JP2003188413A - Optical semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical semiconductor device which is suppressed in transfer of dislocation from a substrate to another layer, small in size, and performs a wiring operation with ease. <P>SOLUTION: The device comprises a substrate 2 composed of single crystals of Si, a blocking layer made of single crystals of Al, a plurality of insulation layers 4 which are separated from one another by gaps 5 and are arranged like strips on the stopping layer 3, a growth layer 6 which is provided so as to cover the gaps 5 and the insulation layers 4 and is made of a III nitride compound, and a light-emitting layer 8 provided above the growth layer 6. Further, a mask layer is provided above the gaps 5 so as to cover the gaps 5 in the growth layer 6. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical semiconductor device.

[0002]

2. Description of the Related Art Conventionally, an element of this type is disclosed in, for example, Japanese Patent Laid-Open No. 6-268259. According to this publication, as shown in the sectional view of FIG.
1, a buffer layer 112, a contact layer 113, a clad layer 114, a light emitting layer 115, and a clad layer 116.
And a contact layer 117 and a P electrode 118. An N electrode 119 is provided on the lower surface of the contact layer 113. The optical semiconductor element 120 is configured by these layers.

[0003]

However, in the above optical semiconductor device 120, the sapphire substrate 111 and the buffer layer 1 are used.
12 has a greatly different lattice constant. As a result, dislocations (strains due to differences in lattice constants) move upward from the sapphire substrate 111. The moving dislocation density is as large as about 10 ¹⁰ cm ^-2 . Impurities are likely to collect at this dislocation portion. As a result, there is a first drawback that impurities penetrate into the light emitting layer 115 and the light output deteriorates.

Further, the optical semiconductor element 120 has a second defect that the outer size of the element becomes large because the outer shape has a step. Furthermore, the P electrode 118 and the N electrode 11
Since 9 is on the front side, connect with 2 wires,
There is a third drawback that wiring is troublesome.

In view of the above-mentioned conventional drawbacks, the present invention provides an optical semiconductor device in which dislocation migration from the substrate to other layers is small, the device size is small, and wiring work is easy.

[0006]

In order to solve the above problems, according to the present invention of claim 1, a substrate made of a single crystal of Si, and a blocking layer provided on the substrate and made of a single crystal of Al are provided. A plurality of insulating layers which are spaced apart from each other and are provided in stripes on the blocking layer; and a growth layer which is provided so as to cover the gap and the insulating layer and which is made of a group III nitride compound. And a light emitting layer provided above the growth layer.

According to the second aspect of the present invention, the mask layer is provided above the gap so as to cover the gap and is provided in the growth layer.

According to the present invention of claim 3, Si doped with a first dopant or GaA doped with a second dopant.
a substrate made of s, a blocking layer formed on the substrate and made of an Al single crystal, a plurality of insulating layers that are spaced apart from each other and are provided in stripes on the blocking layer, A growth layer made of a Group III nitride compound is provided so as to cover the gap and the insulating layer, and a light emitting layer is provided above the growth layer.

According to the present invention of claim 4, a back electrode is provided on the back surface of the substrate.

In the present invention of claim 5, the growth layer is G
It consists of a single crystal of aAlN.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an optical semiconductor element 1 according to a first embodiment of the present invention will be described with reference to the sectional view of FIG. In FIG. 1, a substrate 2 is a wafer obtained by slicing a lump of single crystal Si into a predetermined size. That is,
The substrate 2 is made of a single crystal of Si.

The blocking layer 3 is provided, for example, on the entire surface of the substrate 2 and is made of a single crystal of Al. For example, triisobutylaluminum is thermally vaporized by a bubbler using argon as a carrier gas by a heat activated CVD apparatus on the substrate 2. And GTC (GasTemperature)
It is thermally activated by the controller (gas temperature control unit). Then, the activated material becomes a single crystal layer 3 of aluminum on the heated substrate 2.

The lattice constant of Si constituting the substrate 2 is 5.4.
3 angstroms, the lattice constant of Al forming the blocking layer 3 is 4.05 angstroms, and the lattice mismatch rate is small.

The insulating layer 4 is made of, for example, SiO ₂ or the like, is spaced apart from each other with a gap 5, and is formed in plural stripes on the blocking layer 3.

The growth layer 6 is provided so as to cover the gap 5 and the insulating layer 4, and is provided with a Group III nitride compound (for example, GaAl).
N single crystal, etc.).

The growth layer 6 is formed by MOCVD, for example, and is first formed in the gap 5 between the insulating layers 4 and then,
It is formed (grown) so as to grow laterally and cover the insulating layer 4.

The contact layer 7 is made of, for example, N-type GaN, has a substantially convex cross section, and is formed on the growth layer 6. The light emitting layer 8 is made of, for example, InGaN, and is formed on the surface of the contact layer 7.

The cladding layer 9 is made of P-type GaAlN, for example, and is formed on the light emitting layer 8. Contact layer 1
0 is made of P-type GaN, for example, and is formed on the cladding layer 9.

The P electrode 11 is made of gold or the like and is formed on the contact layer 10. Thus, the light emitting layer 8 is formed above the growth layer 6.

The N electrode 12 is formed on the lower surface of the contact layer 7. The optical semiconductor element (light emitting diode) 1 is composed of the above layers.

In the optical semiconductor device 1, as described above, the lattice mismatch between the Si single crystal of the substrate 2 and the Al single crystal of the blocking layer 3 is small. On the other hand, in the conventional optical semiconductor device 120, the lattice mismatch between the sapphire substrate 111 and the buffer layer 112 is large. As a result,
The lattice mismatch rate between the substrate 2 and the blocking layer 3 is about half that of the conventional one.
Doubled.

The upper part of the insulating layer 4 is covered with the growth layer 6 grown in the lateral direction, and the movement of dislocations upward from the substrate 2 via the blocking layer 3 is blocked by the insulating layer 4.

Therefore, dislocations move only through the gaps 5 between the insulating layers 4. As a result, the movement of dislocations from the substrate 2 to the growth layer 6 is about 3 × 10 ⁶ cm ^-2 , which is significantly smaller than the conventional 10 ¹⁰ cm ^-2 .

Furthermore, since a current flows through the P electrode 11, the contact layer 10, the cladding layer 9, the light emitting layer 8, the contact layer 7, and the N electrode 12 by the applied voltage, there is no problem in the current path.

Next, the optical semiconductor element 13 according to the second embodiment of the present invention will be described with reference to the sectional view of FIG. In FIG. 2, the mask layer 14 is made of, for example, SiO _2, and is located above the gap 5 so as to cover the gap 5 between the insulating layers 4 and is formed in the growth layer 6a.

That is, the mask layer 73 is formed in stripes above the gap 5 and spaced apart from each other with the second gap 15 in between.

The substrate 2 is made of a single crystal of Si, as in FIG. The growth layer 6a is made of a GaAlN single crystal. Layers having the same part number (in FIG. 2) as the part numbers shown in FIG. 1 indicate the same thing.

In this way, the mask layer 1 is formed so as to cover the gap 5.
By providing 4, dislocations moving in the gap 5 are blocked by the mask layer 14. As a result, in the growth layer 6a, the dislocation density is reduced to 2 × 10 ⁵ cm ^-2 .

Depending on the applied voltage, the P electrode 11, the contact layer 10, the cladding layer 9, the light emitting layer 8, the contact layer 7, and the N layer.
Since current flows to the electrode 12, there is no problem in the current path.

Next, the optical semiconductor element 16 according to the third embodiment of the present invention will be described with reference to the sectional view of FIG. In FIG. 3, a substrate 17 is a wafer obtained by slicing a lump of single crystal Si to which a first dopant (for example, phosphorus) is added and dividing the wafer into predetermined sizes. That is, the substrate 17 is the first
It is composed of N-type Si doped with a dopant.

The blocking layer 18 is provided on the entire surface of the substrate 17, for example, and is made of a single crystal of Al. For example, substrate 1
Triisobutylaluminum is thermally vaporized by a bubbler using argon as a carrier gas by a heat activated CVD apparatus. And GTC (Gas Temperature)
It is thermally activated by a re controller (gas temperature control unit). After that, the activated material becomes a single crystal layer (blocking layer) 18 of aluminum (Al) on the heated substrate 17.

The lattice constant of N-type Si forming the substrate 17 is 5.43 Å, and Al forming the blocking layer 18 is
Has a lattice constant of 4.05 angstroms and there is no lattice mismatch.

The insulating layer 19 is made of, for example, SiO ₂ or the like,
A plurality of stripes are formed on the blocking layer 18 and are spaced apart from each other with a gap 20 therebetween.

The growth layer 21 is formed by MOCVD, for example, and is first formed in the gap 20 between the insulating layers 19,
Next, it grows in the lateral direction and is formed (grown) so as to cover the insulating layer 19.

As described above, the growth layer 21 is formed so as to cover the gap 20 and the insulating layer 19 and is made of a group III nitride compound (for example, GaAlN single crystal).

The contact layer 22 is made of, for example, N-type GaN, has a substantially rectangular cross section, and is formed on the surface of the growth layer 21. The light emitting layer 23 is, for example, InGaN
And is formed on the surface of the contact layer 22.

The cladding layer 24 is made of, for example, P-type GaAlN, and is formed on the light emitting layer 23. The contact layer 25 is made of P-type GaN, for example, and is formed on the clad layer 24.

The surface electrode 26 is made of gold or the like and is formed on the contact layer 25. In this way, the light emitting layer 23 is
It is formed above the growth layer 21.

The back electrode 27 is formed on the back surface of the substrate 17. The optical semiconductor element (light emitting diode) 16 is composed of the above layers.

In the optical semiconductor element 16, as described above, the lattice mismatch between the N-type Si single crystal of the substrate 17 and the Al single crystal of the blocking layer 18 is small. On the other hand, in the conventional optical semiconductor device 120, the lattice mismatch between the sapphire substrate 111 and the buffer layer 112 is large. As a result, the lattice mismatch rate between the substrate 17 and the blocking layer 18 is about 1 / the conventional value.
Doubled.

The upper part of the insulating layer 19 is covered with the growth layer 21 grown in the lateral direction, and the insulating layer 19 is covered with the blocking layer 1 from the substrate 17.
The movement of the dislocations upwards via 8 is blocked by the insulating layer 19.

Therefore, dislocations move only through the gaps 20 between the insulating layers 19. As a result, the movement of dislocations from the substrate 17 to the growth layer 21 is about 3 × 10 ⁶ cm ^-2 , which is much smaller than the conventional 10 ¹⁰ cm ^-2 .

Further, the applied voltage causes a current to flow to the front surface electrode 26, the contact layer 25, the cladding layer 24, the light emitting layer 23, the contact layer 22, the growth layer 21, the gap 20, the blocking layer 18, the substrate 17 and the back surface electrode 27. , There is no problem in the current path.

Further, in this way, the surface electrode 26 is provided on the upper part,
Since the back surface electrode 27 is provided in the lower portion, this optical semiconductor element 1
6 can be produced by conventional production equipment for light emitting diodes (GaP, GaAs, etc.).

Further, since the optical semiconductor element 16 has no step in the outer shape, the outer size of the element can be made smaller than that of the conventional light emitting diode having the step (see FIG. 5).

Further, a conventional light emitting diode (see FIG. 5)
However, since both the P electrode 118 and the N electrode 119 are provided on the front surface side, it takes time and effort to connect with two wires.

On the other hand, in this optical semiconductor element 16, since the back electrode 27 is provided on the back surface of the substrate 17, the back electrode 27 can be die-bonded. As a result, it suffices to connect the surface electrode 26 with one wire, which facilitates the wiring work.

Next, the optical semiconductor element 28 according to the fourth embodiment of the present invention will be described with reference to the sectional view of FIG. In FIG. 4, a substrate 29 is a wafer obtained by slicing a lump of single crystal GaAs to which a second dopant (for example, phosphorus) is added and dividing the wafer into a predetermined size. That is, the substrate 29
Consists of GaAs doped with a second dopant.

The materials and structures of the other layers are the same as those in FIG. That is, the layers having the same part numbers (in FIG. 4) as the part numbers shown in FIG. 3 are the same.

That is, in the optical semiconductor element 28, the substrate 29 made of GaAs doped with the second dopant, and the blocking layer 18 made of Al single crystal provided on the substrate 29.
And spaced apart from each other with a gap 20 in between, and blocking layer 18
A plurality of insulating layers 19 provided on the upper side in a stripe shape, a growth layer 21 made of a Group III nitride compound and provided so as to cover the gap 20 and the insulating layer 19, and a light emitting layer provided above the growth layer 21. And 23 are provided.

On the back surface of the substrate 29, the back electrode 27
Is provided. The growth layer 21 is formed of, for example, Ga.
It consists of a single crystal of AlN.

Similar to the optical semiconductor device 16 shown in FIG. 3, in this optical semiconductor device 28, the movement of dislocations from the substrate 29 to the growth layer 21 is about 3 × 10 ⁶ cm ^-2 , which is 10 ^{10 of the} conventional one. It is significantly smaller than cm ^-2 .

Further, a current is applied to the front surface electrode 26, the contact layer 25, the cladding layer 24, the light emitting layer 23, the contact layer 22, the growth layer 21, the gap 20, the blocking layer 18, the substrate 29 and the back surface electrode 27 by the applied voltage. Since it flows, there is no problem in the current path.

The optical semiconductor element 28 is similar to the optical semiconductor element 16 in the conventional light emitting diodes (GaP, Ga).
It can be produced by a production facility for As and the like.

Further, since the optical semiconductor element 28 has no step in the outer shape, the outer size of the element can be made smaller than that of the conventional light emitting diode having the step (see FIG. 5).

In the conventional light emitting diode (see FIG. 5),
Since both the P electrode 118 and the N electrode 119 are provided on the front surface side, it takes time and effort to connect them with two wires.

On the other hand, in this optical semiconductor element 28, since the back electrode 27 is provided on the back surface of the substrate 29, the back electrode 27 can be die-bonded. As a result, it suffices to connect the surface electrode 26 with one wire, which facilitates the wiring work.

[0058]

According to the present invention of claim 1, a substrate made of a single crystal of Si, a blocking layer made of a single crystal of Al provided on the substrate, and a blocking layer located apart from each other with a gap, A plurality of insulating layers provided in stripes on the layer,
A growth layer provided so as to cover the gap and the insulating layer and made of a Group III nitride compound, and a light emitting layer provided above the growth layer. Thus, the lattice mismatch rate between the Si single crystal of the substrate and the Al single crystal of the blocking layer is about 1 of the conventional one.
/ 2 times. Further, the movement of dislocations upward from the substrate through the blocking layer is blocked by the insulating layer. As a result, the movement of dislocations from the substrate to the growth layer is, for example, about 3 × 1.
It is 0 ⁶ cm ^-2 , which is significantly smaller than the conventional 10 ¹⁰ cm ^-3 . Therefore, the impurities gathered in the dislocation portion hardly penetrate into the light emitting layer, so that the deterioration of the light output can be prevented.

According to the second aspect of the present invention, the mask layer is provided above the gap so as to cover the gap and is provided in the growth layer. By providing the mask layer so as to cover the gap between the insulating layers, dislocations moving in the gap are blocked by the mask layer. As a result, the dislocation density in the grown layer is reduced to, for example, about 2 × 10 ⁵ cm ^-2 .

According to the present invention of claim 3, Si doped with the first dopant or GaA doped with the second dopant.
a substrate made of s, a blocking layer provided on the substrate and made of an Al single crystal, and a plurality of insulating layers which are spaced apart from each other and are provided in stripes on the blocking layer, A growth layer made of a Group III nitride compound is provided so as to cover the gap and the insulating layer, and a light emitting layer is provided above the growth layer. The first, which constitutes the substrate
The lattice mismatch ratio between Si doped with a dopant or GaAs doped with a second dopant and the Al single crystal of the blocking layer is about ½ of the conventional value. Further, the movement of dislocations upward from the substrate through the blocking layer is blocked by the insulating layer. As a result, the migration of dislocations from the substrate to the grown layer is
It is significantly less than before.

In the present invention of claim 4, a back electrode is provided on the back surface of the substrate. By providing the front surface electrode on the front surface and the back surface electrode on the back surface with the above configuration, it is possible to perform production by a general production facility for light emitting diodes (GaP etc.). Also,
Since there is no step in the outer shape as in the conventional case, the outer size of the element can be reduced as compared with the conventional light emitting diode having the step. Further, by die-bonding the back surface electrode, it suffices to connect the front surface electrode with one wire, which facilitates the wiring work.

In the present invention of claim 5, the growth layer is G
It consists of a single crystal of aAlN. By using GaAlN for the growth layer, the growth layer formed in the gap between the insulating layers is
Easy to grow laterally. As a result, the growth layer is easily formed on the insulating layer.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical semiconductor device 1 according to a first embodiment of the present invention.

FIG. 2 is an optical semiconductor device 13 according to a second embodiment of the present invention.
FIG.

FIG. 3 is an optical semiconductor device 16 according to a third embodiment of the present invention.
FIG.

FIG. 4 is an optical semiconductor element 28 according to Embodiment 4 of the present invention.
FIG.

FIG. 5 is a sectional view of a conventional optical semiconductor element 120.

[Explanation of symbols]

2 substrates 3 blocking layer 4 insulating layers 5 gap 6 Growth layer 8 Light emitting layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromi Takasu             3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori             Sanyo Electric Co., Ltd. F-term (reference) 5F041 AA03 AA40 AA43 AA44 CA04                       CA34 CA40 CA49 CA65 CA67                       CB05

Claims (5)

[Claims] 1. A substrate made of a Si single crystal, a blocking layer provided on the substrate and made of an Al single crystal, spaced apart from each other, and provided in stripes on the blocking layer. A plurality of insulating layers, a growth layer made of a Group III nitride compound and provided so as to cover the gap and the insulation layer, and a light emitting layer provided above the growth layer. Optical semiconductor device. 2. The optical semiconductor element according to claim 1, further comprising a mask layer which is located above the gap and is provided in the growth layer so as to cover the gap. 3. A substrate made of Si doped with a first dopant or GaAs doped with a second dopant, and a blocking layer provided on the substrate and made of an Al single crystal.
A plurality of insulating layers that are spaced apart from each other and are provided in stripes on the blocking layer; and a growth layer that is provided so as to cover the gaps and the insulating layer and is made of a Group III nitride compound, An optical semiconductor device comprising a light emitting layer provided above the growth layer. 4. The optical semiconductor element according to claim 3, wherein a back electrode is provided on the back surface of the substrate. 5. The growth layer is made of a single crystal of GaAlN, wherein the growth layer is a single crystal of GaAlN.
Optical semiconductor device.