JP3854053B2 - LED for infrared remote control - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an LED using a light emitting layer material such as gallium arsenide, and more particularly to an infrared remote control LED.
[0002]
[Prior art]
As an infrared LED used in a remote controller, there is JP-A-56-24987. After that, the structure by this technique is improved to increase the luminous efficiency by forming irregularities on the light-emitting surface. Although a technique for improving the light emission efficiency by devising the shape of the light extraction surface has been proposed (see Japanese Patent Application Laid-Open No. 11-251639), the light emission efficiency can be sufficiently increased to a degree that is still satisfactory. It is not possible and response speed is insufficient.
[0003]
The configuration of a conventional LED will be described with reference to FIG. In the figure, reference numeral 11 denotes a gallium arsenide (GaAs) substrate. On the GaAs substrate 11, a one-conductivity-type semiconductor layer 12 and a reverse-conductivity-type semiconductor layer 13 are sequentially stacked. Then, a reverse conductivity type semiconductor ohmic electrode 14 is formed, and a one conductivity type semiconductor ohmic electrode 15 is formed on the back surface of the GaAs substrate 11.
[0004]
The one conductivity type semiconductor layer 12 and the opposite conductivity type semiconductor layer 13 are mainly grown by LPE. According to this growth method, when silicon (Si) is doped as an impurity during GaAs film formation, it uses the property of entering a Ga lattice at a high temperature and serving as a donor, and entering a As lattice and accepting at a low temperature. However, it can be manufactured very easily, but on the other hand, it is not sufficient in terms of confining carriers in the light emitting layer, and thus the light emission efficiency cannot be increased. In this case, the emission wavelength is around 940 nm.
[0005]
In such an LED, a voltage is applied between the reverse-conductivity-type semiconductor ohmic electrode 14 and the one-conductivity-type semiconductor ohmic electrode 15 to cause a light-emitting diode to emit light by passing a current.
[0006]
Such an LED has a basic configuration, but actually, a plurality of LED elements are provided on one GaAs substrate as a unit, and at that time, each of the LED elements has a reverse conductivity type semiconductor ohmic electrode 14 and a one conductivity type semiconductor ohmic. The electrode 15 is formed. After that, it is cut by a method such as dicing, whereby each element is separated. Then, die bonding, wire bonding, epoxy resin coating or the like is performed on each of these LED elements to form an LED.
[0007]
[Problems to be solved by the invention]
In recent years, the demand for low power consumption type LEDs, particularly low drive voltage type LEDs, has been increasing, and when using them as infrared remote control LEDs, the power consumption can be reduced by lowering the voltage of the power supply. In order to reduce such a driving voltage, the following technique has been proposed.
[0008]
That is, the driving voltage of the light emitting diode is determined by the current value to be driven, the element resistance, and the threshold value of the light emitting diode, but in order to reduce the driving current value, the light emission efficiency of the LED may be increased, which is necessary. The current required to obtain an output can be reduced.
[0009]
Since the element resistance is determined mainly by the resistance of the element and the ohmic resistance with the electrode, each resistance may be reduced in order to reduce the drive voltage. However, there has not yet been a significant difference in materials that are generally used in recent years.
[0010]
The threshold value of the diode is determined by the band gap of the light emitting layer including the cladding layer. In order to reduce the driving voltage, it is preferable that the light emitting layer has a band gap as small as possible. Therefore, in the case of an infrared remote control LED, it is more advantageous to use a material such as InGaAs having a smaller band gap than using GaAs for the light emitting layer.
[0011]
However, since there is a difference in lattice constant between InGaAs and AlGaAs usually used for the cladding layer, when grown as it is, a good crystal cannot be obtained, and therefore, the current infrared All of the remote control LEDs use GaAs, thereby using light emission having a wavelength of around 940 nm.
[0012]
As a result of diligent research in view of the above circumstances, the present inventor has determined that the light emitting layer constituting the reverse conductivity type semiconductor layer is an InGaAs / GaAs strained superlattice structure in the stack of one conductivity type semiconductor layer and the reverse conductivity type semiconductor layer. Thus, by setting the emission wavelength to 950 to 1050 nm with this InGaAs / GaAs strained superlattice layer, the emission efficiency is improved, the device resistance is reduced, and the threshold value of the diode is reduced, thereby driving voltage. Has been found to be significantly reduced.
[0013]
Therefore, the present invention has been completed based on the above knowledge, and its object is to provide an infrared remote control LED that achieves low power consumption, further enhances responsiveness, and enhances information transmission ability over conventional remote controls. There is.
[0016]
[Means for Solving the Problems]
In the infrared remote control LED of the present invention, a reverse conductivity type semiconductor layer including a one conductivity type semiconductor layer and a light emitting layer and a reverse conductivity type semiconductor ohmic electrode are sequentially formed on a substrate, and one of the one conductivity type semiconductor layers is formed. And removing the conductive layer and the opposite conductivity type semiconductor layer thereon to provide a stepped portion, and forming a one-conductivity-type semiconductor ohmic electrode on the exposed surface of the stepped portion, and exposing the exposed surface in the one-conductivity- type semiconductor layer An AlGaAs / GaAs Bragg reflective layer is inserted below, and the light emitting layer of the reverse conductivity type semiconductor layer has an InGaAs layer and a GaAs layer each having a thickness of 50 to 300 mm, and In _x Ga _1-x As In The composition x was 0.15 to 0.3, the InGaAs / GaAs strained superlattice structure having 5 to 15 layers was used, and the emission wavelength was set to 950 to 1050 nm. It is characterized by that.
[0019]
Hereinafter, the infrared remote control LED of the present invention will be described with reference to FIG. 6, and FIGS. 1, 2, 4 and 5 are shown as reference diagrams of the infrared remote control LED. Incidentally, these figures 1, 2, 4, 5, 6 each a cross-sectional view of an LED infrared remote control.
[0020]
(Example 1)
In the infrared remote control LED (A) shown in FIG. 1, reference numeral 1 denotes a substrate, and a one-conductivity-type semiconductor layer 2 and a reverse-conductivity-type semiconductor layer 3 are sequentially stacked on the substrate 1, thereby forming a reverse-conductivity-type semiconductor layer. A reverse conductivity type semiconductor ohmic electrode 4 is formed on the substrate 3. A one-conductivity type semiconductor ohmic electrode 5 is formed on the back surface of the substrate 1.
[0021]
In the present invention, the light emitting layer constituting the reverse conductivity type semiconductor layer 3 is further formed as an InGaAs / GaAs strained superlattice structure 6.
[0022]
The substrate 1 is made of a single crystal insulating substrate or a single crystal semiconductor substrate such as gallium arsenide (GaAs) or silicon (Si). In the case of a single crystal semiconductor substrate, a substrate in which the (100) plane is turned off by 2 to 7 degrees in the <011> direction is used.
[0023]
The one conductivity type semiconductor layer 2 has a configuration in which a buffer layer 2a and an electron injection layer 2c are sequentially stacked.
[0024]
The buffer layer 2a is formed of gallium arsenide or the like, and the electron injection layer 2c is formed of aluminum gallium arsenide or the like.
[0025]
The thickness of the buffer layer 2a may be about 0.5 to 4 μm, and the thickness of the electron injection layer 2c may be about 0.2 to 1 μm.
[0026]
The buffer layer 2a and the electron injection layer 2c contain about 1 × 10 ¹⁶ to 10 ¹⁸ atoms / cm ³ of one conductivity type semiconductor impurity such as silicon. The Al composition of the electron injection layer 2b is made of Al _x Ga _1-x As so that x is about 0.1 to 0.5.
[0027]
The reverse conductivity type semiconductor layer 3 is configured by sequentially forming a light emitting layer 3a, a cladding layer 3b, and an ohmic contact layer 3c.
[0028]
The light emitting layer 3 a is an InGaAs / GaAs strained superlattice structure 6. The strained superlattices each have a thickness of 50 to 300 mm, the In composition of indium gallium arsenide is x = 0.15 to 0.3, and the number of layers is 5 to 15 layers. In addition, AlAs may be mixed in the GaAs layer in order to improve luminous efficiency. The emission wavelength is determined by the thickness of InGaAs and the In composition of InGaAs, and the emission wavelength is 950 to 1050 nm.
[0029]
For example, by setting x = 0.3, InGaAs film thickness: 30 mm, and superlattice GaAs film thickness: 100 mm, a wavelength of 918 nm can be obtained.
[0030]
Further, by setting x = 0.3, InGaAs film thickness: 40 mm, and superlattice GaAs film thickness: 100 mm, a wavelength of 945 nm can be obtained.
[0031]
Furthermore, by setting x = 0.3, InGaAs film thickness: 50 mm, and superlattice GaAs film thickness: 100 mm, a wavelength of 976 nm can be obtained.
[0032]
The reason why the emission wavelength is defined in the range of 950 to 1050 nm is as follows.
[0033]
In order to lower the threshold value of the light emitting diode, it is desirable to make the emission wavelength as long as possible, but on the other hand, the light receiving sensitivity of the silicon photodiode decreases as it becomes longer. The threshold value of the diode is determined by the band gap of the light emitting layer including the cladding layer. In order to reduce the drive voltage, it is preferable that the light emitting layer has a band gap as small as possible. For this reason, in the case of an infrared remote control LED, it is better to increase the emission wavelength within a range where the efficiency of the light receiving element does not decrease. In the present invention, the optimum emission wavelength is 950 to 1050 nm. This was confirmed by repeated experiments.
[0034]
The clad layer 3b is made of a mixed crystal of aluminum arsenic (AlAs) and gallium arsenide (GaAs) in consideration of the electron confinement effect and the light extraction effect.
[0035]
The light emitting layer 3a and the cladding layer 3b contain about 1 × 10 ¹⁶ to 10 ¹⁸ atoms / cm ³ of a reverse conductivity type semiconductor impurity such as zinc (Zn), and the ohmic contact layer 3c contains a reverse conductivity type semiconductor impurity such as zinc. It contains about 1 × 10 ¹⁹ to 10 ²⁰ atoms / cm ³ .
[0036]
The ohmic contact layer 3c is made of gallium arsenide or the like.
[0037]
The clad layer 3b is preferably formed to a thickness of about 0.2 to 2 μm, and the ohmic contact layer 3c is preferably formed to a thickness of about 0.01 to 0.1 μm.
[0038]
The reverse conductivity type semiconductor ohmic electrode 4 and the one conductivity type semiconductor ohmic electrode 5 are made of gold, a gold germanium alloy, or the like, and are formed with a thickness of about 1 μm.
[0039]
Thus, according to the infrared remote control LED (A) of the present invention, the light emitting layer 3a of the reverse conductivity type semiconductor layer 3 has the InGaAs / GaAs strained superlattice structure 6 so that the light emission wavelength is 950 to 1050 nm. Thereby, by using the light emitting layer of the InGaAs / GaAs strained superlattice structure 6, effective carriers are confined in the InGaAs layer which is a well layer, the light emission efficiency is increased, the light emission intensity is increased, and the light emission wavelength is further increased to 950. By setting the thickness to 1050 nm, the band gap of the light emitting layer can be reduced, and the threshold value of the diode can be reduced. Therefore, the luminous efficiency is improved, the luminous intensity is increased, the element resistance is further reduced, and the threshold value of the diode is reduced. As a result, an infrared remote control LED having a reduced driving voltage is obtained.
[0040]
According to experiments conducted by the present inventors, the conventional infrared remote control LED is driven with a pulse current of about 500 mA and the drive voltage is 2 V or more. In the remote control LED, since the luminous efficiency was improved, the same level of output was obtained by driving at 100 mA, and thus it could be driven at 1.5 V or less.
[0041]
(Example 2)
In the infrared remote control LED (B) of this example, compared to the infrared remote control LED (A) of (Example 1), the AlGaAs / GaAs Bragg reflection layer 7 is provided between the buffer layer 2a and the electron injection layer 2c. Is interposed. Other configurations are the same as those of the infrared remote control LED (A).
[0042]
The AlGaAs / GaAs Bragg reflecting layer 7 is formed by alternately stacking AlGaAs and GaAs having different refractive indexes with an optical thickness of ¼ wavelength, and is used as a reflecting mirror, and is emitted from the light emitting layer 3a to the substrate 1 side. It plays a role of reflecting the reflected light to the light extraction side.
[0043]
The AlGaAs / GaAs Bragg reflection layers 7 each have 3 to 15 layers, and the Al composition of AlGaAs is about 0.5 to 0.9, preferably 0 in Al _x Ga _1-x As. It is good to form about 0.5-0.7. By reducing the Al composition in this way, the resistance of the reflective layer 7 becomes very small.
[0044]
Thus, according to the infrared remote control LED (B) of the present invention, the AlGaAs / GaAs Bragg reflection layer 7 is provided inside the one-conductivity-type semiconductor layer 2 to reflect the light toward the back surface, thereby emitting light. The efficiency was further improved and the emission intensity was increased, so that the drive voltage could be further lowered and the drive voltage could be further reduced.
[0045]
When the present inventor compared the infrared remote control LED (A) and the infrared remote control LED (B), the results shown in FIG. 3 were obtained. The relationship between drive current and light emission intensity with and without the Bragg reflection layer 7 is shown.
[0046]
As is clear from this result, the emission intensity increased 1.7 times by providing the Bragg reflection layer 7. In addition to the increase in drive voltage due to the increase in resistance due to the inclusion of the reflective layer 7, the effect of reducing the drive voltage due to the increase in the light emission intensity of 1.7 is thus increased, and the drive voltage can be reduced. It was.
[0047]
(Example 3)
In the infrared remote control LED (C) of this example, the infrared remote control LED (B) of (Example 2) is etched away so as to expose a part of the one-conductivity-type semiconductor layer 2 (this etching). When the treatment is performed, the opposite conductivity type semiconductor layer 3 on the upper side is also etched), thereby providing a stepped portion and forming the one-conductivity type semiconductor ohmic electrode 5 on the exposed surface of the stepped portion.
[0048]
In this case, since the ohmic contact state with the one-conductivity-type semiconductor layer 2 must be taken, the ohmic contact layer 2b is put in the one-conductivity-type semiconductor layer 2 and etching is performed so as to expose this layer. One conductivity type semiconductor ohmic electrode 5 is formed on the exposed surface of the stepped portion. Therefore, in the infrared remote control LED (C), the one-conductivity-type semiconductor layer 2 has a configuration in which the buffer layer 2a, the ohmic contact layer 2b, and the electron injection layer 2c are sequentially stacked.
[0049]
In addition, the same code | symbol is attached | subjected to the same location as LED (B) for infrared remote controls shown in FIG.
[0050]
The ohmic contact layer 2b is made of gallium arsenide or the like and has a thickness of about 0.5 to 4 μm.
[0051]
The buffer layer 2a and the electron injection layer 2c contain about 1 × 10 ¹⁶ to 10 ¹⁸ atoms / cm ³ of one conductivity type semiconductor impurity such as silicon, whereas the ohmic contact layer 2b is a one conductivity type semiconductor such as silicon. Impurities may be contained in an amount of about 1 × 10 ¹⁶ to 10 ¹⁹ atoms / cm ³ .
[0052]
Thus, according to the infrared remote control LED (C), a part of the one-conductivity-type semiconductor layer 2 is etched away to provide a stepped portion as described above, and the one-conductivity-type semiconductor ohmic is formed on the exposed surface of the stepped portion. By forming the electrode 5, no current flows near the interface between the substrate 1 and the one-conductivity-type semiconductor layer 2, and flows through the ohmic contact layer and the buffer layer. As a result, the element resistance was lowered, and as a result, the drive voltage could be reduced.
[0053]
The present inventor was able to reduce the resistance to 2.5Ω in the infrared remote control LED (C), compared with 2.8Ω (300 μm □) in the conventional infrared remote control LED.
[0054]
(Example 4)
In the infrared remote control LED (D) of this example, the one-conductivity-type semiconductor layer 2 has a configuration in which a buffer layer 2a, an ohmic contact layer 2b, an AlGaAs / GaAs Bragg reflection layer 7, and an electron injection layer 2c are sequentially stacked. .
[0055]
The ohmic contact layer 2b is made of gallium arsenide or the like and has a thickness of about 0.5 to 4 μm.
[0056]
Further, the buffer layer 2a, the AlGaAs / GaAs Bragg reflection layer 7, and the electron injection layer 2c contain about 1 × 10 ¹⁶ to 10 ¹⁸ atoms / cm ³ of one conductivity type semiconductor impurity such as silicon, whereas the ohmic contact layer 2b May contain about 1 × 10 ¹⁶ to 10 ¹⁹ atoms / cm ³ of one conductivity type semiconductor impurity such as silicon.
[0057]
In this example, the AlGaAs / GaAs Bragg reflection layer 7 is disposed between the ohmic contact layer 2b and the electron injection layer 2c.
[0058]
Thus, according to the infrared remote control LED (D), as in the above configuration, a part of the one-conductivity-type semiconductor layer 2 is removed by etching to provide a step portion, and the one-conductivity-type semiconductor is formed on the exposed surface of the step portion. By forming the ohmic electrode 5, no current flows near the interface between the substrate 1 and the one-conductivity-type semiconductor layer 2, thereby reducing the element resistance, and as a result, the driving voltage can be reduced. In addition, by introducing the reflective layer 7, the light emission intensity increased and the drive voltage could be further lowered.
[0059]
The inventor obtained the same result as the effect of Example 2, and was able to further reduce the drive voltage by increasing the emission intensity.
[0060]
(Example 5)
In the infrared remote control LED (D), the one-conductivity-type semiconductor layer 2 has a configuration in which a buffer layer 2a, an ohmic contact layer 2b, an AlGaAs / GaAs Bragg reflection layer 7, and an electron injection layer 2c are sequentially stacked. In the infrared remote control LED (E) of this example, instead of such a stacking order, the one-conductivity-type semiconductor layer 2 includes a buffer layer 2a, an AlGaAs / GaAs Bragg reflection layer 7, an ohmic contact layer 2b, an electron The injection layer 2c is sequentially laminated so that the AlGaAs / GaAs reflection layer 7 is disposed below the exposed surface of the stepped portion.
[0061]
According to such an infrared remote control LED (E), the current flows only through the ohmic contact layer 2b and reaches the electron injection layer 2c, whereby the reverse conductivity type semiconductor ohmic electrode 4 and the one conductivity type are reached. Emitting light by enlarging the current path with the semiconductor ohmic electrode 5 significantly reduced the device resistance and reduced the driving voltage.
[0062]
According to the experiment conducted by the present inventors, the emission intensity was improved to the same level as that in Example 4 and the resistance was reduced to the same level as that in Example 3 by the element resistance.
[0063]
Moreover, when this inventor measured light emission intensity and a current-voltage curve about LED for conventional infrared remote control and LED for infrared remote control (E) of this invention, as shown in FIG.7 and FIG.8. Results were obtained.
[0064]
FIG. 7 shows the relationship between current and emission intensity. FIG. 8 shows a current-voltage curve. As is clear from the results shown in FIG. 7, in the infrared remote control LED (E) of the present invention, the light emission intensity is enhanced by the superlattice structure and the reflective layer, as compared with the conventional infrared remote control LED. This is because the emission intensity is increased about 1.5 times by the superlattice structure, and the emission intensity is increased about 1.7 times by the reflective layer.
[0065]
Further, with respect to the current-voltage curve shown in FIG. 8, the superlattice structure is used to make the emission wavelength longer than 950 nm, thereby reducing the threshold value and exposing a part of the one-conductivity-type semiconductor layer 2. The one-conductivity-type semiconductor ohmic electrode 5 was connected to the exposed portion, and the drive voltage could be reduced by about 0.1 V (compared with 100 mA).
[0066]
[Production Method of Infrared Remote Control LEDs (C), (D) and (E)]
A plurality of island-like semiconductor layers including a one-conductivity-type semiconductor layer 2 and a reverse-conductivity-type semiconductor layer 3 are formed on a large substrate 1, and a part of each reverse-conductivity-type semiconductor layer 3 is etched, whereby one-conductivity-type semiconductor is formed. A part of the layer 2 is etched away to provide a stepped portion, and a one-conductivity-type semiconductor ohmic electrode 5 is formed on the exposed surface of the stepped portion, and a reverse-conductivity-type semiconductor is further formed on each reverse-conductivity-type semiconductor layer 3. A connection is formed to the ohmic electrode 4.
[0067]
The etching includes wet etching using a sulfuric acid hydrogen peroxide-based etching solution and dry etching using CCl ₂ F ₂ gas.
[0068]
The island-shaped semiconductor layer composed of the one-conductivity-type semiconductor layer 2 and the reverse-conductivity-type semiconductor layer 3 may be formed by sequentially stacking by MOCVD.
[0069]
Most of the conventional infrared remote control LEDs shown in FIG. 9 are manufactured by the LPC method. However, the infrared LED obtained by this film forming method has a long carrier diffusion distance, and therefore has a responsiveness. It was inferior to.
[0070]
On the other hand, in the present invention, by forming a film by the MOCVD method, the diffusion distance of carriers is shortened, thereby being excellent in responsiveness and suitable for an infrared LED. In this example, it is manufactured by the MOCVD method.
[0071]
Hereinafter, the MOCVD method will be described in detail.
[0072]
In order to form the one-conductivity-type semiconductor layer 2 and the reverse-conductivity-type semiconductor layer 3, the substrate temperature is set to 400 to 500 ° C., an amorphous gallium arsenide film is formed to a thickness of 200 to 2000 mm, It can be obtained by raising the substrate temperature to 600 to 900 ° C.
[0073]
In order to use this MOCVD method, the source gases are TMG ((CH ₃ ) ₃ Ga), TEG ((C ₂ H ₅ ) ₃ Ga), arsine (AsH ₃ ), TMA ((CH ₃ ) ₃ Al). , TEA ((C ₂ H ₅ ) ₃ Al) or the like is used.
[0074]
Silane (SiH ₄ ), hydrogen selenide (H ₂ Se), TMZ ((CH ₃ ) ₃ Zn), or the like is used as a gas for controlling the conductivity type, and carrier gas includes H ₂ or the like. .
[0075]
The one-conductivity-type semiconductor ohmic electrode 5 and the reverse-conductivity-type semiconductor ohmic electrode 4 are patterned by forming Au, AuGe, or the like by vapor deposition or sputtering.
[0076]
Thereafter, each LED element is cut and separated by a method such as dicing. Then, by applying die bonding, wire bonding and epoxy resin coating to each LED element, an infrared remote control LED is obtained.
[0077]
【The invention's effect】
As described above, according to the infrared remote control LED of the present invention, the reverse conductivity type semiconductor layer including the one conductivity type semiconductor layer and the light emission layer is formed on the substrate, and the light emission layer constituting the reverse conductivity type semiconductor layer is formed of InGaAs. InGaAs / GaAs layers each having a thickness of 50 to 300 mm, In _x Ga _1-x As, In composition x = 0.15 to 0.3, and the number of layers of 5 to 15 layers, respectively. By adopting a GaAs strained superlattice structure and setting the emission wavelength to 950 to 1050 nm, the emission efficiency is improved, the element resistance is reduced, the threshold value of the diode is reduced, and the drive voltage is thereby greatly reduced. As a result, it has been possible to provide a high-performance infrared remote control LED with improved responsiveness and, as a result, improved information transmission capability.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an infrared remote control LED.
FIG. 2 is a cross-sectional view of another infrared remote control LED.
FIG. 3 is a diagram showing a relationship between a current value and emission intensity.
Is a cross-sectional view of another LED infrared remote control Figure 4 is found.
FIG. 5 is a cross-sectional view of another infrared remote control LED.
6 is a cross-sectional view of an LED infrared remote control of the present invention.
FIG. 7 is a diagram showing a relationship between a current value and light emission intensity.
FIG. 8 is a diagram showing a relationship between current and voltage.
FIG. 9 is a cross-sectional view of a conventional infrared remote control LED.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... One conductivity type semiconductor layer, 3 ... Reverse conductivity type semiconductor layer, 4 ... Reverse conductivity type semiconductor ohmic electrode, 5 ... One conductivity type semiconductor ohmic electrode, 6. ..InGaAs / GaAs strained superlattice, 7 ... AlGaAs / GaAs Bragg reflection layer

Claims (1)

A reverse conductivity type semiconductor layer including a one conductivity type semiconductor layer and a light emitting layer and a reverse conductivity type semiconductor ohmic electrode are sequentially formed on a substrate, and a part of the one conductivity type semiconductor layer and the reverse conductivity type semiconductor thereon are formed. The step is provided by removing the layer by etching, and a one-conductivity type semiconductor ohmic electrode is formed on the exposed surface of the step portion, and an AlGaAs / GaAs Bragg reflective layer below the exposed surface in the one-conductivity type semiconductor layer. The InGaAs layer and the GaAs layer each have a thickness of 50 to 300 mm, and the In composition of In _x Ga _1-x As x = 0.15 to 0. Infrared remote control L characterized by having an InGaAs / GaAs strained superlattice structure having 3 layers and 5 to 15 layers and setting the emission wavelength to 950 to 1050 nm ED.

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