JP2003060226A - Laminated structure and light-emitting element, lamp, and light source using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem, when an impurity-added low-temperature buffer layer composed of a boron phosphide-based semiconductor layer is joined to the upper surface of a conductive single-crystal substrate, particularly, a single- crystal silicon substrate, the crystallinity of the substrate near the junction interface between the buffer layer and substrate deteriorating due to the impurity contained in the buffer layer when the impurity infiltrates into the substrate. SOLUTION: An element having a larger atomic radius than phosphorus has is used as the impurity added to the low-temperature buffer layer 102. When the buffer layer 102 is provided on a silicon substrate 101, particularly, an element having atomic radius larger than that of silicon is used as the impurity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated structure provided with a low temperature buffer layer made of a boron phosphide-based semiconductor laminated on a conductive single crystal substrate, and a light emitting device constructed by using the laminated structure. , Lamps, and light sources.

[0002]

2. Description of the Related Art Boron phosphide (BP) group III-V group compound semiconductors (boron phosphide group semiconductors) containing boron (B) and phosphorus (P) as constituent elements are one type of III-V group compound semiconductors. Iwa Teramoto, "Introduction to Semiconductor Devices" (March 30, 1995, first edition issued by Baifukan Co., Ltd., pp. 26-28). Conventionally, boron phosphide or its mixed crystal was used. A technique for forming a blue band or green band light emitting device has been disclosed (Japanese Patent Nos. 2809690, 2809691, 28).
No. 09692 and US Pat. No. 6,069,02
(See No. 1). For example, there is known a technique of forming a light emitting layer that emits green band light from a superlattice structure of boron phosphide (BP) and its multi-element mixed crystal, AlGaInBN (see Japanese Patent No. 2809691). .

A boron phosphide-based semiconductor layer, particularly a boron phosphide (BP) layer, is a laminated structure for constructing the above light emitting device and is used as a buffer layer in addition to the light emitting layer (US Pat. 5,042,043). It is also used to form a current confinement layer for forming a current confinement type laser diode (LD) (Japanese Patent No. 315).
2900). Boron phosphide (lattice constant ≈4.5
The laminated structure including the 38 Å) layer is made of silicon (Si: lattice constant ≈ 5.431 Å), gallium phosphide (GaP: lattice constant ≈ 5.450 Å), or hexagonal wurtzite silicon carbide (SiC: a-axis). The substrate is mainly composed of a conductive single crystal having a lattice constant of approximately 3.086Å) (see the above-mentioned US Pat. No. 6,069,021).

[0004]

Conventionally, a boron phosphide-based semiconductor layer forming a laminated structure for use in a light emitting device is laminated on a substrate having a lattice mismatching relationship. In addition, due to the difference in the coefficient of thermal expansion between the boron phosphide-based semiconductor and the substrate material, when laminating the boron phosphide-based semiconductor layer on the substrate,
This causes a problem that the boron phosphide-based semiconductor layer peels off from the substrate surface. Recently, for example, a low-temperature buffer layer made of an amorphous or polycrystalline boron phosphide-based semiconductor formed at a relatively low temperature is arranged on a substrate made of silicon single crystal, and the above-mentioned problem of peeling occurs. A technical means capable of solving the above problems is disclosed (US Pat. No. 6,069,02 mentioned above).
(See No. 1).

However, on the other hand, when a p-type or n-type impurity is added to obtain a low-temperature buffer layer having excellent conductivity, for the purpose of obtaining better conduction with the conductive substrate, these impurities are not included in the substrate. There is a problem that it diffuses and permeates into the inside, and causes strain and crystal defects in the surface layer of the substrate. There is a drawback that normal flow between the buffer layer and the substrate is hindered due to strain or the like introduced in a region near the interface between the low temperature buffer layer made of a boron phosphide-based semiconductor and the silicon substrate, for example.

The present invention proposes a technical means capable of providing a low temperature buffer layer having excellent conductivity while avoiding the penetration and diffusion of impurities that give good conductivity to the low temperature buffer layer to the substrate material.
Further, the present invention provides a laminated structure constituted by utilizing the technical means, and a light emitting element, a lamp and a light source constituted by the laminated structure.

[0007]

That is, the present invention contains a substrate made of a conductive single crystal and boron (B) and phosphorus (P) provided on the surface of the substrate as constituent elements. What is claimed is: 1. A laminated structure comprising a boron phosphide (BP) -based semiconductor, a polycrystal containing an amorphous body, and a low-temperature buffer layer to which an impurity is added, comprising the following (1) to (5): A laminated structure having the characteristics described in (1) above is provided. (1) A laminated structure characterized in that the impurities added to the low temperature buffer layer are composed of an element having an atomic radius of phosphorus (P) or more. (2) The conductive substrate is made of silicon (Si) single crystal, and the impurity added to the low temperature buffer layer is silicon (S).
i) The laminated structure according to (1) above, which is composed of an element having an atomic radius of the above. (3) The laminate as described in (1) or (2) above, wherein the conductive substrate is made of p-type conductive single crystal, and the impurities added to the low temperature buffer layer are made of zinc (Zn). Structure. (4) The conductive layer made of a boron phosphide (BP) -based semiconductor, to which an element different from the impurities added to the low temperature buffer layer is added, is provided on the low temperature buffer layer. The laminated structure according to any one of (1) to (3). (5) The conductive substrate is made of p-type conductive single crystal, and the conductive layer provided on the low temperature buffer layer is made of a boron phosphide-based semiconductor layer to which magnesium (Mg) is added. The laminated structure according to 3).

The present invention also provides a light emitting device described in the following items (6) and (7). (6) A conductive single crystal that forms a substrate by providing an ohmic surface electrode in contact with the semiconductor layer that forms the surface of the laminated structure according to any one of (1) to (5) above. A light-emitting element comprising an ohmic back surface electrode provided on the back surface of. (7) The light emitting device according to the above (6), wherein the semiconductor layer on the surface of the laminated structure is n-type, and the substrate is a p-type conductive single crystal.

The present invention also provides the following lamp and light source. (8) A lamp comprising the light emitting device described in (6) or (7) above. (9) A light source comprising the lamp as set forth in (8) above.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A cross-sectional structure of a laminated structure 1A for use in an LED 1B according to a first embodiment of the present invention is schematically illustrated in FIG.

The laminated structure 1A for use in a double hetero (DH) structure type light emitting diode (LED) can basically be composed of the elements described in the following items (A) to (E). (A) n-type or p-type conductive conductive silicon (Si)
Alternatively, BP (see Japanese Patent Publication No. 55-3834), Ga
Substrate 101 made of P, GaAs, SiC, etc. (B) Low-temperature conductive conductive buffer layer 102 made of polycrystalline boron phosphide-based semiconductor containing amorphous material (C) Lower barrier layer made of boron phosphide-based semiconductor layer 103 (D) Preferably lattice-matched to the lower barrier layer 103. For example, gallium indium nitride (Ga _x In _1-x N: 0 ≦
X ≦ 1) (see Japanese Patent Publication No. 55-3834 mentioned above) or gallium nitride phosphide (GaN _1-Y P _Y : 0 ≦ Y ≦ 1)
Emitting layer 104 made of III-nitride semiconductor such as (E) Upper barrier layer 105 made of boron phosphide-based semiconductor

Boron (B) and phosphorus (P) are constituent elements.
Temperature buffer layer made of boron phosphide (BP) based semiconductor containing
102 is, for example, the general formula B_αAl_βGa_γIn_{1- α -
β - γ}P _{1- δ}As_δ(0 <α ≦ 1, 0 ≦ β <1, 0 ≦ γ
<1, 0 <α + β + γ ≦ 1, 0 ≦ δ <1)
It can be preferably composed of a boron phosphide-based semiconductor. Also, for example
For example, general formula B_αAl_βGa_γIn_{1- α - β - γ}P_{1- δ}N_δ
(0 <α ≦ 1, 0 ≦ β <1, 0 ≦ γ <1, 0 <α + β +
Li containing nitrogen (N) represented by γ ≦ 1, 0 <δ <1)
It can be composed of a boron nitride semiconductor. Low temperature buffer layer 102
Preferably has a small number of constituent elements and can be simply constructed.
It is composed of a binary crystal or a ternary mixed crystal. For example, monomer
Boron phosphide (BP), aluminum phosphide-boron mixed crystal
(B_αAl_βP: 0 <α ≦ 1, α + β = 1), boron phosphide
Elemental-gallium mixed crystal (B_αGa_δP: 0 <α ≦ 1, α + δ
= 1) or boron phosphide / indium mixed crystal (B_αIn
_{1- α}P: 0 <α ≦ 1) or the like.

A boron phosphide-based semiconductor composed of a polycrystal containing an amorphous material is, for example, a metal organic chemical vapor deposition growth (M
It can be formed at about 250 ° C. to 750 ° C. by means of OCVD) (see US Pat. No. 6,194,744). In particular, the polycrystalline low temperature buffer layer 102 containing an amorphous material is used as the substrate 101.
The lattice mismatch between the lower barrier layer 103 and the lower barrier layer 103 is relaxed, and the lower barrier layer 103 having a low crystal defect density such as misfit dislocations is exerted (US Pat. No. 6,069,021). reference). When the low-temperature buffer layer 102 is composed of a boron phosphide semiconductor containing an element (constituent element) that constitutes the boron phosphide-based semiconductor forming the lower barrier layer 103, the constituent element acts as a “growth nucleus”. There is an advantage that the formation of the continuous lower barrier layer 103 is promoted. Whether the low-temperature buffer layer 102 is a single crystal layer or a polycrystalline layer containing amorphous can be known from, for example, analysis of a diffraction image by a general X-ray diffraction method or electron beam diffraction method. The thickness of the polycrystalline layer forming the low-temperature buffer layer 102 is preferably about 1 nm or more and 500 nm or less, and more preferably 2 nm or more and 100 nm or less.

A feature of the technical means according to the first embodiment of the present invention is that the p-type or n-type impurities added to the low temperature buffer layer 102 are limited. Impurities having an atomic radius greater than that of boron (B) and phosphorus (P) forming the low temperature buffer layer 102 cannot move freely inside the boron phosphide (BP) based semiconductor crystal because of the large atomic radius. Therefore, diffusion of impurities into the substrate material can be prevented, and occurrence of strain inside the substrate 101 in the region near the bonding interface with the low temperature buffer layer 102 can be avoided. The atomic radius of boron (B) is about 0.98Å. Also, the atomic radius of phosphorus (P) (=
r) is about 1.28Å. Therefore, as the n-type impurity added to the low temperature buffer layer suitable for the first embodiment, for example, Si (r = 1.32Å), germanium (Ge; r;
= 1.37Å), tin (Sn; r = 1.62Å), p
Examples of the form impurities include elements having an atomic radius of phosphorus (P) or more such as zinc (Zn; r = 1.38Å) and cadmium (Cd; r = 1.54Å).

Further, in particular, in a structure in which a conductive silicon (Si) single crystal is used as a substrate and the low temperature buffer layer 102 is provided on the surface thereof, the p type or n type impurity added to the low temperature buffer layer 102 is removed from the substrate. Assuming that the element has an atomic radius (r = 1.32Å) or more of silicon (Si) atoms constituting 101,
Impurities can be suppressed from penetrating into the silicon substrate 101, and the strain and crystal defects introduced into the silicon substrate 101 can be effectively reduced. As an n-type or p-type impurity having an atomic radius of boron (r = 0.98Å), phosphorus (r = 1.28Å) or silicon (r = 1.32Å) or more, germanium (Ge; r = 1.37Å) And zinc (Zn; r =
1.38Å) can be illustrated. Therefore, as a good example of the second embodiment of the present invention, a structure in which a low temperature buffer layer made of p-type boron phosphide (BP) to which zinc is added is provided on a p-type silicon substrate.

The invention according to the third embodiment of the present invention is p
A p-type low temperature buffer layer 102 suitable for being provided on a substrate 101 made of a conductive type single crystal is provided.
Zinc (Zn) is boron (B), phosphorus (P) and silicon (S).
The atomic radius is larger than that of i), and the boron phosphide-based buffer layer 1
02 Movement inside 02 is suppressed. Further, for example, since it is difficult to diffuse into the inside of the silicon substrate, it is possible to prevent the surface layer portion of the substrate from becoming disordered. For example, cadmium (r = 1.54Å) or mercury (r = 1.57Å) having an atomic radius larger than that of zinc (Zn) can further suppress the movement in the crystal. However, if an impurity having such an atomic radius enters between the crystal lattices, the regular crystal lattice is disturbed. For this reason,
The electrical activation of impurities is hindered, which hinders stable low-resistivity p-type low-temperature buffer layer 102 from being obtained.
Further, when the crystal lattice is disturbed due to the penetration of impurities having a larger atomic radius than zinc (Zn), for example, in an LED,
It is not preferable because it causes a reverse breakdown voltage failure.

The atomic concentration and concentration distribution of impurities added to the low temperature buffer layer 102 that permeates and diffuses from the low temperature buffer layer 102 into the surface layer region of the substrate 101 are analyzed by an analyzing means such as secondary ion mass spectrometry (SIMS). it can. The pattern of strain and crystal defects such as stacking faults in the substrate 101 near the bonding interface with the low-temperature buffer layer 102 is a cross-sectional TEM using, for example, a transmission electron microscope (TEM).
It can be analyzed by the technique. In the cross-sectional TEM image, the presence of distortion is recognized as black contrast in the bright field image.

The invention according to the fourth embodiment of the present invention provides a preferable structure particularly for a laminated structure for use in a light emitting device. That is, a laminated structure is formed by utilizing the fact that a boron phosphide-based semiconductor layer having particularly excellent crystallinity can be laminated on the low-temperature buffer layer 102 made of a polycrystalline boron phosphide-based semiconductor containing an amorphous material. It is what constitutes. In particular, a boron phosphide-based semiconductor layer having excellent conductivity can be suitably used as the lower barrier layer 103, for example.

In the fourth embodiment of the present invention, the boron phosphide-based semiconductor layer (eg, the lower barrier layer 103) is 750 ° C.
A single crystal layer formed on the low-temperature buffer layer 102 at a temperature of over 1,200 ° C. is suitable. At a high temperature of more than 1200 ° C., for example, a polymeric boron phosphide such as B ₁₃ P ₂ is easily formed, which hinders the formation of a compositionally uniform boron phosphide-based semiconductor layer, which is not preferable (J. Am. ．
Ceramic Soc. , 47 (1) (1964),
See pages 44-46). Particularly preferably 800 ° C to 95
For example, it is formed of a boron phosphide-based semiconductor layer mainly formed of {110} crystal planes arranged in parallel with the surface of the substrate 101, which is formed at a temperature of 0 ° C.

The boron phosphide-based semiconductor layer with controlled conductivity can be obtained by adding p-type or n-type impurities. In order to obtain a conductive boron phosphide-based semiconductor layer, the same impurities as the low temperature buffer layer 102 can be used. For example, on the silicon (Si) -doped n-type low temperature buffer layer 102, the same Si
An example in which a boron phosphide-based semiconductor layer is laminated using s as a dopant. Since the boron phosphide-based semiconductor layer (for example, the lower barrier layer 103) is separated from the substrate 101 by the low temperature buffer layer 102 in distance, it is possible to use impurities having an atomic radius other than the above. Impurities suitable for obtaining an electrically conductive boron phosphide-based semiconductor layer include “shallow” don's rather than atomic radii.
or) or an acceptor that forms an acceptor level. For example, magnesium (Mg) and beryllium (Be) can be exemplified as impurities that can be preferably used to obtain a p-type boron phosphide-based semiconductor layer. In forming a laminated structure from the low-temperature buffer layer 102 of the p-type conductive layer and the boron phosphide-based semiconductor layer, it is particularly preferable to use zinc (Z) as the p-type dopant of the low-temperature buffer layer 102.
n), and the p-type dopant of the boron phosphide-based semiconductor layer is magnesium (Mg).

At 750 ° C to 1200 ° C, (1)
Long speed is 2nm or more per minute and 30nm or less, and (2) V
The supply ratio (V / III ratio) of group III raw material and group III raw material
Preferably, the monomer is formed as 15 or more and 60 or less.
Boron phosphide has a band gap at room temperature.
Is as high as 3.0 ± 0.2 eV and is suitable for use as a barrier layer.
it can. In addition, this high bandgap boron phosphide as a base material
The barrier layer can be formed also from the boron phosphide-based semiconductor. An example
For example, monomeric boron phosphide having a bandgap of 3.1 eV
(BP) and gallium phosphide (GaP: bandgap at room temperature)
≈ 2.3 eV), which is a mixed crystal with a bandgap at room temperature of about
2.7 eV gallium nitride phosphide mixed crystal (B_0.50Ga
_0.50The lower barrier layer 103 can be preferably formed from P). Prohibition
The tongue width is, for example, the refractive index (= n) and the extinction coefficient (= k)
The imaginary part of the complex permittivity (ε ₂= 2 ・ n ・ k)
It is required from the light energy dependence of.

Further, a boron phosphide-based semiconductor layer having the same lattice constant as that of the low temperature buffer layer 102 at the junction interface with the low temperature buffer layer 102 and having a lattice matching with the light emitting layer 104 on the surface of the light emitting layer 104 side is formed. , Misfit rearrangement,
This can contribute to providing a high-quality light emitting layer 104 having a low density of crystal defects such as stacking faults. Buffer layer 102 and light emitting layer 104
A boron phosphide-based semiconductor layer lattice-matched to both layers of the above is a group III group such as boron (B) or a group V group such as phosphorus (P).
It can be composed of a composition gradient layer in which the composition of the constituent elements of the group has a gradient (see JP-A-2000-22211). The composition gradient of the constituent elements can be added uniformly, stepwise, or non-linearly in the increasing direction of the layer thickness. For example, a mixed crystal of boron phosphide and gallium (B _0.02 Ga _0.98 P) lattice-matched to the silicon substrate 101.
On the low temperature buffer layer 102 made of, for example, gallium indium nitride (Ga _0.90 I).
n _{0. 10} N: luminescent layer 1 made of a lattice constant ≒ 4.557Å)
A boron composition ratio (= X) of 0.0
2 to 0.98 and the boron phosphide / gallium composition gradient layer (B _α Ga _δ P: α = 0.02 → 0.
98, and correspondingly δ = 0.98 → 0.02).

The light emitting layer 104 is, for example, gallium indium nitride (Ga _X) capable of emitting short wavelength visible light in the blue band.
In _1-X N: 0 ≦ X ≦ 1) or other group III nitride semiconductor (see Japanese Patent Publication No. 55-3834). In addition, gallium nitride phosphide (GaN _1-X P _X : 0 ≦
X ≦ 1) (Appl.Phys.Let)
t. , 60 (20) (1992), 2540-2542.
See page). Further, gallium arsenide nitride (GaN _1-X As _X :
0 ≦ X ≦ 1). The light emitting layer 104 may have a single or multiple quantum well structure in which these group III-V compound semiconductor layers are used as a well layer. The light emitting layer 104 formed of the quantum well structure has an advantage of emitting light with good monochromaticity.

If the upper barrier layer 105 is provided on the light emitting layer 104, a double hetero (DH) structure type light emitting portion can be formed. The upper barrier layer 105 can be composed of a monomeric boron phosphide having a bandgap of 3.0 ± 0.2 eV at room temperature and a boron phosphide-based mixed crystal based on the same. Also,
It can be composed of a group III nitride semiconductor such as gallium nitride (GaN) or an aluminum nitride / gallium mixed crystal (Al _x Ga _1-x N: 0 <X <1).

The LED 1B of the double heterojunction structure according to the present invention is constructed by providing an ohmic front surface electrode 106 on the upper barrier layer 105 and disposing an ohmic back surface electrode 107 on the back surface of the substrate 101. To do. When the upper barrier layer 105 is made of a boron phosphide-based semiconductor, the p-type ohmic electrode is formed of, for example, gold / zinc (Au /
Zn) alloy, gold / beryllium (Au / Be) alloy, or the like. Further, the n-type ohmic electrode can be formed from a gold alloy such as a gold-germanium (Au.Ge) alloy, a gold-indium (Au.In) alloy, and a gold-tin (Au.Sn) alloy. The surface electrode 106 may be provided on the contact layer having good conductivity in order to form an electrode exhibiting good ohmic contact.
From the boron phosphide-based semiconductor layer having a high bandgap according to the present invention, a contact layer for use as the surface ohmic electrode 106, which also serves as a window layer for transmitting emitted light in the extraction direction, can be preferably formed.

The lamp 10 according to the present invention can be constructed, for example, by the following procedure. As illustrated in FIG. 2, for example, the LED 1B is fixed to a central portion of a metallic bowl body 16 plated with a metal such as silver (Ag) or aluminum (Al) on the pedestal 15 with a conductive bonding material. As a result, the back surface electrode 14 provided on the back surface of the conductive substrate 11 used to form the LED 1B is electrically connected to the one terminal 17 attached to the pedestal 15. Further, for example, the surface electrode 13 provided on the upper barrier layer 12 of the LED 1B is connected to the other one terminal 18 attached to the pedestal 15. Next, the LED 1B is surrounded by a sealing material such as epoxy resin to form a lamp.

A light source can be constructed by assembling the lamps 10 according to the present invention. For example, a plurality of lamps 10
Can be electrically connected in parallel to form a constant voltage drive type light source. Further, a constant current drive type light source can be configured by electrically connecting lamps in series. These light sources do not require electric power for lighting as compared with conventional incandescent fluorescent lamps, and thus can be particularly usefully utilized as light sources of low power consumption and long life. For example, it can be used as a light source for indoor lighting. Further, for example, it can be used as a light source for outdoor display applications and indirect lighting applications.

[0028]

EXAMPLE (First Example) In this example, p-type silicon (S
i) The present invention will be specifically described with reference to a case where a blue LED is formed from a laminated structure including a low temperature buffer layer made of a boron phosphide-based semiconductor to which a p-type impurity is added, on a single crystal substrate. .

FIG. 3 is a schematic sectional view of the LED 2B according to the first embodiment. The LED 2B has the same structure as the laminated structure 2A in which the functional layers described in (2) to (5) are sequentially laminated on the substrate 101 described in (1) below, and the LEDs (2) to (6) to (7). The ohmic front and back electrodes described above were arranged and configured. (1) Boron (B) -doped Si single crystal substrate 101 having p-type (111) plane 101 (2) Triethylboron ((C ₂ H ₅ ) ₃ B) / phosphine (PH ₃ ) / hydrogen (H ₂ ) By atmospheric pressure MOCVD method
Zinc (Zn; atomic radius (r) ≈1.
38 Å) Low temperature buffer layer 102 made of polycrystalline boron phosphide (BP) mainly composed of doped amorphous. Low temperature buffer layer 10
The atomic concentration of zinc in 2 was 4 × 10 ¹⁸ cm ⁻³ , and the layer thickness was 25 nm. (3) Using the MOCVD vapor phase growth means described above, 85
Substrate 1 doped with magnesium (Mg) at 0 ° C.
01 lower barrier layer 103 mainly made of p-type boron phosphide (BP) having {110} crystal planes arranged substantially parallel to the surface
(Carrier concentration ≈ 4 × 10 ¹⁸ cm ^-3 , layer thickness ≈ 700 n
m) (4) Cubic n-type Ga _0.94 In _0.06 N layer (lattice constant =
4.538Å) as the main emission layer 104 (carrier concentration ≈ 4 × 10 ¹⁷ cm ^-3 , layer thickness ≈ 180 nm) (5) Forbidden band width at room temperature grown by the MOCVD reaction system at 400 ° C. Is 3.1 eV and is mainly composed of amorphous silicon (Si) -doped n-type boron phosphide (B
P) layer upper barrier layer 105 (carrier concentration ≈ 6 ×
10 ¹⁶ cm ^-3 , layer thickness ≈ 650 nm) (6) Ohmic surface electrode 106 (7) p made of gold-germanium (Au.Ge) circular electrode (diameter = 120 μm) arranged in the center of the upper barrier layer 105. Ohmic back electrode 1 made of aluminum (Al) provided on almost the entire back surface of the Si substrate 101
07.

The atomic concentration of zinc (Zn) in the depth direction was measured by secondary ion mass spectrometry. As a result, it was confirmed that the zinc impurities did not penetrate into the Si substrate 101 after the buffer layer 102 was grown at a low temperature. Almost never confirmed. Even after the laminated structure 2A was configured through the growth process at high temperature (= 850 ° C.), the permeation distance of zinc into the Si substrate 101 was at most 50 nm. In addition, in the analysis by the bright field cross-section TEM technique using a transmission electron microscope (TEM), Si that forms a junction with the low temperature buffer layer 102.
In the surface layer portion of the substrate 101, black contrast due to strain was not particularly visible.

The constructed blue LED 2B has the following (a)
It became a high-brightness LED exhibiting the characteristics described in (d). (A) Emission center wavelength: 410 nm (b) Brightness: 6 millicandelas (mcd) (c) Forward voltage: 3 V (V) (forward current = 20
mA) (d) Reverse voltage: 8 V (reverse current = 10 μA) Particularly, Si of zinc (Zn) added to the low temperature buffer layer 102.
The diffusion into the substrate 101 is suppressed, and the low temperature buffer layer 102
Since the Si substrate 101 was prevented from becoming disordered in the region near the junction interface with and, the local breakdown voltage (local breakdown) when the reverse voltage was applied to the LED 2B was almost recognized. There wasn't.

(Second Embodiment) In this embodiment, a blue LE is obtained from a laminated structure having a low temperature buffer layer made of an n-type impurity-doped boron phosphide-based semiconductor on an n-type Si single crystal substrate.
The present invention will be specifically described by taking the case of configuring D as an example.

In the second embodiment, (6) to (6) are added to the laminated structure in which the functional layers described in (2) to (5) are sequentially laminated on the substrate described in (1) below. The ohmic front and back electrodes as described in the item (7) are arranged and configured. (1) Antimony (Sb) -doped Si single crystal substrate having an n-type (100) plane (2) Triethylboron ((C ₂ H ₅ ) ₃ B) / phosphine (PH ₃ ) / hydrogen (H ₂ ) system 40 by atmospheric pressure MOCVD method
Boron phosphide / indium (B _0.67 In _0.33 P: lattice constant) having the same lattice constant as that of Si of the substrate, which is mainly composed of tin (Sn: r≈1.62Å) -doped amorphous material grown at 0 ° C. A polycrystalline low temperature buffer layer consisting of ≈5.431 Å). The atomic concentration of tin (Sn) determined by secondary ion mass spectrometry (SIMS) inside the low-temperature buffer layer was set to 2 × 10 ¹⁸ cm ⁻³ . The layer thickness was 35 nm. (3) Using the MOCVD vapor phase growth means described above, 80
0 doped with silicon (Si) at ° C., (100) substantially in parallel arranged to the substrate surface {110} n-type boron indium phosphide composed mainly of crystal plane _{(B X In 1-X P} : X = 0 ．
33 → 0.99) Lower barrier layer composed of a composition gradient layer (carrier concentration≈1 × 10 ¹⁸ cm ⁻³ , layer thickness≈520 nm). The boron (B) composition ratio (= X) of the composition gradient layer is 0.33 at the bonding interface with the low-temperature buffer layer, and is uniformly increased to 0.99 toward the bonding interface with the light emitting layer. . (4) Emission layer (carrier concentration) mainly composed of cubic n-type Ga _0.90 In _0.10 N layer (lattice constant = 4.557Å) grown at 800 ° C. and having the same lattice constant as B _0.99 In _0.01 P ≈5 × 10 ¹⁷ cm ^-3 , layer thickness ≈95 nm). (5) Magnesium (Mg) -doped p-type boron phosphide / indium mixed crystal mainly composed of amorphous material, which is grown at 350 ° C. by the MOCVD reaction system and has a band gap at room temperature of 3.0 eV Upper barrier layer consisting of (B _0.99 In _0.01 P) layer (carrier concentration ≈ 9 × 10 ¹⁶ cm ⁻³ , layer thickness ≈ 70
0 nm) (6) Gold / Zinc (Au / Z) arranged in the center of the upper barrier layer
n) Ohmic front surface electrode made of circular electrode (diameter = 130 μm) (7) Ohmic back surface electrode made of aluminum (Al) provided on substantially the entire back surface of the n-type Si substrate.

When the atomic concentration of tin (Sn) in the depth direction was measured by secondary ion mass spectrometry, the penetration of tin (Sn) atoms into the Si substrate was observed after the buffer layer was grown at a low temperature. Was hardly confirmed. Also, high temperature (= 800
The permeation distance of zinc into the Si substrate is at most 2 even after the laminated structure is formed through the growth process at
It was within 0 nm. In addition, a transmission electron microscope (TE
In the analysis by the bright field cross-section TEM technique using M),
The surface layer of the Si substrate forming a bond with the low-temperature buffer layer has tin (S)
The black contrast due to the distortion accompanying the penetration of n) was not particularly visible.

According to the above means, the following (a) to (d)
A high brightness blue LED having the characteristics described in the above paragraph is provided. (A) Central emission wavelength: 430 nm (b) Brightness: 8 millicandelas (mcd) (c) Forward voltage: 3 V (V) (forward current = 20
mA) (d) Reverse voltage: 8 V (reverse current = 10 μA) In particular, diffusion of tin (Sn) added to the low-temperature buffer layer into the Si substrate is suppressed, and the vicinity of the junction interface with the low-temperature buffer layer is suppressed. Since the Si substrate was prevented from becoming disordered in the region, local breakdown voltage failure (local) when a reverse voltage was applied.
Almost no breakdown was observed.

[0036]

According to the present invention, impurities added to a polycrystalline low temperature buffer layer containing an amorphous material composed of a boron phosphide (BP) based semiconductor layer have an atomic radius larger than that of phosphorus (P) atoms. Since the element is used as the element, the movement of impurities inside the low temperature buffer layer can be avoided, and since it is possible to prevent the substrate crystal from becoming disordered in the junction region with the low temperature buffer layer, it is possible to achieve high withstand voltage with high brightness. A light emitting device can be provided.

In particular, according to the present invention, in a structure in which a low temperature buffer layer made of a boron phosphide-based semiconductor is provided on a conductive silicon single crystal substrate, impurities added to the low temperature buffer layer are boron, phosphorus and Since the element whose atomic radius is larger than that of silicon (Si) is used, movement of impurities inside the low-temperature buffer layer and permeation into the silicon single crystal substrate are suppressed, so that bonding with the low-temperature buffer layer is achieved. It is possible to prevent the Si substrate from becoming disordered in the region near the interface, and thus it is possible to provide a light emitting element having excellent withstand voltage characteristics.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a laminated structure for LED application according to the present invention.

FIG. 2 is a schematic sectional view showing the structure of a lamp according to the present invention.

FIG. 3 is a schematic sectional view of an LED according to the first embodiment of the present invention.

[Explanation of symbols]

1A, 2A laminated structure 1B, 2B LED 10 lamps 11 board 12 Upper barrier layer 13 Surface electrode 14 Back electrode 15 pedestal 16 bowl 17, 18 terminals 19 Sealing resin 101 single crystal substrate 102 low temperature buffer layer 103 Lower barrier layer 104 light emitting layer 105 upper barrier layer 106 surface electrode 107 Back electrode

Claims (9)

[Claims] 1. A substrate made of a conductive single crystal, and a boron phosphide (BP) -based semiconductor provided on the surface of the substrate and containing boron (B) and phosphorus (P) as constituent elements. ,
What is claimed is: 1. A laminated structure comprising a polycrystalline low-temperature buffer layer containing an amorphous material, the impurity being added to the low-temperature buffer layer from an element having an atomic radius of phosphorus (P) or more. And a laminated structure. 2. The conductive substrate is silicon (Si).
The stacked structure according to claim 1, wherein the stacked structure is made of a single crystal, and the impurity added to the low temperature buffer layer is an element having an atomic radius of silicon (Si) or more. 3. The laminated structure according to claim 1, wherein the conductive substrate is made of a p-type conductive single crystal, and the impurities added to the low-temperature buffer layer are made of zinc (Zn). body. 4. Boron phosphide (BP), on which an element different from the impurities added to the low temperature buffer layer is added on the low temperature buffer layer.
The laminated structure according to any one of claims 1 to 3, further comprising a conductive layer made of a system semiconductor. 5. The conductive substrate is made of p-type conductive single crystal, and the conductive layer provided on the low temperature buffer layer is made of magnesium (M).
The laminated structure according to claim 3, which is composed of a boron phosphide-based semiconductor layer to which g) is added. 6. A conductive single crystal forming a substrate, which is provided with an ohmic surface electrode in contact with a semiconductor layer forming a surface of the laminated structure according to claim 1. A light emitting device characterized in that an ohmic back electrode is provided on the back surface. 7. The light emitting device according to claim 6, wherein the semiconductor layer on the surface of the laminated structure is n-type, and the substrate is a p-type conductive single crystal. 8. A lamp comprising the light emitting device according to claim 6 or 7. 9. A light source constituted by assembling the lamps according to claim 8.