JPH1022524A - Semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device having a high max. output of emission, superior emission efficiency and superior high speed response. SOLUTION: An n-AlGaInP lower clad layer 2, p-GaInP active layer 4, first AlGaP upper clad layer 5 and second p-AlGaInP upper clad layer 7 are epitaxially grown on a GaAs substrate 1. A superlattice layer 3 is formed at a position adjacent to the active layer 4 as a part of the lower clad layer 2. A multiple quantum barrier layer 6 is formed at a position adjacent to the first clad layer 5 as a part of the second clad layer 7. The first clad layer 5 is a resonance tunneling-prevented layer. The active layer 4 is set as thin as to 0.1-2.0 microns. Owing to a mini-band communicating with the active layer 4 formed on the super-lattice layer 3, electrons are efficiently injected into the active layer 4 and efficiently confined in the active layer 4 by the potential barrier enhanced by the tunneling prevented layer and barrier layer 6, thus improving the electron confining efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor light emitting device.

[0002]

2. Description of the Related Art One of the performances required for a semiconductor light emitting device is high-speed response. For example, when a light-emitting diode is used as an electric signal-optical signal conversion element of an optical communication device, a light-emitting diode having good high-speed response has a large amount of information that can be transmitted per unit time.
An optical device suitable for high-speed data communication and large-capacity data transmission.

Conventionally, in order to realize a high-speed response of a light-emitting diode, a method of increasing the impurity concentration in an active layer of the light-emitting diode or reducing the thickness (thinning) of the active layer has been adopted. However, although these methods realize a high-speed response, the maximum output of the light emitted from the light emitting diode is reduced accordingly. In particular, the thinning of the active layer makes it possible to relatively easily realize a light-emitting diode having a high-speed response, but with this, the maximum output of emitted light is significantly reduced.

In a semiconductor light emitting device, a double heterojunction structure is often used to efficiently confine injected electrons or holes contributing to light emission in an active layer. The injected carriers are confined by a potential barrier at the heterojunction between the active layer and the cladding layer.
Injecting carriers into the active layer beyond the amount of carriers that can be confined in the active layer does not contribute to the emitted light, and the carriers exceeding the potential barrier overflow from the active layer. When the thickness of the active layer is reduced, the amount of carriers that can be confined in the active layer decreases, so that the maximum output of the emitted light decreases.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a semiconductor light emitting device having a large maximum output of emitted light, excellent luminous efficiency and high-speed response.

A semiconductor light emitting device according to the present invention comprises a semiconductor light emitting device including an active layer and cladding layers provided on both sides of the active layer. One of the cladding layers is formed so as to form a mini-band leading to the active layer. A grid layer is provided,
A multi-quantum barrier layer is provided on the other cladding layer, and a resonance tunneling prevention layer is provided between the active layer and the multi-quantum barrier layer. Preferably, the thickness of the active layer is set to 0.1 μm to 2.0 μm.

[0007] Since a mini-band leading to the active layer is formed in the superlattice layer formed on one clad layer, carriers are efficiently injected into the active layer through the mini-band.
Carriers efficiently injected into the active layer are reflected by the high potential barrier formed by the multiple quantum barrier layer of the other cladding layer. For this reason, carrier overflow hardly occurs, and the carrier is efficiently confined in the active layer. Further, the carriers trapped in the active layer do not leak to the multiple quantum barrier layer due to the resonance tunneling prevention layer between the active layer and the multiple quantum barrier layer.
This also improves the carrier confinement efficiency. Efficient injection of carriers into the active layer enhances the luminous efficiency of the active layer, and the high potential barrier and the anti-resonance tunneling layer improve the confinement efficiency of the carriers, thereby emitting light with high luminous efficiency and high maximum output. Can be done. In addition, even if the active layer is thinned to achieve a high-speed response, it is possible to maintain a high luminous efficiency and increase the light output.

[0008] In one embodiment of the present invention, the energy level of the mini-band leading to the active layer is formed so as to become lower as approaching the active layer. This is realized, for example, by forming each layer of the superlattice layer provided in contact with the active layer so as to gradually increase in thickness as approaching the active layer. Since the miniband is formed so as to decrease from a high energy level to a low energy level as approaching the active layer, carriers can be efficiently injected into the active layer.

[0009] In another embodiment of the present invention, at least one quantum well layer is provided in the active layer. As a result, the emission wavelength of the active layer can be shortened, and the threshold current density can be reduced.

In still another embodiment according to the present invention,
A current constriction structure is provided between the active layer and the light extraction surface of the light emitting element. By forming a current confinement structure between the active layer and the light extraction surface so that the current flows intensively directly below the light extraction region, the active layer emits light more efficiently and the light extraction efficiency is improved.

In still another embodiment according to the present invention,
A reflection layer is provided for reflecting light emitted to the semiconductor substrate side of the light generated in the active layer to the light extraction region. Since the light emitted from the active layer to the side opposite to the light extraction region can be reflected and extracted from the light extraction region to the outside, the light extraction efficiency can be improved. Such a reflective layer is realized by, for example, a multilayer reflective film.

Since the semiconductor light emitting device according to the present invention can have a small light emission diameter and can increase the maximum output of emitted light, it can be used for an optical detection device, an optical information processing device, and other optical devices. Accordingly, various optical devices having good optical performance can be manufactured. Furthermore, since it has high-speed response, high-speed data communication and large-capacity data transmission can be performed by using the optical communication device or the like.

[0013]

【Example】

First Embodiment FIGS. 1A and 1B show a light emitting diode according to a first embodiment. FIG. 1A is a cross-sectional view schematically showing the structure of the light emitting diode, and FIG. 1B shows the energy band gap of its conduction band. Is shown.

This light emitting diode is manufactured by the MBE method (Molecula
r Beam Epitaxy (Molecular Beam Epitaxy), MOCVD (Metal Organic Chemical Vapor Deposition), LPE (Liquid Phase Epitaxy), etc. nA
1GaInP lower cladding layer 2, p-GaInP active layer 4, AlGaP upper first cladding layer 5, and p-AlG
It has a structure in which the aInP upper second cladding layer 7 is sequentially laminated. The superlattice layer 3 is provided at a position in contact with the active layer 4 as a part of the n-AlGaInP lower cladding layer 2. The multiple quantum barrier layer 6 is provided as a part of the p-AlGaInP upper second cladding layer 7 at a position in contact with the AlGaP upper first cladding layer 5. A p-side electrode 8 is formed on the upper surface of the upper second cladding layer 7, and an n-side electrode 9 is formed on the lower surface of the GaAs substrate 1. The light extraction region 10 is the central region of the upper surface of the upper second cladding layer 7 excluding the portion where the p-side electrode 8 is formed. If necessary, a multilayer reflective film layer 11 is provided between the substrate 1 and the lower cladding layer 2. The thickness of the active layer 4 is set as thin as about 0.1 μm to 2.0 μm.

The superlattice layer 3 is formed by alternately laminating a plurality of superlattice well layers 3a and superlattice barrier layers 3b. The energy gap of the superlattice well layer 3a is small, and the energy gap of the superlattice barrier layer 3b is large. N-GaInP is used as the superlattice well layer 3a, and p-AlGaInP is used as the superlattice barrier layer 3b. The superlattice layer 3 has a stacked structure called a superlattice or a multi-quantum barrier (MQB). This is realized by alternately stacking a plurality of thin layers made of two kinds of semiconductor materials having different energy gaps.

Since the superlattice layer 3 has a superlattice structure, a mini band is formed in the energy band structure.
Since the superlattice layer 3 is provided in contact with the active layer 4, the mini band is formed so as to communicate with the active layer 4. A semiconductor layer in which a mini-band leading to the active layer 4 is formed is referred to as a superlattice layer 3 in order to distinguish it from a multiple quantum barrier layer 6 described later.

Further, since the superlattice layer 3 has a multiple quantum barrier structure, a high potential barrier is formed at the hetero interface between the active layer 4 and the superlattice layer 3. The potential barrier formed by the multiple quantum barrier structure has a height that exceeds the potential barrier formed by a single clad layer.

The multiple quantum barrier layer 6 is formed by alternately stacking a plurality of superlattice well layers 6a and superlattice barrier layers 6b. The energy gap of the superlattice well layer 6a is small, and the energy gap of the superlattice barrier layer 6b is large. N-GaInP is used as the superlattice well layer 6a, and p-AlGaInP is used as the superlattice barrier layer 6b. The multiple quantum barrier layer 6 is also a superlattice (Superlat
tice) or Multi-Quantum Barrier: M
It has a laminated structure called QB).

Since the multiple quantum barrier layer 6 also has a superlattice structure, a mini band is formed in its energy band structure. However, since the upper first cladding layer 5 is formed between the multiple quantum barrier layer 6 and the active layer 4, the mini-band formed in the energy structure of the multiple quantum barrier layer 6 does not I don't communicate. Upper first cladding layer 5
Is formed with a large energy gap and a large layer thickness.

The upper first cladding layer 5 also prevents carriers in the active layer 4 from leaking into the multiple quantum barrier layer 6 due to a tunnel effect. That is, the upper first cladding layer 5 forms a resonance tunneling prevention layer.

Further, since the multiple quantum barrier layer 6 has a multiple quantum barrier structure, a high potential barrier is formed at the hetero interface between the active layer 4 and the resonance tunneling prevention layer 5. The high potential barrier increases the reflectivity for carriers that overflow from the active layer to the cladding layer. The high potential barrier due to the multiple quantum barrier structure and the above-mentioned upper first cladding layer (resonant tunneling prevention layer) 5 further enhance the carrier confinement efficiency on the multiple quantum barrier layer 6 side.

The potential barrier in the multiple quantum barrier layer 6 includes a well layer 6a and a barrier layer 6b that constitute the multiple quantum barrier.
Strongly depends on the potential difference between Preferably, n of the superlattice well layer 6a constituting the multiple quantum barrier layer 6 is
-The In composition ratio of GaInP is set to be larger than 0.5. Thereby, the potential barrier in the multiple quantum barrier layer 6 is sufficiently increased. This applies to the superlattice layer 3 as well.

The superlattice layer 3 and the multiple quantum barrier layer 6 can be formed of different materials. For example, n-GaInP is used for the superlattice well layer 3a constituting the superlattice layer 3, p-AlGaInP is used for the superlattice barrier layer 3b, n-InGaAs is used for the superlattice well layer 6a constituting the multiple quantum barrier layer 6, and P-InP can be used for the lattice barrier layer 6b.

When a current flows between the p-side electrode 8 and the n-side electrode 9, carriers are injected into the semiconductor layer forming the light emitting diode. Hereinafter, an example of electron injection will be described. The electrons are excited from the valence band (not shown) to the conduction band, and flow from the n-side electrode 9 side to the p-side electrode 8 side.

Electrons excited from the valence band (not shown) to the conduction band of the superlattice layer 3 are efficiently carried into the active layer 4 through the miniband without being confined in the superlattice well layer 3a.

The efficient injection of electrons into the active layer 4 by the mini-band has the effect of suppressing the temperature rise of the active layer 4. Generally, the light emitting efficiency of a light emitting diode decreases due to an increase in the temperature of the active layer. Since the temperature rise of the active layer 4 is suppressed by efficient electron injection by the mini-band, it is possible to prevent a decrease in the luminous efficiency of the active layer 4.

The electrons efficiently carried into the active layer 4 through the mini-band formed in the superlattice layer 3 and the electrons directly excited from the valence band (not shown) to the conduction band in the active layer 4 are active. The light is efficiently reflected by the high potential barrier formed at the hetero interface between the layer 4 and the upper first cladding layer 5. Therefore, many electrons are confined in the active layer 4, and the electron confinement efficiency is improved. The increase in the electron confinement efficiency due to the potential barrier enhanced by the resonance tunneling prevention layer and the multiple quantum barrier layer 6 can be larger than the decrease in the electron confinement efficiency caused by making the active layer 4 thinner.

Since the electrons are efficiently injected into the active layer 4 through the mini-band, the luminous efficiency of the active layer 4 is improved. Further, by reducing the thickness of the active layer 4, the high-speed response of the light emitting diode can be improved, and the electron trapping efficiency can be improved by the resonance tunneling prevention layer and the high potential barrier. Therefore, a light-emitting diode having high-speed response, high luminous efficiency and a large maximum value of light output is realized. High-output light is extracted from the light extraction region 10 to the outside.

The active layer 4 may have a quantum well structure in which well layers and barrier layers are alternately stacked. This quantum well structure may be either a single quantum well or a multiple quantum well. By providing a quantum well structure in the active layer 4, the active layer 4
The emission wavelength of the light is shortened, and the threshold current density can be reduced.

A part of the light generated in the active layer 4 is directed to the substrate 1 and is absorbed. By providing a multilayer reflective film layer between the substrate 1 and the lower cladding layer 2 as indicated by a chain line 11, the light generated in the active layer 4 and directed to the side opposite to the light extraction region 10 is reflected by the reflective film. And can be extracted from the light extraction area 10. Thereby, light extraction efficiency can be increased. This multilayer reflective film layer 11 is made of Al _0.1
It is formed by alternately stacking Ga _0.9 As layers and AlAs layers.

The multilayer reflective film layer 11 is constituted by stacking 10 to 30 unit layers with two layers having different refractive indexes as one unit. Assuming that the refractive indices of these two layers having different refractive indices are n ₁ and n ₂ respectively, their thicknesses are d ₀₁ and d _02, and the emission wavelength of the active layer 4 is λ ₀ , Related by

[0032]

## EQU1 ## d ₀₁ = λ ₀ / (4n ₁ ) Equation 1 d ₀₂ = λ ₀ / (4n ₂ ) Equation 2

Second Embodiment FIGS. 2A and 2B show a light emitting diode according to a second embodiment. FIG. 2A is a sectional view schematically showing the structure of the light emitting diode, and FIG. 2B shows the energy band gap. I have. This light emitting diode differs from the light emitting diode shown in FIG. 1 in the structure of the superlattice layer.

The superlattice well layer 3a and the superlattice barrier layer 3b constituting the superlattice layer 3 are formed so that their thickness gradually increases from the n-side electrode 9 side to the active layer 4 side. . The energy level at the top of the mini-band (upper bandgap) and the bottom of the mini-band (lower bandgap) where the thickness is small
Width between the energy levels of the (mini-band width)
Is wide and narrow as the film thickness increases.
The energy levels of the upper and lower forbidden bands shift to lower energy levels as the thicknesses of the superlattice well layer 3a and the superlattice barrier layer 3b increase. The energy width of the mini-band and its energy level are
Can be changed by another method such as using another semiconductor material for the superlattice well layer 3a or the superlattice barrier layer 3b. Superlattice well layer 3a and superlattice barrier layer 3
It goes without saying that b satisfies the condition for forming a miniband (thickness to which an electron wave function is connected) even in the place where the layer thickness is the thickest.

When a current is applied between the p-side and n-side electrodes 8 and 9, the electrons injected into the superlattice layer 3 move from the high energy level to the low energy level through the mini band, and the active layer 4 is efficiently made. It is carried to. Therefore, the light emitting layer 4 emits light efficiently.

Although the illustrated mini-band is formed with a large step, it is possible to form a mini-band whose energy width and energy level change more smoothly by gradually changing the thickness of the superlattice layer 3. Is also possible.

In the first and second embodiments, a resonance tunneling prevention layer is provided on the p-cladding layer side for confining electrons in the active layer 4. Focusing on the holes in the active layer 4, n-
A resonance tunneling prevention layer is provided on the cladding layer side.
In this case, a mini-band leading to the active layer 4 is formed on the p-cladding layer side, and holes are efficiently carried into the active layer from the p-side electrode. The holes efficiently carried into the active layer are efficiently reflected at the hetero interface of the active layer on the n-cladding layer side.

Third Embodiment FIG. 3 shows a third embodiment and is a cross-sectional view schematically showing a structure of a light emitting diode.

The structure of this light emitting diode will be described along with its manufacturing process. First, MBE method, MOCVD method, LP
The multilayer reflective film layer 3 is formed on the GaAs substrate 21 by the E method or the like.
1, n-AlGaInP lower cladding layer 22, superlattice layer 2
3, p-GaInP active layer 24, AlGaInP first cladding layer 25, multiple quantum barrier layer 26 and p-AlGaInP
The upper second cladding layer 27 is sequentially epitaxially grown to form a semiconductor chip.

Next, a region on the upper surface of the upper second cladding layer 27 where the light extraction region 20 is to be formed is covered with a resist film, and n-type ions are implanted into the semiconductor chip using the resist film as a mask. The ion implantation is performed so that the upper end and the lower end of the ion implantation region 32 come into the second upper cladding layer 27. Thereby, the second upper cladding layer 27
An n-type inversion layer (ion-implanted region) 32 is formed therein,
The portion of the second upper cladding layer 27 where the inversion layer 32 is not formed becomes the current path region 33.

Thereafter, the above-mentioned resist film is removed,
A resist film is newly formed on the upper surface of the upper second cladding layer 27 so as to match the opening pattern of the light extraction region 20,
A metal is deposited from above. Thereafter, the resist is removed together with the metal deposited on the upper surface. The remaining metal is p
It becomes the side electrode 28. An n-side electrode 29 is provided on the lower surface of the GaAs substrate 21.
To form

When a current flows between the p-side electrode 28 and the n-side electrode 29, a reverse bias pn junction is formed between the lower surface of the inversion layer 32 and the second upper cladding layer 27. Flows only through the current path region 33 surrounded by the inversion layer 32. A current is injected only into a region of the active layer 24 corresponding to the current passage region 33 to emit light. The light emitted from the active layer 24 is emitted from the light extraction region 20 to the outside. That is, a semiconductor light emitting device having a current constriction structure is formed, and the active layer emits light efficiently.

The light extraction area 20 can be formed small corresponding to the current path area 33. By forming a small light extraction region, emitted light with a small emission diameter can be obtained.

APPLICATION EXAMPLE The semiconductor light emitting device according to the present invention has a large maximum output of the emitted light as described above, and can perform a high-speed response.
Since it has a small light emission diameter, it can be applied to many optical devices, optical communication devices, optical processing devices, and the like.

FIG. 4 is a schematic view of an optical fiber type distance sensor provided with the light emitting diode of the above embodiment.

This optical fiber type distance sensor comprises a light emitting diode 41, a light projecting optical fiber 42, a light receiving optical fiber 43,
It comprises a light receiving element 44 and a signal processing device 45.

The light emitting diode 41 is driven by the electric signal provided by the signal processing device 45, and the light emitting diode 41 emits light. The light emitted from the light emitting diode 41 is introduced into the light projecting optical fiber 42 from one end thereof, and is projected onto the object 46 from the other end.

The light reflected from the object 46 is introduced into the light receiving optical fiber 43 and enters the light receiving surface of the light receiving element 43. The light receiving signal of the light receiving element 44 is given to the signal processing device 45. The signal processing device 45 calculates a distance S from the tip of the optical fibers 42 and 43 for light emission and light reception on the object 46 side based on the amplitude of the light reception signal.

In such a distance sensor, the distance is measured within the range of the reception signal level that can be detected by the light receiving element 44. Since the light emitting diameter of the light emitting diode 41 can be reduced, high light coupling efficiency can be obtained between the light emitting diode and the optical fiber. Further light emitting diode 41
Has a large maximum output of the emitted light. Therefore, the distance sensor using the light emitting diode 41 can extend the measurable distance.

FIG. 5 is a schematic diagram of an optical communication device provided with the light emitting diode of the above embodiment.

This optical communication device includes a light emitting circuit 51, a light emitting diode 52, an optical fiber 53, a light receiving element 54, and a light receiving circuit 55.
It is composed of

The light projecting circuit 51 changes the driving current based on the input signal to be transmitted, and performs light modulation (intensity modulation) of the light emitted from the light emitting diode 52. Light-emitting diode 52
Is emitted into the optical fiber 53, is transmitted through the optical fiber 53, and is received by the light receiving element 54. The light receiving signal of the light receiving element 54 is given to a light receiving circuit 55, where it is converted into a predetermined signal (for example, a digital signal).
(Converted to data) and output to the outside. An optical amplifier, a connector, and the like are connected to the optical fiber 53 used for optical transmission as necessary, and the optical fiber cable is extended.

Since the light emitting diode 52 has a very small light emitting diameter and a large maximum output of the emitted light, a high optical coupling efficiency between the light emitting diode and the optical fiber can be obtained. In addition, since it has high-speed response, high-speed and large-capacity data communication and data transmission can be performed. Plastic fibers are preferably used for the optical fibers. Since the plastic fiber has a low loss and a high S / N ratio, accurate optical transmission can be performed.

In the above-mentioned optical communication device, a light emitting circuit is provided on one side and a light receiving circuit is provided on the other side. This is a one-way communication configuration. Prepare at least two sets of light emitting and receiving circuits having both functions of the light emitting circuit and the light receiving circuit,
The light emitting diode of the light emitting circuit and the light receiving element of the light receiving circuit may be optically connected by two optical fibers. This enables two-way optical communication.

FIG. 6A shows a bar code reader provided with the light emitting diodes of the above embodiment. FIG. 2B shows a light receiving (bar code) signal detected by the light receiving element of the bar code reader.

The bar code reader comprises a light emitting diode 61, a light-collecting lens 62, a rotating polygon mirror 66, a motor 67,
A scanning lens 63, a light-receiving-side condenser lens 64, and a light-receiving element 65 are provided.

The light emitted from the light emitting diode 61 is condensed by the light-collecting lens 62 on the light projecting side, and then enters the mirror surface of the rotary polygon mirror 66. Light reflected from the mirror surface of the rotating polygon mirror 66 is projected through the scanning lens 63. The rotary polygon mirror 66 is driven by a motor 67 to rotate in one direction at a constant speed. Since the mirror surface is a polyhedron and rotates at a constant speed in one direction, the projection light from the scanning lens 63 scans over the bar code a.

The light reflected from the bar code a is condensed by the light-receiving side condenser lens 64 and enters the light-receiving element 65. The light receiving element 65 outputs a light receiving signal (bar code signal) corresponding to the light intensity of the incident light, and the light receiving signal is given to a signal processing device (not shown). The signal processing device is a bar code a
Recognition and other signal processing.

The light emitting diode 61 can emit light having a small emission diameter and a large maximum output (about 10 μm). Since the emission diameter is smaller than the minimum value (0.2 mm) of the bar code line width, any width bar code can be read with high accuracy.

[Brief description of the drawings]

1A and 1B show a first embodiment, in which FIG. 1A is a cross-sectional view schematically showing a structure of a light emitting diode, and FIG.
Shows the band gap.

FIGS. 2A and 2B show a second embodiment, in which FIG. 2A is a cross-sectional view schematically showing the structure of a light emitting diode, and FIG.
Shows the band gap.

FIG. 3 is a cross-sectional view schematically showing a configuration of a light emitting diode according to a third embodiment.

FIG. 4 shows an application example and shows a configuration of an optical fiber distance sensor device.

FIG. 5 illustrates an application example and illustrates a configuration of an optical communication device.

6A and 6B show an application example, in which FIG. 6A shows a configuration of a barcode reader, and FIG. 6B shows a light receiving signal (bar code detection signal) of a light receiving element.

[Explanation of symbols]

 1,21 GaAs substrate 2,22 n-AlGaInP lower cladding layer 3,23 superlattice layer 4,24 p-GaInP active layer 5,25 AlGaP upper first cladding layer 6,26 multiple quantum barrier layer 7,27 p-AlGaInP Upper second cladding layer 8, 28 p-side electrode 9, 29 n-side electrode 10, 20 light extraction area 11, 31 multilayer reflective film layer 32 inversion layer 33 current path area 41, 52, 61 light emitting diode 44, 54, 65 light receiving element

Claims (11)

[Claims] In a semiconductor light emitting device including an active layer and cladding layers provided on both sides thereof, a superlattice layer is provided on one cladding layer so as to form a mini-band leading to the active layer. A semiconductor light emitting device, wherein a multiple quantum barrier layer is provided on the other cladding layer, and a resonance tunneling prevention layer is provided between the active layer and the multiple quantum barrier layer. 2. The method according to claim 1, wherein said active layer has a thickness of 0.1 μm to 2.0 μm.
The semiconductor light emitting device according to claim 1, wherein m is m. 3. The semiconductor light emitting device according to claim 1, wherein an energy level of the mini-band communicating with the active layer is formed so as to become lower as approaching the active layer. 4. The superlattice layer in which a mini-band leading to the active layer is formed, the thickness of each superlattice layer being formed so as to gradually increase as approaching the active layer.
3. The semiconductor light emitting device according to item 1. 5. The semiconductor light emitting device according to claim 1, wherein at least one quantum well layer is provided in said active layer. 6. A current constriction structure is provided between the active layer and the light extraction surface of the light emitting device.
The semiconductor light emitting device according to any one of the above. 7. The light-emitting device according to claim 1, further comprising a reflection layer for reflecting light emitted to the semiconductor substrate side among the light generated in the active layer to the light extraction region. The semiconductor light-emitting device according to claim 1. 8. A semiconductor light emitting device, a first optical fiber into which light emitted from the semiconductor light emitting device is introduced at one end, and a light emitted from the other end of the first optical fiber and projected onto an object. An optical sensor device comprising: a second optical fiber into which reflected light is introduced at one end; and a light receiving element that receives light emitted from the other end of the second optical fiber. An optical sensor device, which is the semiconductor light emitting device according to any one of claims 1 to 7. 9. A light projecting device comprising: the semiconductor light emitting device according to claim 1; and a light emitting device that modulates and outputs light emitted from the semiconductor light emitting device based on a signal input from the outside. A circuit, an optical communication path through which light from the semiconductor light emitting element is introduced into one end, and a light receiving circuit that receives a light transmitted through the optical communication path and processes a light receiving signal of the light receiving element; An optical communication device comprising: 10. A first light, comprising: the semiconductor light emitting device according to claim 1; and modulating light emitted from the semiconductor light emitting device based on a signal input from the outside. A light emitting circuit for outputting to a communication path, and a light receiving element for receiving light transmitted through the second optical communication path;
A light receiving circuit for processing a light receiving signal of the light receiving element. 11. A light projecting section for projecting light, an optical scanning section for scanning the light projected by the light projecting section, and receiving reflected light from a bar code of the light scanned by the optical scanning section. In a bar code reader equipped with a light receiving unit,
A bar code reader using the semiconductor light emitting device according to any one of claims 1 to 7 as a light source of the light projecting unit.