JP2001024285A - Semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve element characteristic such as a threshold current and characteristic temperature, in an AlGaInP based light emitting element. SOLUTION: An element is formed on a semiconductor substrate 1. In the element, an n-type clad layer 3 and a p-type clad layer 7 of (Alx1Ga1-x1)y1In1-y1P (0<=x1<=1, 0.51<=y1<=1) whose lattice constant is a value between GaAs and GaP are formed on both sides of an active layer 5. In at least the p-type clad layer 7 out of the n-type clad layer 3 and the p-type clad layer 7, or between the p-type clad layer 7 and the active layer 5, a multiple quantum barrier structure(MQB structure) 6 is formed. The barrier structure 6 is constituted of a well layer 6b of (Alx2Ga1-x2)y2In1-y2P (0<=x2<=1, 0<=y2<=1) whose energy gap is smaller than the p-type clad layer 7, and a barrier layer 6a of the same composition as the p-type clad layer 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device used for an optical recording / reading light source, a light emitting display device and the like.

[0002]

2. Description of the Related Art Conventionally, as a red semiconductor laser in the 630 to 680 nm band, research on a visible light semiconductor laser using GaInP or AlGaInP as an active layer has been conducted. A 630 nm band semiconductor laser has attracted attention as a light source for high-density optical recording due to its short emission wavelength.

However, in this material system, since the height of the hetero-barrier in the conduction band between the p-type cladding (or guide) layer constituting the double hetero structure and the active layer is not sufficiently high, the implantation into the active layer is not performed. There is a problem that the emitted electrons easily overflow into the p-type cladding layer, which causes an increase in the threshold current of the element and a decrease in the characteristic temperature.

The height of the hetero barrier is determined by the band gap energy of the p-type cladding layer and the doping amount of the p-type impurity, and can be increased as the band gap energy is increased and the doping level is increased.

For example, Japanese Patent Application Laid-Open No. 4-114486 discloses that
By increasing the (effective) band gap energy of a part of the cladding layer, the conduction band hetero-barrier between the active layer and the cladding layer is increased, thereby reducing the leakage of electrons to the p-type cladding layer. ing. That is, Japanese Patent Laid-Open No. 4-1
The technique disclosed in No. 14486 provides a multiple quantum barrier (MQB) structure between an active layer and a cladding layer.
The MQB structure is a kind of a superlattice structure, and an electron wave reflected at each interface of the superlattice interferes with each other to form a potential barrier that is effectively higher than the classical potential barrier of the semiconductor layer forming the superlattice. Can be produced. In addition,
In the case of AlGaInP-based materials, the literature “Electronic Letters, Vol. 28, 1992, p.
An example of an MQB structure using nP / AlGaInP has been reported.

[0006] Japanese Patent Application Laid-Open No. 7-235733 discloses that A
A technique of providing a single barrier layer (carrier block layer) having a band gap energy larger than that of the cladding layer in a part of the cladding layer in an lGaInP-based material is disclosed. The carrier block layer is provided sufficiently thick (as a classic barrier layer) so that carriers do not tunnel, thereby reducing electron leakage.

[0007] Separately from these, Japanese Patent Application Laid-Open No. 5-415
No. 60 describes GaAs as an AlGaInP-based material.
An element having a cladding layer having a smaller lattice constant than GaAs is shown on a substrate via a lattice relaxation buffer layer. The technique disclosed in Japanese Patent Application Laid-Open No. 5-41560 mainly describes shortening the wavelength of an AlGaInP-based light emitting device to the 530 nm band. However, it is necessary to select a lattice constant of a cladding layer smaller than that of GaAs. And GaAs
A clad layer having a larger band gap energy is obtained as compared with the case where lattice matching is performed with the substrate.

[0008]

By the way, the carrier block layer provided adjacent to or near the cladding layer has a lattice of the cladding layer to prevent misfit transition and crystal defects due to lattice irregularity. It must be substantially lattice-matched with the constant or within a critical film thickness range. For this reason, AlGaInP that can be used as the carrier block layer is limited to a specific composition by the lattice constant of the cladding layer. Also, in general,
In AlGaInP, the smaller the lattice constant and the larger the Al composition, the larger the band gap energy. In other words, the lattice constant between GaAs and GaP has a composition with a wider gap, and the effect of the AlGaInP carrier block layer and the MQB structure can be expected as much as the composition described above.

However, the technique disclosed in the above-mentioned document "Electronic Letters, Vol. 28, 1992, p. 150" and JP-A-7-235733 is disclosed in
The cladding layer formed on the s substrate has a lattice constant of GaAs.
It is about a light emitting element equal to the substrate,
The device characteristics are subject to the aforementioned restrictions.

In the technique disclosed in Japanese Patent Application Laid-Open No. 5-41560, 530 of an AlGaInP-based laser is mainly used.
It mentions the shortening of the wavelength to the nm band.
No mention is made of a method for reducing leakage to the mold cladding layer, or the effect of the carrier block layer or the MQB structure. Also, there is no mention of application to the 630 nm band. In other words, the visible Al from the 530 nm band
There is room for improvement in the characteristic temperature of the GaInP-based semiconductor laser device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the lattice constant of the cladding layer is GaAs.
It is an object of the present invention to provide a semiconductor light emitting device capable of improving device characteristics such as a threshold current and a characteristic temperature in an AlGaInP-based light emitting device having a value between 530 nm band and a visible range that takes a value between GaP and GaP.

[0012]

According to a first aspect of the present invention, an element portion is formed on a semiconductor substrate, and the element portion has a lattice constant between GaAs and GaP. Take a value (Al _x1 Ga _1-x1 ) _y1 In _1-y1 P (0 ≦ x
An n-type clad layer and a p-type clad layer satisfying 1 ≦ 1, 0.51 <y1 ≦ 1) are provided on both sides of the active layer, and at least a p-type clad layer of the n-type clad layer and the p-type clad layer is provided. In the layer or between the p-type cladding layer and the active layer, (Al _x2 Ga _1-x2 ) _y2 In _1-y2 P (0 ≦ x2 ≦ 1,
It is characterized in that a multiple quantum barrier structure is provided in which 0 ≦ y2 ≦ 1) is a well layer and a layer having the same composition as the p-type cladding layer is a barrier layer.

According to a second aspect of the present invention, an element portion is formed on a semiconductor substrate, and the element portion has a lattice constant of GaAs.
(Al _x1 Ga _1-x1 ) _y1 In which takes a value between s and GaP
_{A 1-y1} P (0 ≦ x1 ≦ 1, 0.51 <y1 ≦ 1) n-type cladding layer and a p-type cladding layer are provided on both sides of an active layer, and an n-type cladding layer and a p-type cladding layer are provided. , At least in the p-type cladding layer or between the p-type cladding layer and the active layer, substantially lattice-matched to the p-type cladding layer, so that the energy gap is larger than that of the p-type cladding layer (Al _x3 Ga _1-x3 ) _{y1 In1 -y1} P (0 ≦ x1 ≦ x3 ≦
1,0.51 <y1 ≦ 1) It is characterized in that a carrier block layer is provided.

According to a third aspect of the present invention, a semiconductor substrate is provided.
An element portion is formed thereon, and the element portion has a lattice constant of GaAs.
s and GaP (Al_x1Ga_1-x1)_y1In
_1-y1P (0 ≦ x1 ≦ 1, 0.51 <y1 ≦ 1) n-type
A lad layer and a p-type cladding layer are provided on both sides of the active layer.
Of the n-type cladding layer and the p-type cladding layer
At least in the p-type cladding layer or p-type cladding
The lattice constant between the cladding layer and the active layer is smaller than that of the cladding layer.
High energy gap (Al _x4Ga
_1-x4)_y4In_1-y4P (0 ≦ x4 ≦ 1, 0.51 <y1 <
y4 ≦ 1) that a carrier block layer is provided
Features.

According to a fourth aspect of the present invention, in the semiconductor light emitting device of the second or third aspect, a plurality of carrier block layers are provided as barrier layers having a multiple quantum barrier structure, and (Al _x5 Ga _{1 -x5} ) _Y5 In _1-y5 P (0 ≦ x5 ≦
1,0.51 <y5 ≦ y1 ≦ 1) is provided as a well layer having a multiple quantum barrier structure.

According to a fifth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to fourth aspects, the carrier block layer or the multiple quantum barrier structure comprises:
It is characterized in that it is provided in the light guide layer or between the active layer and the light guide layer.

According to a sixth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to fifth aspects, the carrier block layer or the multiple quantum barrier structure is
It is characterized in that it is provided in the n-type cladding layer or between the n-type cladding layer and the active layer so as to be symmetrical with respect to the active layer.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
It will be described based on the following. FIG. 1 shows a semiconductor light emitting device according to the present invention.
FIG. 3 is a diagram showing a first configuration example of FIG. Referring to FIG.
In the semiconductor light emitting device, an element portion is formed on the semiconductor substrate 1.
The element part has a lattice constant between GaAs and GaP.
Value (Al_x1Ga_1-x1)_y1In_1-y1P (0 ≦ x1 ≦
1,0.51 <y1 ≦ 1) and n-type cladding layer 3
And a lad layer 7 are provided on both sides of the active layer 5.
At least one of the cladding layer 3 and the p-type cladding layer 7
Also in the p-type cladding layer 7 or
Between the p-type cladding layer 7 and the active layer 5
-Small gap (Al_x2Ga_1-x2)_y2In_{1- y2}P
(0 ≦ x2 ≦ 1, 0 ≦ y2 ≦ 1) is defined as the well layer 6b, and p
A layer having the same composition as the mold cladding layer 7 is used as the barrier layer 6a.
A multiple quantum barrier structure (MQB structure) 6 is provided.

FIG. 2 shows AlInP and GaInP in an unstrained state.
3 shows the relationship between the bandgap energy and the lattice constant of FIG. As shown in FIG. 2, in AlGaInP,
As the lattice constant is smaller and the Al composition is larger, the band gap energy is larger.

The cladding layers 3 and 7 of the first configuration example described above
Is between GaAs and GaP.
The gap is wider than the cladding layer formed on the As substrate and lattice-matched to the substrate. At least the p-type cladding layer 7 of the n-type cladding layer 3 and the p-type cladding layer 7
Inside or between the p-type cladding layer 7 and the active layer 5, AlGaInP having the same composition as that of the cladding layer 7 is used as a barrier portion (barrier layer) 6a, and AlGaInP having a band gap energy smaller than that of the cladding layer 7 is formed in a well. Part (well layer)
By providing the MQB structure 6 configured as 6b, a potential barrier having energy higher than the potential barrier due to the cladding layer 7 can be created.
Higher-energy electrons can be reflected as compared with the case where the MQB structure is not used. As a result, leakage of electrons to the p-type cladding layer 7 is reduced, and device characteristics such as threshold current and characteristic temperature can be improved.

FIG. 3 is a diagram showing a specific example of the semiconductor light emitting device of FIG. The semiconductor light emitting device of FIG. 3 is configured as an AlGaInP-based semiconductor laser device having a ridge stripe structure. Referring to FIG. 3, this semiconductor light emitting device uses an n-type GaAs substrate as a semiconductor substrate 1 and an n-type GaAs substrate through an n-type lattice relaxation buffer layer 2 for eliminating lattice irregularity between the semiconductor substrate 1 and the element portion. An n-type (Al _a1 Ga _1-a1 ) _b1 In _1-b1 P cladding layer 3 having a lattice constant between GaAs and GaP on the lattice relaxation buffer layer 2
(0.51 <b1 <1: For example, a1 = 1, b1 = 0.
66), undoped ( _{Ala2Ga1 -a2} ) _{b2In1 -b2P} optical guide layer 4 (a2 <a1: for example, a2 = 0.15, b2 = b
1), undoped GaInAsP active layer 5, undoped ( _{Ala2Ga1 -a2} ) _{b2In1 -b2P} light guide layer 4, MQB (multiple quantum barrier) structure 6 (p-type ( _Ala1G
a ₁ -a ₁ ) _b1 In _{1 -b1} P clad layer (MQB barrier layer) 6
a, p-type (Al _a6 Ga _1-a6 ) _b6 In _1-b6 P MQB well layer 6b (for example, a6 = 0.15 b6 = b1), p-type (Al _a1 Ga _1-a1 ) _b1 In _{1- b1} P cladding layer 7, p-type Ga _b3 In _1-b3 P intermediate layer 8 (for example, b3 = 0.
66), p-type GaAs _b4 P _{1 -b4} contact layer 9 (for example, b4
= 0.70), a SiO ₂ insulating film 10 is sequentially formed, and electrodes 11 and 12 for conducting are provided on the upper and lower sides of the element, respectively.

In this example, the well layer 6b of the MQB structure 6 has the same composition as the light guide layer 4. Further, strain stress may be applied within the range of the critical film thickness.

In this example, the lattice constants of the cladding layers 3 and 7 and the light guide layer 4 are about -1% from GaAs.
The degree of lattice irregularity is on the order of.

FIG. 4 is a schematic band diagram showing the vicinity of the light emitting portion of the semiconductor laser device of FIG.

Actually, the oscillation wavelength of the semiconductor laser device of FIG. 3 was 630 to 636 nm. Further, when the characteristic temperature of the semiconductor laser device of FIG. 3 was evaluated, the threshold current was lower and the characteristic temperature was higher than that of the semiconductor laser device without the MQB structure.

That is, in the first configuration example, by providing the MQB structure 6, electrons having an energy higher than the classic barrier height of the MQB semiconductor layer can be reflected. As a result, the characteristics of a light emitting device having a cladding layer having a lattice constant between GaAs and GaP can be improved. In the fabricated device, the threshold current of the device was reduced and the characteristic temperature was improved as compared with the device without the MQB structure. In particular, even when the emission wavelength becomes a short wavelength of 600 nm or less, the band gap energy difference between the active layer 5 and the cladding layer 7 is small, and it is difficult to provide a wide gap cladding layer, the characteristics can be improved by the MQB structure 6. And was particularly useful.

FIG. 5 is a diagram showing a second configuration example of the semiconductor light emitting device according to the present invention. Referring to FIG. 5, in the semiconductor light emitting device, an element portion is formed on a semiconductor substrate 19, and the element portion has a lattice constant between GaAs and GaP (Al _x1 Ga _1-x1 ) _y1. In _1-y1 P (0 ≦ x1 ≦
1,0.51 <y1 ≦ 1), the n-type cladding layer 3 and the p-type cladding layer 7 are provided on both sides of the active layer 5, and at least one of the n-type cladding layer 3 and the p-type cladding layer 7 In the p-type cladding layer 7 or in the p-type cladding layer 7
And the active layer 5 are substantially lattice-matched to the p-type cladding layer 7 and have a larger energy gap than the p-type cladding layer 7 (Al _x3 Ga _1-x3 ) _y1 In _1-y1 P (0 ≦ x1) ≦ x3 ≦
1,0.51 <y1 ≦ 1) The carrier block layer 13 is provided.

As described above, in the second configuration example, AlGaInP having a lattice constant between GaAs and GaP is used for the cladding layers 3 and 7, and the n-type cladding layer 3 and the p-type cladding layer are used. 7 or between the p-type cladding layer 7 and the active layer 5
In between, a carrier block layer 13 of AlGaInP having a larger energy gap than the cladding layer 7 and substantially lattice-matched to the cladding layer 7 is provided. This increases the effective potential barrier of the cladding layer 7 as viewed from the active layer 5 as compared with the case of only the AlGaInP cladding layer 7, reduces the leakage of electrons to the p-type cladding layer 7, and reduces the characteristic temperature and the like. Device characteristics can be improved.
Further, at least in the p-type cladding layer 7 of the n-type cladding layer 3 and the p-type cladding layer 7 or
Since it is sufficient to use a wide gap, that is, AlGaInP having a large Al content only between the mold cladding layer 7 and the active layer 5, there are advantages in terms of device reliability, doping efficiency, and the like.

Further, since the carrier block layer 13 is provided in lattice matching with the clad layer 7, there is no limitation on the critical film thickness or the like, and the carrier block layer 13 can be formed sufficiently thick so as not to transmit electrons. There are advantages too. At this time, the height of the potential barrier in the conduction band depends on the carrier block layer 13.
The hole (hole) density of the carrier block layer 13 is the same as that of the cladding layer 7 because the higher the hole (hole) density, the higher the potential barrier of the conduction band is obtained. Desirably, or better.

FIG. 6 is a diagram showing a specific example of the semiconductor light emitting device of FIG. The semiconductor light emitting device of FIG. 6 is configured as an AlGaInP-based semiconductor laser device having a ridge stripe structure. Referring to FIG. 6, in this semiconductor light emitting device, a Ga _b4 As _1-b4 P substrate is used as a semiconductor substrate 19, and a lattice constant between GaAs and GaP is formed on a Ga _b4 As _1-b4 P buffer layer 20. N-type (Al _a1 Ga _1-a1 ) _b1 In _1-b1 P cladding layer 3 (for example, a1 = 0.25, b1 = 0.66), n-type (Al _a5 Ga _1-a5 ) _b5 In _1-b5 P carrier block layer 14 (for example, a5 = 0.8, b5 = b1), undoped (Al _a2 Ga _1-a2 ) _b2 In _1-b2 P light guide layer 4 (for example, a2 = 0.15, b2 = b1), undoped GaInAsP active layer 5, undoped (Al _a2 Ga _1-a2 ) _b2 In _1-b2 P light guide layer 4, p-type (Al _a5 Ga _1-a5 ) _b5 In _1-b5 P carrier block layer 13, p-type _{(Al a1 Ga 1-a1)} b1 In 1-b1 P cladding layer 7, p-type Ga _b3 n _1-b3 P intermediate layer 8 (e.g., b3 = 0.6
6), p-type GaAs _b4 P _{1 -b4} contact layer 9 (for example, b4 =
0.70), a SiO ₂ insulating film 10, are sequentially formed, and electrodes 11 and 12 for conducting are provided on the upper and lower sides of the element, respectively.

In the example of FIG. 6, an n-type carrier block layer 14 is provided between the n-type cladding layer 3 and the light guide layer 4 as described later. Thereby, the refractive index distribution is symmetric with respect to the active layer 5.

In this example, the carrier block layer 1
The thickness of each of the layers 3 and 14 is 500 °.

In this example, the lattice constants of the cladding layers 3 and 7 and the light guide layer 4 are about -1% from GaAs.
The degree of lattice irregularity is on the order of.

The carrier block layers 13 and 14 are substantially lattice-matched to the cladding layers 7 and 3.

FIG. 7 is a schematic band diagram showing the vicinity of the light emitting portion of the semiconductor laser device of FIG.

Actually, the oscillation wavelength of the semiconductor laser device of FIG. 6 was 630 to 635 nm. In addition, when the characteristic temperature of the semiconductor laser device of FIG. 6 was evaluated, the threshold current was lower and the characteristic temperature was higher than that in the case where the carrier block layer was not provided.

That is, when the device as shown in FIG. 6 was manufactured, the threshold current was reduced and the characteristic temperature was improved in the manufactured device as compared with the device using no carrier block layer. As described above, the effective potential barrier of the cladding layer 7 viewed from the active layer 5 can be increased by the carrier blocking layer, and the result is that the leakage of electrons can be reduced. Further, since the effect can be obtained only by using a wide gap layer (having a large Al composition) for only a part of the cladding layer 7, no element deterioration due to Al was observed.

FIG. 8 shows a third embodiment of the semiconductor light emitting device according to the present invention.
FIG. 3 is a diagram showing an example of the configuration. Referring to FIG. 8, the semiconductor light emitting device has an element portion formed on a semiconductor substrate 15,
In the element section, the lattice constant takes a value between GaAs and GaP (Al _x1 Ga _1-x1 ) _y1 In _1-y1 P (0 ≦ x1 ≦ 1,
0.51 <y1 ≦ 1), the n-type cladding layer 3 and the p-type cladding layer 7 are provided on both sides of the active layer 5, and at least p of the n-type cladding layer 3 and the p-type cladding layer 7
In the p-type cladding layer 7 or between the p-type cladding layer 7 and the active layer 5, the lattice constant is smaller and the energy gap is larger than that of the cladding layer 7 (Al _x4 G
a _1−x4 ) _y4 In _1−y4 P (0 ≦ x4 ≦ 1, 0.51 <y1
<Y4 ≦ 1) The carrier block layer 16 is provided.

As described above, in the third configuration example, AlGaInP having a lattice constant between GaAs and GaP is used for the cladding layers 3 and 7, and the n-type cladding layer 3 and the p-type cladding layer 3 are used. 7 or between the p-type cladding layer 7 and the active layer 5
A carrier block layer 16 having a larger energy gap than that of the cladding layer 7 and having a thickness not more than the critical thickness of misfit transition subjected to tensile strain stress from the cladding layer 7 is provided. As shown in FIG. 2, AlGaInP
The smaller the lattice constant, the wider the gap can be used. Thereby, in the third configuration example, by providing the carrier block layer 16, the AlGa
As compared with the case of only the InP cladding layer, the effective potential barrier of the cladding layer 7 viewed from the active layer 5 can be increased, and the leakage of electrons to the p-type cladding layer 7 can be reduced.
Device characteristics such as a characteristic temperature can be improved. In addition, a wide gap, that is, an Al-containing clad layer 3 or a p-type clad layer 7 having a wide gap, that is, only between the p-type clad layer 7 and the active layer 5 is provided. Since a large amount of AlGaInP may be used, there are advantages in terms of device reliability, doping efficiency, and the like. Also, compared to the case where a carrier block layer of the same composition is formed in or close to the clad layer matched to the GaAs substrate, the lattice mismatch can be made smaller and a thick carrier block layer can be provided. There is an advantage that you can. Similarly, since the degree of lattice mismatch is small, the degree of reduction in band gap energy due to tensile strain stress is small, as compared with the case where the lattice gap is provided in or close to the cladding layer lattice-matched to the GaAs substrate. There is also an advantage that a wide gap is provided.

At this time, the height of the potential barrier in the conduction band also depends on the hole (hole) density of the carrier block layer 16, and the higher the hole (hole) density, the higher the potential barrier in the conduction band. The carrier block layer 16
Is desirably about the same as or higher than the cladding layer 7.

FIG. 9 is a diagram showing a specific example of the semiconductor light emitting device of FIG. The semiconductor light emitting device of FIG. 9 is configured as an AlGaInP based semiconductor laser device having a ridge stripe structure. Referring to FIG. 9, this semiconductor light emitting device uses an n-type GaP substrate as a semiconductor substrate 15, and through a lattice relaxation buffer layer 21 for eliminating lattice irregularities between the semiconductor substrate 15 and an element portion, and a lattice relaxation buffer layer 21. An n-type (Al _a1 Ga _1-a1 ) _b1 In _1-b1 P cladding layer 3 having a lattice constant between GaAs and GaP (for example, a1 = 0.3, b1 = 0.8) ), Undoped (Al _a2 Ga _{1 -a 2} ) _b2 In _{1 -b 2} P optical guide layer 4 (for example, a 2 = 0.1, b 2 = b 1), undoped GaInAsP active layer 5, undoped (Al _a2 Ga _{1 -a 2} ) _b2 In1 _-b2 P optical guide layer 4, p-type (Al _a5 Ga _1-a5 ) _b5 In _1-a5 P carrier block layer 16 (for example, a5 = 0.8, b5 = 0.92), p-type ( _{al a1 Ga 1-a1) b1} In 1-b1 P cladding layer 7, p-type G _b3 In _1-b3 P intermediate layer 8 (e.g., b3 = 0.8
0), p-type GaAs _b4 P _{1 -b4} contact layer 9 (for example, b4 =
0.4), an SiO ₂ insulating film 10 is sequentially formed, and electrodes 11 and 12 for establishing conduction are provided above and below the element, respectively.

In this example, the thickness of the carrier block layer 16 is 250 °.

In this example, the lattice constants of the cladding layers 3 and 7 and the light guide layer 4 are about -2% from GaAs.
The degree of lattice irregularity is of the order of magnitude.

The carrier block layer 16 has a lattice constant of about -1% from the cladding layer 7 and receives a tensile strain stress.

FIG. 10 is a schematic band diagram showing the vicinity of the light emitting portion of the semiconductor laser device of FIG.

Actually, the oscillation wavelength of the semiconductor laser device of FIG. 9 was 600 nm. When the characteristic temperature of the semiconductor laser device of FIG. 9 was evaluated, the threshold current was lower and the characteristic temperature was higher than that of the semiconductor laser device without the carrier block layer.

That is, in the third configuration example, the active layer 5 is formed by using the AlGaInP carrier block layer 16 having a tensile strain composition with respect to the cladding layer 7 having a lattice constant between GaAs and GaP. The potential barrier of the cladding layer 7 as viewed from above can be increased,
Leakage of electrons to the cladding layer 7 can be reduced.
In a device in which the lattice constant of the cladding layer 7 has a value between GaAs and GaP, the carrier block layer 16 having a smaller lattice irregularity and a wider gap can be used. As a result, in the fabricated device, the threshold current was reduced and the characteristic temperature was improved as compared with the device without using the carrier block layer. The carrier blocking layer 16 can effectively increase the effective potential barrier of the cladding layer 7 as viewed from the active layer 5 and reduce the leakage of electrons. Further, since the effect can be obtained only by using a wide gap layer (having a large Al composition) in only a part of the cladding layer, no element deterioration due to Al was observed.

According to the present invention, in the semiconductor light emitting device of FIG. 5 or FIG.
6 as a barrier layer of a multiple quantum barrier structure,
_{x5 Ga 1-x5) y5 In} 1-y5 P (0 ≦ x5 ≦ 1,0.51 <
y5 ≦ y1 ≦ 1) may be provided as a well layer having a multiple quantum barrier structure. That is, the carrier block layer 13 or 16 in FIG. 5 or FIG. 8 can be provided as a barrier layer of the MQB structure. In this case, FIG. 5 or FIG.
In addition to the effect of the semiconductor light-emitting device described above, it is possible to effectively reflect electrons having incident energy higher than the potential barrier of the carrier block layer. On this occasion,
The well layer having the MQB structure has an AlGaInP having a band gap energy smaller than that of the cladding layer 7 in a range where the energy gap is larger than that of the active layer 5 and the light guide layer 4.
But it is good. The standard of the energy of the electrons that can be reflected by the MQB structure is about twice the height of the potential barrier layer of the barrier layer viewed from the well layer. By making the band gap energy of the well layer smaller than that of the cladding layer 7, the height of the potential barrier becomes higher, so that higher energy electrons can be reflected.

FIG. 11 is a schematic band diagram of the vicinity of the light emitting portion when the carrier block layer 16 is provided as a barrier layer of the MQB structure in the semiconductor laser device of FIG. 9, for example. That is, the structure of the device having the schematic band diagram of FIG. 11 was manufactured by replacing the carrier block layer 16 of FIG. Here, the barrier layer 17a has a tensile strain stress of -1% due to the cladding layer 7.

The MQB structure in the example shown in FIG. 11 is composed of three barrier layers. Well layer 17b is clad layer 7
And the same composition.

Actually, the oscillation wavelength of the semiconductor laser device of FIG. 11 was 632 to 636 nm. When the characteristic temperature of the semiconductor laser device of FIG. 11 was evaluated, the threshold current was low and the characteristic temperature was high.

That is, in a device having a cladding layer having a lattice constant between GaAs and GaP, the MQB is formed by AlGaInP having a large band gap energy.
A structural barrier layer can be provided. Further, with the MQB structure, it is possible to reduce leakage of electrons having a height equal to or higher than a classic potential barrier into the cladding layer. By making the well layer of the MQB narrower than the cladding layer, the upper limit of the electron energy that can be reflected by the MQB can be further increased. As a result, in the fabricated device, the threshold current was reduced and the characteristic temperature was improved as compared with the device not using the MQB structure. The effect of the MQB structure described above is that the effective barrier between the effective cladding and the active layer can be effectively increased, thereby reducing the leakage of electrons.

In the present invention, the carrier block layer or the multiple quantum barrier structure (M
(QB structure) can be provided in the light guide layer 4 or between the active layer 5 and the light guide layer 4. In the case where the semiconductor light emitting device includes the light guide layer 4, by providing the carrier block layer or the MQB structure as described above, the spread of the carrier overflowing from the active layer 5 can be reduced. Carriers that recombine and disappear in the light guide layer 4 can be reduced. This further reduces the threshold current and improves the characteristic temperature of the device.

FIG. 12 shows a multiple quantum barrier structure (MQB structure).
FIG. 2 is a diagram showing a specific example of a semiconductor light emitting element in which the light emitting element is provided in the light guide layer 4 or between the active layer 5 and the light guide layer 4. The semiconductor light emitting device of FIG. 12 is configured as an AlGaInP semiconductor laser device having a ridge stripe structure. Referring to FIG. 12, in this semiconductor light emitting device, a GaAs substrate is used as a semiconductor substrate 1, and a lattice constant of GaAs and GaP is provided on a lattice relaxation buffer layer 2 for eliminating lattice irregularity between the semiconductor substrate 1 and an element portion. N-type (Al _a1 Ga _1-a1 ) _b1 In _1-b1 P clad layer 3 (for example, a1 = 0.25, b1 = 0.66), undoped (AlGa) InP optical guide layer 4 (For example,
a2 = 0.15, b5 = b1), undoped GaInAsP active layer 5, undoped (Al _a2 Ga _1-a2 ) _b2 In _1-b2 P light guide layer 4, MQB structure 18, p-type (Al _a1 Ga _{1- a1} ) _b1 In1 _-b1 P clad layer 7, p-type Gab3 _{In1 -b3} P intermediate layer 8 (for example, b3 = 0.6
6), p-type GaAs _b4 P _{1 -b4} contact layer 9 (for example, b4 =
0.70), a SiO ₂ insulating film 10, are sequentially formed, and electrodes 11 and 12 for conducting are provided on the upper and lower sides of the element, respectively.

In this example, the MQB structure 18 is formed of (Al
_{a5Ga1 -a5} ) _{b5In1 -b5P} (for example, a5 = 0.8, b
5 = b1) 18a and (Al _a6 Ga _1-a6 ) _b6 In _1-b6 P
(For example, a6 = a2, b6 = b1) 18b.

In this example, the lattice constants of the cladding layers 3 and 7 and the light guide layer 4 are about -1% from GaAs.
The degree of lattice irregularity is of the order of magnitude.

The barrier layer of the MQB structure 18 is substantially lattice-matched to the cladding layer 7. The well layer of the MQB structure 18 has the same composition as the light guide layer 4.

FIG. 13 is a schematic band diagram of the vicinity of the light emitting portion of the semiconductor laser device of FIG.

Actually, the oscillation wavelength of the semiconductor laser device of FIG. 12 was 632 to 635 nm. When the characteristic temperature of the semiconductor laser device of FIG. 12 was evaluated, the threshold current was low and the characteristic temperature was high.

As described above, when the carrier block layer or the MQB layer shown in FIG. 5, 8 or 11 is provided in the light guide layer 4 or between the light guide layer 4 and the active layer 5, the active layer Since the overflow of the carriers from 5 can be suppressed, there is an effect that the number of electrons that recombine in the light guide layer 4 is reduced. As a result, the threshold current of the fabricated device decreases,
The characteristic temperature was improved.

In the present invention, the carrier block layer and the MQB structure of each of the above-mentioned constitutional examples are also provided between the active layer 5 and the n-type cladding layer 3 as shown in FIG. Can be made symmetrical with respect to the active layer 5. Thereby, the light emission spot of the element can be made symmetric.

[0062]

As described above, according to the first aspect,
According to the invention, an element portion is formed on a semiconductor substrate,
In the part, the lattice constant takes a value between GaAs and GaP
(Al _x1Ga_1-x1)_y1In_1-y1P (0 ≦ x1 ≦ 1,0.
51 <y1 ≦ 1) n-type clad layer and p-type clad layer
Are provided on both sides of the active layer, and the n-type cladding layer and
And at least the p-type cladding layer of the p-type cladding layer
Or between the p-type cladding layer and the active layer,
(A) having a smaller energy gap than the p-type cladding layer
l_x2Ga_1-x2)_y2In_1-y2P (0 ≦ x2 ≦ 1, 0 ≦ y2
≦ 1) as a well layer and a layer having the same composition as the p-type cladding layer.
A multi-quantum barrier structure as a barrier layer is provided
Semiconductor devices with good device characteristics such as threshold current and characteristic temperature
An optical element can be provided.

According to the second aspect of the present invention, the element portion is formed on the semiconductor substrate, and the element portion has a lattice constant between GaAs and GaP (Al _x1 Ga _{1 -x1).} )
_{y1 In 1-y1 P (0} ≦ x1 ≦ 1,0.51 <y1 ≦ 1) and the n-type cladding layer and the p-type cladding layer is provided on both sides of the active layer, n-type cladding layer and p-type At least in the p-type cladding layer of the cladding layer or between the p-type cladding layer and the active layer, substantially lattice-matched to the p-type cladding layer, so that the energy gap is larger than that of the p-type cladding layer (Al _x3 Ga _1-x3 ) _y1 In _1-y1 P (0 ≦ x1 ≦ x
3 ≦ 1, 0.51 <y1 ≦ 1) Since the carrier block layer is provided, it is possible to provide a highly reliable semiconductor light emitting device having good device characteristics such as threshold current and characteristic temperature.

According to the third aspect of the present invention, an element portion is formed on a semiconductor substrate, and the element portion has a lattice constant between GaAs and GaP (Al _x1 Ga _{1 -x1).} )
_{y1 In 1-y1 P (0} ≦ x1 ≦ 1,0.51 <y1 ≦ 1) and the n-type cladding layer and the p-type cladding layer is provided on both sides of the active layer, n-type cladding layer and p-type At least in the p-type cladding layer of the cladding layer or between the p-type cladding layer and the active layer, the lattice constant is smaller than the cladding layer and the energy gap is larger (A
l _x4 Ga _1-x4 ) _y4 In _1-y4 P (0 ≦ x4 ≦ 1,0.51
<Y1 <y4 ≦ 1) Since the carrier block layer is provided, it is possible to provide a semiconductor light emitting device having good device characteristics such as threshold current and characteristic temperature and high reliability.

According to a fourth aspect of the present invention, in the semiconductor light emitting device according to the second or third aspect, a plurality of carrier block layers are provided as barrier layers having a multiple quantum barrier structure, and (Al _{x 5} Ga _{1 -x5} ) _{y5 In1 -y5} P (0 ≦ x
Since 5 ≦ 1, 0.51 <y5 ≦ y1 ≦ 1) is provided as the well layer of the multiple quantum barrier structure, a semiconductor light emitting device with improved threshold current, characteristic temperature, and the like can be provided.

According to a fifth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to fourth aspects, a carrier block layer or a multiple quantum barrier structure is provided in the light guide layer. Alternatively, since the semiconductor light emitting device is provided between the active layer and the light guide layer, it is possible to provide a semiconductor light emitting device with further improved threshold current, characteristic temperature, and the like.

According to a sixth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to fifth aspects, the carrier block layer or the multiple quantum barrier structure is formed in the n-type cladding layer. Or between the n-type cladding layer and the active layer so as to be symmetrical with respect to the active layer, it is possible to provide a semiconductor light emitting device with further improved characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first configuration example of a semiconductor light emitting device according to the present invention.

FIG. 2 is a diagram showing the relationship between the band gap energy and the lattice constant of AlInP and GaInP in an unstrained state.

FIG. 3 is a diagram showing a specific example of the semiconductor light emitting device of FIG. 1;

FIG. 4 is a schematic band diagram around a light emitting portion of the semiconductor laser device of FIG. 3;

FIG. 5 is a diagram showing a second configuration example of the semiconductor light emitting device according to the present invention.

6 is a diagram showing a specific example of the semiconductor light emitting device of FIG.

FIG. 7 is a schematic band diagram around a light emitting portion of the semiconductor laser device of FIG. 6;

FIG. 8 is a diagram showing a third configuration example of the semiconductor light emitting device according to the present invention.

9 is a diagram showing a specific example of the semiconductor light emitting device of FIG.

FIG. 10 is a schematic band diagram around a light emitting portion of the semiconductor laser device of FIG. 9;

FIG. 11 is a schematic band diagram around a light emitting portion when a carrier block layer is provided as a barrier layer having an MQB structure in the semiconductor laser device of FIG. 9;

FIG. 12 is a diagram showing a specific example of a semiconductor light emitting device in which a multiple quantum barrier structure (MQB structure) is provided in an optical guide layer or between an active layer and an optical guide layer.

FIG. 13 is a schematic band diagram around a light emitting portion of the semiconductor laser device of FIG. 12;

[Explanation of symbols]

Reference Signs List 1 semiconductor substrate 2 n-type lattice relaxation buffer layer 3 n-type cladding layer 4 optical guide layer 5 active layer 6 multiple quantum barrier structure (MQB structure) 6a barrier layer 6b well layer 7 p-type cladding layer 8 intermediate layer 9 contact layer 10 SiO ₂ Insulating film 11, 12 Electrode 19 Semiconductor substrate 13 Carrier block layer 20 Buffer layer 14 Carrier block layer 15 Semiconductor substrate 16 Carrier block layer 21 Lattice relaxation buffer layer 18 MQB structure

 ──────────────────────────────────────────────────の Continued on the front page (72) Takashi Takahashi Inventor Ricoh F term (reference) 5-3, Nakamagome 1-3-6, Ota-ku, Tokyo 5F073 AA45 AA71 BA06 BA09 CA14 CA17 EA23

Claims (6)

[Claims] An element portion is formed on a semiconductor substrate, and the element portion has a lattice constant between GaAs and GaP (Al _x1 Ga _1-x1 ) _y1 In _1-y1 P (0 ≦ x1 ≦ 1,0.
51 <y1 ≦ 1), an n-type cladding layer and a p-type cladding layer are provided on both sides of the active layer, and in at least the p-type cladding layer of the n-type cladding layer and the p-type cladding layer, or (Al _x2 Ga _1-x2 ) _y2 In _1-y2 P (0 ≦ x2 ≦ 1,0 ≦) having a smaller energy gap than the p-type cladding layer between the p-type cladding layer and the active layer.
A semiconductor light emitting device comprising: a multi quantum barrier structure in which y2 ≦ 1) is a well layer and a layer having the same composition as the p-type cladding layer is a barrier layer. 2. An element portion is formed on a semiconductor substrate, and the element portion has a lattice constant between GaAs and GaP (Al _x1 Ga _1-x1 ) _y1 In _1-y1 P (0 ≦ x1 ≦ 1,0.
51 <y1 ≦ 1), an n-type cladding layer and a p-type cladding layer are provided on both sides of the active layer, and in at least the p-type cladding layer of the n-type cladding layer and the p-type cladding layer, or , Between the p-type cladding layer and the active layer, the lattice is substantially lattice-matched to the p-type cladding layer, and the energy gap is larger than that of the p-type cladding layer (Al _x3 G
a _1-x3 ) _y1 In _1-y1 P (0 ≦ x1 ≦ x3 ≦ 1,0.51
<Y1 ≦ 1) A semiconductor light emitting device comprising a carrier block layer. 3. An element section is formed on a semiconductor substrate, and the element section has a lattice constant between GaAs and GaP (Al _x1 Ga _1-x1 ) _y1 In _1-y1 P (0 ≦ x1 ≦ 1,0.
51 <y1 ≦ 1), an n-type cladding layer and a p-type cladding layer are provided on both sides of the active layer, and in at least the p-type cladding layer of the n-type cladding layer and the p-type cladding layer, or (Al _x4 Ga _{1 -x4} ) _y4 In _{1 -y4} P having a smaller lattice constant and a larger energy gap than the cladding layer between the p-type cladding layer and the active layer.
(0 ≦ x4 ≦ 1, 0.51 <y1 <y4 ≦ 1) A semiconductor light emitting device comprising a carrier block layer. 4. A semiconductor light emitting device according to claim 2 or claim 3.
In an optical device, the carrier block layer is a multiple quantum barrier.
A plurality of barrier layers having a wall structure are provided. _x5G
a_1-x5)_y5In_1-y5P (0 ≦ x5 ≦ 1, 0.51 <y5
≦ y1 ≦ 1) is provided as a well layer of a multiple quantum barrier structure.
A semiconductor light-emitting device, characterized in that it is manufactured. 5. The semiconductor light emitting device according to claim 1, wherein the carrier block layer or the multiple quantum barrier structure is provided in the light guide layer, or between the active layer and the light guide layer. A semiconductor light emitting device, which is provided between them. 6. The semiconductor light emitting device according to claim 1, wherein the carrier block layer or the multiple quantum barrier structure is provided in the n-type cladding layer or in the n-type cladding layer. A semiconductor light emitting device provided between an active layer and the active layer so as to be symmetrical with respect to the active layer.