JPH1174560A - GaN-based compound semiconductor light emitting device and method of manufacturing the same - Google Patents

Abstract

(57) Abstract: Provided is a GaN-based compound semiconductor light-emitting device having improved light-emitting characteristics and electrical characteristics by forming a GaN-based compound semiconductor layer having extremely excellent crystallinity, and a method of manufacturing the same. The purpose is to do. A substrate, a buffer layer provided on the substrate and made of a compound semiconductor containing at least one of phosphorus (P) and arsenic (As), and a GaN-based compound provided on the buffer layer And a light-emitting layer made of a semiconductor, so that distortion caused by lattice mismatch between the substrate and the GaN-based compound semiconductor layer is reduced, and crystallinity is improved. Nag
A light-emitting element including an aN-based compound semiconductor layer can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a GaN-based compound semiconductor, and more particularly, to a GaN-based compound semiconductor light emitting device and a method of manufacturing the same.

[0002]

2. Description of the Related Art Since a single crystal of a GaN-based compound semiconductor has a direct transition type band structure, highly efficient light emission is expected. Here, in this specification, “GaN-based compound semiconductor” refers to In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1,0 ≦
In the chemical formula of y ≦ 1, x + y ≦ 1), semiconductors of all compositions in which the composition ratios x and y are changed within respective ranges are included. For example, InAlN (x = 0.
4, y = 0.6) is also included in the “GaN-based compound semiconductor”. Further, “GaN-based compound semiconductor” in the present specification refers to a compound obtained by adding any of phosphorus (P), arsenic (As), and an impurity element serving as a dopant to a compound represented by the above chemical formula. It also includes semiconductors.

[0003] A GaN-based compound semiconductor can change its band gap at room temperature from 6.2 eV to 2.0 eV, and is therefore a very promising material for producing a light-emitting device that emits light in the visible region. However, since the GaN single crystal has a high melting point and the equilibrium vapor pressure of nitrogen near the growth temperature is high, it is difficult to grow a bulk single crystal from the melting point, and there is no lattice-matched substrate. Therefore, a GaN-based compound semiconductor light emitting device, for example, n-type Ga
In manufacturing an element in which an N layer, an InGaN layer as a light emitting layer, and a p-type GaN layer are sequentially laminated, a sapphire substrate, a GaN substrate, or the like has been mainly used conventionally.

[0004] Of these substrates, the sapphire substrate has a high melting point of about 2020 ° C and has good heat resistance.
Lattice mismatch occurs with aN. Therefore, in order to prevent the crystallinity from deteriorating due to the lattice mismatch, Al _x Ga ₁ -xN
A buffer layer (0 ≦ x ≦ 1) was grown at a low temperature, and a predetermined element structure was laminated thereon.

On the other hand, a GaN substrate is disclosed in Japanese Unexamined Patent Publication No. 7-9478.
As disclosed in Japanese Patent Application Publication No. 4 (1999) -104, a GaN single crystal is grown on a sapphire substrate, and then the sapphire substrate is removed to obtain a predetermined element structure.

[0006]

However, conventionally, when these substrates are used, there are problems as described below. First, a problem when a sapphire substrate is used will be described. Since the GaN layer has low conductivity, it is necessary to grow an n-type GaN layer having a thickness of 4 μm or more on the buffer layer in order to diffuse the current throughout the light emitting element. However, as described above, since the lattice mismatch between the sapphire substrate and GaN is very large, there is a limit to the improvement in crystallinity by the buffer layer. That is, as the n-type GaN layer grows thicker, the crystallinity deteriorates, and the crystallinity of the light emitting layer laminated thereon also deteriorates. As a result, there is a problem that it is difficult to obtain a highly efficient light-emitting element, and the reliability of the electrical characteristics is also likely to be reduced.

Further, since the sapphire substrate is an insulator, in the case of a light-emitting element manufactured on sapphire, it is necessary to make both p-side and n-side electrode contacts on the side of the laminated semiconductor layer. For this reason, a part of the growth layer is etched to the p-type GaN layer, and from the same surface side, the n-type GaN layer and the p-type G
2. Description of the Related Art A light emitting element is formed by forming an electrode on an aN layer. However, in this method, since two electrodes are formed on the light extraction surface side, there is a problem that the area of the light extraction portion must be reduced.
For this reason, there has been proposed a configuration or a light emitting device in which the mounting on the lead frame is upside down and the sapphire surface which is a light-transmitting substrate is used as a light extraction surface. However, in the light emitting device having such a configuration, it is difficult to reduce the interval between the lead frames for taking the electrodes.
A new problem arises in that the chip size increases and the number of chips that can be obtained from one wafer decreases. In addition, there is a problem that the mass productivity is reduced due to the necessity of setting a fine position between the lead frames, and a short circuit is liable to occur due to the protrusion of the solder.

Next, a problem in the case of using a GaN substrate will be described. Table 1 shows InG having various In compositions.
3 shows the band edge wavelength, the lattice constant, and the lattice mismatch ratio between the aN layer and the GaN substrate, respectively.

[0009]

[Table 1] As can be seen from the table, when the In composition is 10% or more, the lattice mismatch ratio with the InGaN layer exceeds 1%, and
Since the crystallinity of the GaN layer is significantly deteriorated, there is a problem that a highly efficient light emitting element cannot be obtained.

On the other hand, the sapphire substrate and the GaN substrate described above are both difficult to cleave because of their high crystal hardness, and the yield in the chip cutting process is at most 70%.
%.

The present invention has been made in view of such a problem. That is, an object of the present invention is to provide a GaN-based compound semiconductor light-emitting device in which light-emitting characteristics and electric characteristics are improved by forming a GaN-based compound semiconductor layer having extremely excellent crystallinity, and a method of manufacturing the same. is there.

[0012]

In order to achieve the above-mentioned object, a GaN-based compound semiconductor light emitting device according to the present invention is provided on a substrate and provided on the substrate, and comprises a phosphor (P) and an arsenic (As). A buffer layer made of a compound semiconductor containing at least any one of the following, and a light emitting layer made of a GaN-based compound semiconductor provided on the buffer layer, wherein the substrate and the GaN-based It is possible to provide a light-emitting element including a GaN-based compound semiconductor layer having good crystallinity by relaxing strain caused by lattice mismatch between compound semiconductor layers.

Further, by providing a single crystal layer made of a compound semiconductor containing at least one of phosphorus (P) and arsenic (As) between the buffer layer and the light emitting layer, a higher crystallinity can be obtained. A light-emitting element including a favorable GaN-based compound semiconductor layer can be provided.

The material of the buffer and the single crystal layer may be a composition formula of GaN _1-x1-y1 P _{x 1} As _y1 (where,
It is desirable to employ a compound semiconductor represented by 0 <x ₁ + y ₁ <1, 0 ≦ x ₁ , 0 ≦ y ₁ ).

Further, it is preferable that the light emitting layer is made of InGaN, and the buffer layer is made of a material lattice-matched with the light emitting layer.

On the other hand, the light emitting layer has a composition formula of In _z Ga _{1 -z}
N (where 0 <z <1), and at least one of the buffer layer and the single crystal layer has a composition formula of GaN _1-x P _x (where,
0 <x ≦ 1) or GaN _{1- y} As _y (where 0 <y ≦
1) wherein the composition z and the composition x or the composition y in the above composition formula are represented by the following formula: (351/317) z−0.0317 ≦ x ≦ (351/31)
7) z + 0.0317 or (351/400) z-0.04 ≦ y ≦ (351
By constructing the relationship satisfying the relationship expressed by (/400)z+0.04, lattice distortion can be remarkably reduced.

Alternatively, at least one of the buffer layer and the single crystal layer has a composition formula of GaN
_{1-wx- (1-w) y} P _wx As _{(1-w) y} (where 0 ≦ w ≦ 1, 0
.Ltoreq.x.ltoreq.1 and 0.ltoreq.y.ltoreq.1), wherein the composition ratio x or the composition ratio y in the composition formula satisfies the relationship represented by the above formula. Likewise preferred.

The thickness of the GaN-based compound semiconductor laminated between the buffer layer and the light emitting layer is 0.2 μm.
With the following, lattice distortion of the light emitting layer can be suppressed.

Further, the substrate is made of sapphire, Zn
By employing any material of O, GaAs, spinel, SiC, and Si, a high-performance light-emitting element can be easily obtained.

On the other hand, a light emitting device according to the present invention is provided with a first electrode and a first conductivity type provided on the first electrode and containing at least one of phosphorus (P) and arsenic (As). A first layer connected to the first electrode, a second layer made of a first conductivity type GaN-based compound semiconductor provided on the first layer, A light-emitting layer made of a GaN-based compound semiconductor provided on the second layer, a third layer made of a second-conductivity-type GaN-based compound semiconductor provided on the light-emitting layer, The second electrode provided on the layer can also be configured to have a structure in which the light extraction efficiency is improved and the chip area can be reduced.

Here, the first layer is made of GaN _x P _y As
_1-xy (where 0 <x <1, 0 ≦ y <1, x + y ≦
It is desirable to configure it by comprising 1).

The second layer is made of GaN,
The light emitting layer is made of In _z Ga _{1 -zN} (where 0 <z ≦ 1).
, And the third layer is made of GaN, whereby a light emitting element having good light emitting characteristics in a blue region can be provided.

Alternatively, the second layer is made of AlGaN, and the light emitting layer is made of In _z Ga _{1 -zN} (where 0 ≦ z
.Ltoreq.1), and the third layer is made of AlGaN to provide a light-emitting element having good light-emitting characteristics in the ultraviolet region.

In these light-emitting elements, the light-emitting region has a pn junction, at least a single heterojunction,
It is desirable that the quantum well structure be composed of one or multiple quantum well structures.

In the method of manufacturing a GaN-based compound semiconductor light emitting device according to the present invention, a step of depositing a compound semiconductor layer containing at least one of phosphorus (P) and arsenic (As) on a substrate; GaN on the buffer layer
And a step of depositing a system compound semiconductor layer, whereby a light emitting element having a light emitting layer with good crystallinity can be provided.

Further, by removing the substrate, electrodes are formed on both the upper and lower surfaces, so that a light-emitting element having a high light extraction efficiency and a small chip area can be manufactured.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view illustrating the configuration of a GaN-based compound semiconductor light emitting device according to the first embodiment of the present invention. In this example, n-type GaN _1-x P _x (or GaN _1-y A
_sy ) Low temperature buffer layer 2, n-type GaN _1-x P _{x (} or G
aN _1-y As y) layer 3, n-type GaN layer 4, InGaN active layer 5, p-type GaN layer 6 are formed in this order. Further, n-type GaN _1-x partially exposed by etching
An n-type electrode 7 is formed on the P _x (or GaN _1-y Asy) layer 3, while a p-type electrode 8 is formed on the p-type GaN layer 6 to form a pair of electrodes.

That is, in this embodiment, GaN _1-x grown on a substrate such as sapphire at a relatively low temperature is used.
P _x or GaN _1-y As _y (where 0 <x <1, 0 <
y <1) Buffer layer 2 is deposited. The growth temperature of such a buffer layer can be selected, for example, within the range of 550 to 800 ° C. The semiconductor layer deposited on the substrate at such a temperature is amorphous or polycrystalline composed of extremely fine crystal grains immediately after the deposition. Then, in order to grow another crystal layer on the buffer layer, when the temperature is raised to, for example, 1000 ° C. or more, the crystallization progresses and becomes polycrystalline. In this specification, such a buffer layer grown at a relatively low temperature is referred to as a “low-temperature buffer layer”.

Hereinafter, the effect of the buffer layer in the present invention will be described in detail. FIG. 2 shows a conventional buffer layer,
FIG. 3 is a graph showing a relationship between a composition ratio x of a buffer layer according to the present invention and an InGaN layer serving as a light emitting layer with respect to a lattice constant. The InGaN layer used as the light emitting layer has a tendency that the lattice constant increases as the composition x of In increases. However, in the GaAlN layer which is a conventional buffer layer, the lattice constant decreases as the Al composition ratio x increases, and the difference from the lattice constant of the InGaN layer tends to increase. On the other hand, according to the present invention, in any case of GaN _1-x P _x or GaN _1-x As _x used as the buffer layer, the lattice constant increases with an increase in the composition x, The difference in lattice constant from the InGaN layer can be reduced. Further, as exemplified by the line AA in FIG. 2, by adjusting the composition of the GaN _1-x P _x or GaN _1-x As _x layer, the lattice constant can be matched with that of the InGaN layer.

Here, as an example, the lattice mismatch ratio (Δa / a) between the buffer layer and the InGaN layer at the composition x = 0.1 shown by the line BB in FIG. For example, it is about 0.2%, and about 2.1% when the conventional buffer layer is used. That is, according to the present invention, the lattice mismatch rate can be reduced to about 1/10 of the conventional one.

That is, according to the present invention, especially when the In composition is increased to the blue region, a light emitting layer having less lattice distortion than the conventional one can be easily formed by selecting the composition of P or As. it can.

Table 2 shows preferred combinations of such compositions.

[0034]

[Table 2] Here, when Table 2 described above is expressed by a general formula, the light emitting layer is expressed as In _z Ga ₁ -zN, and the buffer layer is expressed as GaN _1-x P _x
Or when expressed as GaN _1-y As _y are x, y, and preferred combination of conditions of z can be expressed as follows.

(351/317) z−0.0317 ≦ x ≦ (351/317) z + 0.0317 (351/400) z−0.04 ≦ y ≦ (351/400) z + 0.04 In this case, the buffer layer A GaN-based compound semiconductor layer laminated between the InGaN light-emitting layer, for example, GaN
It is desirable that the thickness of the cladding layer be in the range of 0.05 to 0.2 microns. The reason for this is that if the thickness is more than this, the crystallinity of the InGaN light-emitting layer tends to deteriorate due to the strain due to lattice mismatch.

As described above, according to the present invention, a high-quality light-emitting layer can be obtained by reducing the strain of the light-emitting layer as compared with the related art, so that the light-emitting efficiency of the light-emitting element is improved. be able to.

Further, in the embodiment shown in FIG.
On such a low temperature buffer layer 2, GaN
_1-x P x (or GaN _1-y As y) layer 3 is laminated. This layer 3 is grown at a relatively high temperature and is configured as a single crystal. On the low temperature buffer layer 2, by laminating such a GaN _1-x P _x (or GaN _1-y As _y) layer 3, the crystallinity of the layers 4-6 of the light-emitting device grown thereon Can be further improved.

[0038] However, in the present invention, such a single crystalline GaN _1-x P x (or GaN _1-y As y) layer 3
May be directly laminated on the low-temperature buffer layer 2 without laminating the layers. Even in such a simplified configuration, it is possible to obtain an effect that the crystallinity of the InGaN active layer 5 is improved and the light emission characteristics are improved as compared with the case where the conventional AlGaN buffer layer is used.

[0039] Further, GaN _1-x P x layer and GaN _1-y As y
The layer has better conductivity than the GaN layer. Therefore,
Even if the thickness of the n-type GaN layer 4 is reduced, there is an advantage that the current injected from the n-side electrode can be diffused throughout the device.

[0040] Here, in the present embodiment, as the buffer layer, GaN _1-x P x layer and GaN _1-y As y layer is employed. However, a quaternary mixed crystal represented by GaNPAs may be used instead. Such a quaternary mixed crystal can also easily achieve lattice matching with the InGaN layer.

Further, a single-crystal GaN _1-x P _x epitaxially grown on such a quaternary low-temperature buffer layer is used.
Layer, GaN _1-y As y layer, or GaNPAs layer may be stacked. In this case, the composition of the low-temperature buffer layer and the composition of the single crystal quaternary mixed crystal layer thereon may be different or the same. When the compositions are the same, an effect of reducing lattice mismatch can be obtained because the lattice constants match.

Next, a second embodiment according to the present invention will be described.

FIG. 3 is a schematic sectional view illustrating the configuration of the second light emitting device according to the present invention. In this example, n
N-type GaN layer 12, InGaN layer 13, p-type GaN layer 1 on n _- type GaN _1-x P _x (or GaN _1-y Asy) layer 11
4 are formed in this order. Furthermore, n-type GaN _1-x
P _x (or GaN _1-y As y) n-side electrode 15 on the back side of the layer 11 is formed, p-side electrode 1 on the p-type GaN layer 14
6 are formed to form a pair of electrodes.

The light emitting device of the present embodiment is formed, for example, on an n-type GaN _1-x P _x (G
growing aN _1-y As y) layer 11, as a new substrate layer 11 obtained by dividing the substrate, such as sapphire, the layer 12
14 can be formed by sequentially growing them.

Alternatively, it can be formed by growing layers 11 and 12 on a substrate such as sapphire (not shown), removing the substrate, and growing layers 13 and 14 thereon.

Alternatively, layers 11 to 14 may be sequentially formed on a substrate such as sapphire (not shown), and then the substrate may be removed.

Here, GaN _1-x P _x (or GaN
_1-y As _y) layer 11 may have a stacked structure of a single crystalline layer laminated on the low-temperature buffer layer. That is, on a substrate such as sapphire (not shown), first at a relatively low temperature to deposit the GaN _1-x P _x (or GaN _1-y As _y) layer, a relatively high temperature in the single crystalline GaN thereon _{1- x} P
laminating _x (or GaN _1-y As _y) layer, by removing the substrate thereafter, it is possible to form the layer 11. Further, GaNPAs may be used if the layer 11 is a quaternary mixed crystal instead of GaN _1-x P x or GaN _1-y As y.

Also in this embodiment, n-type GaN _1-x P _x
(Or GaN _1-y As y) using the layer 11 as a buffer layer or the substrate, since the growth of the layers 12 to 14 thereon, as described above with reference to FIG. 2, InGa
The lattice distortion of the N light emitting layer 13 can be reduced as compared with the related art, so that a light emitting element having good light emitting characteristics can be realized.

In this embodiment, since the sapphire substrate is removed, only one of the pair of electrodes (p-type electrode) can be formed on the light emitting surface side. Therefore, there is an advantage that the ratio of the light emitting portion can be increased as compared with the case where both electrodes are provided on the light emitting surface side.

FIG. 4 is a schematic plan view of the light emitting element viewed from the light emitting surface side. That is, FIG. 1A is a light emitting device according to the present invention, and FIG. 1B is a plan view of a conventional light emitting device. In the figure, a hatched portion corresponds to a region from which light can be extracted. In the conventional light emitting device, the ratio of the light emitting area is 50% as shown in FIG.
On the other hand, in the light emitting device according to the present invention, as shown in FIG.
%. The reason is that in the conventional GaN-based light emitting device, the n-type and p
This is because it is necessary to form both electrodes of the mold, whereas in the light emitting device according to the present invention, only one of the electrodes needs to be formed on the light emitting surface side. Therefore, in the light emitting device according to the present invention, the light output can be increased in accordance with the ratio of the light emitting section. Further, in the present embodiment, as described above, by removing the substrate such as sapphire, the yield of the scribing step at the time of chipping can be greatly improved from about 70% of the conventional case to 95% or more.

Next, a third embodiment of the present invention will be described. FIG. 5 is a schematic sectional view illustrating the configuration of the third light emitting device according to the present invention.

In the example shown in FIG.
1, InGaN layer 32, p-type GaN layer 33 and p-type G
An aN _1-x P _x (GaN _1-y As _y ) layer 34 is laminated, and an n-side electrode 35 is formed adjacent to the layer 31.
A p-side electrode 36 is formed thereon to form a pair of electrodes. The light-emitting element shown in FIG. 1 is formed by sequentially growing layers 31 to 34 on a substrate such as sapphire via a layer such as ZnO and then removing the substrate as described later in detail. can do.

Since this light emitting element also has a configuration in which the substrate such as sapphire is removed, the light output area can be increased by increasing the light extraction area, as in the light emitting element shown in FIG.

The GaN _1-x P _x layer or GaN _1-y A
It s _y layer is electrically conductive than GaN layer is good. This effect is particularly remarkable in the p-type conductivity type. For example,
When the hole concentration in the p-type cited case of 2 × 10 ¹⁸ cm ^-3 as an example, the resistivity of the GaN _1-x P _x layer or GaN _1-y As _y layer is 0.01? cm, whereas GaN resistor The rate is 0.
17 Ωcm. That is, a GaN _1-x P _x layer or a GaN
Resistivity of _1-y As y layer is 1/10 or less of the GaN layer. Therefore, the ohmic property in contact with the p-side electrode 36 can be significantly improved.

[0055] In addition, GaN _1-x P x layer and GaN _1-y As y
Since the layer exhibits semimetallicity depending on the composition, the ohmic property in contact with the p-side electrode 36 can be further improved. As a result, the operating voltage can be reduced as compared with the case where the electrode is brought into contact with the p-type GaN layer. That is, the power consumption of the light emitting element is reduced,
Life can be extended.

Further, also in this embodiment, by removing the substrate such as sapphire, the yield of the scribing step at the time of chip formation can be reduced from about 70% to 95% of the conventional one.
It can be greatly improved as described above.

Also in this embodiment, the p-side electrode and the n-side electrode can be respectively formed on the opposite surfaces of the light emitting element. Therefore, when the area of the light emitting element is the same as the conventional one, according to the present invention, the ratio of the light shielded by the electrode can be reduced, and the area of the light emitting portion is increased to increase the light emission amount. Can be.

In the specific example described above, the light emitting element having the double hetero type structure has been described as an example.
However, the present invention is not limited to this. That is, the present invention can be similarly applied to, for example, a structure having a single hetero junction, a structure having a pn junction, or a structure having one or more quantum well structures, other than the double hetero structure. Thus, the above-described effects can be obtained in the same manner.

The material that can be used as the substrate in the present invention is not limited to sapphire as an example. That is, for example, ZnO, G
Similar effects can be obtained by using aAs, spinel, SiC, Si, or the like.

Further, in the above-described embodiment, the InGaN layer is used as the light emitting layer, but the present invention is not limited to this. That is, the present invention also provides, for example, a light emitting layer composed of a GaN layer,
The same can be applied to a light-emitting element having a structure sandwiched between N-layer clad layers. Furthermore, the present invention also relates to a light-emitting element in which light having a wavelength in the ultraviolet region obtained from a light-emitting element having such a structure is converted into a wavelength by a predetermined phosphor to obtain light of a desired wavelength. Can be applied in the same manner to obtain the various effects described above.

[0061]

Next, a method of manufacturing a light emitting device according to the present invention and a light emitting device obtained by the method will be specifically described.

(Example 1) FIG. 6 is a schematic sectional view showing a manufacturing process of a light emitting device according to a first example of the present invention.

In this example, first, sapphire was used as a substrate, and a GaN-based compound semiconductor layer was grown on the sapphire substrate by MOCVD. Group III raw materials include trimethyl gallium (TMG) and trimethyl indium (TMI), and group V raw materials include ammonia (NH
₃ ), phosphine (PH ₃ ) was used. Monosilane (SiH ₄ ), dimethyl zinc (DMZ)
n), cyclopentadienyl magnesium (cp2 M
g) was used.

First, the sapphire substrate 1 is introduced into an MOCVD apparatus, and the substrate is heated to 1000 ° C. After holding for 10 minutes, the substrate temperature is set to 500 ° C. Here, NH ₃ 0.5 μmol / min and PH ₃ 0.2 μm
The GaN _0.935 P _0.065 buffer layer 2 is grown for 5 minutes by flowing ol / min and 80 μmol / min of TMG. Thereafter, the substrate temperature is set to 900 ° C., and TMG
mol / min and SiH ₄ 0.008 μmol / m
in is flowed to grow a GaN _0.935 P _0.065 single crystal layer 3. After the growth for 30 minutes, the supply of TMG and SiH ₄ was stopped, the substrate temperature was set to 1000 ° C., and the flow of PH ₃ was stopped in the reaction tube, and TMG 80 μmol / min and SiH ₄ 0.008 μmol / min were flowed to allow GaN to flow. Layer 4
Start growing. After growth for 3 minutes, supply of TMG and SiH ₄ is stopped, and the temperature of the substrate is set at 850 ° C. When the substrate temperature reaches 850 ° C., TMG 12 μmol
/ Min, TMI 120 μmol / min, SiH ₄
0.0008 μmol / min, DMZn 0.05 μm
ol / min to grow the InGaN layer 5 for one hour. The composition of In in the InGaN layer 5 after the growth was about 6%. After growing for 1 hour, TMG, TMI, SiH ₄ , DM
The supply of Zn is stopped, and the temperature of the substrate is set at 1000 ° C. When the temperature of the substrate reaches 1000 ° C., TMG
80 μmol / min, cp2 Mg 0.5 μmol / m
GaN layer 6 is grown for 20 minutes, and TMG, c
The supply of p2Mg is stopped, and the power of the heating system is turned off to stop the heating of the substrate. When the temperature of the substrate returns to room temperature, supply of NH3 is stopped, and the substrate is taken out of the reactor. A part of the semiconductor layer thus obtained is etched from the surface side to expose the GNP layer 3. Further, an n-side electrode 7 is formed on the GaN layer 3, and a p-side electrode 8 is formed on the GaN layer 6, thereby completing the light emitting device. (Embodiment 2) FIG. 7 is a schematic sectional view showing a manufacturing process of a light emitting device according to a second embodiment of the present invention.

In this embodiment, first, an n-type G is deposited on a substrate such as sapphire by vapor phase epitaxy (VG) or the like.
aN _0.935 P _0.065 is grown to a thickness of 10 μm to 500 μm. Thereafter, the substrate such as sapphire is removed and G
A single crystal layer of aN _0.935 P _0.065 is obtained. This GaN _0.935
A GaN-based compound semiconductor layer was grown by MOCVD using P _0.065 single crystal 11 as a substrate. Group III raw materials include trimethyl gallium (TMG) and trimethyl indium (TMI), and group V raw materials include ammonia (N
H ₃ ) and phosphine (PH ₃ ) were used. Monosilane (SiH ₄ ), dimethyl zinc (DMZ)
n), cyclopentadienyl magnesium (cp2 M
g) was used.

GaN _0.935 P prepared in advance
_0.065 single crystal layer 11 was introduced into the MOCVD apparatus,
H ₃ 0.5μmol / min and PH3 0.2μmol /
The substrate is heated to 1000 ° C. while flowing min.
Here, the flow of PH ₃ into the reaction tube was stopped, and TMG
mol / min and SiH4 0.008 μmol / m
and the growth of the GaN layer 12 is started. After growth for 3 minutes, supply of TMG and SiH ₄ was stopped, and the temperature of the substrate was reduced to 8 ° C.
Set to 50 ° C. When the substrate temperature reached 850 ° C., TMG 12 μmol / min, TMI 120 μm
ol / min, SiH ₄ 0.0008 μmol / mi
n, DMZn 0.05μmol / min, InG
The aN layer 13 is grown for one hour. The In composition of the grown InGaN layer 13 was about 6%. After growing for one hour, T
The supply of MG, TMI, SiH ₄ and DMZn is stopped, and the temperature of the substrate is set at 1000 ° C. Substrate temperature is 100
When the temperature reached 0 ° C., TMG 80 μmol / min,
By supplying 0.5 μmol / min of cp2 Mg, the GaN layer 14 is grown for 20 minutes, the supply of TMG and cp2 Mg is stopped, the power of the heating system is turned off, and the heating of the substrate is stopped. When the temperature of the substrate returns to room temperature, the supply of NH3 is stopped, and the substrate is taken out of the reactor. Furthermore, n
The side electrode 15 and the p-side electrode 16 are formed to complete the light emitting device. FIG. 8 is a graph showing the light output of the light emitting device obtained in this manner. That is, the current value 2
The light output at 0 mA was 1.5 times higher in the device of the present invention than in the conventional device. Instead of GaNP layer as the substrate 11, similar high light output even when using the GaN _1-y As y layer is obtained.

(Embodiment 3) FIG. 9 is a schematic sectional view showing a manufacturing process of a light emitting device according to a third embodiment of the present invention.

[0068] In this embodiment, first, a GaN _0.935 P _{0. 065} of n-type on the sapphire substrate 20 10Myuemu～5
It was grown to a thickness of 00 μm and used as a substrate for MOCVD. Here, in addition to the MOCVD method, for example, a vapor phase growth method (VG) such as a halide vapor phase growth method, a chemical beam epitaxy method (CBE), and a metalorganic molecular beam epitaxy ( M
OMBE).

MO for growing GaN-based compound semiconductor layer
In the CVD method, group III raw materials include trimethyl gallium (TMG), trimethyl indium (TMI), and V
Group raw materials include ammonia (NH ₃ ), arsine (AsH)
₃ ) was used. Monosilane (SiH
₄ ), dimethyl zinc (DMZn) and cyclopentadienyl magnesium (cp2 Mg) were used.

First, the above-mentioned substrate, that is, the substrate on which the GaN layer 21 was grown on the sapphire substrate 10 was introduced into an MOCVD apparatus, and while flowing 0.5 μmol / min of NH _{3 and} 0.1 μmol / min of AsH ₃ , The substrate is heated to 900C. When the temperature of the substrate reached 900 ° C., TMG 200 μmol / min, SiH 4
0.02 μmol / min, n-type GaN _0.945
The As _0.055 layer 22 is grown to about 10 μm. TMG,
The supply of SiH ₄ is stopped, and n-type GaN _0.945 As
After stopping the growth of the _0.055 layer 22, NH ₃ 0.5 μmo
The substrate is heated to 1000 ° C. while flowing 1 / min and 0.2 μmol / min of PH ₃ . Here, AsH ₃
Was stopped flowing into the reaction tube, and TMG 80 μmol / min.
And 0.008 μmol / min of SiH ₄ and n
The growth of the GaN 23 of the type is started. After growing for 3 minutes, TMG
And supply of SiH4 are stopped, and the temperature of the substrate is set at 850.degree. When the substrate temperature reaches 850 ° C, TM
G12μmol / min, TMI120μmol / mi
n, SiH ₄ 0.0008 μmol / min, DMZn
At a supply of 0.05 μmol / min, the InGaN layer 24 is grown for one hour. The In composition of the grown InGaN layer 24 was about 6%. After growing for 1 hour, TMG, TM
The supply of I, SiH ₄ and DMZn is stopped, and the temperature of the substrate is set at 1000 ° C. When the temperature of the substrate reached 1000 ° C., TMG 80 μmol / min, cp 2 Mg
At a supply of 0.5 μmol / min, the GaN layer 25 is grown for 20 minutes, the supply of TMG and cp2 Mg is stopped, and the power supply of the heating system is turned off to stop the heating of the substrate. When the temperature of the substrate returns to room temperature, supply of NH ₃ is stopped, and the substrate is taken out of the reaction furnace.

The sapphire substrate 20 of the sample taken out
Was removed by polishing or the like, and an n-side electrode 26 and a p-side electrode 27 were formed to produce a light-emitting element. The characteristics of the device manufactured in this manner exhibited the same good characteristics as those shown in Example 2.

(Example 4) FIG. 10 is a schematic sectional view showing a manufacturing process of a light emitting device according to a fourth example of the present invention.

In this embodiment, first, a layer 30B made of a material close to the lattice constant of a GaN-based compound semiconductor such as ZnO is formed on a sapphire substrate 30A by sputtering or the like.
Is formed with a thickness of 0.1 μm to 10 μm. This is M
Used as a substrate for OCVD.
An aN-based compound semiconductor layer was grown. Trimethyl gallium (TMG) and trimethyl indium (TMI) were used as group III raw materials, and ammonia (NH ₃ ) and phosphine (PH ₃ ) were used as group V raw materials. Monosilane (SiH ₄ ), dimethyl zinc (DMZn), and cyclopentadienyl magnesium (cp 2 Mg) were used as dopant raw materials.

The above substrate is introduced into an MOCVD apparatus, and the substrate is heated to 1000 ° C. in an N ₂ atmosphere.
Here, 0.5 μmol / min of NH ₃ was started to flow,
Then, TMG 80 μmol / min and SiH ₄
Starting to flow 0.008 μmol / min, n-type GaN
Start growing 31. After growing for 3 minutes, TMG and SiH ₄
Is stopped, and the temperature of the substrate is set to 850 ° C. When the substrate temperature reached 850 ° C., TMG 12 μm
ol / min, TMI 120 μmol / min, SiH
₄ 0.0008 μmol / min, DMZn 0.5 μm
ol / min to grow the InGaN layer 32 for one hour. The In composition of the grown InGaN layer 32 is about 6%
Met. After growing for one hour, TMG, TMI, SiH ₄ ,
The supply of DMZn is stopped, and the temperature of the substrate is set at 1000 ° C. When the temperature of the substrate reaches 1000 ° C., T
MG80μmol / min, cp2 Mg0.5μmol
/ Min supply, grow for 20 minutes, TMG, cp2 Mg
Is stopped, the growth of the p-type GaN 33 is terminated, the power of the heating system is turned off, and the heating of the substrate is stopped. When the temperature of the substrate returns to room temperature, the supply of NH3 is stopped, and the substrate is taken out of the reactor. On top of this, by vapor phase growth method etc.
A p-type GaN _0.935 P _0.065 layer 34 of 10 μm to 100 μm
m, and the sample is soaked in an acid or the like, and the ZnO layer 3
By melting 0B, the sapphire substrate 30A was separated from the compound semiconductor crystal phase. The characteristics of the light-emitting element manufactured by forming the n-side electrode 35 and the p-side electrode 36 on the laminate obtained in this manner showed good characteristics equivalent to those of the element in Example 2.

In the above embodiment, GaN / InGa
The light-emitting element having the N / GaN double hetero structure has been described as an example, but the present invention is not limited to the double hetero structure, and can be similarly applied to other structures.

Although the substrate is exemplified by GaN _0.935 P _0.065 as an example, other compositions can be similarly applied as long as the lattice constant of the layer serving as the light emitting layer is matched. Further, the same case of using the GaN _1-y As _y, it is preferable to to fit the lattice constant of the layer as an emission layer. The growth temperature and the supply amount of the raw material can also be appropriately selected according to the conditions for obtaining a desired crystal.

[0077]

The present invention is embodied in the form described in detail above, and has the following effects.

First, according to the present invention, by providing a buffer layer containing phosphorus or arsenic, a GaN-based compound semiconductor layer having good crystallinity can be grown on a substrate such as sapphire having a different lattice constant. become. As a result, it becomes possible to improve the light emission characteristics and electrical characteristics of the GaN-based compound semiconductor light emitting device.

Further, according to the present invention, it is used as a crystal substrate made of a material including phosphorus or arsenic, such as GaN _1-x P x and GaN _1-y As y, or, GaN on a sapphire substrate _{1 x} P _x or grown light emitting layer of the GaN-based on growing the GaN _1-y As _y, then the sapphire substrate was removed, and to produce a device, or the light emitting layer of GaN based on a sapphire substrate And grow G on it
After growing aN _1-x P _x or GaN _1-y As _y, by removing the sapphire substrate, to fabricate an element, since the area of the electrode portions to be formed on the light emitting extraction surface can be reduced, Light extraction efficiency can be increased, a highly efficient light emitting element can be obtained, and the chip size can be reduced.

Further, by adjusting the lattice constant of the layer containing phosphorus or arsenic to the lattice constant of the light-emitting layer, distortion applied to the light-emitting layer can be reduced, and a light-emitting layer with good crystallinity can be obtained. Can be obtained.

Further, according to the present invention, by removing a sapphire substrate or a GaN substrate having a high crystal hardness,
The cleavage of the light emitting element can be facilitated, and the yield in the chip cutting step can be improved.

As described above, according to the present invention, it is possible to obtain a GaN-based compound semiconductor light-emitting device having excellent light-emitting characteristics with a simple structure, and the industrial advantage is great.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating the configuration of a GaN-based compound semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a composition ratio x of a conventional buffer layer, a buffer layer according to the present invention, and an InGaN layer serving as a light emitting layer and a lattice constant.

FIG. 3 is a schematic sectional view illustrating the configuration of a second light emitting device according to the present invention.

FIG. 4 is a schematic plan view of the light emitting element viewed from a light emitting surface side. That is, FIG. 1A is a light emitting device according to the present invention, and FIG. 1B is a plan view of a conventional light emitting device.

FIG. 5 is a schematic sectional view illustrating the configuration of a third light emitting device according to the present invention.

FIG. 6 is a schematic process sectional view illustrating a process for manufacturing the light emitting device according to the first embodiment of the present invention.

FIG. 7 is a schematic process sectional view illustrating a process for manufacturing the light emitting device according to the second embodiment of the present invention.

FIG. 8 is a graph showing the light output of the light emitting device according to the second embodiment.

FIG. 9 is a schematic process sectional view illustrating a process of manufacturing a light emitting device according to a third example of the present invention.

FIG. 10 is a schematic process sectional view illustrating a process for manufacturing a light emitting device according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 sapphire substrate 2 n-type _{GaN 1-x P x (GaN} 1-y As y) buffer layer 3 n-type _{GaN 1-x P x (GaN} 1-y As y) layer 4 N-type GaN layer 5 InGaN active layer 6 p-type GaN layer 7 n-type electrode 8 p-type electrode 11 n-type _{GaN 1-x P x (GaN} 1-y As y) substrate 12 n-type GaN layer 13 InGaN layer 14 p-type GaN layer 15 n-type electrode 16 p-type Electrode 21 Sapphire substrate 22 Al _1-x Ga _x N buffer layer 23 n-type GaN layer 24 InGaN active layer 25 p-type GaN layer 26 n-type electrode 27 p-type electrode 31 n-type GaN layer 32 InGaN layer 33 p-type GaN layer 34 p-type _{GaN 1-x P x (GaN} 1-y As y) layer 35 n-type electrode 36 p-type electrode

Claims (24)

[Claims] 1. A substrate, a buffer layer provided on the substrate, made of a compound semiconductor containing at least one of phosphorus (P) and arsenic (As), and a GaN-based layer provided on the buffer layer A GaN-based compound semiconductor light-emitting device, comprising: a light-emitting layer made of a compound semiconductor. 2. A single crystal layer comprising a compound semiconductor containing at least one of phosphorus (P) and arsenic (As) is provided between the buffer layer and the light emitting layer. The GaN-based compound semiconductor light emitting device according to claim 1. 3. The method according to claim 1, wherein the buffer layer has a composition formula of GaN _1-x1-y1.
P _x1 As _y1 (where 0 <x ₁ + y ₁ < ₁ , 0 ≦ x ₁ , 0
3. The GaN-based compound semiconductor light-emitting device according to claim 1, comprising a compound semiconductor represented by ≦ y ₁ ). 4. The single crystal layer has a composition formula of GaN _1-x2-y2 P
_{x2 Asy2} (where 0 <x ₂ + y ₂ <1, 0 ≦ x ₂ , 0 ≦
GaN-based compound semiconductor light emitting device according to any one of claims 1 to 3, characterized in that a compound semiconductor represented by y _2). 5. The method according to claim 1, wherein the light emitting layer is formed of In _z Ga _{1 -zN} (where
5. The GaN-based compound semiconductor light-emitting device according to claim 1, wherein 0 <z <1), and wherein the buffer layer is made of a material that lattice-matches with the light-emitting layer. 6. The light emitting layer is made of a compound semiconductor represented by a composition formula In _z Ga _{1 -zN} (here, 0 <z <1), and at least one of the buffer layer and the single crystal layer. Either one has the composition formula GaN _1-x P _x (where 0 <x ≦
1) or GaN _1-y As _y (where 0 <made of a compound semiconductor represented by any of the y ≦ 1), and the composition z of the composition formula, and a composition x or composition y following formula : Satisfies the relationship represented by (351/317) z−0.0317 ≦ x ≦ (351/317) z + 0.0317 or (351/400) z−0.04 ≦ y ≦ (351/400) z + 0.04 The GaN-based compound semiconductor light-emitting device according to claim 1, wherein: 7. The light emitting layer is made of a compound semiconductor represented by a composition formula In _z Ga _{1 -zN} (here, 0 ≦ z ≦ 1). At least one of the formulas GaN _{1-wx- (1-w) y} P _wx As _{(1-w) y}
(Where 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, and 0 ≦ y ≦
1) a compound semiconductor represented by the following formula, and a composition ratio x or a composition ratio y in the composition formula.
And (351/317) z−0.0317 ≦ x ≦ (351/317) z + 0.0317 and (351/400) z−0.04 ≦ y ≦ (351/400) z + 0.04 The GaN-based compound semiconductor light-emitting device according to any one of claims 1 to 5, which is satisfied. 8. The GaN-based compound semiconductor according to claim 1, wherein a thickness of the GaN-based compound semiconductor laminated between said buffer layer and said light-emitting layer is 0.2 μm or less. Light emitting element. 9. The substrate is made of sapphire, ZnO, GaAs.
The GaN-based compound semiconductor light-emitting device according to any one of claims 1 to 8, wherein the GaN-based compound semiconductor light-emitting device is made of any material selected from the group consisting of s, spinel, SiC, and Si. 10. A first electrode, comprising: a first conductive compound semiconductor provided on the first electrode and containing at least one of phosphorus (P) and arsenic (As); A first layer connected to the first electrode, a second layer of a first conductivity type GaN-based compound semiconductor provided on the first layer, and a second layer on the second layer. A light-emitting layer made of a GaN-based compound semiconductor provided; a third layer made of a second conductivity type GaN-based compound semiconductor provided on the light-emitting layer; and a light-emitting layer provided on the third layer. A GaN-based compound semiconductor light-emitting device, comprising: a second electrode; Wherein said first _{layer, GaN 1-xy P x As} y
11. The GaN-based compound semiconductor light-emitting device according to claim 10, wherein (0 <x + y <1, x ≧ 0, y ≧ 0). 12. The GaN-based compound semiconductor light emitting device according to claim 10, wherein said first conductivity type is n-type, and said second conductivity type is p-type. 13. The GaN-based compound semiconductor light emitting device according to claim 10, wherein the first conductivity type is a p-type, and the second conductivity type is an n-type. 14. The method of claim 13, wherein the second layer is made of GaN, the light emitting _{layer, In z Ga 1-z N} ( where, 0 <z ≦ 1)
The GaN-based compound semiconductor light-emitting device according to any one of claims 10 to 13, wherein the third layer is made of GaN. 15. The light emitting device according to claim 15, wherein the second layer is made of AlGaN, and the light emitting layer is made of In _z Ga _{1 -zN} (where 0 ≦ z ≦ 1).
The GaN-based compound semiconductor light-emitting device according to any one of claims 10 to 13, wherein the third layer is made of AlGaN. 16. The GaN-based compound semiconductor light-emitting device according to claim 1, wherein the light-emitting region of the light-emitting device comprises a pn junction. 17. The GaN-based compound semiconductor light-emitting device according to claim 1, wherein the light-emitting region of the light-emitting device comprises at least one heterojunction. 18. The light-emitting device according to claim 1, wherein the light-emitting region of the light-emitting element has one or multiple quantum well structures.
Item 3. The GaN-based compound semiconductor light-emitting device according to item 1. 19. A method according to claim 19, wherein phosphorous (P) and arsenic (As) are formed on the substrate.
A step of depositing a compound semiconductor layer containing at least one of the following: and a step of depositing a GaN-based compound semiconductor layer on the compound semiconductor layer. Manufacturing method. 20. A step of removing the substrate after the step of depositing the GaN-based compound semiconductor layer, the step of removing the substrate, the step of removing the substrate and the uppermost surface of the laminate and the lowermost surface of the laminate. 20. The method of manufacturing a GaN-based compound semiconductor light-emitting device according to claim 19, further comprising: providing an electrode. 21. Phosphorus (P) and arsenic (As) on a substrate
Depositing a compound semiconductor layer containing at least one of the following: removing the substrate to take out the compound semiconductor layer; depositing a GaN-based compound semiconductor layer on the taken-out compound semiconductor layer G characterized by comprising:
A method for manufacturing an aN-based compound semiconductor light emitting device. 22. A step of depositing a GaN-based compound semiconductor layer on a substrate; and forming a compound semiconductor layer containing at least one of phosphorus (P) and arsenic (As) on the GaN-based compound semiconductor layer. A step of depositing; a step of removing the substrate; and a step of providing electrodes on the top surface of the laminate obtained by the step of removing the substrate and the back surface of the bottom layer, respectively. A method for manufacturing a GaN-based compound semiconductor light emitting device, which is characterized by the following. 23. The compound semiconductor layer, the following formula: (where, 0 <x + y <1 , x ≧ 0, y ≧ 0) GaN 1-xy P x As y that a compound semiconductor represented by A method according to any one of claims 19 to 22, characterized in that: 24. The GaN-based compound semiconductor layer includes at least a light-emitting layer represented by a composition formula In _z Ga _{1 -zN} (here, 0 ≦ z ≦ 1); The compound semiconductor layer containing at least one of arsenic (As) has a composition formula of GaN
_{1-wx- (1-w) y} P _wx As _{(1-w) y} (where 0 ≦ w ≦ 1, 0
≦ x ≦ 1, 0 ≦ y ≦ 1, excluding x = y = 0), and the composition z in the composition formula and the composition ratio x or the composition ratio y
And (351/317) z−0.0317 ≦ x ≦ (351/317) z + 0.0317 and (351/400) z−0.04 ≦ y ≦ (351/400) z + 0.04 24. The method according to claim 19, wherein the method is satisfied.