of a ternary mixed crystal, the Al concentration is lower and the heat resistance is further improved.

Because the active layer is composed of the composition formula (In _X1 Ga _1-X1 ) As (0 X1 1) The well layer formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) Since the structure of the laminated structure of the barrier layer is formed, it is suitable for mass production by the MOCVD method.

In the case of using a GaAs substrate which is a growth substrate of a compound semiconductor layer, by a composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The composition of the barrier layer formed by X2 and Y1 is made to take 0 X2 0.2, 0.5 < Y1 The structure of 0.7 can alleviate the skew of the well layer of the GaAs substrate and can suppress the decrease in crystallinity.

By forming the functional substrate into a structure composed of GaP, SiC, ruthenium or iridium, the stress can be reduced by the fact that the thermal expansion coefficient of the light-emitting portion is close to that. In addition, since it is a material that is hard to corrode, moisture resistance will increase.

By adopting a structure in which any of the functional substrate and the current diffusion layer is made of GaP, the bonding can be facilitated and the bonding strength can be increased.

By forming the current diffusion layer as a structure composed of GaInP, it is possible to integrate the crystal lattice with the InGaAs well layer to improve crystallinity.

The light-emitting diode lamp of the present invention can have an emission peak wavelength of 850 nm or more, particularly 900 nm or more, and has high monochromaticity, high output/high efficiency, and excellent moisture resistance. A polar body, a light source suitable for a wide range of applications such as sensor use.

Hereinafter, a light-emitting diode according to an embodiment of the present invention and a light-emitting diode lamp using the same will be described in detail with reference to the drawings. Incidentally, the drawings used in the following description are for easily understanding the features and for facilitating the enlargement of the features, and the dimensional ratios and the like of the respective constituent elements are not limited to the same as the actual ones.

<Light emitting diode lamp>

1 and 2 are diagrams for explaining a light-emitting diode lamp using a light-emitting diode according to an embodiment of the present invention: Fig. 1 is a plan view; and Fig. 2 is shown along Fig. 1 A section of the A-A' line in the middle.

As shown in FIGS. 1 and 2, in the light-emitting diode lamp 41 of the light-emitting diode 1 of the present embodiment, one or more light-emitting diodes 1 are mounted on the surface of the mounting substrate 42.

More specifically, the n electrode terminal 43 and the p electrode terminal 44 are provided on the surface of the mounting substrate 42. Further, the n-type ohmic electrode 4 of the first electrode of the light-emitting diode 1 and the n-electrode terminal 43 of the mounting substrate 42 are connected (wire-bonded) using the gold wire 45. On the other hand, the p-type ohmic electrode 5 of the second electrode of the light-emitting diode 1 and the p-electrode terminal 44 of the mounting substrate 42 are connected using the gold wire 46. Further, as shown in FIG. 2, the third electrode 6 is provided on the surface opposite to the surface on which the n-type and p-type ohmic electrodes 4, 5 of the light-emitting diode 1 are disposed, whereby the third electrode is provided 6. The light-emitting diode 1 is connected to the n-electrode terminal 43 and fixed to the mounting substrate 42. Here, the n-type ohmic electrode 4 and the third electrode 6 are electrically connected so as to be equipotential or approximately equipotential by the n-electrode terminal 43. With the third electrode, the overcurrent does not flow into the active layer for the excessive reverse voltage, and the current flows between the third electrode and the p-type electrode, thereby preventing damage of the active layer. High output can also be performed on the interface between the third electrode and the substrate. In addition, by adding a eutectic metal, solder, or the like to the surface side of the third electrode, a simpler assembly technique such as eutectic solid crystal can be utilized. Further, the surface of the light-emitting diode 1 in which the mounting substrate 42 is mounted is sealed by a general sealing resin 47 such as silicone resin or epoxy resin.

<Light Emitting Diode (Embodiment 1)>

3 and 4 are views for explaining a pattern of a light-emitting diode according to a first embodiment of the present invention: FIG. 3 is a plan view; and FIG. 4 is a B-B shown in FIG. 'The sectional view of the line. In addition, Fig. 5 is a cross-sectional view showing a laminated structure of a well layer and a barrier layer.

The light-emitting diode according to the first embodiment is characterized in that it includes a light-emitting portion 7 having an alternating layer composition formula (In _X1 Ga _1-X1 ) As (0) X1 1) The well layer 17 is formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The active layer 11 of the quantum well structure of the barrier layer 18 formed, and the composition formula (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P(0) sandwiching the active layer 11 X3 1, 0 < Y2 1) The first guiding layer 10 and the second guiding layer 12, and the first cladding layer 9 and the second package sandwiching the active layer 11 via the respective layers of the first guiding layer 10 and the second guiding layer 12 a cladding layer 13; a current diffusion layer 8 formed on the light-emitting portion 7; and a functional substrate 3 bonded to the current diffusion layer 8; and the first cladding layer 9 and the second cladding layer 13 are composed of Formula (Al _X4 Ga _1-X4 ) _Y3 In _1-Y3 P(0 X4 1, 0 < Y3 1) constitutes.

In addition, the light-emitting diode 1 has a schematic configuration including an n-type ohmic electrode (first electrode) 4 and a p-type ohmic electrode (second electrode) 5 provided on the main light extraction surface.

In addition, the main light extraction surface in the present embodiment is attached to the compound semiconductor layer 2, and the surface opposite to the surface of the functional substrate 3 is attached.

As shown in FIG. 4, the compound semiconductor layer (also referred to as an epitaxial growth layer) 2 has a structure in which a light-emitting portion 7 of a pn junction type and a current diffusion layer 8 are sequentially laminated. In the structure of the compound semiconductor layer 2, a conventional functional layer can be added as appropriate. For example, a contact layer for reducing the contact resistance of an ohmic electrode and a current diffusion layer for planarly diffusing the element drive current to the entire light-emitting portion can be provided; instead, the element drive current is limited. A conventional layer structure such as a current blocking layer or a current constriction layer in a region.

Further, the compound semiconductor layer 2 is preferably formed by epitaxial growth and formed on a GaAs substrate.

As shown in FIG. 4, the light-emitting portion 7 is at least on the current diffusion layer 8. The p-type lower cladding layer (first cladding layer) 9, the lower guiding layer 10, the active layer 11, the upper guiding layer 12, and the n-type upper cladding layer (second cladding layer) 13 are formed. That is, the light-emitting portion 7 is a carrier that causes radiation recombination and is used to "cut" the light into the active layer 11. Preferably, the light-emitting portion 7 is provided under the active layer 11 for obtaining high-intensity light. The lower cladding layer 9, the lower guide layer 10, the upper guide layer 12, and the upper cladding layer 13 disposed on the side and the upper side are so-called double heterogeneous (English abbreviated as DH).

As shown in Fig. 5, the active layer 11 is used to control the light-emitting wavelength of the light-emitting diode (LED) to constitute a quantum well structure. That is, the active layer 11 has a multilayer structure (laminate structure) of the well layer 17 and the barrier layer 18 having the barrier layer 18 at both ends.

The layer thickness of the active layer 11 is preferably in the range of 50 to 1000 nm. Further, the conductivity type of the active layer 11 is not particularly limited, and any of undoped, p-type, and n-type can be selected. In order to improve the luminous efficiency, it is desirable to form an undoped or a carrier concentration of less than 3 × 10 ¹⁷ cm ^{-3 which} is excellent in crystallinity.

Fig. 6 shows that the In composition (X1) of the well layer 17 is fixed at 0.1, and the layer is shown to be related to the wavelength of the luminescence peak. The data values shown in Figure 6 are shown in Table 1. When the well layer is thickened to 3 nm, 5 nm, and 7 nm, the wavelength is monotonically grown to 820 nm, 870 nm, and 920 nm.

Figure 7 shows the correlation between the luminescence peak wavelength of the well layer 17 and its In composition (X1) and layer thickness. Fig. 7 is a view showing the composition of the In composition (X1) and the layer thickness of the well layer 17 in which the illuminating peak wavelength of the well layer 17 is set to a predetermined wavelength. Specifically, the composition of the In composition (X1) and the layer thickness of the well layer 17 having the emission peak wavelengths of 920 nm and 960 nm, respectively, is shown. The composition of In composition (X1) and layer thickness at other wavelengths of 820 nm, 870 nm, 985 nm, and 995 nm is further shown in Fig. 7. The data values shown in Fig. 7 are shown in Table 2.

When the illuminating peak wavelength is 920 nm, if the In composition (X1) is decreased from 0.3 to 0.05, since the layer thickness corresponding to this is monotonously thickened from 3 nm to 8 nm, it can be easily found by the same industry. It becomes a combination of 280 nm wavelength of the illuminating peak.

In addition, when the In composition (X1) is 0.1, when the layer thickness is increased to 3 nm, 5 nm, 7 nm, and 8 nm, the wavelength of the luminescence peak becomes 820 nm, 870 nm, and 920 nm. 960 nm. In addition, when the In composition (X1) is 0.2, when the layer thickness is increased to 5 nm or 6 nm, the wavelength of the luminescence peak becomes 920 nm and 960 nm, and when the composition of In (X1) is 0.25. When the layer thickness is thickened to 4 nm and 5 nm, the wavelength of the luminescence peak becomes 920 nm and 960 nm, and when the composition of In (X1) is 0.3, the layer thickness becomes 3 At nm and 5 nm, the wavelength of the luminescence peak is 920 nm and 985 nm.

In addition, when the layer thickness is 5 nm, if the In composition (X1) is increased to 0.1, 0.2, 0.25, and 0.3, the wavelength of the luminescence peak becomes 870 nm, 920 nm, 960 nm, and 985 nm; When (X1) is increased to 0.35, the wavelength of the luminescence peak becomes 995 nm.

In Fig. 7, when the combination of the In composition (X1) of the 720 nm and 960 nm and the layer thickness is obtained by connecting the wavelength of the luminescence peak, the display shows an approximate straight line. In addition, it is presumed that a line which is a combination of the In composition (X1) and the layer thickness which is a predetermined emission peak wavelength in a wavelength band of 850 nm or more and up to 1000 nm is also approximately linear. Furthermore, it is presumed that the shorter the wavelength of the luminescence peak of the line connecting the combinations, the lower the lower the left, and the longer the longer, the higher the upper limit.

Based on the above regularity, the In composition (X1) and the layer thickness having a desired emission peak wavelength of 850 nm or more and 1000 nm or less can be easily found.

Fig. 8 shows the correlation between the In composition (X1) in which the layer thickness of the well layer 17 is fixed at 5 nm and the luminescence peak wavelength and its luminescence output. The data values shown in Fig. 8 are shown in Table 3.

When the composition of In (X1) is increased to 0.12, 0.2, 0.25, 0.3, and 0.35, the wavelength of the luminescence peak becomes 870 nm, 920 nm, 960 nm, 985 nm, and 995 nm. More specifically, as the In composition (X1) increases from 0.12 to 0.3, the luminescence peak wavelength increases approximately monotonically from 870 nm to 985 nm. However, even if the In composition (X1) is increased from 0.3 to 0.35, although the length is changed from 985 nm to 995 nm, the rate of change to the long wavelength becomes small.

In addition, when the illuminating peak wavelength is 870 nm (X1 = 0.12), 920 nm (X1 = 0.2), and 960 nm (X1 = 0.25), the illuminating output is as high as 6.5 mW; even 985 nm (X1 = 0.3) In practice, it is practically up to a value of up to 5 mW; however, in the case of 995 nm (X1 = 0.35), it is as low as 2 mW.

Based on Figures 6 through 8, the well layer 17 preferably has (In _X1 G _a1-X1 ) As (0 X1 The composition of 0.3). The above X1 can be adjusted in such a manner as to achieve the desired wavelength of light emission.

When the wavelength of the luminescence peak is made to be 900 nm or more, preferably 0 X1 0.3; below 900 nm, preferably 0 X1 0.1.

The layer thickness of the well layer 17 is suitably in the range of 3 to 20 nm. More preferably in the range of 3 to 10 nm.

The barrier layer 18 has (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The composition. The above X2 is preferably formed to have a band gap larger than that of the well layer 17, and more preferably in the range of 0 to 0.2. Further, Y1 is used to alleviate the skew due to lattice unconformity of the well layer 17, preferably from 0.5 to 0.7, more preferably from 0.52 to 0.60.

The layer thickness of the barrier layer 18 is preferably equal to or thicker than the layer thickness of the well layer 17, whereby the luminous efficiency of the well layer 17 can be improved.

In Fig. 9, when the layer thickness of the well layer 17 is 5 nm, the In composition (X1) = 0.2, and the composition of the barrier layer X2 = 0, Y1 = 0.55 (i.e., (A1 ₀₁ Ga _0.9 ) ₀₅₅ In ₀₄₅ P), showing the correlation between the number of pairs of well layers and barrier layers and the luminescence output. The data values shown in Fig. 9 are shown in Table 4. A case where a GaAs substrate is used as a growth substrate.

Yet, in order to show the effect of the barrier layer, Comparative Example display of consolidation of the barrier layer A1 _0.3 Ga0 _.7 As for.

The _{A1 0. 3 Ga 0. 7} As for the case of Comparative Example barrier layer, logarithmically 1-10 pairs up, having two or more emission output based value of up to 6.5 mw, but with respect to the case of 20 pairs is reduced to 5 Mw; the present invention maintains a high value of about 6.5 mw or more up to a logarithmic number of 20 pairs. In this way, even if the number of pairs is increased, the high light-emitting output can be maintained, which is caused by the composition of the barrier layer of the composition X2 = 0.1 and Y1 = 0.55 (that is, (A1 _0.1 Ga _0.9 ) _0.55 In _0.45 P). In _x1 Ga _1-x1 )As(0 X1 1) The well layer formed by the skew of the GaAs grown substrate (that is, the barrier layer is skewed in the opposite direction to the well layer) suppresses the decrease in crystallinity. The effect of mitigating skew is further described using FIG.

Figure 10 shows the Y1 of the barrier layer when the layer thickness of the well layer 17 is 5 nm, the In composition (X1) = 0.2 (the emission wavelength is 920 nm), and the Al composition of the barrier layer is X2 = 0.1. , (Al _0.1 Ga _0.9 ) _y In _1-y P) is related to the light output. The data values shown in Fig. 10 are shown in Table 5. A case where a GaAs substrate is used as a growth substrate.

In order to show the effect of the barrier layer, the barrier layer as a comparative example is the same as the present invention, and it is shown that the GaAs layer of the same material as the growth substrate (that is, the case where there is no skew with respect to the growth substrate) is used for the well layer.

In the case of the present invention, the maximum luminous output is 7 mW, and the Y1 of the barrier layer shows approximately 7 mW in the range of 0.52 to 0.60. In view of this, it is known that the case where the GaAs layer is used for the well layer is a maximum of 6.5 mW of the light-emitting output, and the range indicating the high output is also narrower than the case of the present invention.

This result is in the present invention, since the reverse skew of the barrier layer will moderate the skew of the well layer and suppress the decrease in crystallinity, and the composition range of the barrier layer which is high in light emission output and exhibits high output is also wide, in the comparative example, When the combination of the well-free layer and the barrier layer having the skew is obtained, it is understood that the crystallinity is lowered and the light-emitting output characteristics are lowered.

In Figure 11, the dependence of the forward current on the luminescence output is shown in terms of the number of pairs of well layers and barrier layers. The data system sets the layer thickness of the well layer 17 to 5 nm, the In composition (X1) = 0.2, and the composition of the barrier layer X2 = 0.1, Y1 = 0.55 (that is, (Al _0.1 Ga _0.9 ) _0.55 In _0.45 P), which is shown as In the case where the logarithm is 3 pairs and 5 pairs, the data values shown in Fig. 11 are shown in Table 6.

The forward current is up to 30 mA, and any of the 3 pairs and 5 pairs is approximately proportional to the increase in current, and the luminous output is increased. However, at 50 mA, 100 mA, the approximate ratio is maintained for 5 pairs, and for the increase of current, the illuminating output is increased; but for 3 pairs, 50 mA, 100 mA and 5 pairs are respectively When the situation is compared, the luminous output is reduced by 2 mW and 9 mW, respectively.

Therefore, for a large current/high output light-emitting diode, it is known that five pairs are suitable for three pairs. The larger the number of pairs, the higher the current/high output, the more the barrier layer of the growth substrate is formed by the composition of X2=0.1, Y1=0.55 (ie, (Al _0.1 Ga _0.9 ) _0.55 In _0.45 P). Composition (In _X1 Ga _1-X1 ) As (0 X1 1) The well layer skew formed is moderated and the decrease in crystallinity is suppressed.

In the multilayer structure of the well layer 17 and the barrier layer 18, the number of pairs of the alternate buildup well layer 17 and the barrier layer 18 is not particularly limited, and according to Fig. 9, it is preferably one pair or more and 20 pairs or less. That is, it is preferable to contain 1 to 20 layers in the active layer 11. Here, according to Fig. 9, the well layer 17 is sufficient as the luminous efficiency of the active layer 11 as a suitable range; however, according to Fig. 10, the luminous efficiency is improved especially under high current conditions. , especially good for multiple layers. Further, since there is a lattice irregularity between the well layer 17 and the barrier layer 18, if a plurality of pairs are formed, the luminous efficiency is lowered due to the occurrence of crystal defects. Therefore, it is preferably 2 or less, more preferably 10 or less.

As shown in Fig. 4, the lower guiding layer 10 and the upper guiding layer 12 are respectively disposed on the lower surface and the upper surface of the active layer 11. Specifically, a lower guiding layer 10 is provided below the active layer 11, and an upper guiding layer 12 is provided on the upper surface of the active layer 11.

The lower guiding layer 10 and the upper guiding layer 12 have (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P(0 X3 1, 0 < Y2 1) The composition. The above X3 preferably has a composition in which the barrier layer 18 is equal to the energy band gap or becomes larger than the barrier layer 18, and more preferably in the range of 0.2 to 0.5. Further, Y2 is preferably made to be 0.4 to 0.6.

X3 is selected from a function as a coating layer and is transparent to an emission wavelength, and Y2 is selected from a range in which a coating layer is a thick film and a crystal lattice is integrated with a substrate to form a favorable crystal growth.

The lower guiding layer 10 and the upper guiding layer 12 are respectively arranged to reduce The transfer of impurities between the lower cladding layer 9 and the upper cladding layer 13 and the active layer 11. That is, in the present invention, impurities are doped at a high concentration in the lower cladding layer 9 and the upper cladding layer 13, and the diffusion of the active layer 11 of the impurity is a cause of deterioration in performance of the light-emitting diode. In order to effectively reduce the diffusion of the impurities, the layer thickness of the lower guiding layer 10 and the upper guiding layer 12 is preferably 10 nm or more, more preferably 20 nm to 100 nm.

The conductivity type of the lower guiding layer 10 and the upper guiding layer 12 is not particularly limited, and any of undoped, p-type, and n-type can be selected. In order to improve the luminous efficiency, it is desirable to form a carrier concentration which is excellent in undoped or lower than 3 × 10 ¹⁷ cm ^-3 .

As shown in Fig. 4, the lower cladding layer 9 and the upper cladding layer 13 are respectively disposed on the lower surface of the lower guiding layer 10 and the upper surface of the upper guiding layer 12.

For the materials of the lower cladding layer 9 and the upper cladding layer 13, (Al _X4 Ga _1-X4 ) _Y3 In _1-Y3 P (0) is used. X4 1, 0 < Y3 The semiconductor material of 1) is preferably a material having a larger gap than the buffer layer 15, and more preferably a material having a larger gap than the lower guiding layer 10 and the upper guiding layer 12. The above material preferably has (Al _X4 Ga _1-X4 ) _Y3 In _1-Y3 P(0 X4 1, 0 < Y3 1) X4 is a composition of 0.3 to 0.7. Further, Y3 is preferably 0.4 to 0.6. X4 is selected from a function as a coating layer and is transparent to an emission wavelength. From the viewpoint that the coating layer is a thick film and is integrated with the crystal lattice of the substrate, Y3 is selected from the range in which the crystal growth is formed.

The lower cladding layer 9 and the upper cladding layer 13 are configured to have different polarities. Further, the carrier concentration and thickness of the lower cladding layer 9 and the upper cladding layer 13 can be appropriately determined by using a suitable range, and it is preferable to optimize the conditions for improving the luminous efficiency of the active layer 11. Further, by controlling the composition of the lower cladding layer 9 and the upper cladding layer 13, the bending of the compound semiconductor layer 2 can be reduced.

Specifically, it is desirable that the lower cladding layer 9 is made of, for example, Mg-doped p-type (Al _X4a Ga _1-X4a ) _Ya In _1-Ya P (0.3 X4a 0.7, 0.4 Y3a 0.6) The semiconductor material formed. Further, the carrier concentration is preferably in the range of 2 × 10 ¹⁷ to 2 × 10 ¹⁸ cm ^-3 , and the layer thickness is preferably in the range of 0.1 to 1 μm.

On the other hand, it is desirable that the upper cladding layer 13 is made of, for example, an n-type (Al _X4b Ga _1-X4b ) _Yb In _1-Yb P (0.3) doped with Si. X4b 0.7, 0.4 Y3b 0.6) The semiconductor material formed. Further, the carrier concentration is preferably in the range of 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ^-3 , and the layer thickness is preferably in the range of 0.1 to 1 μm.

Further, the polarities of the lower cladding layer 9 and the upper cladding layer 13 can be selected in consideration of the element structure of the compound semiconductor layer 2.

Further, above the structural layer of the light-emitting portion 7, a contact layer for reducing the contact resistance of the Ohmic electrode, a current diffusion layer for diffusing the element drive current planarly to the entire light-emitting portion, and the like may be provided. A conventional layer structure such as a current blocking layer or a current confinement layer in a region where the element drive current is limited.

As shown in FIG. 4, the current diffusion layer 8 is provided below the light-emitting portion 7. The current diffusion layer 8 can be made of a material transparent to the light-emitting wavelength from the light-emitting portion 7 (active layer 11), such as GaP or GaInP.

In the case where GaP is applied to the current diffusion layer 8, by using the functional substrate 3 as a GaP substrate, it is easy to perform bonding and high joint strength can be obtained.

Further, in the case where GaInP is applied to the current diffusion layer 8, the InGaAs having the same lattice constant as that of the well layer 17 of the laminated current diffusion layer 8 is set by changing the ratio of Ga to In, and is capable of being latticed with the well layer 17 The effect of integration. Therefore, it is preferable to select the composition ratio of GaInP such that the lattice constant becomes the same as the composition ratio of InGaAs selected from the desired light emission wavelength.

Further, the thickness of the current diffusion layer 8 is preferably in the range of 0.5 to 20 μm. When it is 0.5 μm or less, current spreading is insufficient, and when it is 20 μm or more, the cost of growing crystals until the thickness thereof increases.

The functional substrate 3 is bonded to the main light extraction surface of the compound semiconductor layer 2 and the surface on the opposite side. That is, as shown in FIG. 4, the functional substrate 3 is bonded to the side of the current diffusion layer 8 constituting the compound semiconductor layer 2. This functional substrate 3 has sufficient strength for the mechanically supported light-emitting portion 7, and is made of a material having a wide band gap and optically transparent to the light-emitting wavelength from the light-emitting portion 7.

The functional substrate 3 is a substrate having a thermal expansion coefficient close to that of the light-emitting portion and having excellent moisture resistance. Further, it is preferably composed of GaP, GaInP, SiC or sapphire having high mechanical strength. Further, in order to support the light-emitting portion 7 with sufficient mechanical strength, the functional substrate 3 is preferably formed to have a thickness of, for example, about 50 μm or more. Further, in order to facilitate the mechanical processing of the functional substrate 3 after bonding to the compound semiconductor layer 2, it is preferable to form a thickness of not more than about 300 μm. The functional substrate 3 is preferably composed of an n-type GaP substrate from the viewpoints of transparency, stress, and cost of a thickness of about 50 μm or more and about 300 μm or less.

Further, as shown in Fig. 4, the side surface of the functional substrate 3 is on the side close to the compound semiconductor layer 2 and is set to be approximately perpendicular to the vertical plane 3a with respect to the main light extraction surface; on the side away from the compound semiconductor layer 2 and opposite The inclined surface 3b inclined to the inner side is set on the main light extraction surface. Thereby, the light radiated from the active layer 11 to the side of the functional substrate 3 can be efficiently taken out to the outside. Further, part of the light emitted from the active layer 11 toward the functional substrate 3 side is reflected on the vertical surface 3a and can be taken out on the inclined surface 3b. On the other hand, the light reflected by the inclined surface 3b can be taken out on the vertical surface 3a. In this manner, the efficiency of light extraction can be improved by the multiplication effect of the vertical surface 3a and the inclined surface 3b.

Further, as shown in Fig. 4, in the present embodiment, it is preferable that the angle α formed by the inclined surface 3b and the surface parallel to the light-emitting surface is in the range of 55 to 80 degrees. By making such a range, it is possible to efficiently take out the light reflected at the bottom of the functional substrate 3 to the outside.

Further, it is preferable to set the width (thickness direction) of the vertical surface 3a in the range of 30 μm to 100 μm. By making the width of the vertical surface 3a within the above range, the light reflected at the bottom of the functional substrate 3 can be efficiently returned to the light-emitting surface on the vertical surface 3a, and the light can be radiated from the main light extraction surface. . Therefore, the luminous efficiency of the light-emitting diode 1 can be improved.

Further, it is preferable that the inclined surface 3b of the functional substrate 3 is roughened. By roughening the inclined surface 3b, it is possible to obtain an effect of improving the light extraction efficiency of the inclined surface 3b. In other words, by roughening the inclined surface 3b, total reflection on the inclined surface 3b can be suppressed, and the light extraction efficiency can be improved.

Further, the functional substrate 3 has a reflectance of 90% or more with respect to the light-emitting wavelength, and has a reflective layer (not shown) disposed opposite to the light-emitting portion. In this configuration, it is possible to extract light efficiently from the main light extraction surface.

The reflective layer is composed of, for example, silver (Ag), aluminum (Al), gold (Au), or the like. These materials have a high light reflectance and a light reflectance from the reflective layer 23 of 90% or more.

The functional substrate 3 can be bonded to an inexpensive substrate such as ruthenium or iridium which is close to the thermal expansion coefficient of the light-emitting portion by using a eutectic metal such as AuIn, AuGe or Ausn on the reflective layer. In particular, the AuIn-based bonding temperature is low, the thermal expansion coefficient is different from that of the light-emitting portion, and the most inexpensive bonding of the germanium substrate (germanium layer) is the optimum combination.

From the viewpoint of quality stability, it is also desired that the functional substrate 3 is a high-melting-point metal such as Ti, w, Pt or the like in which the current diffusion layer, the reflective metal, and the eutectic metal are not mutually diffused, or a transparent conductive oxide in which ITO or the like is inserted. .

The bonding interface between the compound semiconductor layer 2 and the functional substrate 3 has a high resistance layer. In other words, a high resistance layer (not shown) is provided between the compound semiconductor layer 2 and the functional substrate 3. This high-resistance layer exhibits a high resistance value compared to the functional substrate 3, and in the case where a high-resistance layer is provided, it has a function of reducing the reverse current from the side of the current diffusion layer 8 of the compound semiconductor layer 2 toward the functional substrate 3. In addition, a junction structure that exhibits withstand voltage is inadvertently applied to the current diffusion layer 8 side from the side of the functional substrate 3, and the falling voltage is preferably lower than the reverse voltage of the pn junction type light-emitting portion 7. The way to make it up.

The n-type ohmic electrode (first electrode) 4 and the p-type ohmic electrode (second electrode) 5 are ohmic electrodes of a low-resistance film provided on the main light extraction surface of the light-emitting diode 1. Here, the n-type ohmic electrode 4 is provided above the upper guiding layer 11, and for example, an alloy composed of AuGe or Ni alloy/Au can be used. On the other hand, as shown in FIG. 4, the p-type ohmic electrode 5 can use an alloy composed of AuBe/Au or AuZn/Au on the surface of the current diffusion layer 8 which is exposed.

Here, in the light-emitting diode 1 of the present embodiment, it is preferable that the p-type ohmic electrode 5 as the second electrode is formed on the current diffusion layer 8. By constructing such a structure, the effect of lowering the operating voltage can be obtained. Further, by forming the p-type ohmic electrode 5 on the current diffusion layer 8 composed of p-type GaP, in order to obtain a good ohmic contact, the operating voltage can be lowered.

Further, in the present embodiment, it is preferable that the polarity of the first electrode is made n-type and the polarity of the second electrode is made p-type. With such a configuration, it is possible to achieve high luminance of the light-emitting diode 1. On the other hand, when the first electrode is formed into a p-type, current spreading is deteriorated, resulting in a decrease in luminance. On the other hand, by forming the first electrode into an n-type, current spreading is improved, and the luminance of the light-emitting diode 1 can be increased.

As shown in FIG. 3, in the light-emitting diode 1 of the present embodiment, it is preferable that the n-type ohmic electrode 4 and the p-type ohmic electrode 5 are disposed at diagonal positions. Further, it is preferable to form a structure in which the periphery of the p-type ohmic electrode 5 is surrounded by the compound semiconductor layer 2. By constructing such a structure, the effect of lowering the operating voltage can be obtained. Further, by surrounding the periphery of the p-type ohmic electrode 5 by the n-type ohmic electrode 4, the current easily flows to the periphery, and as a result, the operating voltage is lowered.

Further, in the light-emitting diode 1 of the present embodiment, as shown in FIG. 3, it is preferable that the n-type ohmic electrode 4 is formed into a honeycomb or a lattice shape. By constructing such a structure, an effect of improving reliability can be obtained. Further, by forming a lattice shape, a current can be uniformly injected into the active layer 11, and as a result, an effect of improving reliability can be obtained.

Further, in the light-emitting diode 1 of the present embodiment, it is preferable to use a pad-shaped electrode (pad electrode) and a linear electrode (linear electrode) having a width of 10 μm or less. By having such a structure, it is possible to achieve high luminance. Further, by narrowing the width of the linear electrode, the opening area of the light extraction surface can be increased, so that high luminance can be achieved.

The third electrode can be further increased in output by being formed on the back surface of the functional substrate and reflecting on the transparent substrate to the substrate side. As the reflective metal material, materials such as Au, Ag, and Al can be used.

Further, by forming the electrode surface side as a eutectic metal such as AuSn or a solder material, the grain bonding step is simplified and it is not necessary to use a slurry. Further, by using a metal to be connected, heat conduction is improved and the heat radiation characteristics of the light-emitting diode are improved.

<Method of Manufacturing Light Emitting Diode>

Next, a method of manufacturing the light-emitting diode 1 of the present embodiment will be described. Fig. 12 is a cross-sectional view showing an epitaxial wafer used in the light-emitting diode 1 of the present embodiment. Further, Fig. 13 is a cross-sectional view showing a bonded wafer used in the light-emitting diode 1 of the present embodiment.

(Step of forming a compound semiconductor)

First, the compound semiconductor layer 2 shown in Fig. 12 was produced. The compound semiconductor layer 2 is formed on the GaAs substrate 14 by sequentially laminating a buffer layer 15 made of GaAs, an etch stop layer (not shown) provided for selective etching, and an n-type contact doped with Si. Layer 16, n-type upper cladding layer 13, upper guiding layer 12, active layer 11, lower guiding layer 10, p-type lower cladding layer 9, current diffusion layer 8 composed of Mg-doped p-type GaP And made.

As the GaAs substrate 14, a commercially available single crystal substrate obtained by a conventional production method can be used. It is desirable that the surface of the GaAs substrate 14 to be epitaxially grown is smooth. From the viewpoint of quality stability, it is desirable that the surface orientation of the surface of the GaAs substrate 14 is easily epitaxially grown, and the (100) plane and the substrate having an offset of (100) ± 20° are produced. Further, the range of the plane orientation of the GaAs substrate 14 is more preferably ±5° from the (100) direction by 15° in the (0-1-1) direction.

Moreover, in the specification of the present invention, in the indication of the Miller Index, "-" means a horizontal line attached to its subsequent index.

It is desirable that the rearrangement density of the GaAs substrate 14 is such that the crystallinity of the compound semiconductor layer 2 is improved and the lower the better. Specifically, for example, it is suitably 10,000 cm ^-2 or less, and more desirably 1,000 cm ^-2 or less.

The GaAs substrate 14 may be either n-type or p-type. The carrier concentration of the GaAs substrate 14 can be appropriately selected from the desired conductivity and device structure. For example, in the case where the GaAs substrate 14 is an n-type doped with germanium, the carrier concentration is preferably in the range of 1 × 10 ¹⁷ to 5 × 10 ¹⁸ cm ^-3 . To this end, in the case where zinc is doped to the p-type of the GaAs substrate 14, the carrier concentration is preferably in the range of 2 × 10 ¹⁸ to 5 × 10 ¹⁹ cm ^-3 .

The thickness of the GaAs substrate 14 has an appropriate range in accordance with the size of the substrate. If the thickness of the GaAs substrate 14 is thinner than the appropriate range, there is a fear of cracking in the process of the compound semiconductor layer 2. On the other hand, when the thickness of the GaAs substrate 14 is thicker than the appropriate range, the material cost will increase. Therefore, in the case where the substrate size of the GaAs substrate 14 is large, for example, in the case of a diameter of 75 mm, in order to prevent cracking during operation, a thickness of 250 to 500 μm is desirable. Similarly, in the case of a diameter of 50 mm, a thickness of 200 to 400 μm is desired; in the case of a diameter of 100 mm, a thickness of 350 to 600 μm is desired.

In this manner, by thickening the thickness of the substrate in accordance with the substrate size of the GaAs substrate 14, the bending of the compound semiconductor layer 2 due to the light-emitting portion 7 can be reduced. Thereby, the wavelength distribution in the plane of the active layer 11 can be made small in order to make the temperature distribution in epitaxial growth uniform. Further, the shape of the GaAs substrate 14 is not particularly limited to a circular shape, and there is no problem even if it is a rectangle or the like.

A buffer 15 is used to reduce the transmission of structural layer defects of the GaAs substrate 14 and the light-emitting portion 7. Therefore, if the quality of the substrate or the epitaxial growth conditions are selected, the buffer layer 15 is not necessarily required. Further, the material of the buffer layer 15 is preferably made of the same material as the substrate on which the epitaxial growth is performed. Therefore, in the present embodiment, it is preferable that the buffer layer 15 is made of GaAs similarly to the GaAs substrate 14. Further, in the buffer layer 15, a multilayer film made of a material different from that of the GaAs substrate 14 can be used to reduce the transmission of defects. The thickness of the buffer layer 15 is preferably 0.1 μm or more, and more preferably 0.2 μm or more.

The contact layer 16 (omitted in FIG. 4) is provided in order to reduce the contact resistance with the electrodes. The material of the contact layer 16 is preferably a material having a larger band gap than the active layer 11, and can be suitably used for Al _X Ga _1-X As, (Al _X Ga _1-X ) _Y In _1-Y P (0). X 1, 0 < Y1 1). Further, the lower limit of the carrier concentration of the contact layer 16 is to lower the contact resistance with the electrode, and is preferably 5 × 10 ¹⁷ cm ^-3 or more, more preferably 1 × 10 ¹⁸ cm ^-3 or more. The upper limit of the carrier concentration is desirably 2 × 10 ¹⁹ cm ^-3 or less which is liable to cause a decrease in crystallinity. The thickness of the contact layer 16 is preferably 0.5 μm or more, and most preferably 1 μm or more. Although the upper limit of the thickness of the contact layer 16 is not particularly limited, it is desirably 5 μm or less in order to make the cost of epitaxial growth into an appropriate range.

In the present embodiment, a conventional growth method such as a molecular line epitaxy method (MBE method) or a reduced pressure metalorganic chemical vapor deposition method (MOCVD method) can be employed. Among them, the MOCVD method having excellent mass productivity is most desirable. Specifically, the GaAs substrate 14 used for the epitaxial growth of the compound semiconductor layer 2 is desirably subjected to a pretreatment such as a cleaning step or a heat treatment before the growth to remove the surface contamination or the natural oxide film. Each of the layers constituting the compound semiconductor layer 2 can be mounted in an MOCVD apparatus with a GaAs substrate 14 having a diameter of 50 to 150 mm, and is epitaxially grown to be laminated. Further, the MOCVD apparatus can be a commercially available large-scale apparatus such as a self-propelled transformation or a high-speed rotation type.

When the epitaxial crystal grows each layer of the compound semiconductor layer 2, a raw material of the group III constituent element can be, for example, trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga), and Methyl indium ((CH ₃ ) ₃ In). Further, as the doping raw material of Mg, for example, biscyclopentadienyl magnesium (bis-(C ₅ H ₅ ) ₂ Mg) or the like can be used. Further, as the doping raw material of Si, for example, dioxane (Si ₂ H ₆ ) or the like can be used.

Further, as a raw material of the group V structural element, phosphine (PH ₃ ), hydrazine (AsH ₃ ) or the like can be used.

Further, in the case where p-type GaP is used as the current diffusion layer 8, the growth temperature of each layer can be 720 to 770 ° C, and in the case of other layers, 600 to 700 ° C can be employed.

Further, in the case where p-type GaInP is used as the current diffusion layer 8, 600 to 700 ° C can be used.

Further, the carrier concentration, the layer thickness, and the temperature conditions of each layer can be appropriately selected.

The compound semiconductor layer 2 obtained in this manner can obtain a good surface state with few crystal defects even though it has the light-emitting portion 7. Further, the compound semiconductor layer 2 may be subjected to surface processing such as polishing in accordance with the element structure.

(Joining step of functional substrate)

Next, the compound semiconductor layer 2 and the functional substrate 3 are bonded. The bonding of the compound semiconductor layer 2 and the functional substrate 3 is performed by first polishing the surface of the current diffusion layer 8 constituting the compound semiconductor layer 2 to perform mirror processing. Next, the functional substrate 3 attached to the mirror-polished surface of the current diffusion layer 8 is prepared. Further, the surface of the functional substrate 3 is polished before being bonded to the current diffusion layer 8. Next, the compound semiconductor layer 2 and the functional substrate 3 are carried into a general semiconductor material attaching device, and electrons are collided with the surface of both surfaces which have been mirror-polished in a vacuum, and then the neutralized Ar beam is irradiated. Then, the load can be applied at room temperature by superimposing the surfaces of both in the attaching device that maintains the vacuum (see Fig. 13). Regarding the joining, it is more desirable that the joint surface be the same material from the viewpoint of the stability of the joining condition.

Bonding (attaching) is optimum for room temperature bonding under such a vacuum, and bonding can also be performed using a eutectic metal or an adhesive.

(Step of forming the first and second electrodes)

Next, the n-type ohmic electrode 4 of the first electrode and the p-type ohmic electrode 5 of the second electrode are formed.

The n-type ohmic electrode 4 and the p-type ohmic electrode 5 are formed by first selectively removing the GaAs substrate 14 and the buffer layer 15 from the compound semiconductor layer 2 bonded to the functional substrate 3 by an ammonia-based etchant. Next, an n-type ohmic electrode 4 is formed on the surface of the exposed contact layer 16. Specifically, the AuGe and Ni alloy/Pt/Au are laminated by a vacuum deposition method in an arbitrary thickness, and then patterned by a general photolithography method to form the n-type ohmic electrode 4.

Next, the current diffusion layer 8 is exposed to a predetermined range of the contact layer 16, the upper cladding layer 13, the upper guiding layer 12, the lower guiding layer 10, and the p-type lower cladding layer 9, and is exposed. The surface of the current diffusion layer 8 forms a p-type ohmic electrode 5. Specifically, for example, AuBe/Au is laminated by a vacuum deposition method to have an arbitrary thickness, and then patterned by a general photolithography method to form a p-type ohmic electrode 5. Thereafter, the alloy is alloyed by heat treatment at, for example, 400 to 500 ° C for 5 to 20 minutes, whereby the low-resistance n-type ohmic electrode 4 and the p-type ohmic electrode 5 can be formed.

(Step of forming the third electrode)

The third electrode is formed on the back surface of the functional substrate. Depending on the configuration of the components, it is possible to combine the functions of an ohmic electrode, a Schottky electrode, a reflection function, a eutectic grain bonding structure, and the like. A material such as Au, Ag, or Al is formed on the transparent substrate to form a structure for reflection. For example, a transparent film of ruthenium oxide, ITO or the like can be inserted between the substrate and the above material. The formation method can be a conventional technique such as a sputtering method or a vapor deposition method.

Further, by making the electrode surface side a eutectic metal such as AuSn or the like, a lead-free solder material or the like, the grain bonding step is simplified and it is not necessary to use a paste. The formation method can be a conventional technique such as a sputtering method, a vapor deposition method, plating, or printing.

By using a metal connection, heat conduction is improved and the heat release characteristics of the light-emitting diode are improved.

In the case where the above two functions are combined, it is also suitable to insert the barrier metal or oxide so that the metal does not diffuse. These are capable of selecting the optimum by the element structure and the substrate material.

(Processing steps of functional substrate)

Next, the shape of the functional substrate 3 is processed.

The processing of the functional substrate 3 first performs a V-shaped trench on the surface on which the third electrode 6 is not formed. At this time, the inclined surface 3b having the inner side surface on the third electrode 6 side of the V-shaped groove and the angle α which is parallel to the surface of the light-emitting surface is formed. Next, from the side of the compound semiconductor layer 2, dicing is performed at predetermined intervals to form a wafer. Further, the vertical surface 3a of the functional substrate 3 is formed by dicing at the time of wafer formation.

The method for forming the inclined surface 3b is not particularly limited, and can be used in combination with a conventional method such as a wet etching method, a dry etching method, a scribing method, or a laser processing, but it is preferable to adopt shape controllability and production. High cutting method. The manufacturing yield can be improved by using a cutting method.

Further, the method of forming the vertical surface 3a is not particularly limited, and is preferably formed by a laser processing, a scribing/cracking method, or a dicing method.

The manufacturing cost can be reduced by using a laser processing or scribing/cracking method. That is, when the wafer is separated, it is not necessary to provide a cut, and since a large number of light-emitting diodes can be manufactured, the manufacturing cost can be reduced.

On the other hand, the cutting method has excellent cutting stability.

Finally, if necessary, the crushed layer and the dirt are removed by etching using a sulfuric acid/hydrogen peroxide mixed solution or the like. The light-emitting diode 1 is manufactured in this manner.

As described above, the light-emitting diode 1 according to the present embodiment includes the composition formula (In _X1 Ga _1-X1 ) As (0). X1 1) The compound semiconductor layer 2 of the light-emitting portion 7 of the well layer 17 formed.

Further, in the light-emitting diode 1 of the present embodiment, the current diffusion layer 8 is provided on the light-emitting portion 7. The current spreading layer 8 is transparent to the light-emitting wavelength, and does not absorb the light emitted from the light-emitting portion 7, and can produce the light-emitting diode 1 having high output and high efficiency. The functional substrate is excellent in moisture resistance due to stability and corrosion-free corrosion.

Therefore, according to the light-emitting diode 1 of the present embodiment, it is possible to provide the light-emitting diode 1 having an emission wavelength of 850 nm or more and having excellent monochromaticity and high output/high efficiency and moisture resistance. Further, when the light-emitting diode 1 of the present embodiment is compared with a transparent substrate-type AlGaAs-based light-emitting diode obtained by a conventional liquid phase epitaxy method, it is possible to provide light emission of about 2 times or more. High efficiency output LED 1 for efficiency. In addition, high temperature and high humidity reliability is also improved.

<Light Emitting Diode (Second Embodiment)>

Figs. 14A and 14B are views for explaining a pattern of a light-emitting diode according to a second embodiment of the present invention: Fig. 14A is a plan view; and Fig. 14B is taken along line C-C' shown in Fig. 14A. The cross-sectional view (the guide layers 10 and 12 are omitted from illustration).

The light-emitting diode according to the second embodiment is characterized in that it includes a light-emitting portion 7 having an alternating layer consisting of a composition formula (In _X1 Ga _1-X1 ) As (0). X1 1) The well layer 17 is formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The active layer 11 of the quantum well structure of the barrier layer 18 formed, and the composition formula (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P(0) sandwiching the active layer 11 X3 1, 0 < Y2 1) The first guiding layer 10 and the second guiding layer 12, and the first cladding layer 9 and the second package sandwiching the active layer 11 via the respective layers of the first guiding layer 10 and the second guiding layer 12 a cladding layer 13; a current diffusion layer 8 formed on the light-emitting portion 7, and a functional substrate 31 disposed opposite to the light-emitting portion 7 and including a reflective layer 23 having a reflectance of 90% or more for an emission wavelength And bonding to the current diffusion layer 8; and the first cladding layer 9 and the second cladding layer 13 are composed of a composition formula (Al _X4 Ga _1-X4 ) _Y3 In _1-Y3 P(0 X4 1, 0 < Y3 1) constitutes.

In the light-emitting diode of the second embodiment, since the light-emitting wavelength has a reflectance of 90% or more and the functional substrate 31 including the reflective layer 23 disposed on the light-emitting portion 7, it can effectively The main light extraction surface takes out the light.

In the example shown in FIGS. 14A and 14B, the functional substrate 31 includes the second electrode 21 on the lower surface 8b of the current diffusion layer 8, and further includes a transparent conductive layer so as to cover the second electrode 21 thereof. A reflective structure composed of the film 22 and the reflective layer 23, and a layer (substrate) 30 composed of tantalum or niobium.

In the light-emitting diode of the second embodiment, the functional substrate 31 preferably contains a layer composed of tantalum or niobium. Since it is a material that is difficult to corrode, moisture resistance will increase.

The reflective layer 23 is made of silver (Ag), aluminum (Al), gold (Au), or the like. These materials are high reflectance, and the light reflectance from the reflective layer 23 can be made 90% or more.

The functional substrate 31 can be bonded to the reflective layer 23 by a combination of inexpensive eutectic substrates (layers) such as ruthenium or iridium by a eutectic metal such as AuIn, AuGe or Ausn. In particular, the AuIn-based bonding temperature is low, the thermal expansion coefficient is different from that of the light-emitting portion, and the most suitable combination of the germanium substrate (tantalum layer) for bonding is suitable.

From the viewpoint of quality stability, it is also desirable that the functional substrate 31 is such that the current diffusion layer, the reflective metal, and the eutectic metal do not diffuse into each other, for example, by inserting titanium (Ti), tungsten (w), platinum (pt), or the like. The structure of the layer formed by the melting point metal.

<Light Emitting Diode (3rd Embodiment)>

Fig. 15 is a view for explaining a pattern of a light-emitting diode according to a third embodiment of the present invention.

The light-emitting diode according to the third embodiment is characterized in that it includes a light-emitting portion 7 having an alternating layer consisting of a composition formula (In _X1 Ga _1-X1 ) As (0). X1 1) The well layer 17 is formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The active layer 11 of the quantum well structure of the barrier layer 18 formed, and the composition formula (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P(0) sandwiching the active layer 11 X3 1, 0 < Y2 1) The first guiding layer 10 and the second guiding layer 12, and the first cladding layer 9 and the second package sandwiching the active layer 11 via the respective layers of the first guiding layer 10 and the second guiding layer 12 a cladding layer 13; the current diffusion layer 8 is formed on the light-emitting portion 7, and the functional substrate 51 is disposed opposite to the light-emitting portion 7 and includes a reflective layer having a reflectance of 90% or more with respect to an emission wavelength. The reflective layer 53 and the metal substrate 50 are bonded to the current diffusion layer 8; and the first cladding layer 9 and the second cladding layer 13 are composed of a composition formula (Al _X4 Ga _1-X4 ) _Y3 In _1-Y3 P (0) X4 1, 0 < Y3 1) constitutes.

In the light-emitting diode of the third embodiment, the point that the functional substrate contains the metal substrate is a structure characterized by the light-emitting diode of the second embodiment.

The metal substrate 50 is highly exothermic, and contributes to light-emitting of the light-emitting diode and high life of the light-emitting diode.

From the viewpoint of heat dissipation, the metal substrate 50 is particularly preferably composed of a metal having a thermal conductivity of 130 W/m‧K or more. A metal having a thermal conductivity of 130 W/m‧K or more, for example, molybdenum (138 W/m‧K) or tungsten (174 W/m‧K); silver (thermal conductivity = 420 W/m‧K), copper (thermal conductivity = 398W/m‧K), gold (thermal conductivity = 320W/m‧K), aluminum (thermal conductivity =236W/m‧K).

As shown in Fig. 15, the compound semiconductor layer 2 has the active layer 11 and sandwiches the first cladding layer (lower cladding layer) 9 and the second cladding layer with the guide layer (not shown) interposed therebetween. (upper cladding layer) 13, a current diffusion layer 8 on the lower side of the first cladding layer (lower cladding layer) 9, and a first electrode 55 on the upper side of the second cladding layer (upper cladding layer) 13. And a contact layer 56 of substantially the same size.

The functional substrate 51 includes a second electrode 57 on the lower surface 8b of the current diffusion layer 8, and a reflective structure in which the transparent conductive film 52 and the reflective layer 53 are laminated so as to cover the second electrode 57, and The metal substrate 50 is configured such that the bonding surface 50a of the metal substrate 50 is bonded to the surface 53b on the opposite side to the compound semiconductor layer 2 constituting the reflective layer 53 of the reflective structure.

The reflective layer 53 is made of a metal such as copper, silver, gold, aluminum, or the like, or the like. These materials are high light reflectance, and the light reflectance from the reflective structure can be made 90% or more. By forming the reflective layer 53, the light from the active layer 11 is reflected by the reflective layer 53 to the front direction f, and the light extraction efficiency in the front direction f can be improved. Thereby, the luminance of the light-emitting diode can be made higher.

The reflective layer 53 is preferably a laminated structure composed of an Ag, a Ni/Ti barrier layer, and an Au-based eutectic metal (a metal for connection) from the side of the transparent conductive film 52.

The metal for connection described above has a low electrical resistance and is molten at a low temperature. By using the above-described metal for connection, it is possible to connect the metal substrate without imparting thermal stress to the compound semiconductor layer 2.

The metal for connection is chemically stable and uses an Au-based eutectic metal having a low melting point. The Eu-based eutectic metal may, for example, be a eutectic metal (Au-based eutectic metal) of an alloy such as AuSn, AuGe or AuSi.

Further, it is preferable to add a metal such as titanium, chromium or tungsten to the metal for connection. Thereby, a metal such as titanium, chromium, or tungsten functions as a barrier metal, and impurities or the like contained in the metal substrate diffuse to the side of the reflective layer 53 to suppress the reaction.

The transparent conductive film 52 is formed of an ITO film, an IZO film, or the like. Further, the reflective structure may be composed only of the reflective layer 53.

Further, a so-called cold mirror using a refractive index difference of a transparent material such as a titanium oxide film, a multilayer film of a hafnium oxide film or white aluminum oxide, AlN instead of the transparent conductive film 52, or a transparent conductive film 52 may be used. Combined with the reflective layer 53.

The metal substrate 50 can be formed of a plurality of metal layers.

The structure of the plurality of metal layers is preferably formed by alternately laminating two metal layers, that is, the first metal layer 50A and the second metal layer 50B, as shown in Fig. 15.

In particular, the number of layers of the first metal layer 50A and the second metal layer 50B is preferably an odd number in total.

In this case, when the second metal layer 50B is made of a material having a smaller thermal expansion coefficient than the compound semiconductor layer 2, the first metal layer 50A preferably uses the compound semiconductor layer 3 from the viewpoint of bending or cracking of the metal substrate. The material whose thermal expansion coefficient is large is composed. Since the thermal expansion coefficient of the entire metal substrate is close to the thermal expansion coefficient of the compound semiconductor layer, bending or cracking of the metal substrate when the compound semiconductor layer and the metal substrate are bonded can be suppressed, so that the manufacturing yield of the light-emitting diode can be improved. improve. Similarly, when the second metal layer 50B is made of a material having a larger thermal expansion coefficient than the compound semiconductor layer 2, the first metal layer 50A is preferably made of a material having a smaller thermal expansion coefficient than the compound semiconductor layer 2. . Since the thermal expansion coefficient of the entire metal substrate is close to the thermal expansion coefficient of the compound semiconductor layer, bending or cracking of the metal substrate when the compound semiconductor layer and the metal substrate are bonded can be suppressed, so that the manufacturing yield of the light-emitting diode can be improved. improve.

From the above viewpoints, either of the two metal layers may be used regardless of the first metal layer or the second metal layer.

The two metal layers can be used, for example, of silver (coefficient of thermal expansion = 18.9 ppm/K), copper (coefficient of thermal expansion = 16.5 ppm/K), gold (coefficient of thermal expansion = 14.2 ppm/K), and aluminum (coefficient of thermal expansion = 23.1 ppm/K) ), nickel (coefficient of thermal expansion = 13.4 ppm / K) and any of these alloys consisting of molybdenum (coefficient of thermal expansion = 5.1 ppm / K), tungsten (coefficient of thermal expansion = 4.3 ppm / K) A combination of chromium (coefficient of thermal expansion = 4.9 ppm/K) and a metal layer of any of these alloys.

A suitable example is a metal substrate composed of three layers of Cu/Mo/Cu. From the above viewpoints, the same effect can be obtained even with a metal substrate composed of three layers of Mo/Cu/Mo, because the metal substrate composed of three layers of Cu/Mo/Cu is made of easily processed Cu. The structure in which the mechanical strength of Mo is sandwiched is advantageous in that it is easier to cut than a metal substrate composed of three layers of Mo/Cu/Mo.

For example, in the case of a metal substrate composed of three layers of Cu (30 μm) / Mo (25 μm) / Cu (30 μm), the thermal expansion coefficient of the entire metal substrate is 6.1 ppm / K, from Mo (25 μm) / Cu The case of a metal substrate composed of three layers of (70 μm)/Mo (25 μm) was 5.7 ppm/K.

Further, from the viewpoint of heat release, the metal layer constituting the metal substrate is preferably made of a material having a high thermal conductivity. Thereby, the heat dissipation property of the metal substrate is improved, so that the light-emitting diode can be made to emit light with high luminance, and the life of the light-emitting diode can be extended.

For example, it is preferable to use silver (thermal conductivity = 420 W/m‧K), copper (thermal conductivity = 398 W/m‧K), gold (thermal conductivity = 320 W/m‧K), aluminum (thermal conductivity = 236 W/m‧K), molybdenum (138 W/m‧K), tungsten (174 W/m‧K) and alloys of these.

More preferably, the metal layer has a coefficient of thermal expansion which is approximately equal to the coefficient of thermal expansion of the compound semiconductor layer. Particularly, the material of the metal layer is preferably a material having a thermal expansion coefficient of a compound semiconductor layer within a thermal expansion coefficient of ±1.5 ppm/K. Thereby, the stress caused by the heat of the light-emitting portion when the metal substrate and the compound semiconductor layer are bonded can be reduced, so that cracking of the metal substrate due to heat when the metal substrate and the compound semiconductor layer are connected can be suppressed. Therefore, the manufacturing yield of the light-emitting diode can be improved.

The thermal conductivity of the entire metal substrate, for example, a metal substrate composed of three layers of Cu (30 μm) / Mo (25 μm) / Cu (30 μm) becomes 250 W / m ‧ K; from Mo (25 μm) The case of a metal substrate composed of three layers of /Cu (70 μm) / Mo (25 μm) was 220 W/m‧K.

[Examples]

Hereinafter, the effects of the present invention will be specifically described using examples. Moreover, the invention is not limited by such embodiments.

In the present embodiment, an example of producing a light-emitting diode according to the present invention will be specifically described. Further, in the light-emitting diode system obtained in the present embodiment, an infrared light-emitting diode having an active layer composed of a quantum well structure, which is composed of a well layer composed of InGaAs and a barrier layer composed of AlGaInP. In the present embodiment, a compound semiconductor layer grown on a GaAs substrate is bonded to a functional substrate to fabricate a light-emitting diode. Further, for the characteristic evaluation, a light-emitting diode lamp in which a light-emitting diode wafer was mounted on a substrate was produced.

(Example 1)

Embodiment 1 is an embodiment shown in the embodiment of Fig. 4.

In the light-emitting diode system of the first embodiment, an epitaxial wafer was first formed by sequentially laminating a compound semiconductor layer on a GaAs substrate made of a Si-doped n-type GaAs single crystal.

The GaAs substrate was a growth surface which was inclined by 15° from the (100) plane toward the (0-1-1) direction, and the carrier concentration was 2 × 10 ¹⁸ cm ^-3 . The compound semiconductor layer uses an n-type buffer layer composed of GaAs doped with SiO, an n-type contact layer composed of (Si _0.7 Ga _0.3 ) _0.5 In _0.5 P doped with Si, and is doped with Si (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, an n-type upper cladding layer, an upper guiding layer composed of (Al _0.3 Ga _0.7 ) _0.5 In _0.5 P, and In _0.2 Ga _0.8 As/(Al _0.1 Ga _0.9 ) _0.5 In _0.5 P of three pairs of well layer / barrier layer formed of a (Al _0.3 Ga _{0.7) 0.5} in _0.5 P a lower guide layer formed, the Mg-doped _{(Al 0.7 Ga 0.3) 0.5 in} 0.5 P is formed a p-type lower cladding layer, an intermediate layer of a film made of (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P, and a current diffusion layer made of Mg-doped p-type GaP.

In the present embodiment, a compound semiconductor layer was epitaxially grown on a GaAs substrate having a diameter of 76 mm and a thickness of 350 μm using a reduced-pressure organic metal chemical vapor deposition apparatus (MOCVD apparatus) to form an epitaxial wafer. When the epitaxial growth layer is grown, the raw materials of the group III constituent elements are trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga), and trimethyl indium (( CH ₃ ) ₃ In). Further, as the doping raw material of Mg, for example, bis-cyclopentadienyl magnesium (bis-(C ₅ H ₅ ) ₂ Mg) can be used. Further, as the doping raw material of Si, for example, dioxane (Si ₂ H ₆ ) can be used. Further, as a raw material of the group V structural element, phosphine (PH ₃ ) or hydrazine (AsH ₃ ) can be used. Further, the growth temperature of each layer was grown at 750 ° C by a current diffusion layer composed of p-type GaP. The other layers were grown at 700 °C.

The buffer layer composed of GaAs has a carrier concentration of about 2 × 10 ¹⁸ cm ^-3 and a layer thickness of about 0.5 μm. The contact layer has a carrier concentration of about 2 × 10 ¹⁸ cm ^-3 and a layer thickness of about 4 μm. The upper cladding layer has a carrier concentration of about 1 × 10 ¹⁸ cm ^-3 and a layer thickness of about 0.5 μm. The upper guiding layer was made undoped and had a layer thickness of about 50 nm. The well layer is made of In _0.2 Ga _0.8 As which is undoped and has a layer thickness of about 5 nm, and the barrier layer is made of (Al _0.1 Ga _0.9 ) _0.51 In _0.5 P which is undoped and has a layer thickness of about 10 nm. In addition, the well layer and the barrier layer are alternately laminated. The lower guiding layer was made undoped and had a layer thickness of about 50 nm. The lower cladding layer has a carrier concentration of about 8 × 10 ¹⁷ cm ^-3 and a layer thickness of about 0.5 μm. The intermediate layer was formed to have a carrier concentration of about 8 × 10 ¹⁷ cm ^-3 and a layer thickness of about 50 nm.

The current diffusion layer composed of GaP has a carrier concentration of about 3 × 10 ¹⁸ cm ^-3 and a layer thickness of about 10 μm.

Next, the current diffusion layer was polished from the surface up to a depth of about 1 μm, and mirror-finished.

The surface roughness (rms) of the current diffusion layer was made 0.18 nm by this mirror processing.

On the other hand, a functional substrate composed of n-type GaP attached to the mirror-polished surface of the current diffusion layer is prepared. In the functional substrate to be attached thereto, a single crystal in which Si is added and the plane orientation is (111) is used so that the carrier concentration becomes about 2 × 10 ¹⁷ cm ^-3 . Further, the functional substrate has a diameter of 76 mm and a thickness of 250 μm. The surface of the functional substrate was ground to a mirror surface before being bonded to the current diffusion layer, and the surface roughness (rpm) was processed to 0.12 nm.

Next, the above-described functional substrate and epitaxial wafer are carried into a general semiconductor material attaching device, and the inside of the device is evacuated to 3 × 10 ^-5 Pa.

Next, on the surface of both the functional substrate and the current diffusion layer, the electron beam collides with the neutralized Ar beam after being irradiated for 3 minutes. Thereafter, the surface of the functional substrate and the current diffusion layer were superposed on each other in a vacuum-applied apparatus, and the load was applied so that the pressure on each surface became 50 g/cm ² , and both were joined at room temperature. The bonding wafer is formed in such a manner.

Next, the GaAs substrate and the GaAs buffer layer are selectively removed from the bonded wafer by an ammonia-based etchant. Then, the surface of the contact layer was formed by vacuum deposition on the surface of the first electrode so that AuGe and Ni alloy were 0.5 μm thick, Pt was 0.2 μm thick, and Au was 1 μm thick. Thereafter, pattern formation is performed by a general photolithography method, and the first electrode is an n-type ohmic electrode. Next, the surface of the light extraction surface on the surface on which the GaAs substrate is removed is subjected to a roughening treatment.

Next, the second electrode selectively removes the epitaxial layer in the region where the p-type ohmic electrode is formed, and exposes the current diffusion layer. On the surface of the current diffusion layer which was exposed, a p-type ohmic electrode was formed by a vacuum deposition method so that AuBe became 0.2 μm and Au became 1 μm. Thereafter, the film was heat-treated at 450 ° C for 10 minutes to form a low-resistance p-type and n-type ohmic electrode. Further, Au having a thickness of 0.2 μm was formed on the back surface of the functional substrate, and a pattern was formed in a square of 220 μm.

Then, using a dicing cutter, the thickness of the vertical surface was set to 80 μm while the angle α of the inclined surface was 70° from the back surface of the functional substrate in the region where the third electrode was not formed. V-shaped trenching. Next, using a die cutter, the compound semiconductor layer was cut at a gap of 350 μm to be wafer-formed. The light-emitting diode of Example 1 was produced by etching a sulfuric acid/hydrogen peroxide mixed solution to remove the fracture layer and the dirt caused by the grain cutting.

A light-emitting diode lamp was assembled by mounting the light-emitting diode wafer of the first embodiment obtained as described above on a mounting substrate. The light-emitting diode lamp is supported by a die bonder (erected), and the n-type ohmic electrode of the light-emitting diode and the n-electrode terminal provided on the surface of the erected substrate are connected by a gold wire, and the gold wire is used. After the wire is bonded to the p-type ohmic electrode and the p-electrode terminal, it is obtained by sealing with a general epoxy resin.

The results of evaluating the characteristics of this light-emitting diode (light-emitting diode lamp) are shown in Table 7.

As shown in Table 7, after flowing a current between the n-type and p-type ohmic electrodes, infrared light having a peak wavelength of 920 nm was emitted. The forward voltage (Vf) at the time of the current flowing in the forward direction of 20 microamperes (mA) is reflected in the low resistance of the junction interface between the current diffusion layer constituting the compound semiconductor layer and the functional substrate, and the good ohmic of each ohmic electrode. Characteristic, and become about 1.22 volts. The luminous output when the forward current was made to 20 mA was 7 mW. Further, in a high-temperature and high-humidity environment at a temperature of 60 ° C and a humidity of 90%, a 1000-hour electrification test (20 mA energization) was carried out, and the results of measuring the residual ratio of the luminescence output are shown in Table 7.

100 lamps were used, and a high-temperature and high-humidity electric current test was performed at 60 ° C, 90 RH%, and 20 mA. The average output residual rate after 1000 hours was 100%.

Measuring current = 20mA

Reliability (%): 60°C ‧90RH%/20mA energization, output residual rate after 1000 hours

(Example 2)

Embodiment 2 shows an embodiment of the second embodiment shown in Figs. 14A and 14B.

The case where the light-emitting diode system of Embodiment 2 is combined with a reflective layer and a functional substrate. The formation of the other light-emitting portions is the same as in the first embodiment. Further, the lower guide layer 10 and the upper guide layer 12 are not shown.

On the surface of the current diffusion layer 8, eight electrodes (second electrodes) 21 are formed at equal intervals from the edge of the light extraction surface, and are formed of AuBe/Au alloy at a thickness of 0.2 μm and 20 μm Φ. Composition.

Next, an ITO film 22 of a transparent conductive film was formed by a sputtering method to a thickness of 0.4 μm. Further, a layer 23 made of a silver alloy/Ti/Au was formed to a thickness of 0.2 μm/0.1 μm/1 μm to form a reflecting surface 23.

On the other hand, a layer 32 made of Ti/Au/In is formed on the surface of the tantalum substrate (functional substrate) 31 with a thickness of 0.1 μm/0.5 μm/0.3 μm. On the back surface of the ruthenium substrate 31, a layer 33 made of Ti/Au is formed to a thickness of 0.1 μm/0.5 μm. The Au surface on the side of the light-emitting diode wafer and the In surface on the side of the germanium substrate were superposed, heated at 320 ° C and pressurized at 500 g/cm ^{2 to} bond the functional substrate to the light-emitting diode wafer.

The GaAs substrate was removed, and an ohmic electrode (first electrode) 25 having a diameter of 100 μm and a thickness of 3 μm made of AuGe/Au was formed on the surface of the contact layer 16, and heat-treated at 420 ° C for 5 minutes to alloy the p and n. Ohmic electrode.

Next, the surface of the contact layer 16 is roughened.

The semiconductor layer and the reflective layer and the eutectic metal for separating into a predetermined cut portion of the wafer are removed, and Ti/AuSn/Au of 0.3 μm/1 μm/0.1 μm is formed on the back electrode of the germanium substrate. Using a cutter, it was cut into squares at a pitch of 350 μm.

The results of evaluating the characteristics of this light-emitting diode (light-emitting diode lamp) are shown in Table 7.

As shown in Table 7, after flowing current into the upper and lower electrodes, infrared light having a peak wavelength of 920 nm was emitted. The forward voltage (Vf) at the time of the current flowing in the forward direction of 20 microamperes (mA) is reflected in the low resistance of the junction interface between the current diffusion layer constituting the compound semiconductor layer and the functional substrate, and the good ohmic of each ohmic electrode. Characteristic, and become about 1.20 volts (V). The luminous output when the forward current was made to 20 mA was about 6 mW. Further, in a high-temperature and high-humidity environment at a temperature of 60 ° C and a humidity of 90%, a 1000-hour electrification test (20 mA energization) was carried out, and the results of measuring the residual ratio of the luminescence output are shown in Table 7.

In the same manner as in Example 1, 100 lamps were used, and a high-temperature and high-humidity electric current test was performed at 60 ° C, 90 RH %, and 20 mA. The average output residual rate after 1000 hours was 99%.

(Example 3)

The embodiment of the third embodiment of the light-emitting diode system of the third embodiment is a structure in which a functional substrate including a reflective layer and a metal substrate is bonded to a current diffusion layer. The light-emitting diode of Example 3 will be described with reference to Fig. 15.

First, a metal substrate is produced. Two Cu plates having a thickness of about 10 μm and a plate having a thickness of about 10 μm were prepared, and a Mo plate having a thickness of approximately 75 μm was formed, and the Mo plate was inserted between the two Cu plates, and the metal plates were placed in an overlapping manner, and the substrate was placed. In the pressurizing device, at a high temperature, for these metal plates, a load is applied to the direction in which the metal plates are sandwiched. Thus, a metal substrate composed of three layers of Cu (10 μm) / Mo (75 μm) / Cu (10 μm) was produced.

The compound semiconductor layer is formed between the buffer layer and the contact layer, and is made of Si-doped (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P, except for the point of forming an etch stop layer having a layer thickness of 0.5 μm. The conditions of 1 are formed under the same conditions.

On the surface 8b of the current diffusion layer 8, a layer of Au having a thickness of 0.2 μm was deposited on AuBe having a thickness of 0.4 μm, and a circular shape of 20 μm Φ was formed in plan view, and the second electrode 57 was formed at intervals of 60 μm.

Next, the ITO film 52 of the transparent conductive film was formed to have a thickness of 0.8 μm by a sputtering method so as to cover the second electrode 57.

Next, a film made of a silver (Ag) alloy of 0.7 μm is formed on the ITO film 52 by a vapor deposition method, and then a film made of nickel (Ni)/titanium (Ti) of 0.5 μm is formed. A reflective film 53 is formed by a film of 1 μm made of gold (Au).

Then, the structure in which the ITO film 52 and the reflection film 53 are formed on the current diffusion layer 8 of the compound semiconductor layer is placed so as to face the metal substrate, and is placed in the decompression device, and heated at 400 ° C. The bonded structure was formed by joining the load with a load of 500 kg.

Then, the GaAs substrate and the buffer layer which are the growth substrates of the compound semiconductor layer are selectively removed from the bonded structure by the ammonia-based etchant, and the etching stop layer is selectively removed by the hydrochloric acid-based etchant.

Then, AuGe having a thickness of 0.15 μm was formed on the contact layer by a vacuum deposition method, and Ni of 0.05 μm in thickness was formed, and Au having a thickness of 1 μm was further formed to form a conductive film for the first electrode. Next, the electrode conductive film was patterned into a circular shape in plan view by photolithography to obtain a first electrode 55 having a diameter of 100 μm and a thickness of 3 μm.

Next, the first electrode is used as a mask, and a contact layer 56 is formed by etching away portions other than the first electrode by an ammonia-based etchant in the contact layer.

The semiconductor layer and the reflective layer and the eutectic metal for separating into a predetermined cut portion of the wafer were removed, and the metal substrate was cut by laser cutting to form a square at a pitch of 350 μm.

The results of evaluating the characteristics of this light-emitting diode (light-emitting diode lamp) are shown in Table 7.

As shown in Table 7, after flowing a current between the n-type and p-type ohmic electrodes, infrared light having a peak wavelength of 920 nm was emitted. The forward voltage (V _F ) at the time of the current flowing in the forward direction of 20 microamperes (mA) is reflected in the low resistance of the junction interface between the current diffusion layer constituting the compound semiconductor layer and the functional substrate, and the good ohmic electrodes. Ohmic characteristics, and become 1.2 volts. The luminous output when the forward current was made to 20 mA was 5.9 mW.

60 lamps were used, and a high-temperature and high-humidity electric current test was performed at 60 ° C, 90 RH%, and 20 mA.

The average output residual rate after 1000 hours was 100%.

(Example 4)

In the examples of the first embodiment of the light-emitting diode system of the fourth embodiment, in order to make the emission peak wavelength 870 nm, the same conditions as in the first embodiment were obtained except that the In composition of the well layer was made X1 = 0.12.

The results of evaluating the characteristics of the light-emitting diode (light-emitting diode lamp) are as shown in Table 7, and the infrared light having a peak wavelength of 870 nm is emitted, the light-emitting output (P ₀ ), the forward voltage (V _F ), The average output residual ratio is 6.8 mW, 1.31 V, and 100%, respectively.

(Example 5)

In the embodiment of the second embodiment of the light-emitting diode system of the fifth embodiment, in order to make the emission peak wavelength 870 nm, the same conditions as in the second embodiment were obtained except that the In composition of the well layer was made X1 = 0.12.

The results of evaluating the characteristics of the light-emitting diode (light-emitting diode lamp) are as shown in Table 7, and the infrared light having a peak wavelength of 870 nm is emitted, the light-emitting output (P ₀ ), the forward voltage (V _F ), The average output residual ratio is 6.1 mW, 1.3 V, and 100%, respectively.

(Example 6)

In the embodiment of the first embodiment of the light-emitting diode system of the sixth embodiment, in order to make the emission peak wavelength 960 nm, the same conditions as in the first embodiment were obtained except that the In composition of the well layer was X1 = 0.25.

The results of evaluating the characteristics of the light-emitting diode (light-emitting diode lamp) are as shown in Table 7, and the infrared light having a peak wavelength of 960 nm is emitted, the light-emitting output (P ₀ ), the forward voltage (V _F ), The average output residual ratio is 6.5 mW, 1.2 V, and 99%, respectively.

(Example 7)

In the embodiment of the second embodiment of the light-emitting diode system of the seventh embodiment, in order to make the emission peak wavelength 960 nm, the same conditions as in the second embodiment were obtained except that the In composition of the well layer was X1 = 0.25.

The results of evaluating the characteristics of the light-emitting diode (light-emitting diode lamp) are as shown in Table 7, and the infrared light having a peak wavelength of 960 nm is emitted, the light-emitting output (P ₀ ), the forward voltage (V _F ), The average output residual ratio is 5.3 mW, 1.2 V, and 99%, respectively.

(Example 8)

In the embodiment of the first embodiment of the light-emitting diode system of the eighth embodiment, in order to make the emission peak wavelength 985 nm, the same conditions as in the first embodiment were obtained except that the In composition of the well layer was X1 = 0.3.

The results of evaluating the characteristics of the light-emitting diode (light-emitting diode lamp) are as shown in Table 7, and the infrared light having a peak wavelength of 985 nm is emitted, the light-emitting output (P ₀ ), the forward voltage (V _F ), The average output residual ratio is 5.0 mW, 1.2 V, and 99%, respectively.

(Example 9)

In the embodiment of the second embodiment of the light-emitting diode system of the ninth embodiment, in order to make the emission peak wavelength 985 nm, the same conditions as in the second embodiment were obtained except that the In composition of the well layer was X1 = 0.3.

The results of evaluating the characteristics of the light-emitting diode (light-emitting diode lamp) are as shown in Table 7, and the infrared light having a peak wavelength of 985 nm is emitted, the light-emitting output (P ₀ ), the forward voltage (V _F ), The average output residual rate is 3.8 mW, 1.2 V, and 99%, respectively.

(Embodiment 10)

The embodiment of the first embodiment of the light-emitting diode system of the tenth embodiment, except that the layer thickness of the barrier layer is not doped is made to be (Al _0.1 Ga _0.9 ) _0.55 In _0.45 P of about 10 nm, and in addition, five pairs of wells are alternately laminated. The layer and the barrier layer were produced in the same manner as in Example 1.

The results of evaluating the characteristics of the light-emitting diode (light-emitting diode lamp) are as shown in Table 7, and the infrared light having a peak wavelength of 920 nm is emitted, the light-emitting output (P ₀ ), the forward voltage (V _F ), The average output residual ratio is 7.0 mW, 1.24 V, and 99%, respectively.

(Comparative Example 1)

The light-emitting diode system of Comparative Example 1 was formed by an epitaxial method of a conventional technique. It is changed to a light-emitting diode having a double heterostructure light-emitting portion having Al _0.01 Ga _0.99 As as a light-emitting layer on a GaAs substrate.

Specifically, the light-emitting diode of Comparative Example 1 was produced on an n-type (100)-plane GaAs single crystal substrate, and an n-type upper cladding layer having an interface composition of 50 μm Al _0.2 Ga _0.8 As, 20 μm of Si-doped luminescent layer composed of Al _0.03 Ga _0.97 As, 20 μm of p-type lower cladding layer composed of Al _0.1 Ga _0.9 As, and 60 μm of transparent light-emitting wavelength from Al _0.25 The p-type thick film layer composed of Ga _0.75 As was obtained by a liquid phase epitaxy method. After the epitaxial growth, the GaAs substrate is removed. Next, an n-type ohmic electrode having a diameter of 100 μm was formed on the surface of the n-type AlGaAs upper cladding layer.

Next, a p-type ohmic electrode having a diameter of 20 μm was formed on the back surface of the p-type AlGaAs thick film layer at intervals of 80 μm, and heat treatment was performed at 420 ° C for 5 minutes to alloy the p and n ohmic electrodes. Next, after cutting at 350 nm intervals by a cutter, the fracture layer was removed by etching, and the surface was roughened for high output to obtain a light-emitting diode wafer of Comparative Example 1.

The results of evaluating the characteristics of the light-emitting diode lamp of the light-emitting diode of Comparative Example 1 are shown in Table 7.

As shown in Table 7, after flowing a current between the n-type and p-type ohmic electrodes, infrared light having a peak wavelength of 920 nm was emitted. In addition, the forward voltage (V _F ) at a current of 20 microamperes (mA) in the forward direction is about 1.2 volts (V). In addition, the luminous output when the forward current was 20 mA was 2 mW. Further, in comparison with the examples of the present invention, the output of any of the samples of Comparative Example 1 was low. Further, a 500-hour energization test (20 mA energization) was carried out in a high-temperature and high-humidity environment at a temperature of 60 ° C and a humidity of 90%, and the results of measuring the residual ratio of the luminescence output are shown in Table 1. The reason for the decrease in output is considered to be due to the increase in absorption of light due to corrosion of the AlGaAs surface.

Further, in the same manner as in the examples, 100 lamps were used, and a high-temperature and high-humidity electric current test was performed at 60 ° C, 90 RH %, and 20 mA. Compared with the beginning of the experiment, the average output residual rate after 500 hours was also reduced by 14%; compared with the example of being reduced by less than 1%, it was greatly reduced.

[Possibility of industrial use]

The light-emitting diode of the present invention can be utilized as a light-emitting diode product having high output/high efficiency and emitting infrared light having an emission peak wavelength of 850 nm or more, particularly 900 nm or more.

1‧‧‧Lighting diode

2‧‧‧ compound semiconductor layer

3‧‧‧ functional substrate

3a‧‧‧Vertical

3b‧‧‧ sloped surface

4‧‧‧n type ohmic electrode (first electrode)

5‧‧‧p type ohmic electrode (2nd electrode)

6‧‧‧3rd electrode

7‧‧‧Lighting Department

8‧‧‧current diffusion layer

9‧‧‧Lower coating (1st cladding)

10‧‧‧Lower guide layer

11‧‧‧Active layer

12‧‧‧ upper guide layer

13‧‧‧Upper cladding (2nd cladding)

14‧‧‧GaAs substrate

15‧‧‧buffer layer

16‧‧‧Contact layer

17‧‧‧ Wells

18‧‧ ‧ barrier layer

20‧‧‧Lighting diode

twenty one. . . electrode

twenty two. . . Transparent conductive film

twenty three. . . Reflective surface

25. . . Bonding electrode

30. . .矽 substrate

31. . . Functional substrate

41. . . Light-emitting diode lamp

42. . . Mounting substrate

43. . . N electrode terminal

44. . . P electrode terminal

45. . . Gold Line

47. . . Sealing resin

50. . . Metal substrate

51. . . Functional substrate

52. . . Transparent conductive film

53. . . Reflective layer

55. . . First electrode

56. . . Contact layer

57. . . Second electrode

α. . . The angle between the inclined surface and the surface parallel to the light emitting surface

Fig. 1 is a plan view showing a light-emitting diode lamp using a light-emitting diode according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing the light-emitting diode of the light-emitting diode according to the embodiment of the present invention taken along the line A-A' in Fig. 1.

Fig. 3 is a plan view showing a light-emitting diode according to an embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view showing a light-emitting diode according to an embodiment of the present invention taken along line B-B' in Fig. 3.

Fig. 5 is a view for explaining a pattern of an active layer constituting a light-emitting diode according to an embodiment of the present invention.

Fig. 6 is a graph showing the correlation between the layer thickness of the well layer of the light-emitting diode and the wavelength of the luminescence peak in an embodiment of the present invention.

Fig. 7 is a view showing the In composition (X1) of the well layer of the light-emitting diode according to the embodiment of the present invention and the correspondence between the thickness of the well layer and the wavelength of the luminescence peak.

Fig. 8 is a graph showing the relationship between the In composition (X1) of the well layer of the light-emitting diode of one embodiment of the present invention and the luminescence peak wavelength and its luminescence output.

Fig. 9 is a view showing the correlation between the number of pairs of the well layer and the barrier layer of the light-emitting diode of one embodiment of the present invention and the light-emission output.

Fig. 10 is a view showing the relationship between the In composition (Y1) of the barrier layer of the light-emitting diode of one embodiment of the present invention and the light-emission output.

Fig. 11 is a graph showing the dependence of the forward current of the light-emitting diode on the number of pairs of the well layer and the barrier layer in relation to the light-emitting output of one embodiment of the present invention.

Fig. 12 is a schematic cross-sectional view showing an epitaxial wafer for use in a light-emitting diode according to an embodiment of the present invention.

Fig. 13 is a schematic cross-sectional view showing a bonded wafer for use in a light-emitting diode according to an embodiment of the present invention.

Fig. 14A is a plan view showing a light-emitting diode according to an embodiment of the present invention.

Fig. 14B is a schematic cross-sectional view taken along the line C-C' shown in Fig. 14A.

Fig. 15 is a schematic cross-sectional view showing a light-emitting diode according to another embodiment of the present invention.

Claims (19)

A light-emitting diode characterized by comprising: a light-emitting portion having an alternating layer consisting of a composition formula (In _X1 Ga _1-X1 ) As (0.1 X1 0.3) The well layer formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The active layer of the quantum well structure of the barrier layer formed, and the composition formula (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P(0) sandwiching the active layer X3 1, 0 < Y2 1) a first guiding layer and a second guiding layer, and a first cladding layer and a second cladding layer sandwiching the active layer via the respective layers of the first guiding layer and the second guiding layer; a diffusion layer formed on the light-emitting portion; and a functional substrate bonded to the current diffusion layer; the first and second cladding layers being composed of a composition formula (Al _X4 Ga _1-X4 ) _Y3 In _{1 -Y3} P(0 X4 1, 0 < Y3 1) The light-emitting wavelength is 900 nm or more and 985 nm or less. For example, in the light-emitting diode of claim 1, wherein the composition of the barrier layer X2 and Y1 are respectively 0. X2 0.2, 0.5 < Y1 0.7, the composition of the first and second guiding layers X3 and Y2 are respectively 0.2 X3 0.5, 0.4 < Y2 0.6, the composition of the first and second cladding layers X4 and Y3 are respectively 0.3 X4 0.7, 0.4 < Y3 0.6. The light-emitting diode of claim 1, wherein the functional substrate is transparent to an emission wavelength. Such as the light-emitting diode of claim 1 of the patent scope, wherein the functional base The plate system is composed of GaP or SiC. The light-emitting diode of claim 1, wherein a side surface of the functional substrate has a vertical surface that is approximately perpendicular to a main light extraction surface on a side close to the light-emitting portion, and a side that is away from the light-emitting portion The main light extraction surface is inclined toward the inner side. The light-emitting diode of claim 5, wherein the inclined surface contains a rough surface. A light-emitting diode characterized by comprising: a light-emitting portion having an alternating layer consisting of a composition formula (In _X1 Ga _1-X1 ) As (0.1 X1 0.3) The well layer formed by the composition formula (Al _X2 Ga _1-X2 ) _Y1 In _1-Y1 P(0 X2 1, 0 < Y1 1) The active layer of the quantum well structure of the barrier layer formed, and the composition formula (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P(0) sandwiching the active layer X3 1, 0 < Y2 1) a first guiding layer and a second guiding layer, and a first cladding layer and a second cladding layer sandwiching the active layer via the respective layers of the first guiding layer and the second guiding layer; a diffusion layer formed on the light-emitting portion; and a functional substrate disposed opposite to the light-emitting portion and including a reflective layer having a reflectance of 90% or more with respect to an emission wavelength, and bonded to the current diffusion layer The first and second cladding layers are composed of a composition formula (Al _X4 Ga _1-X4 ) _Y3 In _1-Y3 P(0 X4 1, 0 < Y3 1) The light-emitting wavelength is 900 nm or more and 985 nm or less. For example, in the light-emitting diode of claim 7, wherein the composition of the barrier layer X2 and Y1 are respectively 0. X2 0.2, 0.5 < Y1 0.7, the composition of the first and second guiding layers X3 and Y2 are respectively 0.2 X3 0.5, 0.4 < Y2 0.6, the composition of the first and second cladding layers X4 and Y3 are respectively 0.3 X4 0.7, 0.4 < Y3 0.6. The light-emitting diode of claim 7, wherein the functional substrate comprises a layer composed of ruthenium or osmium. The light-emitting diode of claim 7, wherein the functional substrate comprises a metal substrate. The light-emitting diode of claim 10, wherein the metal substrate is composed of a plurality of metal layers. The light-emitting diode of claim 1 or 7, wherein the current diffusion layer is composed of GaP or GaInP. The light-emitting diode of claim 1 or 7, wherein the current diffusion layer has a thickness in the range of 0.5 to 20 μm. The light-emitting diode according to claim 1 or 7, wherein the first electrode and the second electrode are provided on the main light extraction surface side of the light-emitting diode. The light-emitting diode of claim 14, wherein the first electrode and the second electrode are ohmic electrodes. The light-emitting diode of claim 14 is further provided with a third surface on the opposite side of the main light extraction surface side of the functional substrate. electrode. A light-emitting diode lamp characterized by comprising the light-emitting diode according to any one of claims 1 to 16. A light-emitting diode lamp comprising the light-emitting diode according to item 16 of the patent application, wherein the first electrode or the second electrode is connected to the third electrode at approximately the same potential. A lighting device that is provided with a plurality of light-emitting diodes according to any one of claims 1 to 16 and/or a light-emitting diode according to at least one of claims 17 or 18. light.