JP2002198562A - Group iii nitride semiconductor light emitting diode and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a group III nitride semiconductor light emitting diode of high performance in which a high quality silicon substrate of low cost is used, by solving the problem where a group III nitride semiconductor light emitting diode having high light emitting intensity is not obtained, since the light from a light emitting part is absorbed in a silicon substrate in the conventional group III nitride semiconductor light emitting diode in which silicon is used as the substrate. SOLUTION: A reflecting layer having a semiconductor multilayer laminated structure constituted of laminate of boron phosphide and gallium phosphide nitride is arranged between a silicon substrate and a light emitting part. Consequently, the light from the light emitting part is reflected in a light lead-out direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a pn junction type double hetero junction structure using a silicon single crystal as a substrate.
The present invention relates to a technique for forming a group III nitride semiconductor light emitting diode.

[0002]

2. Description of the Related Art A conventional electric insulating sapphire (α-Al
₂ O ₃ ) single crystal substrate (Mat. Res. Soc. Symp. Proc., Vol. 46)
8 (1977), pp. 481 to 486) instead of silicon (S
i) A technique for forming a group III nitride semiconductor light emitting diode (LED) using a single crystal as a substrate has been disclosed (Ele
ctron. Lett., Vol. 33 No. 23 (1997) P. 1986-1987). If a silicon single crystal exhibiting conductivity and cleavage is used as a substrate, a group III nitride semiconductor light-emitting diode can be easily formed by a simple device fabrication process (Appl. Phys. Lett., Vol. 72 No. .4 (1998), P.415
417).

[0003] In the group III nitride semiconductor light-emitting diode, typically, on a single crystal substrate of aluminum gallium indium nitride _{(Al α Ga β In 1-} α-β N: 0 ≦
A light emitting portion having a pn junction type double hetero (DH) junction structure composed of a group III nitride semiconductor crystal layer such as α, β, α + β ≦ 1) is formed. The light emitting part of the DH junction structure refers to a part that emits light in a structure in which a light emitting layer is sandwiched between p-type and n-type clad layers. Both the light emitting layer and the cladding layer can be composed of an aluminum gallium nitride layer. In this case, by making the aluminum mixed crystal ratio (α) of the clad layer higher than the aluminum mixed crystal ratio of the light emitting layer, the forbidden band width of the clad layer is made larger than the forbidden band width of the light emitting layer. An effect of confining injected electrons is provided. The light emitting layer for emitting short wavelength visible light in the blue band or green band, gallium indium nitride: it is exclusively be composed of _{(Ga β In 1-β N} 0 ≦ β ≦ 1) ( See JP-B-55-3834).

However, when a silicon single crystal is used as a substrate, the band gap of the silicon single crystal is about 1.1 eV (Iwao Teramoto, "Introduction to Semiconductor Devices", March 30, 1995, Baifukan Co., Ltd.) (See the first edition, page 28), the transition energy corresponding to the emission in the blue band is less than half or less, so that the short-wavelength light emitted from the light emitting portion is used as the silicon single crystal used as the substrate. That is, in the group III nitride semiconductor light emitting diode formed on the silicon substrate, there is a problem that it is difficult to obtain an LED having high light emission intensity due to absorption of light emitted by the substrate. .

[0005]

SUMMARY OF THE INVENTION The present invention relates to a group III nitride semiconductor light emitting diode having a single crystal silicon substrate as a substrate. Since light from a light emitting portion is absorbed by a silicon substrate, high intensity light is emitted. The purpose of the present invention is to solve the problem that a Group III nitride semiconductor light-emitting diode having a high emission intensity can be obtained by using an inexpensive and high-quality silicon substrate. It is an object to provide a light emitting diode.

[0006]

Means for Solving the Problems] To solve the above problems, the light emitting diode of the present invention is laminated on a silicon single crystal substrate, the general formula _{Al a Ga b In 1-ab} N c M 1-c
(However, 0 ≦ a, b, a + b ≦ 1, M is the Vth other than nitrogen)
III-nitride semiconductor light-emitting device having a pn junction type double hetero (DH) junction light-emitting portion composed of a III-nitride semiconductor layer represented by a group element and represented by 0 <c ≦ 1) A diode, wherein a boron phosphide (BP) crystal layer and a gallium nitride phosphide (GaN _1-X P _X : 0 ≦ X ≦ 1) crystal layer are alternately provided between the silicon single crystal substrate and the light emitting portion. A group III nitride semiconductor light emitting diode provided with a reflective layer having a multilayer laminated structure. With this structure, the light emitted from the light-emitting portion to the substrate side is reflected by the light-extraction side and can be effectively extracted to the viewing side without being absorbed by the substrate.
A group I nitride semiconductor light emitting diode can be obtained.

In the present invention, a multilayer laminated structure is used.
Constituting boron phosphide crystal layer and gallium nitride phosphide crystal
The carrier concentration of the layer is 1 × 10¹⁷cm^-35 × 10¹⁹
cm ^-3It is preferable to set the following. This level of carrier concentration
If the temperature is high, the conductivity is high, so the multilayer laminate structure and silicon
Operating current up and down the light emitting diode through the
Flow, simplifying the structure of the light emitting diode
Has the advantage that can be provided in the price. In addition, the present invention
In the above, the nitrided phosphide
The phosphorus (P) composition ratio of the lithium crystal layer is 2% or more and 4% or less.
Is preferred. Phosphorus composition ratio is 2% or more and 4% or less
If it is, it is the other crystal layer which constitutes the multilayer laminated structure
Lattice matching with boron phosphide crystal is obtained, and good crystalline
This is because a multilayer laminated structure can be obtained.

In the present invention, the number of cycles of lamination of the multilayer laminated structure is preferably 2 or more, more preferably 7 or more. When the number of cycles becomes 2 or more, the reflectance increases rapidly, and
This is because when the above is achieved, a reflectance of almost 100% is obtained in the visible light region.

In the present invention, it is preferable to use a {111} crystal plane as the plane orientation of the silicon single crystal substrate surface. This is because the {111} crystal plane has densely arranged Si atoms, thereby preventing intrusion of impurity atoms and easily obtaining a flat surface. Further, a buffer layer is preferably provided between the silicon single crystal substrate and the multilayer laminated structure. This is because the propagation of crystal defects in the silicon single crystal substrate is prevented by the buffer layer, so that it is easy to obtain a high-quality multilayered structure having excellent crystallinity.

In the present invention, an organometallic chemical vapor deposition method can be used to form the multilayered structure. This is because according to the metal organic chemical vapor deposition method, the composition of the crystal phase to be laminated is easily adjusted, and a high-quality multilayer laminated structure is easily obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The group III nitride semiconductor light-emitting diode of the present invention uses a silicon single crystal which has a high quality crystal and can be obtained relatively inexpensively as a substrate. There is no special restriction on the crystal plane orientation of the silicon single crystal used as the substrate,
Generally, {111} or {100} single crystals can be used. The {111} crystal plane is smaller than the {100} crystal plane by S
i atoms are densely present. Therefore, the effect of suppressing the thermal diffusion of boron (B) and phosphorus (P), which are constituent elements of the boron phosphide layer constituting the multilayer laminated structure of the present invention, to the inside of the substrate is exerted. That is, it is advantageous to prevent the silicon substrate surface from becoming uneven due to the diffusion and penetration of boron and phosphorus.

On the surface of the silicon single crystal substrate, there are formed a boron phosphide (BP) crystal layer and a gallium nitride phosphide (GaN _1-X P _X : 0 ≦ X ≦ 1) crystal layer which constitute a reflection layer. To form a multilayer laminated structure. The multilayer stack can be deposited directly on the silicon substrate, or alternatively, it can be deposited with a buffer layer in between. As a material forming the buffer layer, gallium phosphide (GaN _0.02 P _0.98 , lattice constant = 5.431 °) lattice-matched to a silicon single crystal (lattice constant: 5.4309 °), gallium arsenide (GaN _0.19 As) _0.81 , lattice constant = 5.4
31 °), boron gallium phosphide (B _0.02 Ga _0.98 P, lattice constant = 5.431 °) (see JP-A-11-266006), or boron gallium arsenide (B _0.25 Ga _0.75 A).
s, lattice constant = 5.431Å) (JP-A-11-2607)
No. 20) can be used. Further, indium phosphide (B _0.33 In _0.67 P, lattice constant = 5.431４３) containing indium (In) as a constituent element, indium arsenide (B _0.40 In _0.60 As, lattice constant =
5.431Å) is also available. Furthermore, cubic indium nitride phosphide (InN _0.49 P _0.51 , lattice constant = 5.4)
31Å) or indium arsenide nitride (InN _0.58 A
s _0.42 , lattice constant = 5.431 °) and the like can also be used. The use of the buffer layer has the advantage that the propagation of crystal defects in the silicon substrate can be prevented and the diffusion of impurities can be prevented.

Further, the buffer layer may be made of a material having a different lattice constant from that of the silicon single crystal. For example, when a buffer layer is composed of boron phosphide (BP, lattice constant = 4.538 °), the buffer layer (low-temperature buffer layer) grown at a relatively low temperature is nearly amorphous, and has a silicon single crystal and a multilayer laminated structure. This has the advantage that the lattice mismatch between the body and the substrate can be relaxed to obtain a multilayered structure having excellent crystallinity.
For example, a low-temperature boron phosphide buffer layer formed at a relatively low temperature of 250 ° C. or more and 500 ° C. or less has a lattice mismatch between silicon single crystal and boron phosphide crystal or gallium nitride phosphide crystal of about 16% (“Japan Journal of Crystal Growth Society, Vol. 24,
No. 2 (1997), p. 150) is relaxed to provide a high-quality multilayer laminated structure having a low density of crystal defects such as misfit dislocations (see US Pat. No. 6,069,021). .

When a multi-layer laminated structure is formed by laminating a large number of semiconductor layers having different refractive indexes at a specific interval, a function of reflecting light of a specific wavelength according to Bragg's law occurs. This is the so-called Bragg reflection layer (Distributed Bragg Refle)
ctor: DBR). In the present invention, as semiconductor layers having different refractive indexes, a boron phosphide (BP) crystal layer having a refractive index difference of 0.5 or more and gallium phosphide (GaN) are used.
_1-X P _X ) Use a crystal layer. BP crystal layer (refractive index = 3.
In order to make the refractive index difference from 1) 0.5 or more, GaN
The phosphorus mixed crystal ratio x of the _1-X P _X crystal layer may be a value in the range of x = 0 (GaN, refractive index = 2.0) to x = 1 (GaP, refractive index = 2.1). . Further, the phosphorus mixed crystal ratio x of the GaN _1-X P _X crystal layer is set in a range of x = 0.02 to x = 0.04 in consideration of lattice matching with the BP crystal layer as described later. Is preferred. The thickness (nm) of each layer to be laminated is set to λ / 4N with respect to the emission wavelength λ (nm). Here, N is the optical refractive index of the semiconductor material constituting each layer. The multilayer laminated structure having such a thickness is laminated to form a total thickness of 0.2 to 3 μm.

In the multilayer laminated structure, BP or GaN _1-X P _X (0 ≦ X
.Ltoreq.1). Further, the outermost layer of the multilayer laminated structure can be formed using either BP or GaN _1-X P _X. It is not necessary that the lowermost layer and the outermost layer be made of the same material. What is essential is that a BP crystal layer and a GaN _1-X P _X crystal layer are alternately laminated to form a multilayer laminated structure, which constitutes a so-called Bragg reflection layer (see “General Description of Semiconductor Devices”, page 28). ). 1
If the laminated unit structure composed of the BP crystal layer and the GaN _1-X P _X crystal layer is one cycle, it is desirable that the multilayer laminated structure has at least two or more cycles. A semiconductor multilayer reflector having a wide reflection bandwidth (reflectors such as Iga and Iga) are obtained from a periodic laminated structure composed of BP and GaN _1-X P _X.
Koyama, "Surface emitting laser", September 25, 1990,
Published by Ohmsha, 1st edition, 1st printing, 118th to 119th
Page).

For example, GaN having a composition ratio of BP to phosphorus of 3% is used.
FIG. 1 shows theoretically calculated values of the reflectance of blue light having a wavelength of 450 nm with respect to the number of periods of the multilayer laminated structure composed of _0.97 P _0.03 . BP has a refractive index of 3.1 and GaN
That of _0.97 P _0.03 is set to 2.0. BP and G
aN _0.97 P _0.03 The thickness of each constituent layer was 36 nm and 5
6 nm. The reflectance sharply increases when the number of periods exceeds two. If the number of periods is 7 or more, a reflectance of about 99.8% can be obtained.

The layer thickness (nm) of each constituent layer of the multilayer laminated structure having the function as a Bragg reflection layer is λ / (4 × N) (where λ (nm) is the wavelength of light to be reflected). , N is the refractive index). For example, when the refractive index of boron phosphide is set to 3.1 and the refractive index of gallium nitride phosphide is set to 2.0, a multilayer laminate structure capable of reflecting red light having a wavelength (λ) of 600 nm with high efficiency is as follows. , Layer thickness of about 48n each
It may be composed of a periodic multilayer structure of GaN _0.97 P _0.03 layers and BP layers and 75nm to m. FIG. 2 shows a BP layer having a thickness of about 48 nm and a GaN _0.97 P having a thickness of 75 nm, respectively.
10 shows the reflectance of a multilayer laminated structure in which _0.03 layers are alternately laminated for 10 periods. The center wavelength was 460 for reflection.
It is red light having a center wavelength of 700 nm from blue of nm.
In a multilayer laminated structure composed of a BP layer and a GaN _1-X P _X layer, by changing the layer thickness of the multilayer laminated structure constituting layer in accordance with the wavelength to be reflected, a small number of about 10 periods is obtained. A reflectance close to 100% can be obtained in the number of periods.

In the present invention, the constituent layers of the periodic multilayer structure are composed of a conductive BP crystal layer and a GaN _1-X P _X crystal layer. In particular, the carrier concentration is 1 × 10 ¹⁷ c
It is preferable that the conductive layer is formed of an n-type or p-type conductive layer having a size of m ⁻³ or more and 5 × 10 ¹⁹ cm ⁻³ or less. If a multilayer laminated structure is formed from conductive constituent layers, the driving current of the LED can be conducted from the upper part of the structure toward the silicon single crystal substrate, so that one electrode can be formed on the surface of the silicon substrate. Simplicity and manufacturing advantages. When the carrier concentration is less than 1 × 10 ¹⁷ cm ^−3, it is difficult to form a constituent layer having a resistance sufficiently low to supply a drive current. As the carrier concentration exceeds 5 × 10 ¹⁹ cm ⁻³ , the crystallinity of the layer to which the carrier impurity is added at a high concentration is deteriorated, so that it is difficult to obtain a multilayer laminated structure having sufficiently stable reflection performance. The p-type carrier concentration can be adjusted by appropriately controlling the doping amount of zinc (Zn) or magnesium (Mg) during film formation. The n-type carrier concentration is adjusted by appropriately controlling the doping amount of an n-type impurity such as silicon (Si) or selenium (Se).

The conductive type of each constituent layer constituting the periodic laminated structure is the same. When the constitutive layers having the opposite conductivity types are joined, a pn junction is formed inside the multilayer laminated structure. Therefore, energization of the LED driving current to the silicon single crystal substrate is disturbed, which is not preferable. In addition, the conductivity type of the multilayer structure constituting layer is unified to the conductivity type of the silicon single crystal used as the substrate. When the conductivity types of the silicon substrate and the multilayer laminated structure are opposite to each other, a pn junction is formed at a bonding interface between the silicon substrate and the multilayer laminated structure. For this reason, there is a disadvantage that the LED driving current is not sufficiently supplied to the silicon substrate. The same conductive constituent layers as those of the silicon single crystal substrate can be formed by, for example, a halogen vapor deposition method, a hydride vapor deposition method, or a metal organic chemical vapor deposition (MOCVD) method. .

In the present invention, the GaN _1-X P X crystal layer constituting the multilayer laminate structure with BP crystal layer, GaN _1-X P X crystal layer that the phosphorus composition ratio of 2% to 4% (0 .0
2 ≦ X ≦ 0.04). According to Vegard's law, the lattice constant of a cubic GaN _1-X P _X crystal layer having a phosphorus composition ratio in the range of 2% to 4% is 4.
It is in the range of 548 ° to 4.529 °. On the other hand, the lattice constant of zinc-blende BP is 4.538 ° (see “General Description of Semiconductor Devices”, p. 28). Therefore, when the phosphorus composition ratio is limited to the above range, a GaN _1-X P _X crystal layer that is substantially lattice-matched with the BP crystal layer can be obtained. 3% phosphorus composition ratio
(0.03) GaN _0.97 P _0.03 is 4.538 は
And a lattice match with BP. Therefore, B
Ga with a P crystal layer and a phosphorus composition ratio in the range of 3% ± 1%
The lattice mismatch with the N _{1 -X} P _X crystal layer (0.02 ≦ X ≦ 0.04) is within about ± 0.2%, and a good multilayered structure can be formed from good lattice matching. There are advantages that can be done. At this time, the refractive index of the GaN _1-X P _X crystal layer is about 2.1, and the difference in the refractive index of 0.5 or more between the GaN crystal layer and the BP crystal layer is excellently maintained. A multilayer laminated structure can be configured. As a result, the forward voltage (V
It is possible to obtain a group III nitride semiconductor light emitting diode excellent in f) having excellent electric characteristics.

On the multilayer laminated structure, a general formula Al _a G
forming a light emitting portion of _{a b In 1-ab N c} M 1-c made of a Group III nitride layer, denoted by pn junction type double hetero junction structure. Here, 0 ≦ a, b, a + b ≦ 1, and M represents a Group V element other than nitrogen (N) such as phosphorus (P), arsenic (As), antimony (Sb), and 0 <c ≦ It is one.
Therefore, the double heterojunction structure forming the light emitting portion in the present invention includes at least one of Al, Ga, and In as a group III element, and includes nitrogen (N) as an essential element as a group V element. .

The light emitting portion having the DH junction structure is a light emitting portion having a structure in which a light emitting layer is sandwiched between p-type and n-type cladding layers.
To either the light-emitting layer or cladding layer Al _a Ga _b In
_{It is only} necessary to include the _1-ab N _c M _1-c layer. Al _{a for the} light emitting layer
Using _{Ga b In 1-ab N c} M 1-c layer can be a short wavelength based light-emitting diodes of blue system.

The mixed crystal ratio of the group III element in the cladding layer is set higher than the mixed crystal ratio of the group III element in the light emitting layer, so that the band gap of the cladding layer is made larger than the band gap of the light emitting layer. The effect of confining electrons injected into the light emitting layer is enhanced. The thickness of the light emitting layer is usually 5 to 30 nm, and the thickness of the cladding layer is 100 to 800 nm, which is thicker than that.

Ohmic electrodes for applying a drive current are formed on the upper and lower sides of the stacked body as described above to obtain a light emitting diode. As the electrode material constituting the _{Al a Ga b In 1-ab} N c M 1-c layer and ohmic contact, in the case of n-type electrode of aluminum (Al) is, in the case of p-type electrode can be used gold (Au) is . As the material of the ohmic electrode formed on the silicon substrate, aluminum (Al) can be used for an n-type electrode, and aluminum-antimony (Al-Sb) alloy can be used for a p-type electrode. Since the resistance of the entire LED is low, a drive current can be passed through the substrate.

[0025]

According to the present invention, a periodic multilayer structure composed of a BP crystal layer and a GaN _1-X P _X crystal layer is used as a so-called Bragg reflection structure for reflecting light emitted from a light emitting portion. It is.

In the present invention, the BP crystal layer and the GaN _1-X
The carrier concentration of the conductive periodic multilayer structure composed of the PX crystal layer and the _Px crystal layer was limited to a specific range so that LED driving current could be passed through the silicon substrate.

Further, in the present invention, the lattice matching between the BP crystal layer and the GaN _1-X P _X crystal layer is improved by using the GaN _1-X P _X crystal layer in which the composition ratio of phosphorus is limited to a specific range. By maintaining this, excellent crystallinity of the periodic multilayer structure is ensured.

[0028]

(Example 1) On a silicon single crystal substrate, a multilayer laminated structure which is a Bragg reflection layer made of a mixed crystal of boron phosphide and gallium phosphide nitride is provided to form a group III nitride semiconductor light emitting diode. The present invention will be specifically described with an example of a configuration. Light emitting diode 10 according to the present embodiment
Is shown in FIG.

The silicon substrate 101 has boron-doped p.
A silicon single crystal (111) was used. On the silicon substrate 101, a low-temperature buffer layer 102 made of boron phosphide was deposited. The low-temperature buffer layer 102 is made of triethyl boron ((C ₂
The H _{5) 3} B) / phosphine (PH ₃₎ / hydrogen (H ₂₎ an atmospheric pressure MOCVD method using a reaction gas, were deposited at 350 ° C.. The layer thickness of the low-temperature buffer layer 102 was about 10 nm. On the surface of the low-temperature buffer layer 102, the same high temperature buffer layer 103 is formed at 1000 ° C.
To form a zinc (Zn) -doped p-type BP layer. Dimethyl zinc ((C ₂ H ₅ ) ₂ Zn) was used as a zinc doping source. The carrier concentration of the high temperature buffer layer 103 is about 7 × 10
¹⁸ cm ^-3 . The layer thickness was 500 nm.

On the high temperature buffer layer 103, a Bragg reflection layer
Constituent layer 10 constituting multilayer stack structure 104 to be formed
As 4-1, zinc with a phosphorus (P) composition ratio of 0.03
Doped p-type gallium nitride phosphide (GaN_0.97P_0.03)
The layers were stacked. GaN_0.97P _0.03The layer is trimethyl gall
Um ((CH_Three)_ThreeGa) / phosphine (PH)_Three )/Ann
Monia (NH_Three) / Hydrogen (H_Two) Normal pressure using reaction gas
It was grown at 1000 ° C. by MOCVD. Career
The concentration is about 8 × 10¹⁷cm^-3And the layer thickness is about 59 nm
Was. On the first constituent layer 104-1, the second constituent layer 10
4-2, zinc-doped p-type with a layer thickness of about 38 nm
A BP layer was laminated. Similarly, the first and second constituent layers 1
A total of 8 units of the laminated unit consisting of 04-1 and 104-2
It was stacked again. Accordingly, the silicon substrate 101 side
GaN lower layer_0.97P_0.03Layer and the outermost layer as BP
The multilayer laminated structure 104 having the period of 8 was formed.

The internal structure of the multilayer laminated structure 104 was observed using a normal sectional TEM method. Crystal defects such as misfit dislocations were observed inside the low-temperature buffer layer 102. There are few dislocations propagating inside the multilayer laminated structure 104, and the low-temperature buffer layer 102
Since the misfit with 01 was relieved, it was interpreted as containing a defect. By the action of the low-temperature buffer layer 102, each of the constituent layers 104-1 and 104-1 of the multilayer laminated structure 104 is formed.
In 4-2, a good crystal having a small crystal defect density was obtained.

On the surface of the multi-layer structure 104, a lower cladding layer 105 is formed of (CH ₃ ) ₃ Ga / PH ₃ / NH ₃ / H ₂
1000 by normal pressure MOCVD using reactive gas
Laminated at ℃. The lower cladding layer 105 was composed of a zinc-doped p-type GaN _0.97 P _0.03 layer lattice-matched to the BP layer, which is the outermost layer of the multilayer structure 104. The carrier concentration of the lower cladding layer 105 is about 8 × 10 ¹⁷ cm ^−3.
And the layer thickness was 800 nm.

On the lower cladding layer 105, silicon-doped n-type gallium indium nitride (Ga _0.90 In
_The light emitting layer 106 of _0.10 N) was laminated. Light emitting layer 1
06 is trimethylgallium ((CH ₃ ) ₃ Ga) / trimethyl indium ((CH ₃ ) ₃ In) / phosphine (P
It was grown at 890 ° C. by a normal pressure MOCVD method using an H ₃ ) / ammonia (NH ₃ ) / hydrogen (H ₂ ) based reaction gas. The average indium composition ratio of the light emitting layer 106 was set to 0.10. The layer thickness was about 30 nm. The carrier concentration was about 3 × 10 ¹⁸ cm ⁻³ .

Light emitting layer 106 made of Ga _0.90 In _0.10 N
On the upper side, as an upper cladding layer 107, a silicon-doped n-type aluminum-gallium nitride mixed crystal (Al _γ Ga _1-γ
N) layers were laminated. The Al composition ratio (γ) was substantially linearly and monotonically decreased from 0.2 to 0 (zero) in the direction of increasing the layer thickness, thereby giving a gradient to the aluminum composition. The layer thickness is 2
00 nm.

The above-mentioned p-type GaN _0.97 P _0.03 lower cladding layer 105, n-type Ga _0.90 In _0.10 N light-emitting layer 106, and upper cladding layer 107 composed of an n-type Al _γ Ga _1-γ N layer
Light emitting part 1 having a pn junction type double hetero junction structure from three layers
08.

On the back surface of the p-type silicon single crystal substrate 101, a p-type ohmic electrode 109 made of aluminum-antimony (Al-Sb) was formed. On the surface of the upper cladding layer 107, a circular n-type ohmic electrode 110 made of aluminum was formed. The diameter of the n-type ohmic electrode 110 was about 130 μm. Thereafter, the silicon single crystal substrate 101 is cut in the [110] direction by using the cleavage property, and a chip having a side of about 300 μm is formed.
To obtain a light emitting diode 10.

Both p-type and n-type ohmic electrodes 109 to 11
During a period of 0, an LED driving current was supplied. Current-voltage (I
-V) The characteristics showed normal rectification characteristics due to the good pn junction characteristics of the light emitting unit 108. The forward voltage (Vf) obtained from the IV characteristic is about 3.0 V (forward current = 20
mA). The reverse voltage was about 15 V (reverse current = 10 μA). When an operation current of 20 mA was applied in the forward direction, blue light having an emission center wavelength of about 470 nm was emitted. The half width of the emission spectrum is about 1
It was 8 nm. The light emission intensity in a chip state measured using a general integrating sphere was about 14 μW, and a group III nitride semiconductor light emitting device with high light emission intensity was obtained.

(Embodiment 2) Next, as a second embodiment of the present invention, only a low-temperature buffer layer is deposited on an n-type silicon substrate, and a multilayer laminated structure serving as a Bragg reflection layer is deposited thereon. An example in which a group III nitride semiconductor light emitting unit is formed is shown.
FIG. 4 is a schematic sectional view of a light emitting diode according to a second embodiment of the present invention.

Phosphorus-doped n-type silicon single crystal substrate 20
1 on the (111) plane, a low-temperature buffer layer 202 made of BP
By a reduced pressure MOCVD method using a diborane (B ₂ H ₆ ) / phosphine (PH ₃ ) / hydrogen (H ₂ ) -based reaction gas.
The layers were laminated at ℃. V / III ratio, ie, group V source gas and I
The supply ratio with the group II source gas (= PH ₃ / B ₂ H ₆ ) was set to about 120. The pressure of the reaction system during growth is about 3 × 10
⁴ Pa, and disilane (Si
₂ H ₆₎ - was used hydrogen (H ₂₎ mixed gas. The thickness of the low-temperature buffer layer 202 was about 17 nm.

The internal structure of the low-temperature buffer layer 202 is shown by a cross-sectional TEM.
Observed by the method. At the time of forming the low-temperature buffer layer 202 (as-grown state), the upper region from the bonding surface with the silicon single crystal substrate 201 to approximately 2 nm was mainly composed of BP single crystal. Therefore, no separation was observed between the low-temperature buffer layer 202 and the silicon single crystal substrate 201,
Good adhesion was maintained. The upper portion of the low-temperature buffer layer 202 was mainly composed of a BP amorphous body.

On the low-temperature buffer layer 202, a silicon-doped n-type BP crystal layer was formed as the first layer 204-1 of the multilayer laminated structure 204 serving as a Bragg reflection layer. This BP crystal layer was formed at 980 ° C. by using the above-mentioned reduced pressure MOCVD method, setting the pressure of the reaction system to about 3 × 10 ⁴ Pa. According to analysis by X-ray diffraction, it was confirmed that this BP crystal layer was a BP crystal layer mainly composed of cubic crystals. The layer thickness is about 41 nm and the carrier concentration is about 1 × 10 ¹⁸
cm ^-3 .

After completion of the formation of the first layer 204-1, most of the amorphous body in the low-temperature buffer layer 202 starts from the single crystal layer existing in the boundary region with the silicon single crystal substrate 201. As a single crystal. Also,
As the BP crystal layer, the low-temperature buffer layer 202 is
01, the silicon single crystal substrate 201
And the first layer 204-1 was a continuous film without peeling.

On the first layer 204-1, a silicon-doped n-type gallium nitride phosphide (GaN _0.97 P _0.03 ) layer was stacked as a second constituent layer 204-2. 3% of the phosphorus composition ratio of the gallium phosphide layer is lattice-matched to BP. The second constituent layer 204-2 disilane as a dopant for silicon (Si ₂ H ₆₎ - hydrogen (H
₂ ) Utilize a mixed gas at a pressure of about 3 × 10 ⁴ Pa
The film was formed at 80 ° C. The layer thickness was about 64 nm, and the carrier concentration was about 9 × 10 ¹⁷ cm ⁻³ .

The first and second constituent layers 204 as described above
-1, 204-2 are repeatedly laminated for 10 periods to form a Bragg reflection layer, a multilayer laminated structure 20
No. 4 was constructed. The multilayer laminated structure 204 includes the silicon substrate 2
The lowermost layer on the 01 side is a BP layer, and the outermost layer is GaN _0.97 P
_A total layer thickness of _0.03 layers was about 1050 nm.

On the multilayer laminated structure 204, a silicon-doped n-type GaN _0.97 P _{0.03 is} formed as a lower cladding layer 205.
A layer was formed. The lower cladding layer 205 is made of (CH ₃ ) ₃ G
Decompression MO using a / PH ₃ / NH ₃ / H ₂ reaction gas
The layers were stacked at 980 ° C. by the CVD method. Layer thickness is about 800n
m, and the carrier concentration were about 2 × 10 ¹⁸ cm ⁻³ . The carrier concentration was adjusted by controlling the amount of disilane added to the MOCVD reaction system.

On the lower cladding layer 205, (C
The light emitting layer 206 was laminated at 980 ° C. by a reduced pressure MOCVD method using a H ₃ ) ₃ Ga / PH ₃ / NH ₃ / H ₂ based reaction gas as a raw material. The light emitting layer 206 is a silicon-doped n-type Ga
_It was composed of a _0.82 In _0.18 N layer. The layer thickness was about 10 nm, and the carrier concentration was about 2 × 10 ¹⁸ cm ⁻³ . The carrier concentration was adjusted by controlling the amount of disilane added to the MOCVD reaction system.

On the light emitting layer 206, an upper clad layer 207 composed of a zinc-doped p-type GaN _0.97 P _0.03 layer was laminated. The upper cladding layer 207 is made of (CH ₃ ) ₃ Ga / P
Reduced pressure MOCV using H ₃ / NH ₃ / H ₂ reaction gas as raw material
The layers were laminated at 980 ° C. by Method D. Upper cladding layer 207
Has a layer thickness of about 100 nm and a carrier concentration of about 8 × 10 ¹⁷ c
m ^-3 . The carrier concentration was adjusted by controlling the amount of disilane added to the MOCVD reaction system.

The above-mentioned n-type GaN _0.97 P _0.03 lower cladding layer 205, n-type Ga _0.82 In _0.18 N light-emitting layer 206, and upper cladding layer 207 composed of p-type GaN _0.97 P _0.03 layer
The light emitting section 208 having a pn junction type double hetero junction structure was constructed from the above.

On the back surface of the n-type silicon single crystal substrate 201, an n-type ohmic electrode 209 made of an aluminum (Al) alloy was formed. On the surface of the upper cladding layer 207, a circular p-type ohmic electrode 210 made of gold (Au) was formed. The diameter of the p-type ohmic electrode 210 was about 110 μm. After that, the silicon single crystal substrate 201 is cleaved in the [110] direction by about 3
The light-emitting diode 20 was cut into a chip having a size of 50 μm.

Both p-type and n-type ohmic electrodes 209 to 21
The LED driving current was supplied during 0. Current-voltage (I-
V) The characteristics showed normal rectification characteristics due to the good pn junction characteristics of the light emitting section 208. The forward voltage (Vf) obtained from the IV characteristic is about 3.2 V (forward current = 20 mA)
It became. The reverse voltage is about 15 V (reverse current =
10 μA). When an operation current of 20 mA was applied in the forward direction, blue-green light having an emission center wavelength of about 510 nm was emitted. The half width of the emission spectrum is about 22n
m. The light emission intensity in a chip state measured using a general integrating sphere is about 18 μW, which is a high light emission intensity II.
A group I nitride semiconductor light emitting device was obtained.

[0051]

According to the present invention, there is provided a reflection device having a semiconductor multilayer structure in which a boron phosphide crystal layer and a gallium phosphide nitride crystal layer are alternately stacked between a silicon single crystal substrate and a light emitting portion. Since the layer is provided, light emitted from the light emitting portion can be reflected and extracted in the light extraction direction, so that a group III nitride semiconductor light emitting diode with high emission intensity can be provided.

Further, according to the present invention, the multilayer laminated structure reflection
Boron phosphide crystal layer and gallium phosphide nitride constituting layer
The carrier concentration of the crystal layer is 1 × 10¹⁷cm^-35 ×
10 ¹⁹cm^-3In the case of the following, particularly excellent crystallinity
LED can be driven by forming a thin layer with good conductivity
Electric current can flow in the vertical direction of the laminated structure,
Group III nitride half with high emission intensity by using easy deviceization means
Conductive light emitting diodes can be provided.

Further, according to the present invention, when the phosphorus composition ratio of the gallium nitride phosphide crystal layer constituting the multilayer laminated structure reflection layer is set to 2% or more and 4% or less, the boron phosphide crystal constituting the reflection layer is formed. Since good lattice matching with the layer can be maintained, a reflective layer having few crystal defects and excellent crystallinity can be formed, and there is an effect that a group III nitride semiconductor light emitting diode with higher emission intensity can be provided. .

[Brief description of the drawings]

FIG. 1 is a diagram showing the dependency of the reflectance on the number of lamination cycles.

FIG. 2 is a diagram showing the wavelength dependence of the reflectance of a reflective layer.

FIG. 3 is a schematic cross-sectional view of the light-emitting diode described in Example 1.

FIG. 4 is a schematic cross-sectional view of the light-emitting diode described in Example 2.

[Explanation of symbols]

10, 20: light emitting diode, 101, 201: single crystal silicon substrate, 102, 202: low temperature buffer layer, 10
3 ・ ・ ・ High temperature buffer layer, 104,204 ・ ・ ・ Multilayer laminated structure, 1
05, 205: Lower cladding layer, 106, 206 ... Light emitting layer, 107, 207: Upper cladding layer, 108, 2
08 ... light-emitting portion, 109, 209 ... p-type ohmic electrode, 110,210 ... n-type ohmic electrode,

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F041 AA04 AA40 CA04 CA33 CA34 CA40 CA49 CA53 CA57 CA64 CA65 CA83 CA85 CB15

Claims (8)

[Claims] 1. A semiconductor device comprising: a silicon single crystal substrate;
Formula _{Al a Ga b In 1-ab} N c M 1-c ( where, 0 ≦ a,
b, a + b ≦ 1, M represents a Group V element other than nitrogen,
A group III nitride semiconductor light emitting device comprising a group III nitride layer represented by 0 <c ≦ 1) and having a pn junction type double hetero junction light emitting portion, wherein the silicon single crystal A group III nitride semiconductor light emitting diode comprising a reflective layer having a multilayer laminated structure in which a boron phosphide crystal layer and a gallium phosphide crystal layer are alternately laminated between a substrate and the light emitting portion. . 2. A carrier concentration of the boron phosphide crystal layer and the gallium phosphide crystal layer constituting the multilayer laminated structure is not less than 1 × 10 ¹⁷ atom cm ^{-3 and not} more than 5 × 10 ¹⁹ atom cm ^-3. The group III nitride semiconductor light emitting diode according to claim 1, wherein: 3. The group III according to claim 1, wherein the gallium nitride phosphide crystal layer constituting the multilayer laminated structure has a phosphorus composition ratio of 2 atomic% or more and 4 atomic% or less. Nitride semiconductor light emitting diode. 4. The group III nitride semiconductor light emitting diode according to claim 1, wherein the number of cycles of lamination of the multilayer laminated structure is two or more. 5. The group III nitride semiconductor light emitting diode according to claim 4, wherein the number of cycles of lamination of the multilayer laminated structure is 7 or more. 6. The surface of a silicon single crystal substrate is {111}
6. A crystal plane according to claim 1, wherein the crystal plane is a crystal plane.
6. The group III nitride semiconductor light-emitting diode according to item 1. 7. The group III nitride semiconductor light emitting diode according to claim 1, wherein a buffer layer is interposed between the silicon single crystal substrate and the multilayer laminated structure. 8. The method for manufacturing a group III nitride semiconductor light emitting diode according to claim 1, wherein the multilayered structure is formed by a metal organic chemical vapor deposition method.