JP2003282862A - Nitride semiconductor layer, nitride semiconductor element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride semiconductor element obtained by applying a nitride semiconductor containing P or As having a characteristic differing from the conventional nitride semiconductor containing P or As to each structure of the nitride semiconductor element, wherein an atomic fraction of N of the nitride semiconductor containing P or As is greater than the atomic fraction of P or As. <P>SOLUTION: A nitride semiconductor layer is that an atomic fraction of P or As occupied in the nitride semiconductor layer is 30% or less. P or As contains at least a site of group III, so that the nitride semiconductor layer having a characteristic differing from the conventional nitride semiconductor layer containing P or As can be obtained. Further, a lattice constant in a c-axial direction of such the nitride semiconductor layer has a characteristic of being smaller than that of the nitride semiconductor layer not containing P or As. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor device using a nitride-based compound semiconductor material containing an element of As or P.

[0002]

2. Description of the Related Art GaN _1-x P _{x formed} by adding P to a hexagonal GaN crystal is known as Jpn. J. Appl. Phys. V
ol. 35 (1996) pp. L1634-L1637
Was reported in. The GaN _1-x P _x is GSMBE (Gas
Source Molecular Beam Ep
Itaxy) device. This GaN _1-x P _x is
The composition x of P is 0.015, and the lattice constant in the c-axis direction is 0.5.
It is 202 nm. On the other hand, the underlying layer, GaN, has a lattice constant of 0.5185 nm. Thus, conventionally,
In nitride-based semiconductors, P and As are added to certain materials.
Is added, the semiconductor layer to which P or As is added (GaNP in the above example) has a c-axis lattice constant larger than that of a semiconductor layer to which P or As is not added (GaN for GaNP). Was large and the emission wavelength was a long wavelength.

[0003]

Up to now, in order to obtain a nitride-based semiconductor material having a lattice constant smaller than that of GaN, only the method of adding Al to GaN has been available.
However, Al is also a substance that easily oxidizes, and in order to increase the degree of freedom in device design, it has been eagerly desired to obtain a nitride semiconductor that does not contain Al and has a smaller lattice constant.

[0004]

DISCLOSURE OF THE INVENTION As a result of repeated studies in view of the above problems, the present inventors have found that P or As-added nitride semiconductors have properties different from those previously reported. We succeeded in producing a nitride semiconductor.

The semiconductor layer of the present invention is (A, In, Ga)
A nitride semiconductor layer containing at least one of these, N, and P or As (hereinafter, simply referred to as “P or As”).
The nitride semiconductor layer containing “) includes P or As in the nitride semiconductor layer having an atomic fraction of 30% or less, and P or As is contained in at least a group III site. And Further, such a nitride semiconductor layer (hexagonal system) is a semiconductor layer whose lattice constant in the c-axis direction is obtained by removing P and As from the nitride semiconductor layer (hereinafter, referred to as "nitride containing no P or As. It has been found from the results of the study by the present inventors that it becomes smaller than the lattice constant in the c-axis direction of the "semiconductor layer").

This is because conventional GaNP (GaN N is P
The larger amount of GaNP) exhibits the property opposite to the property that the lattice constant increases when P is added to GaN. In addition, GaN _1-x P _x reported as a conventional example
As shown in the description, the composition ratio is G: P + N and the composition ratio is 1: 1.
Becomes That is, P is considered to be in the V group site.

Here, the atomic fraction of P or As contained in a certain nitride semiconductor layer described in this specification is expressed as follows. Atomic fraction of P or As (%)
= 100 × (P or As) / (all group III atoms of a certain nitride semiconductor layer + all group V elements of a certain nitride semiconductor layer). Here, all the group V elements of a certain nitride semiconductor layer include P and As described above. For example, when a certain nitride semiconductor layer is GaNP, the atomic fraction of P is 100 × P /
(Ga + N + P). Similarly, in the case of GaNAs, the atomic fraction of As = 100 × As / (Ga + N + A)
s). In the case of GaNPAs, the atomic fraction of As and P = 100 × (As + P) / (Ga + N + As +
P), and in the case of InGaNP, the atomic fraction of P = 100 × P / (In + Ga + N + P).

The nitride conductor layer of the present invention is characterized in that the lattice constant in the c-axis direction is smaller than the lattice constant in the c-axis direction of the semiconductor layer obtained by removing P and As from the nitride semiconductor layer.

The nitride semiconductor device of the present invention is characterized by including the above-mentioned nitride semiconductor layer.

The nitride semiconductor device of the present invention is a light emitting device.

The nitride semiconductor device of the present invention is characterized in that the nitride semiconductor layer is included in a light emitting layer.

The nitride semiconductor device of the present invention is characterized in that the nitride semiconductor layer is n-type.

The nitride semiconductor device of the present invention is characterized in that the nitride semiconductor layer is p-type.

The nitride semiconductor device of the present invention is characterized by having a multilayer film structure or a superlattice structure including at least the nitride semiconductor layer.

The nitride semiconductor device of the present invention is characterized in that the nitride semiconductor layer is used as a contact layer.

The nitride semiconductor device of the present invention is characterized in that the nitride semiconductor layer is used as an optical guide layer.

The nitride semiconductor device of the present invention is characterized in that the nitride semiconductor layer is used as a cladding layer.

According to the method of manufacturing a nitride semiconductor device including the first nitride semiconductor layer and the second nitride semiconductor layer of the present invention, the first nitride semiconductor layer is (Al, In, Ga). At least one of these and N, and further P or A
s, and the atomic fraction of P or As contained in the nitride semiconductor layer is 30% or less, and the second nitride semiconductor layer is a semiconductor obtained by removing P and As from the first nitride semiconductor layer. The first nitride semiconductor layer has a growth rate of the second layer.
By making the growth rate of the nitride semiconductor layer slower than that of the first nitride semiconductor layer.
Characterized by entering the II group site.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment><Characteristics of P- or As-Containing Nitride Semiconductor According to the Present Invention> The present invention has a P or As atomic ratio of 30% in the nitride semiconductor. The following nitride semiconductor layer is characterized in that P or As thereof is contained in at least a group III site. Further, the lattice constant in the c-axis direction of the nitride semiconductor layer is P or As described above.
It is characterized in that it is made smaller than that of the nitride semiconductor layer not containing. Such a nitride semiconductor layer can be manufactured as follows using a metal organic chemical vapor deposition (MOCVD) apparatus. As an example,
The nitride semiconductor layer containing at least one of (A, In, Ga) and N, and further containing P or As is Ga.
The case of NP will be described.

First, the sapphire substrate was set in the MOCVD apparatus, and NH _{3 as a} group V source and TMG as a group III source were used.
By supplying a (trimethylgallium), a low temperature GaN buffer layer was grown to a thickness of 30 nm at a growth temperature of 550 ° C. Next, the substrate temperature was raised to 1050 ° C., and NH ₃ and T were added again.
MGa is supplied to form a GaN underlayer having a thickness of about 3 μm. Subsequently, the substrate temperature was lowered to 900 ° C., and PH ₃ (phosphine) was added to the raw material at 1 sccm to grow GaNP. PH ₃ used here is nitrogen-based 10
The one diluted in% was used.

According to the experimental results by the present inventors, the growth temperature of the GaNP crystal according to the present invention is 800 ° C. or higher 11
The temperature is preferably 00 ° C or lower, more preferably 850 ° C or higher and 1000 ° C or lower. In addition, it is preferable to mix nitrogen in addition to hydrogen as a carrier gas when growing the GaNP crystal, and the ratio of the nitrogen carrier gas in the total carrier gas is preferably 0.01% or more and 50% or less. . When the ratio of the nitrogen carrier gas exceeds 50%, the crystallinity is lowered, which is not preferable. Also, P or As
A nitride semiconductor containing In and a nitride semiconductor containing In must always contain hydrogen as a carrier gas. Otherwise, the surface morphology was deteriorated and epitaxial growth could not be performed.

Further, the growth rate of GaNP is 0.3.
A value of μm / h or less was preferable. According to the experimental results of the present inventors, it was difficult to grow epitaxially a GaNP crystal well if the growth rate was too fast. On the other hand, G
The growth rate of aN is 3 to 4 μm / h, and the growth rate of GaNP in the present application is considerably slow. By making the growth rate of the first semiconductor layer, that is, the GaNP crystal, slower than the growth rate of the second semiconductor layer, that is, GaN, it is considered that the P of GaNP enters the group III site.

The thus-produced GaNP was a pale yellow transparent film. This GaNP film was measured with an Auger electron spectroscopy (AES) device, and a standard sample (GaN
And GaP) were used for sensitivity calibration of the composition ratio (atomic fraction) of each constituent element. As a result, assuming that the atomic fraction of the constituent elements of GaNP is 100%, the atomic fraction of Ga element is 47.6%, the atomic fraction of P element is 2.4%, and the atomic fraction of N element is 50%. %Met. From the AES measurement results, considering the distribution of P such that the stoichiometry of the group III element and the group V element of the nitride semiconductor is 50%, it is well explained that P is added to the group III site. Holds. In other words, P is a V group, so originally N and P are 5
Although it should be 0%, it is considered that P is included in the group III site in GaNP of the present application because the above AES results in 50% for N alone. In this way, the present inventors have found that P is a nitride semiconductor III
It was determined that it was included in the tribe site. G prepared by using the same method as described above and varying only the supply amount of PH ₃
Table 1 shows the atomic fractions of the constituent elements of aNP. By using this Table 1 and the determination method described above, it can be seen that P of GaNP is included in the group III site of the nitride semiconductor.
Furthermore, according to the results of experiments conducted by the present inventors, the same PH ₃
It was confirmed that even with the supply amount, the higher the growth rate of GaNP, the higher the atomic fraction of P, and the lower the growth temperature, the higher the atomic proportion of P.

[0024]

[Table 1]

Although the above description has been made with respect to GaNP, GaNAs, GaNAsP, InGaNP, In
GaNAs, AlGaNP, AlGaNAs, AlGa
The same applies to NPAs, AlInGaNP, AlInGaNAs, and AlInGaNPAs.

Further, in the above description, P is a nitride semiconductor II
Although it was investigated by AES measurement that it was contained in the site of the group I element, EPMA (electron beam microanalyzer)
It was confirmed by the present inventors that the measurement can be similarly performed.

Next, the above-described GaNP having an atomic fraction of P of 2.4% was analyzed by using an X-ray apparatus (an optical system is 4 crystals). The result at that time is shown in FIG. FIG. 4 shows a measurement result by a 2θ-ω scan which is one of X-ray measurement techniques. As you can see from this figure, Ga
A (0002) reflection spectrum due to the N underlayer and a spectrum due to GaNP were observed on a higher angle side than the spectrum (this spectrum due to GaNP is not due to Kα of Cu of the X-ray source). It has been confirmed by the present inventors that there is none). Thus, G
The spectrum due to aNP is (000
2) Since it appeared on the higher angle side than the reflection spectrum, G
The c-axis lattice constant of aNP is GaN that does not contain P.
It became clear that it was smaller than that. In fact, when the surface of the above-mentioned GaNP (GaNP thickness was 0.5 μm, GaN underlayer thickness was 3 μm) film was observed using an optical microscope, cracks were scattered.

Further, referring to FIG. 4, since nothing is observed near the spectral position where the GaP (111) reflection (2θ = 28.333 °) of the zinc blende structure appears, the GaP base in the present crystal is not observed. It was found that GaPN (cubic system) was not included (this crystal is GaN-based hexagonal GaNP, and phase separation does not occur between the hexagonal system and the cubic system).

In the above description, it was explained using GaNP that the lattice constant in the c-axis direction of the nitride semiconductor containing P or As is smaller than that of the nitride semiconductor layer not containing P or As. The relationship can be similarly explained even if the nitride semiconductor containing P or As is GaNAs and the nitride semiconductor layer not containing P or As is GaN. Similarly, a nitride semiconductor containing P or As is G
When the nitride semiconductor layer which does not contain P or As in aNAsP is GaN, the nitride semiconductor layer which contains P or As is In
In NGP, the nitride semiconductor layer containing no P or As is I
In the case of nGaN, the nitride semiconductor containing P or As is I
When the nitride semiconductor layer of nGaNAs that does not include P or As is InGaN, the nitride semiconductor that includes P or As is AlGaNP, and the nitride semiconductor layer that does not include P or As is AlGaN, the nitride that includes P or As When the semiconductor is AlGaNAs and the nitride semiconductor layer not containing P or As is AlGaN, the nitride semiconductor layer containing P or As is AlGaNPAs and the nitride semiconductor layer not containing P or As is AlGaN, it contains P or As. When the nitride semiconductor is AlInGaNP and the nitride semiconductor layer containing no P or As is AlInGaN, the nitride semiconductor containing P or As is AlInGaNAs, and the nitride semiconductor layer containing no P or As is AlInGaN, and P Alternatively, the nitride semiconductor containing As is AlI
The same can be applied to the case where the nitride semiconductor layer of nGaNPAs containing no P or As is AlInGaN. <Regarding the atomic fraction of P or As in the nitride semiconductor> The atomic fraction of P in the nitride semiconductor is 0.1%.
It is preferably not less than 30% and not more than 30%. More preferably, 0.3%
Or more and 15% or less, more preferably 0.5% or more 10
% Or less. When the atomic fraction of P exceeds 30%, the crystallinity is deteriorated, which is not preferable.
If it is less than%, it may be difficult to obtain the effect of the present invention.

On the other hand, the atomic fraction of As in the nitride semiconductor is preferably 0.1% or more and 30% or less. More preferably, 0.3% or more and 12% or less, and further preferably,
It is 0.5% or more and 8% or less. The atomic fraction of As is 30%
Is not preferable because the crystallinity is deteriorated.
If the atomic fraction of is less than 0.1%, it may be difficult to obtain the effect of the present invention. <When the Nitride Semiconductor According to the Present Invention is Applied to the Light Emitting Layer> Here, the light emitting layer is composed of a well layer for emitting light and a barrier layer for confining electrons and holes. When the light emitting layer has a single quantum well structure, it is possible to use only the well layer or the structure of barrier layer / well layer / barrier layer. When the light emitting layer has a multi-quantum well structure, a barrier layer / well layer / barrier layer /.../ barrier layer structure starting with a barrier layer and ending with a barrier layer, or starting with a well layer and ending with a well layer A well layer / barrier layer / well layer /.../ well layer structure can be used.

By including the nitride semiconductor layer described above in this light emitting layer, the following effects can be obtained.

By using the nitride semiconductor containing P or As according to the present invention as the well layer, it is possible to easily shorten the emission wavelength or the oscillation wavelength. This property is due to the previously reported GaNP.
(Or GaNAs) has the opposite property. According to the results of experiments conducted by the present inventors, the photoluminescence due to GaNP emitted light on the shorter wavelength side than that of GaN. Thus, for example, GaNP, GaNAs, G
aNAsP emits light having a shorter wavelength than GaN
P, InGaNAs, InGaNAsP are InGaN
Light on the shorter wavelength side than AlGaNP, AlGaNA
s, AlGaNAsP transmits light on the shorter wavelength side than AlGaN to AlInGaNP, AlInGaNAs, AlI.
nGaNAsP can emit light on the shorter wavelength side than AlInGaN.

The nitride semiconductor containing P or As according to the present invention can have a larger bandgap energy than that of a nitride semiconductor containing no P or As.
It can be used as a barrier layer. For example, when InGaN is a well layer, the barrier layer may be GaNAs, GaNP, Ga.
NAsP, InGaNAs, InGaNP, InGaN
AsP or the like can be used. When GaN is a well layer, the barrier layer is formed of GaNAs, GaNP, or GNA.
sP, AlGaNAs, AlGaNP, AlGaNAs
P or the like can be used. Further, when AlGaN is a well layer, the barrier layer is made of AlGaNAs, AlGaN.
P, AlGaNAsP, etc. can be used. Furthermore, when AlInGaN is a well layer, the barrier layer is A
lGaNAs, AlGaNP, AlGaNAsP, Al
InGaNAs, AlInGaNP, AlInGaNA
sP or the like can be used. <When the Nitride Semiconductor According to the Present Invention is Applied as an n-Type Layer> According to the experimental results of the present inventors, the polarity of the nitride semiconductor containing P or As according to the present invention is the addition of an impurity serving as a donor. It was possible to easily obtain the n-type without doing so. When a donor impurity is added to the nitride semiconductor of the present invention, Si is most preferable as the impurity, and the impurity concentration is 1 × 10 ^{17 to} 5 × 10 ¹⁸ / cm 3.
It was preferred to be in the range of ³ . <When the nitride semiconductor according to the present invention is applied as a p-type layer> The nitride semiconductor containing P or As according to the present invention can have a p-type polarity by adding Mg. The present inventors utilized bisethylcyclopentadienyl magnesium as a raw material for Mg. P
Alternatively, it is preferable that the Mg impurity concentration in the nitride semiconductor containing As is in the range of 1 × 10 ^{20 to} 5 × 10 ²¹ / cm ³ . <When the nitride semiconductor according to the present invention is used in a multilayer film structure or a superlattice structure> P or A according to the present invention
The nitride semiconductor containing s can be used as part of a multilayer film structure or a superlattice structure. For example, a P- or As-containing nitride semiconductor layer according to the present invention and a P- or As-free nitride semiconductor layer are alternately stacked to form a multilayer film structure or a superlattice structure, or a P- or As-containing first structure.
Can be used for a multilayer film structure or a superlattice structure in which the nitride semiconductor layer and the second nitride semiconductor layer containing P or As are alternately laminated.

Specifically, by using an AlGaN / GaNP multilayer film or superlattice, an AlGaN / GaNAs multilayer film or superlattice, it is possible to reduce the lattice mismatch with each other, and thus prevent the occurrence of cracks. In addition, it can have a function as a cladding layer. For example, conventional Al0.15Ga0.85N
/ GaN multi-layered film or superlattice has a lattice constant of 0.5159n for Al0.15Ga0.85N layer.
m, the GaN layer is 0.5190 nm. The lattice mismatch difference is 0.0031 nm. On the other hand, according to the present application, Al 0.15 Ga 0.
The lattice constant of each layer made of 85N / GaNP (atomic fraction of P is 2.4%) is 0.5159 nm for Al0.15Ga0.85N layer and 0.5156 nm for GaNP layer. The lattice mismatch difference is 0.0003 nm. That is, when the present application is used, the lattice mismatch difference can be reduced to about 1/10 as compared with the conventional one.

FIG. 5 shows the relationship between the P atomic fraction of GaNP and its lattice constant in the c-axis direction, and the relationship between the P atomic fraction of GaNP and the lattice constant of GaN that is the underlying layer of GaNP. . The black squares in FIG. 5 represent GaNP, and the white circles in FIG. 5 represent GaN, which is the underlayer of GaNP produced at each P atomic fraction (the blank with a P atomic fraction of 0). The circles are the lattice constants of the GaN layer that was crystal-grown on the sapphire substrate.
It is considered that the lattice constant is smaller than that of aN because it is subjected to compressive strain due to GaNP grown on the GaN layer). As you can see from this figure, Ga
It can be seen that as the P atom fraction of NP increases, the lattice constant of GaNP in the c-axis direction decreases.

In the above, P or As according to the present invention
The description of the lattice constant of the nitride semiconductor including is given by taking GaNP as an example. However, the above description is
However, the present invention is not limited to this, and also corresponds to a nitride semiconductor containing P or As according to the present invention.

When the polarity of the above-mentioned multilayer film or superlattice is n-type, AlGaN and GaNP (or GaNAs)
Si can be added to both layers or only to one layer. On the other hand, when the polarity of the multilayer film or superlattice is p-type, AlGaN and GaNP (or Ga
It is possible to add Mg to both layers (NAs) or only one layer.

The same effect as described above is obtained by AlInGaN / G.
aNP multilayer film or superlattice, AlInGaN / GaNA
s multilayer film, GaN / GaNP multilayer film or superlattice, Ga
N / GaNAs multilayer film or superlattice, AlInGaNP
/ GaNP multilayer film or superlattice, AlInGaNAs /
It is also possible to obtain a GaNAs multilayer film, a GaNP / GaNP multilayer film or a superlattice, a GNAs / GaNAs multilayer film or a superlattice, and the like.

On the other hand, the InGaN / GaNP multi-layer film or superlattice, the InGaN / GaNAs multi-layer film or superlattice is inserted in contact with two nitride semiconductor layers having different lattice constants so that these nitride semiconductor layers It has the effect of alleviating the lattice mismatch of and preventing the occurrence of cracks. It can also be used as a light guide layer. When the polarity of the above-mentioned multilayer film or superlattice is n-type, Si can be added to both layers of InGaN and GaNP (or GaNAs), or to only one layer. On the other hand, when the polarity of the multilayer film or superlattice is p-type, InGaN and GaNP (or GaNA) are used.
Mg can be added to both layers of s) or to only one layer.

InGaN / InG has the same effect as described above.
aNP multilayer film or superlattice, InGaN / InGaNA
s multilayer film, GaN / GaNP multilayer film or superlattice, Ga
N / GaNAs multilayer or superlattice, InGaNP / I
nGaNP multilayer film or superlattice, InGaNAs / In
It is also possible to obtain a GaNAs multilayer film, a GaNP / GaNP multilayer film or a superlattice, a GNAs / GaNAs multilayer film or a superlattice, and the like.

The thickness of the nitride semiconductor layer containing P or As contained in the above-mentioned multilayer film structure or superlattice structure is preferably 1 nm or more and 50 nm or less, and more preferably 2 nm or more and 25 nm or less. <When the Nitride Semiconductor According to the Present Invention is Used as a Contact Layer> The nitride semiconductor containing P or As according to the present invention is an n-type contact layer in contact with an n-type electrode or a p-type contact layer in contact with a p-type electrode. It can be used as.

When the nitride semiconductor layer containing P or As according to the present invention is used as an n-type contact layer, n
At least one of Ti, Al, Hf, and Au can be used as the mold electrode. This is preferable because the contact resistance of the n-electrode can be reduced. The thickness of the n-type contact layer of the nitride semiconductor according to the present invention is 2 nm.
It is preferably 0.6 μm or less.

On the other hand, when the nitride semiconductor layer containing P or As according to the present invention is used as the p-type contact layer, at least one of Pd, Pt, Mo, Ni and Au is used as the p-type electrode. You can This is preferable because the contact resistance of the p-electrode can be reduced and the electrode peeling can be prevented. Further, the nitride semiconductor layer on the opposite side of the p-type electrode and in contact with the main surface of the p-type contact layer was most preferably GaN having p-type polarity in order to reduce the contact resistance. The p-type contact layer of the nitride semiconductor according to the present invention has a thickness of 0.02 μm.
It is preferably m or more and 0.2 μm or less. <When the Nitride Semiconductor According to the Present Invention is Used as an Optical Guide Layer> The nitride semiconductor containing P or As according to the present invention can be used as an optical guide layer of a semiconductor laser. The clad layer generally used in a nitride semiconductor laser device is an AlGaN layer (layer thickness is about 1 μm).
Or AlGaN (layer thickness is several nm) / GaN (layer thickness is several n)
m) and the like. An optical guide layer generally used in a nitride semiconductor laser device is a GaN layer (layer thickness is about 0.1 μm). Of course, these layers are made of, for example, Si or Mg in order to make their polarities n-type or p-type.
Can be added.

Generally, in the nitride semiconductor laser device, the optical guide layer and the cladding layer are formed in contact with each other. Further, the lattice constant of the cladding layer is smaller than that of the light guide layer. This feature causes cracks in the nitride semiconductor laser device using these layers, resulting in a decrease in production yield.

However, P or As according to the present invention
The use of a nitride semiconductor containing Al for the optical guide layer makes it possible to reduce the lattice mismatch between the cladding layer and the optical guide layer and reduce cracks. This leads to an improvement in the yield rate of the nitride semiconductor laser device.

A specific light guide layer according to the present invention is
GaNP, GaNAs, InGaNP, InGaNAs
And so on. These light guide layers are doped with impurities.
N-type or p-type may be used, and impurities are intended.
Does not need to be added (i-type). Impurity added
When the light guide layer is made to have n-type polarity,
Then, Si can be used. Si impurities at this time
Concentration range is 1 × 10 ¹⁷~ 3 x 10¹⁸/ Cm³Is preferred
Yes. On the other hand, impurities are added to change the polarity of the light guide layer to p-type.
In case of, Mg can be used as an impurity.
It At this time, the Mg impurity concentration range is 1 × 10.¹⁹~ 3
× 10²⁰/ Cm³Is preferred.

The atomic fraction of P or As added to these optical guide layers should be larger than the refractive index of the clad layer formed in contact with the optical guide layer, or the band gap energy of the clad layer should be larger than the refractive index of the clad layer. Is also adjusted to be smaller. Specifically, P contained in the light guide layer
The atomic fraction of is preferably 0.1% or more and 5% or less. On the other hand,
The atomic fraction of As in which light is contained in the well layer is preferably 0.1% or more and 5% or less. <When the Nitride Semiconductor According to the Present Invention is Used as a Clad Layer> The nitride semiconductor containing P or As according to the present invention is used as a clad layer of a nitride semiconductor light emitting device (including a semiconductor laser and a light emitting diode). can do. Generally, the cladding layer used in a nitride semiconductor light emitting device is an AlGaN layer (layer thickness is about 1 μm) or AlGa.
It is a superlattice made of N (layer thickness is several nm) / GaN (layer thickness is several nm). Further, for example, Si or Mg is added to these layers in order to make their polarities n-type or p-type.

The cladding layer needs to have a smaller refractive index than these layers in order to confine light in the light emitting layer and the light guide layer. However, the refractive index of a conventional cladding layer made of a nitride semiconductor containing Al (not containing As or P) has a large difference in refractive index compared with that of an active layer made of InGaN or an optical guide layer made of GaN. It was difficult to obtain (a crack was generated when the Al composition ratio was increased), and it was difficult to sufficiently confine light.

However, when the nitride semiconductor containing P or As according to the present invention is used for the cladding layer, it is possible to confine light with a thinner layer thickness as compared with the conventional cladding layer. As a result, the incidence of cracks in the nitride semiconductor light emitting device was reduced, and light confinement could be satisfied.

A concrete cladding layer according to the present invention is G
aNP, GaNAs, AlGaNP, AlGaNAs,
Examples include AlInGaNP and AlInGaNAs. Si may be added to make the polarities of these layers n-type, and Mg may be added to make them p-type. The Si impurity concentration range is preferably 1 × 10 ^{17 to} 5 × 10 ¹⁸ / cm ³ , and the Mg impurity concentration range is 1 × 10 ^{19 to} 5 × 1.
0 ²¹ / cm ³ is preferable. Further, the atomic fraction of the elements forming these cladding layers is such that the refractive index thereof is smaller than the refractive index of the optical guide layer and the active layer, or the band gap energy of the optical guide layer or the light emitting layer. It is adjusted to be larger than the band gap energy. Specifically, the atomic fraction of P contained in the cladding layer is preferably 0.1% or more and 10% or less. On the other hand, the atomic fraction of As contained in the cladding layer is 0.1% or more and 1
0% or less is preferable. Furthermore, the layer thickness of these clad layers is preferably 0.3 μm or more and 1 μm or less.

This clad layer is not limited to the single layer as described above,
The multilayer film or superlattice structure described above can be used for the cladding layer. In particular, the p-type multilayer film or the p-type superlattice structure according to the present invention is preferably used because a high hole carrier concentration can be obtained. <Regarding Semiconductor Device Utilizing the Present Invention> The nitride semiconductor element according to the present invention can provide a highly reliable nitride semiconductor element with a low element defect rate. For example, the nitride semiconductor laser device according to the present invention is preferably used for an optical device such as a magneto-optical reproducing / recording device, a DVD device, a laser printer, a bar code reader, and a projector using a laser of three primary colors (blue, green, red). . Further, the nitride semiconductor light emitting diode element according to the present invention includes a white light source device, a backlight of a liquid crystal display device,
It is preferably used for an optical device such as a backlight of a mobile phone, a display device using a light emitting diode of three primary colors, and a copying machine. Furthermore, the nitride semiconductor electronic device according to the present invention is preferably used for communication transmission devices such as mobile phones and high-speed switching devices. <Embodiment 2> In this embodiment, the case where the nitride semiconductor containing P or As according to the present invention is applied to a nitride semiconductor laser device will be described. Other matters related to the present invention are the same as those in the first embodiment.

The nitride semiconductor laser device shown in FIG.
01) plane n-type GaN substrate 100, n-type In _0.07 Ga _0.93
N crack prevention layer 101, n-type Al _0.1 Ga _0.9 N cladding layer 102, n-type GaN light guide layer 103, light-emitting layer 10
4, p-type Al _0.3 Ga _0.7 N carrier block layer 105,
p-type GaN optical guide layer 106, p-type Al _0.1 Ga _0.9 N cladding layer 107, p-type GaN layer 108, p-type GaNP
(P atomic fraction is 2%) Contact layer 109, n-electrode 1
10, a p-electrode 111 and a SiO ₂ dielectric film 112.

First, using a metal organic chemical vapor deposition (MOCVD) apparatus, a GaN substrate 100 is formed on a GaN substrate 100 with NH ₃ and I as group V raw materials.
Group III source TMGa or TEGa (triethylgallium) to TMIn (trimethylindium) III
Group material and SiH ₄ are added, and n at the growth temperature of 800 ° C
Type In _0.07 Ga _0.93 N crack prevention layer 101 is 40 nm
Grown up Next, the substrate temperature is raised to 1050 ° C,
A group III raw material of TMAl or TEAl (triethylaluminum) is used, and 1.2 μm thick n-type Al is used.
_0.1 Ga _0.9 N cladding layer 102 (Si impurity concentration 1 × 1
0 ¹⁸ / cm ³⁾ is grown, followed by n-type GaN optical guide layer 103 (Si impurity concentration 1 × 10 ¹⁸ / cm ³⁾ is 0.
It was grown to 1 μm.

After that, the substrate temperature is lowered to 800 ° C.,
A light emitting layer (multiquantum well structure) 104 composed of three periods of an In _0.15 Ga _0.85 N well layer having a thickness of 4 nm and an In _0.01 Ga _0.99 N barrier layer having a thickness of 8 nm is a barrier layer / well layer /
The layers were grown in the order of barrier layer / well layer / barrier layer / well layer / barrier layer. At that time, SiH ₄ (S
The i impurity concentration was 1 × 10 ¹⁸ / cm ³ ).

When As is added to the light emitting layer, AsH ₃
(Arsine), if P is added to the light emitting layer, PH ₃
(Phosphine) should be added respectively. Further, when the light emitting layer is formed, dimethylhydrazine other than NH ₃ may be used as the N raw material. These raw materials are preferably used for the nitride semiconductor layer containing P or As according to the present invention.

Next, it is heated to a substrate temperature again 1050 ° C., p-type GaN optical guide layer of a thickness of 20 nm p-type Al _{0. 3} Ga _0.7 N carrier block layer 105,0.1μm 106,0.5μm The p-type Al _0.1 Ga _0.9 N cladding layer 107 and the 0.1-μm p-type GaN layer 108 were sequentially grown. Then, the substrate temperature is lowered to 900 ° C. and p-type GaN is used.
The P (atomic fraction of P is 2%) contact layer 109 is 0.1
μm was grown. As the p-type impurity, Mg (EtCP)
₂ Mg: bisethylcyclopentadienyl magnesium) was added.

Subsequently, the epi-wafer grown above was taken out from the MOCVD apparatus, and electrodes were formed. n
The electrode 110 was formed on the back surface of the epi-wafer in the order of Hf / Al. Then, Au was vapor-deposited on the n-electrode 110 as an n-type electrode pad. In addition to the n-electrode material, Ti
/ Al, Ti / Mo, Hf / Au, or the like may be used.

The p electrode portion was etched in a stripe shape to form a ridge stripe portion (FIG. 1). The width of the ridge stripe portion was 1.7 μm. Then Si
An O ₂ dielectric film 112 is vapor-deposited to a thickness of 200 nm to form p-type GaN.
The P contact layer 109 is exposed, and the P electrode 111 is P
d (15nm) / Mo (15nm) / Au (200n
It was formed by vapor deposition in the order of m).

The In _0.07 Ga _0.93 N crack prevention layer 102 described above may have an In composition ratio other than 0.07, or may not have the InGaN crack prevention layer itself. However, when the lattice mismatch between the clad layer and the GaN substrate becomes large, it is preferable to insert the crack prevention layer in terms of crack prevention. Although the InGaN crack prevention layer is used in the present embodiment, the nitride semiconductor layer according to the present invention described in Embodiment 1 may be used as the crack prevention layer. For example,
GaNP (0.1 μm), GaNAs (0.1 μm),
InGaNP (0.05 μm), InGaNAs (0.
05 μm), GaNP (10 nm) / GaN (10 n
m) Multilayer film or superlattice, GaNAs (10 nm) / G
Examples thereof include an aN multilayer film (10 nm) or a superlattice.

Although the light emitting layer 104 described above has a structure starting with a barrier layer and ending with a barrier layer, it may have a structure starting with a well layer and ending with a well layer. Further, the number of well layers is not limited to the above-mentioned three layers, but if the number is 10 or less, the threshold current density is low and continuous oscillation at room temperature is possible. The light-emitting layer 104 described above has S in both the well layer and the barrier layer.
i (SiH ₄ ) was added at 1 × 10 ¹⁸ / cm ³ , but Si
Does not have to be added. Further, the impurities may be added not only to both the well layer and the barrier layer but to only one layer. Further, the light emitting layer 104 may include the nitride semiconductor according to the present invention described in the first embodiment.

The p-type Al _0.3 Ga _0.7 N carrier block layer 107 described above may have an Al composition ratio other than 0.3, or may not have the p-type carrier block layer itself. However, when the light emitting layer contains the nitride semiconductor according to the present invention, it has p-type polarity,
Further, without the nitride semiconductor layer (carrier block layer) containing at least Al, it was difficult to improve the emission intensity and reduce the threshold current density.

In the above description, Al _0.1 Ga _0.9 N crystal was used as the p-type cladding layer and the n-type cladding layer, but the nitride semiconductor according to the present invention described in the first embodiment may be used. it can.

In the nitride semiconductor laser device described in the second embodiment, by using the p-type GaNP contact layer according to the present invention, the contact resistance is reduced and the peeling of the p-electrode is prevented, and the yield ratio is increased. Has improved.
It goes without saying that the contact layer described in the first embodiment can be used in addition to the above contact layer.

In the second embodiment, the nitride semiconductor laser device having the ridge stripe structure has been described, but the same effect can be obtained even when applied to the nitride semiconductor laser device having the current blocking layer. is there.

In this embodiment, the substrate is Ga
Although an N substrate was used, an AlGaN substrate, a sapphire substrate,
ELOG (Epitaxially lateral) formed on a (111) surface of a Si substrate and a sapphire substrate.
A ly overgrown GaN substrate, an ELOG substrate formed on a GaN substrate, or an ELOG substrate formed on a Si (111) plane may be used. When using these ELOG substrates, a growth suppressing film (for example, Si
It is formed so that the ridge stripe portion of the nitride semiconductor laser device or its current constriction portion is not included above the center of the width of the O ₂ film) and above the center of the region where the growth suppressing film is not formed. . This is preferable because the oscillation life of the laser is extended.

The nitride semiconductor laser device manufactured in this manner is used in laser printers, bar code readers,
It is preferably used for a projector or the like using a laser of three primary colors of light (blue, green, red). <Third Embodiment> In the third embodiment, the P according to the present invention is used.
Alternatively, a case where a nitride semiconductor containing As is applied to a nitride semiconductor light emitting diode element will be described with reference to FIG. Other matters related to the present invention are the same as those in the first embodiment.

The nitride semiconductor light emitting diode device of FIG. 2 comprises a (0001) plane n-type GaN substrate 200, an n-type short period superlattice 201, an n-type Al _0.3 Ga _0.7 N carrier block layer 202, a light-emitting layer 203 and a p-type. Al _0.3 Ga _0.7 N carrier block layer 204, p-type short period superlattice 205, p-type G
aNAs (As atomic ratio is 6%) Contact layer 20
6, p-type transparent electrode 207, p-electrode 208, n-electrode 20
Including 9.

In this embodiment, the n-type short period superlattice 201 is used.
As 100 cycles of GaNP (P atomic fraction 4%, thickness
Only 1.5 nm, Si-doped) / Al_0.2Ga_0.8N (thickness
1.5 nm, Si-doped) was used. As the light emitting layer 203
For 3 cycles of Al_0.06Ga _0.94N well layer (thickness 2n
m, Si doped) / Al_0.12Ga_0.88N (4 nm thickness,
Si doped) was used. p-type short period superlattice 205
100 cycles of GaNP (P atomic fraction 4%, thickness
1.5 nm, Mg doped) / Al_0.2Ga_0.8N (thickness
1.5 nm, Mg-doped) was used. In addition, p-type GaN
As (atomic fraction of As is 6%) contact layer 206 is
Al of p-type short period superlattice 205_0.2Ga_0.830n on N
m stacked. The p-type transparent electrode 207 is Pd (7 nm)
However, Au (500 nm) is used for the p electrode 208.
Was given.

Each layer of the light emitting diode element described in the third embodiment can be variously replaced with the nitride semiconductor layer according to the present invention described in the first embodiment. <Fourth Embodiment> In the fourth embodiment, the P according to the present invention is used.
Alternatively, a case where a nitride semiconductor containing As is applied to a nitride semiconductor heterojunction field effect transistor device will be described with reference to FIG. Other matters related to the present invention are the same as those in the first embodiment.

The nitride semiconductor heterojunction field effect transistor device shown in FIG. 3 has a (0001) plane i-type GaN substrate 3
00, n-type AlGaN layer 301, n-type InGaNP (I
The atomic fraction of n is 5%, and the atomic fraction of P is 3%).

In this embodiment, the n-type AlGaN layer 301 is used.
As the material, Al _0.25 Ga _0.75 N (thickness: 50 nm, Si impurity concentration: 5 × 10 ¹⁸ / cm ³ ) was used. n-type In
GaNP (the atomic fraction of In is 5%, the atomic fraction of P is 3
%) The contact layer 305 has a thickness of 5 nm and a Si impurity concentration of 5 × 10 ¹⁸ / cm ³ . Ti (15 nm) / Al (30 n) as electrodes for the source 302 and the drain 304
m) / Au (100 nm) was used. As an electrode of the gate 303, PdSi (15 nm) / Au (100 nm)
Was used.

In the transistor element described in the fourth embodiment, the use of the nitride semiconductor according to the present invention in the contact layer prevents the gate electrode from being peeled off and improves the yield.

Each layer of the transistor element described in the fourth embodiment can be variously replaced with the nitride semiconductor layer according to the present invention described in the first embodiment.

[0074]

According to the present invention, the emission wavelength is shortened,
Reduction of lattice constant, increase of bandgap energy,
The refractive index can be reduced. As a result, the nitride semiconductor containing P or As according to the present invention can be used as a light emitting layer, an n-type layer, a p-type layer, a multilayer film structure, a superlattice structure, a crack prevention layer, an n-type contact layer, a p-type contact layer. It can be preferably used for a light guide layer, a clad layer and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a nitride semiconductor laser device.

FIG. 2 is an example of a nitride semiconductor light emitting diode device.

FIG. 3 is an example of a nitride semiconductor heterojunction field effect transistor device.

FIG. 4 is an X-ray spectrum of GaNP (2θ-ω scan).

FIG. 5 is a diagram showing a relationship between an atomic fraction of GaNP and a lattice constant.

[Description of Reference Signs] 100, 200 ... n-type GaN substrate 101 ... n-type In _0.07 Ga _0.93 N crack prevention layer 102 ... n-type Al _0.1 Ga _0.9 N cladding layer 103 ... n-type GaN light guide layers 104, 203 ... light-emitting layer 105 p-type Al _0.3 Ga _0.7 N carrier block layer 106 p-type GaN optical guide layer 107 p-type Al _0.1 Ga _0.9 N cladding layer 108 p-type GaN layer 109 p-type GaNP contact layers 110, 209 n electrodes 111, 208 ... p electrode 112 ... SiO ₂ dielectric film 201 ... n-type short period superlattice 202 ... n-type Al _0.3 Ga _0.7 N carrier block layer 204 ... p-type Al _0.3 Ga _0.7 N carrier block layer 205 ... p-type short Periodic superlattice 206 ... p-type GaNAs contact layer 206 207 ... p-type transparent electrode 300 ... i-type GaN substrate 301 ... n-type AlGaN layer 302 Source 303 ... Gate 304 ... drain 305 ... InGaNP contact layer 101 ...

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 33/00 H01L 29/80 B H01S 5/323 610 (72) Inventor Yuichi Mohri Mayor Abeno Ward, Osaka City Ikemachi 22-22 No.22 F-term in Sharp Co., Ltd. (reference) 5F041 AA43 CA05 CA34 CA40 CA49 CA57 CA65 5F045 AA04 AB17 AC08 AC12 AC19 AD13 AF09 BB16 CA09 5F052 JA07 JA10 KA02 KA03 5F073 AA13 AA45 AA74 CA07 CA00 CA20 DA05 CA17 CA20 DA20 CA17 CA20 DA05 CA20 GB01 GC01 GD01 GJ04 GL04 GM04 GQ01 GR01 GS01 GT01 GT05

Claims (12)

[Claims] 1. At least one of (A, In, Ga)
In the nitride semiconductor layer containing seed and N, and further containing P or As, the atomic fraction of P or As contained in the nitride semiconductor layer is 30% or less, and P or As is at least III. A nitride semiconductor layer characterized in that it is included in a group site. 2. The lattice constant in the c-axis direction of the nitride conductor layer is smaller than the lattice constant in the c-axis direction of the semiconductor layer obtained by removing P and As from the nitride semiconductor layer. 1. The nitride semiconductor layer according to 1. 3. A nitride semiconductor device, comprising the nitride semiconductor layer according to claim 1 or 2. 4. The nitride semiconductor device according to claim 3, wherein the nitride semiconductor device is a light emitting device. 5. The nitride semiconductor device according to claim 4, wherein the nitride semiconductor layer is included in a light emitting layer. 6. The nitride semiconductor device according to claim 3, wherein the nitride semiconductor layer is n-type. 7. The nitride semiconductor device according to claim 3, wherein the nitride semiconductor layer is p-type. 8. The nitride semiconductor device according to claim 3, comprising a multilayer film structure or a superlattice structure including at least the nitride semiconductor layer. 9. The nitride semiconductor device according to claim 3, wherein the nitride semiconductor layer is a contact layer. 10. The nitride semiconductor device according to claim 4, wherein the nitride semiconductor layer is an optical guide layer. 11. The nitride semiconductor device according to claim 4, wherein the nitride semiconductor layer is a clad layer. 12. A method for manufacturing a nitride semiconductor device, comprising a first nitride semiconductor layer and a second nitride semiconductor layer, wherein the first nitride semiconductor layer is (Al, In, Ga). At least one of them, N, and P or As are further included, and the atomic fraction of P or As contained in the nitride semiconductor layer is 30% or less, and the second nitride semiconductor layer is 1 nitride semiconductor layer to P
And As in the semiconductor layer, and the growth rate of the first nitride semiconductor layer is slower than the growth rate of the second nitride semiconductor layer so that P or As of the first nitride semiconductor layer is at least A method for manufacturing a nitride semiconductor device, characterized by entering a group III site.