JPH10163523A - Manufacturing iii-v compd. semiconductor and light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a III-V compd. semiconductor, having high productivity, improved yield and stable characteristic, and a light- emitting element using the same. SOLUTION: The method of manufacturing a III-V compd. semiconductor, whereby a first Gaa Alb N (0<=a<=1, 0<=b<=1, a+b=1) III-V compd. semiconductor layer 3 over 1000 deg.C and then a second Inx Gay Alz N (0<x<=1, 0<=y<1, 0<=z<1, x+y+z=1) III-V compd. semiconductor layer 5 below 1000 deg.C are grown comprises, prior to growing the second layer 5, which makes a third Gav Alw N (0<=v<=1, 0<=w<=1, v+w=1) III-V compd. semiconductor layer 4 below 1000 deg.C grown.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a Group 3-5 compound semiconductor and a light emitting device using the compound semiconductor obtained by the method.

[0002]

BACKGROUND ART ultraviolet, blue or green light emitting diodes or ultraviolet, as a material for light emitting elements such as blue or green laser diodes, the general formula In _x Ga _y Al _z N
(However, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1,
Group 3-5 compound semiconductors represented by 0 ≦ z ≦ 1) are known. Hereinafter, x, y, and z in this general formula may be referred to as an InN mixed crystal ratio, a GaN mixed crystal ratio, and an AlN mixed crystal ratio, respectively. In the group 3-5 compound semiconductor,
In particular, those containing 10% or more of InN in the mixed crystal ratio can adjust the emission wavelength in the visible region according to the InN mixed crystal ratio.
Particularly important for display applications.

[0003] The group 3-5 compound semiconductor is sapphire,
Attempts have been made to form films on various substrates such as GaAs, ZnO, etc. However, since the lattice constant and chemical properties are significantly different from those of the compound semiconductor, sufficiently high quality crystals have not been obtained. For this reason, it has been attempted to first grow a GaN crystal having a similar lattice constant and chemical properties to the compound semiconductor, and then obtain an excellent crystal by growing the compound semiconductor thereon. JP-B-55-3834).

Incidentally, among the group 3-5 compound semiconductors, those containing In and those not containing In have a large difference in growth conditions and thermal stability. Specifically, the 3-
It is known that among the group V compound semiconductors, those not containing In have relatively high thermal stability and can obtain good crystallinity at temperatures exceeding 1000 ° C. On the other hand, In
The group 3-5 compound semiconductor having low thermal stability,
By growing at a relatively low temperature of about 800 ° C., good crystallinity can be obtained.

Under the circumstances described above, according to the conventional method, after growing a layer containing no In, the growth is temporarily stopped, and during that time, the temperature of the substrate is adjusted to the growth temperature of the layer containing In. After the adjustment is completed, the growth of the In-containing layer is started again. However, when the interruption time of the growth is long, characteristics such as a decrease in luminance of the light emitting element may be deteriorated. Further, if the interruption time of the growth is not constant, the crystallinity of the next In-containing layer changes, and as a result, the characteristics of the light emitting element become unstable. In order to prevent such a decrease in characteristics and realize stable characteristics with good reproducibility, the above-mentioned growth interruption time is preferably as short as possible, and a production method with high productivity has been desired. .

Incidentally, the temperature of the substrate greatly depends on the heat release of the substrate and a portion called a susceptor on which the substrate is mounted, the reflectance and the transmittance of the wall of the growth apparatus, and the like. That is, even if the same amount of heat is applied to the susceptor, the temperature of the substrate changes due to the degree of contamination of the susceptor and the wall of the growth apparatus. As described above, control for keeping the temperature of the substrate constant even when the state of the growth apparatus changes can be performed relatively simply and accurately by a method generally called PID control. However, with respect to the control for changing the temperature from a certain temperature to another temperature, even if the PID control is used, the time required for the change depends on the temperature of the growth device around the substrate, the degree of contamination of the growth device, and the like. It is difficult to stabilize the target temperature within a short time. As described above, in the conventional method, it is difficult to sufficiently reduce the interruption time of the growth, so that the desired characteristics cannot be obtained in the characteristics such as driving voltage, luminance, lifetime, and emission wavelength in the final light emitting element, or In such a case, the in-plane distribution on the epi-substrate having the above characteristics tends to be large, and the yield is inevitably reduced.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a group III-V compound semiconductor having high productivity, improved yield, and stable characteristics, and a light emitting device using the same. is there.

[Means for Solving the Problems]

The present inventors have conducted intensive studies in view of such a situation. As a result, a method of growing a layer containing no In at a temperature exceeding 1000 ° C. and then growing a layer containing In at a temperature of 1000 ° C. or less, The present inventors have found that the above-mentioned problem can be solved by growing an intermediate layer under specific conditions before growing the layer containing In. That is, the present invention relates to [1] a general formula Ga _a Al _b N (where 0 ≦ a ≦
1,0 ≦ b ≦ 1, a + b = 1) a first layer comprising a Group III-V compound semiconductor represented by a temperature in excess of 1000 ° C. After growth, the general formula In _x Ga _y Al _z N ( Where 0
<X ≦ 1, 0 ≦ y <1, 0 ≦ z <1, x + y + z = 1)
In the method for growing a group III-V compound semiconductor, in which the second layer composed of the group III-V compound semiconductor layer represented by
_v Al _w N (where 0 ≦ v ≦ 1, 0 ≦ w ≦ 1, v + w =
The present invention relates to a method for manufacturing a Group 3-5 compound semiconductor, wherein a third layer made of a Group 3-5 compound semiconductor represented by 1) is grown at a temperature of 1000 ° C. or lower. Also, the present invention
[2] A light emitting device using a Group 3-5 compound semiconductor obtained by the method for manufacturing a Group 3-5 compound semiconductor according to [1]. Next, the present invention will be described in detail.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a Group 3-5 compound semiconductor according to the present invention uses a general formula Ga _a Al _b N (where 0 ≦ a ≦
1,0 ≦ b ≦ 1, a + b = after growing a first layer of a 3-5 group compound semiconductor represented by a temperature exceeding 1000 ° C. 1), the general formula In _x Ga _y Alz N (wherein Medium, 0
<X ≦ 1, 0 ≦ y <1, 0 ≦ z <1, x + y + z = 1)
Before growing the second layer made of a group III- _V compound semiconductor layer represented by the formula below at 1000 ° C. or less, the general formula Ga _v Al _w
A third layer made of a Group 3-5 compound semiconductor represented by N (where 0 ≦ v ≦ 1, 0 ≦ w ≦ 1, v + w = 1) is 100
The growth is performed at a temperature of 0 ° C. or less.

FIG. 1 shows an example of the structure of a light emitting device using a Group 3-5 compound semiconductor obtained according to the present invention. In the example shown in FIG. 1, a buffer layer 2, an n-type GaN layer 3 as a first layer, a third layer 4, a light-emitting layer 5 including a second layer, a protective layer 6, The mold layer 7 is laminated in this order. An n-type GaN layer 3 serving as a first layer is provided with an n-electrode, and a p-type layer 7 is provided with a p-electrode. By applying a voltage in the forward direction, current is injected and light emission from the light emitting layer 5 is obtained.

Hereinafter, the present invention will be described in more detail with reference to FIG. The first layer has a general formula of Ga _a Al _b N (where
3-5 represented by ≦ a ≦ 1, 0 ≦ b ≦ 1, a + b = 1)
It consists of a group III compound semiconductor. The first layer is grown at a temperature above 1000 ° C. Specific examples of the first layer are layers grown directly on a substrate or via a buffer layer. Further, the first layer may be grown at a temperature higher than 1000 ° C. over the In-containing Group 3-5 compound semiconductor layer or the In-free Group 3-5 compound semiconductor layer.

When the AlN mixed crystal ratio of the first layer is high,
When used in a light emitting device, the driving voltage tends to be high, so that the AlN mixed crystal ratio is preferably 0.5 or less, more preferably 0.3 or less, and particularly preferably 0.1 or less.
2 or less. When the first layer is not doped with an impurity, the resistance of the first layer may increase depending on the AlN mixed crystal ratio or the film thickness. In such a case, the driving voltage is increased when the light-emitting element is used. Therefore, it is preferable that the first layer be doped so as not to lower the crystallinity. From the viewpoint of not lowering the crystallinity, the first layer is composed of n
Preferably, the mold is doped. A preferable n-type carrier concentration is 1 × 10 ¹⁶ cm ⁻³ or more and 1 × 10 ²² c
m ^-3 or less. A more preferable range of the carrier concentration is 1 × 10 ¹⁷ cm ⁻³ or more and 1 × 10 ²¹ cm ⁻³ or less. When the carrier concentration is less than 1 × 10 ¹⁶ cm ⁻³ , sufficient conductivity may not be obtained, and when the carrier concentration is more than 1 × 10 ²² cm ⁻³ , the crystallinity of the first layer may be reduced. May decrease.

The third layer according to the present invention has the general formula Ga _v
Al _w N (where 0 ≦ v ≦ 1, 0 ≦ w ≦ 1, v + w =
It consists of a group 3-5 compound semiconductor represented by 1). The third layer is in contact with the first layer, and is grown at a temperature of 1000 ° C. or less. The third layer is 1000 ° C.
A stacked structure of a plurality of layers having different mixed crystal ratios grown below may be used. If the growth temperature of the third layer is lower than 600 ° C., the crystallinity of the third layer may be undesirably reduced. A preferred growth temperature range for the third layer is 600
C. or higher and 980 ° C. or lower, more preferably 650 ° C.
It is higher than 950 ° C. When the growth temperature of the third layer is within the above range, the effect of the present invention is excellent, but
Further, by focusing on the following points, the growth temperature can be optimized according to the purpose. That is, when it is desired to improve the crystallinity of the third layer as much as possible, or when it is desired to grow the third layer at a growth rate as high as possible, the growth temperature is preferably higher. In this case, the growth temperature may be set higher within the range of the growth temperature. On the other hand, when trying to shorten the time of the growth interruption between the third layer and the second layer,
The growth temperature of the third layer may be the same as the growth temperature of the second layer. In addition, the growth temperature of the third layer can be appropriately set in consideration of the characteristics of the manufacturing apparatus, the overall growth time, and the like.

When the AlN mixed crystal ratio of the third layer is high,
When used in a light emitting device, the driving voltage tends to be high, so that the AlN mixed crystal ratio is preferably 0.5 or less, more preferably 0.3 or less, and particularly preferably 0.1 or less.
2 or less. When the third layer is not doped with an impurity, the resistance of the third layer may increase depending on the AlN mixed crystal ratio or the film thickness. In such a case, the driving voltage becomes high when the light emitting element is used, so the third layer
It is preferable to dope as long as the crystallinity is not reduced. From the viewpoint of not lowering the crystal, the third layer is preferably doped with n-type. A preferable n-type carrier concentration is 1 × 10 ¹⁶ cm ⁻³ or more and 1 × 10 ²² cm.
^-3 or less. A more preferable range of the carrier concentration is 1 × 10 ¹⁷ cm ⁻³ or more and 1 × 10 ²¹ cm ⁻³ or less. When the carrier concentration is less than 1 × 10 ¹⁶ cm ⁻³ , sufficient conductivity may not be obtained, and when the carrier concentration is more than 1 × 10 ²² cm ⁻³ , the crystallinity of the first layer may be reduced. May decrease.

The preferred range of the thickness of the third layer is 5 ° to 1 μm, and the more preferred range is 20 ° to 5000 °. When the third layer is thinner than 5 °, the effect of the present invention is not remarkable. On the other hand, if it is thicker than 1 μm, it takes too much time for growth, which is not practical. Since the third layer grows at a relatively low temperature, the crystallinity may decrease when the growth rate is high. A preferable range of the growth rate for securing good crystallinity is 1Å / min or more.
00 ° / min or less. When the growth rate of the third layer is less than 1 ° / min, the growth of the third layer takes too much time and is not practical. If it is larger than 500 ° / min,
It is difficult to obtain good crystallinity.

Next, the second layer will be described. Since the second layer is useful as an active layer of a light-emitting element, the second layer may be hereinafter referred to as a light-emitting layer. The lattice constant of the group III-V compound semiconductor greatly changes depending on the mixed crystal ratio. Third
When there is a large difference in the lattice constant between the second layer and the second layer, the thickness of the second layer is reduced by reducing the thickness of the second layer according to the magnitude of the strain due to the lattice mismatch. This is preferable because the occurrence of defects can be suppressed in some cases. The preferred thickness range of the second layer depends on the magnitude of the strain. When a layer having an InN mixed crystal ratio of 10% or more is laminated as the second layer, the preferred thickness is 300 ° or less, and more preferably 90 ° or less. If it is larger than 300 °, defects are generated in the second layer, which is not preferable. In the case where the second layer is used as an active layer of a light-emitting element, charge can be confined in the light-emitting layer with high density by reducing the thickness of the second layer, so that emission efficiency can be improved. it can. Therefore, even if the difference in lattice constant is smaller than the above example,
The thickness of the second layer is preferably the same as in the above example. Note that when the second layer is used as an active layer of a light-emitting element, the thickness of the second layer is preferably 5 ° or more, more preferably 15 ° or more. If the thickness of the second layer is less than 5 °, the luminous efficiency will not be sufficient.

When the second layer contains Al, impurities such as O are easily taken in and the luminous efficiency may be reduced. In such a case, as the second layer, generally it does not contain Al formula In _x Ga _y N (provided that, x + y = 1,0 <x ≦
1, 0 ≦ y <1) can be used.

If not according to the invention, the second layer is the first
Will grow directly on this layer. In this case, as the thickness of the second layer becomes thinner, the influence of the interface between the first layer and the second layer becomes relatively large, so that the influence of the growth interruption at the time of changing the growth temperature also becomes stronger. In other words, the thinner the second layer is, the more remarkable the degradation of the final device characteristics and the yield are. In this regard, the present invention has a great effect when the second layer having a very small thickness as described above is used.

The light emitting layer may be a single layer or a plurality of light emitting layers. As an example of such a structure, a stacked structure of (2n + 1) layers in which n light-emitting layers and layers having a band gap larger than that of the (n + 1) light-emitting layers are alternately stacked. Here, n is a positive integer, preferably 1 or more and 50 or less, more preferably 1 or more.
It is 30 or less. When n is 50 or more, the luminous efficiency is reduced, and the growth may take a long time, which is not preferable. Such a structure having a plurality of light-emitting layers is particularly useful for producing a semiconductor laser requiring a high light output.

By doping the light emitting layer with an impurity, light can be emitted at a wavelength different from the band gap of the light emitting layer. This is called impurity light emission because light is emitted from impurities. In the case of impurity emission, the emission wavelength is determined by the composition of the Group 3 element and the impurity element in the light emitting layer. In this case, the InN mixed crystal ratio of the light emitting layer is preferably 5% or more. I
When the nN mixed crystal ratio is less than 5%, the emitted light is almost ultraviolet light, and sufficient brightness cannot be felt. The emission wavelength becomes longer as the InN mixed crystal ratio increases, and the emission wavelength can be adjusted from purple to blue and green.

As an impurity suitable for impurity emission, a Group 2 element is preferable. Among the group II elements, Mg, Zn, C
Doping with d is preferable because of high luminous efficiency.
Particularly, Zn is preferable. The concentration of these elements is preferably 10 ¹⁸ to 10 ²² cm ⁻³ . The light emitting layer may be simultaneously doped with Si or Ge together with these Group 2 elements. The preferred concentration range of Si and Ge is 10 ¹⁸ to 10
²² cm ^-3 .

In the case of impurity light emission, the light emission spectrum is generally broad, and the light emission spectrum may shift as the amount of injected charge increases. Therefore, when high color purity is required or when it is necessary to concentrate light emission power in a narrow wavelength range, it is more advantageous to use band edge emission. In order to realize a light-emitting element using band-edge light emission, the amount of impurities contained in the light-emitting layer must be kept low. Specifically, the concentration of each element of Si, Ge, Mg, Cd and Zn is preferably 10 ¹⁹ cm ⁻³ or less, more preferably 10 ¹⁸ cm ⁻³ or less.

In the group III-V compound semiconductor, when the mixed crystal ratio of InN in the light emitting layer is high, thermal stability is not sufficient, and deterioration may occur during crystal growth or a semiconductor process. For the purpose of preventing such deterioration, a charge injection layer 6 having a low InN mixed crystal ratio is laminated on the light emitting layer,
This layer can have a function as a protective layer.
In order to provide the protective layer with a sufficient protective function, the InN mixed crystal ratio of the protective layer is preferably 10% or less.
Is preferably 5% or more. More preferably I
The nN mixed crystal ratio is 5% or less, and the AlN mixed crystal ratio is 10% or more.

In order to provide the protective layer with a sufficient protective function, the thickness of the protective layer is preferably from 10 to 1 μm, more preferably from 50 to 5000 μm.
It is as follows. If the thickness of the protective layer is less than 10 °, a sufficient effect may not be obtained. On the other hand, if the thickness is more than 1 μm, the luminous efficiency may decrease. After growing the light-emitting layer, 100
When kept at a high temperature exceeding 0 ° C. for a long time, the thermal degradation of the light-emitting layer may progress. In this regard, it is preferable that the growth temperature of the protective layer be 1000 ° C. or less.

The protective layer has a current injection effect of the light emitting element.
It is preferable to have p-type conductivity from the viewpoint of the rate. The
To make the protective layer have p-type conductivity, an acceptor type
It is necessary to dope impurities at a high concentration. Acceptor type
Specific examples of the impurity include a Group 2 element. This
Among them, Mg and Zn are preferable, and Mg is more preferable.
Good. However, the protective layer was doped with a high concentration of impurities.
In this case, the crystallinity of the protective layer is reduced and the characteristics of the light emitting element are changed.
May be lowered. In such cases,
It is necessary to lower the substance concentration. Not lower crystallinity
The concentration of the pure substance is preferably 1 × 10¹⁹cm^-3
Hereinafter, more preferably 1 × 10¹⁸cm ^-3It is as follows.

In the example shown in FIG. 1, charges are injected into the second layer, which is a light emitting layer, through the third layer and the protective layer. May be noted. The difference in band gap between the charge injection layer and the light emitting layer is preferably 0.1 eV or more, and more preferably 0.3 eV or more. When the difference between the band gaps of the charge injection layer and the light emitting layer is smaller than 0.1 eV, the carriers are not sufficiently confined in the light emitting layer, and the luminous efficiency may decrease. However, when the band gap of the protective layer is 5
If it exceeds eV, the voltage required for charge injection will increase,
The band gap of the protective layer is preferably 5 eV or less.

The case where the second layer is a light-emitting layer has been described above with reference to the example of FIG. 1, but other examples are shown in FIGS. The example of FIG. 2 includes a substrate 1, a buffer layer 2, an n-type GaN 3 as a first layer, a third layer 4, an n-type InGaN layer 8 as a second layer, an n-type GaAlN layer 9, and a light-emitting layer. Certain non-doped InGaN layer 5, protective layer 6, p
The mold layer 7 is laminated. In the example of FIG. 2, an n-type InGaN layer 8 and an n-type GaAlN layer 9 are grown before the light-emitting layer 5 is grown. According to the structure of FIG. 2, the crystallinity of the InGaN layer as the light emitting layer 5 may be further increased. FIG.
In this example, the GaAlN layer 9 in the example of FIG. 2 is omitted.

Next, a method of growing a substrate and a compound semiconductor used in the present invention will be described. Substrates for crystal growth of the group III-V compound semiconductor include sapphire and Zn.
O, GaAs, Si, SiC, NGO (NdGa
O ₃ ), spinel (MgAl ₂ O ₄ ) or the like is used.
Sapphire is particularly important because it is transparent and a large-area high-quality crystal can be obtained. In growth using these substrates, ZnO, SiC, GaN, AlN, G
A so-called two-step growth method of growing a thin film of aAlN and a laminated film thereof as a buffer layer, which is preferable because a semiconductor such as GaN, AlN, GaAlN, and InGaAlN with high crystallinity can be grown.

As a method for producing the group 3-5 compound semiconductor, a molecular beam epitaxy (hereinafter, sometimes referred to as MBE) method, an organic metal vapor phase epitaxy (hereinafter, sometimes referred to as MOVPE) method, Hydride vapor phase epitaxy (hereinafter HV)
Sometimes referred to as PE. ) Method. In addition,
When the MBE method is used, nitrogen gas may be nitrogen gas,
A gas source molecular beam epitaxy (hereinafter sometimes referred to as GSMBE) method, which is a method for supplying ammonia and other nitrogen compounds in a gaseous state, is generally used. In this case, the nitrogen source is chemically inert,
Nitrogen atoms may not be easily incorporated into the crystal. In that case, the nitrogen material is excited by microwaves or the like,
By supplying in an activated state, the efficiency of nitrogen uptake can be increased.

Next, the M of the Group 3-5 compound semiconductor of the present invention
The manufacturing method by the OVPE method will be described. MOVP
In the case of the method E, the following raw materials can be used.
That is, as a Group 3 raw material, trimethylgallium [(CH
_Three)_ThreeGa may be referred to as TMG hereinafter. ], Trie
Chilgallium [(C_TwoH_Five)_ThreeGa, hereinafter referred to as TEG
Sometimes. General formula R such as₁R_TwoR_ThreeGa (where,
R₁, R_Two, R _ThreeRepresents a lower alkyl group. )
Trialkyl gallium; trimethyl aluminum
[(CH_Three)_ThreeAl], triethyl aluminum [(C
_TwoH_Five)_ThreeAl, hereinafter sometimes referred to as TEA. ]
Liisobutyl aluminum [(i-C _FourH₉)_ThreeAl]
General formula R such as₁R_TwoR_ThreeAl (where R₁, R_Two, R
_ThreeIs the same as defined above. Trialkyl represented by)
Aluminum; trimethylamine alane [(CH_Three)
_ThreeN: AlH_Three]; Trimethylindium [(CH_Three)
_ThreeIn, hereafter referred to as TMI. ], Triethyl
Indium [(C_TwoH_Five)_ThreeIn] or other general formula R₁R_Two
R_ThreeIn (where R₁, R_Two, R_ThreeIs the same as defined above
The same. Trialkylindium etc.
I can do it. These may be used alone or as a mixture.

Next, as Group V raw materials, ammonia, hydrazine, methylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, t-butylamine, ethylenediamine and the like can be mentioned. These may be used alone or as a mixture. Among these raw materials, ammonia and hydrazine do not contain a carbon atom in the molecule, and thus are suitable because they do not cause much carbon contamination in the semiconductor.

As a p-type dopant for the group 3-5 compound semiconductor, a group 2 element is important. Specifically, Mg, Z
Among them, n, Cd, Hg, and Be can be mentioned. Of these, Mg, which is easy to produce a low-resistance p-type, is preferable. Mg
As a raw material of the dopant, biscyclopentadienyl magnesium, bismethylcyclopentadienyl magnesium, bisethylcyclopentadienyl magnesium, bis-n-propylcyclopentadienyl magnesium, bis-i-propylcyclopentadienyl magnesium General formula (RC ₅ H ₄ ) ₂ Mg (where R
Represents hydrogen or a lower alkyl group having 1 to 4 carbon atoms. The organic metal compound represented by the formula (1) is suitable because it has an appropriate vapor pressure.

As the n-type dopant of the group 3-5 compound semiconductor, a group 4 element and a group 6 element are important. Specific examples include Si, Ge, and O, and among these, low-resistance n
Si that can be easily molded and has high raw material purity
Is preferred. Suitable materials for the Si dopant include silane (SiH ₄ ), disilane (Si ₂ H ₆ ), and monomethylsilane (CH ₃ SiH ₃ ).

As a growth apparatus by the MOVPE method which can be used for manufacturing the group 3-5 compound semiconductor, a usual single- or multi-piece growth apparatus can be used. In the case of a plurality of wafers, it is preferable to grow under reduced pressure in order to ensure the uniformity of the epitaxial film in the wafer surface. The preferable range of the growth pressure in the multiple-sheet take-up apparatus is 0.001 atm or more and 0.8 atm or less.

As the carrier gas, a gas such as hydrogen, nitrogen, argon, helium or the like can be used alone or as a mixture. However, when hydrogen is contained in the carrier gas, sufficient crystallinity may not be obtained when the compound semiconductor having a high InN mixed crystal ratio is grown. In this case, it is necessary to lower the partial pressure of hydrogen in the carrier gas. The preferred partial pressure of hydrogen in the carrier gas is 0.1 atm or less.

Among these carrier gases, hydrogen and helium are mentioned because they have a large kinematic viscosity coefficient and hardly cause convection. However, helium is more expensive than other gases, and when hydrogen is used, the crystallinity of the compound semiconductor is not good as described above. Since nitrogen and argon are relatively inexpensive, they can be suitably used when a large amount of carrier gas is used.

[0037]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 A Group 3-5 compound semiconductor having the structure shown in FIG. 4 was produced by MOVPE. As the substrate 1, a substrate obtained by mirror-polishing the sapphire C surface was used after organic cleaning. Regarding the growth method, a two-stage growth method using GaN as a low-temperature growth buffer layer was used. GaN with a thickness of about 300mm at 550 ° C
Buffer layer 2, n-type GaN layer 11 doped with Si having a thickness of about 3 μm at 1100 ° C., first layer of 1500 ° C.
Was grown using hydrogen as a carrier gas.

Next, at a substrate temperature of 750 ° C. and a carrier gas
To 1 ppm with carrier gas, TEG and nitrogen
4 slm each of diluted silane and ammonia,
0.04sccm, 5sccm, 4slm
The GaN layer 4 doped with Si, which is the third layer, is formed to a thickness of 300%.
Lengthened. At the same temperature, the TEG, TMI and
0.04sccm, 0.24scc
m, 4 slm to supply the second layer of non-doped In
_0.3Ga_0.770 seconds for N layer 5, TEG, TEA,
Nearly non-doped Ga_0.8Al_0.2N protective layer 6
Was grown for 10 minutes. However, slm and sccm are
A unit of gas flow, where 1 slm is a standard per minute.
In this state, a gas weighing 1 liter is flowing.
1000 sccm is equivalent to 1 slm
You. The layers 9 and 4 have the same thickness.
Growth rate obtained from the thickness of the layer grown for a longer period of time
Are 43 ° / min and 30 ° / min, respectively.
The film thickness required from a long time is 50 ° and 300 °, respectively.
計算 can be calculated.

After growing the protective layer 6, the temperature of the substrate is set to 1100
° C, and the p-type layer 7 made of Mg-doped GaN is
It grew by $ 000. The sample thus prepared was subjected to a heat treatment at 800 ° C. for 20 minutes in nitrogen at 1 atm to reduce the resistance of the Mg-doped layer. An electrode was formed on the thus obtained sample according to a conventional method to obtain an LED. Ni as p electrode
-Au alloy, Al was used as the n electrode. When a current of 20 mA was applied to this LED in the forward direction, most of the L
ED showed clear blue light emission. Defective products that did not emit light even when voltage was applied were 12% of the total. When the drive voltage at 20 mA was inspected for the LEDs excluding defective products, the average value was 3.7 V, and 95% of the whole was 4.0 V or less.

Example 2 In the same manner as in Example 1, an LED was manufactured and evaluated eight times. The defective product rate in the production and evaluation of each epi substrate is 9 to 13%, and the average drive voltage of the LEDs excluding defective products is 3.6 to 3.8 V.
The ratio of LEDs having a drive voltage of 4.0 V or less is 93%.
９６96%.

Comparative Example 1 An LED was manufactured and evaluated in the same manner as in Example 1 except that the GaN layer 4 as the third layer was not grown. The defective product rate was 15%. LE excluding defective products
The average value of the drive voltage for D is 3.8V, and 4.
The ratio of LEDs having a drive voltage of 0 V or less was 35%. Further, the average value of the luminance was reduced by about 10% as compared with the example 1.

Comparative Example 2 In the same manner as in Comparative Example 1, an LED was manufactured and evaluated eight times. The defective product rate in each production and evaluation of the epitaxial substrate is 12 to 20%, and the average drive voltage of the LED excluding the defective product is 3.7 to 20%.
LE having a drive voltage of 4.5 V or less than 4.0 V
The ratio of D was 20 to 45%.

Example 3 An LED was fabricated and evaluated in the same manner as in Example 1 except that the first layer was non-doped Ga _0.85 Al _0.15 N. The reject rate was 11%, and the average drive voltage of the LEDs excluding rejects was 3.6.
V, and the ratio of LEDs having a drive voltage of 4.0 V or less was 93%.

Example 4 An LED was fabricated and evaluated in the same manner as in Example 1 except that the third layer was Ga _0.8 Al _0.2 N doped with Si. The reject rate is 12%, and the average drive voltage for the LEDs excluding the reject is:
LE which was 3.7 V and the drive voltage was 4.0 V or less
The proportion of D was 91%.

Example 5 An LED was fabricated and evaluated in the same manner as in Example 1 except that the third layer was GaN doped with Si having a thickness of 1000 °. The defective product rate was 12%, and the average value of the driving voltage of the LEDs excluding defective products was 3.6 V, and the ratio of the LEDs having the driving voltage of 4.0 V or less was 94%. Was.

Embodiment 6 In the same manner as in Embodiment 1, a thickness of about 3 was formed on a sapphire substrate.
A non-doped GaN layer as a first layer having a thickness of about 3 μm and a GaN buffer layer of 00 ° was grown. Further, the third layer, ie, a 300 ° GaN layer, and the second layer, ie, 5 °, were formed in the same manner as in Example 1 except that the carrier gas was Ar.
A 0 ° In _0.3 Ga _0.7 N layer and a 300 ° Ga _0.8 Al _0.2 N layer as a protective layer were grown. When the photoluminescence spectrum of the quantum well structure thus obtained was measured, clear blue light emission from the quantum well was observed.
It was confirmed that a high quality quantum well was produced.

[0047]

According to the method for producing a Group 3-5 compound semiconductor of the present invention, a light emitting device having high productivity, improved yield, and excellent characteristics can be produced with good reproducibility, and has great industrial value.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a Group 3-5 compound semiconductor of the present invention.

FIG. 2 is a cross-sectional view showing one example of a Group 3-5 compound semiconductor of the present invention.

FIG. 3 is a sectional view showing an example of a Group 3-5 compound semiconductor of the present invention.

FIG. 4 is a cross-sectional view illustrating a Group 3-5 compound semiconductor of the present invention manufactured in Example 1.

[Explanation of symbols]

 1. . . Substrate 2. . . Buffer layer 3. . . 3. n-type GaN layer as first layer . . 4. GaAlN layer as third layer . . 5. InGaN light emitting layer as second layer . . Protective layer 7. . . 7. p-type layer . . 8. n-type InGaN layer . . n-type GaAlN layer 10. . . 10. Non-doped GaN layer as first layer . . N-type GaN layer 11 doped with Si

Claims (6)

[Claims] (1) The general formula Ga _a Al _b N (where 0 ≦ a ≦
1,0 ≦ b ≦ 1, a + b = 1) a first layer comprising a Group III-V compound semiconductor represented by a temperature in excess of 1000 ° C. After growth, the general formula In _x Ga _y Al _z N ( Where 0
<X ≦ 1, 0 ≦ y <1, 0 ≦ z <1, x + y + z = 1)
In the method for growing a group III-V compound semiconductor, in which the second layer composed of the group III-V compound semiconductor layer represented by
_v Al _w N (where 0 ≦ v ≦ 1, 0 ≦ w ≦ 1, v + w =
A method for producing a Group 3-5 compound semiconductor, comprising: growing a third layer made of a Group 3-5 compound semiconductor represented by 1) at a temperature of 1000 ° C. or lower. 2. The method according to claim 1, wherein the first layer is of the general formula Ga _a Al _b N (wherein
2. The production of a Group 3-5 compound semiconductor according to claim 1, comprising a Group 3-5 compound semiconductor represented by 0 ≦ a ≦ 0.8, 0 ≦ b ≦ 0.2, a + b = 1). Method. 3. The method according to claim 1, wherein the thickness of the third layer is not less than 5 ° and not more than 1 μm. 4. The method according to claim 1, wherein the thickness of the second layer is not less than 5 ° and not more than 90 °.
A method for producing a group III compound semiconductor. 5. The method according to claim 1, wherein the second layer contains Si, Ge, Zn, and C.
The concentration of each element of d and Mg is 1 × 10 ¹⁹ cm
^{5. The} method for producing a Group 3-5 compound semiconductor according to claim 1, 2, 3 or 4, wherein the value is ^-3 or less. 6. A light-emitting device using a Group 3-5 compound semiconductor obtained by the method for producing a Group 3-5 compound semiconductor according to claim 1.