JP2003168711A - Method of measuring carrier concentration and method of manufacturing iii-v compound semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which the carrier concentration of a III-V compound semiconductor can be measured in a non-contacting and non- destructing state. <P>SOLUTION: The carrier concentration of a III-V compound semiconductor wafer on which an n-type buffer layer is formed is measured through C-V measurement and, in addition, the photoluminescence of the wafer is also measured. Then the luminous intensity ratio between the pale rose-color spectrum and yellow-green spectrum in obtained photoluminescence spectra is found. A calibration curve is prepared in advance between the carrier concentration obtained through the C-V measurement and the luminous intensity ratio (step i). Then the photoluminescence of the n-type buffer layer that becomes an object to be evaluated is measured and the luminous intensity ratio between the rose-color spectrum and yellow-green spectrum is found from the obtained photoluminescence, and then, the carrier concentration corresponding to the luminous intensity ratio is read from the calibration curve (step ii). After the carrier concentration of the n-type buffer layer is evaluated in the steps i and ii, a new epitaxial layer is grown by melting back the buffer layer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a carrier concentration, particularly a method for measuring a carrier concentration in a III-V group compound semiconductor, and further to a III-V group compound semiconductor wafer made of the III-V group compound semiconductor. It relates to a manufacturing method.

[0002]

2. Description of the Related Art III-V compound semiconductor wafers, for example, GaP epitaxial wafers having a GaP epitaxial layer formed on a GaP single crystal substrate are made into light emitting elements such as light emitting diodes and semiconductor lasers. It is used as a substrate. As the GaP epitaxial wafer W used as the substrate for the light emitting device,
As shown in FIG. 5, Si is formed on the n-type GaP single crystal substrate 10.
The n-type GaP buffer layer 11 containing, etc. as a donor is formed, and the n-type GaP layer 12, the nitrogen (N) -doped n-type GaP layer 13 and the p-type GaP layer 14 containing Zn etc. as an acceptor are further formed thereon. The thing laminated | stacked in this order can be illustrated.

The GaP epitaxial wafer W as described above can be manufactured by growing each layer by a so-called meltback method. That is, the n-type GaP buffer layer 11 containing Si as a dopant (donor) is liquid-phase epitaxially grown on the n-type single crystal substrate 10 to prepare a GaP wafer W ′ which is a raw material of the GaP epitaxial wafer W. Then, the n-type Ga
A Ga solution is brought into contact with the P buffer layer 11 and at least an upper portion thereof is melted back to obtain the n-type GaP.
Using a Ga solution in which the buffer layer 11 is dissolved as a raw material, an n-type GaP layer 12, an N-doped n-type GaP layer 13, and a p-type Ga
Liquid phase epitaxial growth of a new epitaxial layer such as the P layer 14 (meltback method).

On the other hand, when a substrate for a light emitting device is manufactured by adopting the meltback method as described above, the carrier concentration of the n-type GaP buffer layer 11 before the meltback process is a factor for manufacturing the light emitting device. It becomes an important characteristic. For example, the carrier concentration of the n-type GaP buffer layer to be melted back is set to the N-doped n-type GaP forming the light emitting region 15.
It not only affects the carrier concentration in the layer 13 and the p-type GaP layer 14, but also affects the light emission drive voltage of the light emitting element. Therefore, before performing the meltback step, the n
It is very important to measure the carrier concentration of the type GaP buffer layer 11 and confirm whether the desired carrier concentration is obtained or not in order to efficiently obtain a high-performance light emitting device.

[0005]

Conventionally, in order to measure the carrier concentration of the n-type GaP buffer layer 11, CV (Capa
citance-Voltage) measurement method is adopted. However, the C
The -V measurement method is destructive inspection. That is, since the wafer whose carrier concentration has been measured cannot be supplied to the subsequent process, the production yield is deteriorated. Moreover, since it is not possible to inspect all products, it is inevitable to perform a sampling inspection for measuring the carrier concentration only for a certain wafer. Furthermore, in the C-V measurement method, it is necessary to attach a measurement electrode to the inspected product by vacuum vapor deposition or the like, and this takes time, so that it takes time to measure the carrier concentration, and eventually, for a light emitting device. The substrate manufacturing process will also be delayed. The above-mentioned GaP epitaxial wafer W
However, the same problem arises when the carrier concentration of the III-V compound semiconductor layer is measured in the method of manufacturing a III-V compound semiconductor wafer.

The present invention has been made in view of the above problems, and in a method for measuring the carrier concentration of a III-V group compound semiconductor, it is possible to reduce the number of steps for preparing a sample and to measure the carrier concentration nondestructively. Providing a measurement method and further improving productivity and product yield
An object is to provide a method for manufacturing a III-V compound semiconductor wafer.

[0007]

In order to solve the above-mentioned problems, the carrier concentration measuring method of the present invention comprises:
In a photoluminescence spectrum emitted from a III-V group compound semiconductor containing a dopant, it is possible to measure a carrier concentration of the III-V group compound semiconductor based on an emission intensity ratio between a spectrum of pink and a spectrum of yellow green. Characterize.

Further, in the method for producing a III-V compound semiconductor wafer of the present invention, a growth solution for melting a dopant is brought into contact with a substrate to form a buffer layer of the III-V compound semiconductor in a liquid phase on the substrate. For the photoluminescence spectrum that is grown and emitted from the buffer layer,
After measuring the emission intensity ratio between the light red spectrum and the yellow green spectrum, melt back the buffer layer,
It is characterized in that a new epitaxial layer is liquid phase grown using this as a raw material.

The present inventor conducted photoluminescence measurement on a III-V group compound semiconductor, and in the obtained photoluminescence spectrum, the emission intensity ratio of the spectrum of pink and yellow green was the carrier of the III-V group compound semiconductor. We found that there was a correlation with the concentration. And
By utilizing the correlation, it was found that the carrier concentration can be determined by performing photoluminescence measurement without directly measuring the carrier concentration, and the present invention has been completed. In addition, in the present specification, light pink has a wavelength of 630.
~ 660nm light color means yellow-green 548-57
It refers to the color of light of 7 nm.

In the photoluminescence measurement, if only the measurement system is installed, the photoluminescence spectrum can be obtained only by making the excitation light incident on the product to be inspected.
Therefore, the carrier concentration can be measured nondestructively by using the correlation between the emission intensity ratio and the carrier concentration as described above. Further, since it is not necessary to perform special processing for measurement on the inspected product, it is possible to reduce the time required for measurement.

In the photoluminescence measurement, the absolute value of the emission intensity of the spectrum may vary depending on the measurement conditions and the like. Therefore, the emission intensity ratio of the light red and yellow green spectra is measured. According to this, even if the absolute values of the emission intensities of these two spectra vary depending on the measurement conditions or the like, the intensity ratio is likely to be constant regardless of the measurement conditions in the same semiconductor layer. Therefore, a more precise carrier concentration can be obtained.

Further, in the carrier concentration measuring method of the present invention, the carrier concentration obtained by CV measurement,
It is preferable to obtain a calibration curve with the emission intensity ratio in advance and measure the carrier concentration based on the calibration curve. Emission intensity ratio defined above (emission intensity ratio of light red and yellow-green spectra in photoluminescence spectrum)
And the carrier concentration have a correlation as described above, and these relations are acquired in advance as a calibration curve.
According to this, in the III-V group compound semiconductor to be evaluated, if the emission intensity ratio is obtained, the corresponding carrier concentration can be promptly obtained based on the calibration curve, so that the carrier concentration can be easily measured.

Furthermore, in the method for producing a III-V compound semiconductor wafer of the present invention, the III-V compound semiconductor wafer is not destroyed even if photoluminescence measurement is performed before meltback. The inspected wafers are finally commercialized. Therefore, the product yield is improved. Further, since the carrier concentration measurement in the past can be performed only by the destructive inspection, the sampling inspection is limited. However, according to the present invention, it is possible to inspect all the products, which also contributes to the reduction of the defective rate of the finally obtained III-V compound semiconductor wafer. Also,
Since it is not necessary to perform special processing on the inspected item,
The process time required for the entire manufacturing process of the III-V compound semiconductor wafer can be reduced.

The carrier concentration in the buffer layer is important for manufacturing the III-V group compound semiconductor wafer by melting back the buffer layer. According to the manufacturing method of the present invention, photoluminescence measurement is performed. You may only do it. That is, even if the carrier concentration is not determined from the calibration curve as in the above-described method for measuring the carrier concentration of the present invention, if a suitable range of the emission intensity ratio is known, the III-V group compound semiconductor is based on this. Wafer manufacturing control can be performed.

For example, in the method for producing a III-V compound semiconductor wafer according to the present invention, the amount of the dopant melted in the growth solution is determined based on the above emission intensity ratio obtained from the photoluminescence spectrum emitted from the buffer layer. It may be adjusted.

When a substrate for a light emitting device is manufactured by the meltback method, the same growth solution may be used in a plurality of batches for growing a buffer layer which is a raw material for a new epitaxial layer such as a light emitting region. . That is, the growth solution used to grow the buffer layer in one particular batch may also be used to grow the buffer layer in the next batch. In this case, the amount of dopant in the growth solution may vary from batch to batch. Therefore, by measuring the carrier concentration of the buffer layer before meltback, the concentration of the dopant in the growth solution is estimated, and the dopant is newly added to the growth solution to adjust the amount of the dopant in the growth solution. Is done. Therefore, when such a manufacturing method is adopted, photoluminescence measurement is performed before meltback, and the dopant concentration in the growth solution is estimated by utilizing the correlation between the obtained emission intensity ratio and the carrier concentration. C-V
Since the photoluminescence measurement takes less time than the measurement method, the photoluminescence measurement enables quick feedback to the subsequent steps.

The dopant contained in the III-V group compound semiconductor may be Si. Among dopants for III-V group compound semiconductors, Si may have both a donor function and an acceptor function. Therefore, even if a predetermined amount of Si is added to the semiconductor layer in order to obtain a desired carrier concentration, the proportion of the Si behaves as a donor (or an acceptor). Is not clear from. Therefore, the actual carrier concentration in the III-V compound semiconductor is difficult to specify from the amount of Si added as a dopant, and the measurement of the carrier concentration is particularly important. In the production of the group III-V compound semiconductor wafer by liquid phase growth, in addition to Si to be added to the initial as a dopant, sometimes the Si from stone Eiji ingredients like is mixed into the growth solution. Therefore, Si-doped III-V
It is important to measure the carrier concentration after producing a group compound semiconductor. Furthermore, adopting the above-mentioned meltback method II
In the case of the method for manufacturing the IV compound semiconductor wafer, Si is used.
When is used as a dopant, the carrier concentration in the buffer layer tends to be unstable. Therefore, it can be said that the effect of measuring the carrier concentration or the emission intensity ratio related to the carrier concentration before the meltback step is very large.

Further, the III-V compound semiconductor is GaP.
Can be As mentioned above, it is made of GaP
Since III-V compound semiconductor wafers are often formed by the meltback method, it is important to measure the carrier concentration before the meltback. Further, the dominant emission wavelength in the emission from the GaP light emitting element is in the red to green region, and if the photoluminescence spectrum emitted from GaP is measured, the emission intensity ratio of the spectrum of light pink and yellow green can be easily specified. can do. When GaP contains Si as a dopant, a shallow donor level based on Si and a shallow acceptor level are formed between the band gaps of GaP. And when measuring the photoluminescence spectrum,
A pink spectrum based on the transition between the levels is obtained, and the emission intensity ratio of the pink spectrum and the yellow green spectrum according to the present invention can be specified.

[0019]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
An embodiment of the present invention will be described. In this embodiment, the III-V compound semiconductor wafer is a GaP used as a substrate for a light emitting device as shown in FIG.
The epitaxial wafer W is manufactured by melt-backing the upper portion of the n-type GaP buffer layer 11 as a raw material and performing liquid phase epitaxial growth. A method of manufacturing the GaP epitaxial wafer W by the meltback method according to the present invention will be described with reference to FIG.

First, on the n-type GaP single crystal substrate 10, G
An aP polycrystal and a Ga solution 20a in which a donor such as Si is dissolved are arranged (A), and the temperature is lowered to form an n-type GaP.
Approximately 10 n-type GaP buffer layers 11 are formed on the single crystal substrate 10.
It is grown to about 0 μm (B) to obtain a GaP wafer W ′ (C). Then, with respect to the GaP wafer W ′, the n-type GaP buffer layer 11 was measured by photoluminescence measurement.
In, it is evaluated whether the desired carrier concentration is obtained. At this time, the carrier concentration may be actually measured by the method described below, or the emission intensity ratio between the light pink spectrum and the yellow green spectrum may be evaluated.

Then, on the thus obtained GaP wafer W '(C), the Ga melt 20b containing neither GaP polycrystal nor donor is arranged (D), and the GaP wafer W'is arranged. By raising the temperature in the system, the upper portion of the n-type GaP buffer layer 11 is exposed to the Ga melt 20b.
Melt back in (E). The n-type GaP buffer layer 11 is not completely melted and remains after the meltback process. At this time, the Ga melt 20b is an n-type GaP.
The GaP and the donor (S
i) becomes Ga solution 20c which melts. Then, the temperature in the system is lowered to a desired temperature to grow the n-type GaP layer 12 on the n-type GaP buffer layer 11 (F), and then an ammonia (NH ₃ ) gas is used as a carrier gas (for example, H 2 ₂ )
At the same time, while flowing into the system, the temperature is further lowered to grow the nitrogen (N) -doped n-type GaP layer 13 (G). Finally, by stopping the inflow of ammonia gas and raising the temperature in the system, by lowering the growth temperature while flowing into the system together with the carrier gas in the state where the acceptor, for example, zinc (Zn) is evaporated, p-type G
The aP layer 14 is grown (H). And Ga solution 20
When taken out from c, the GaP epitaxial wafer W shown in FIG. 5 is obtained.

According to the above-described meltback method, the n-type GaP buffer layer 11 is once formed, and a new epitaxial layer is formed by using at least the upper portion of the n-type GaP buffer layer 11 as a raw material. . It is known that by epitaxially growing a buffer layer on a substrate, the density of dislocations generated in the substrate is reduced in the epitaxial layer. Then, by using this buffer layer as a raw material, a new epitaxial layer with less dislocations can be formed thereon. Therefore, the meltback method is generally often used for manufacturing a substrate for a light emitting element of a light emitting element that requires high brightness.

For example, according to the meltback method, p-type G
When forming the aP layer 14, the n-type GaP buffer layer 11 is formed.
The acceptor must be contained in such a manner as to compensate for the carriers in the p-type GaP layer 1 when the carrier concentration is high.
It becomes difficult to make the carrier concentration of 4 desired.
On the contrary, if the carrier concentration of the n-type GaP buffer layer 11 to be melted back is low, the carrier concentration of the n-type GaP buffer layer 11 remaining after the melt-back also becomes low.
In the manufactured light emitting element, the light emission drive voltage increases. In addition, the brightness of the light emitting device depends on the carrier concentration in the N-doped n-type GaP layer 13, which is greatly influenced by the carrier concentration of the melted-back n-type GaP buffer layer 11. As described above, the carrier concentration of the n-type buffer layer 11 that is melted back greatly affects the characteristics of the light emitting device.

The method for measuring the carrier concentration according to the present invention will be described in detail below. FIG. 1 shows an example of steps of the carrier concentration measuring method of the present invention. In this embodiment, the carrier concentration measuring method can be divided into two steps (i) and (ii) as shown in FIG. In the step (i), the carrier concentration is measured by CV measurement in the same III-V group compound semiconductor (specifically, the n-type buffer layer 11 of the GaP wafer W ′ before the meltback step). , A calibration curve is previously prepared between the carrier concentration and the emission intensity ratio by obtaining the emission intensity ratio between the pink spectrum and the yellow green spectrum in the photoluminescence spectrum obtained by performing photoluminescence measurement. Is.
On the other hand, in the step (ii), the III-V group compound semiconductor (n-type buffer layer 11 of the GaP wafer W ′) to be evaluated is
In contrast, performing photoluminescence measurement, and the above emission intensity ratio obtained from the photoluminescence spectrum,
The carrier concentration corresponding to the above emission intensity ratio is read from the calibration curve in comparison with the calibration curve.

In the step (i), a known method can be adopted for the CV measurement. Specifically, a metal electrode is formed on the main surface of the GaP wafer W'and a Schottky junction is formed with the main surface. Then, a voltmeter and a capacitance measuring device were connected to the metal electrode, and the electric capacitance was measured while increasing the voltage while applying a reverse voltage to the Schottky junction, and the CV characteristic in this GaP wafer was measured. To get The carrier concentration in the n-type GaP buffer layer can be obtained from the C-V characteristic. The method for obtaining the carrier concentration is well known and will not be described in detail.

Subsequently, photoluminescence measurement is performed on the same GaP wafer W '. The photoluminescence measurement can be performed by an apparatus as shown in FIG. The n-type GaP buffer layer 11 is irradiated with, for example, Ar laser as excitation light from a laser light source, the generated emission spectrum is condensed by a converging lens, and then the emission intensity at each wavelength is measured by a spectroscope, Obtain the luminescence spectrum. FIG. 3 shows an example of the obtained photoluminescence spectrum.
Spectrum of yellow-green color which appears in the vicinity of the emission wavelength 558nm is believed to be due to interband transitions based on the band gap of GaP constituting the n-type GaP buffer layer 11. Pink of space <br/> spectrum appearing in the vicinity of the emission wavelength 644nm are believed to n-type GaP buffer layer 11 is due to Si being contained as a donor.
Specifically, it is considered to be based on the transition between the shallow donor level and the shallow acceptor level. Therefore, in the present embodiment, in the photoluminescence spectrum obtained by entering the excitation light with the excitation wavelength of 514.5 nm, the emission intensity of the reddish spectrum at the position of the emission wavelength of 644 nm (hereinafter, also referred to as the R component). And the intensity ratio (hereinafter, also referred to as G component) of the yellow-green spectrum at the position where the emission wavelength is 558 nm (hereinafter, R /
(Also referred to as G ratio) is the emission intensity ratio in the present invention.
This makes it easy to quantify the emission intensity, and
The fluctuation of the measurement information due to the measurement conditions and the like is suppressed, and the calibration curve described later is easily determined.

As the excitation light incident on the III-V compound semiconductor in order to obtain the photoluminescence spectrum, one having at least energy larger than the band gap energy of the III-V compound semiconductor should be used. Is good. In the case of this embodiment, III
Si is doped as a dopant in the -V compound semiconductor, and a shallow donor level and a shallow acceptor level due to Si are formed in the band gap of the semiconductor. The shallow donor level is formed at a level slightly lower than the lowest end of the conduction band of the III-V compound semiconductor, and the shallow acceptor level is higher than the uppermost end of the valence band of the III-V compound semiconductor. Since it is formed at a slightly higher level, the energy difference between the donor level and the acceptor level is smaller than the band gap energy of the semiconductor. Therefore, when excitation light having an energy larger than the bandgap energy of the semiconductor layer is incident, a spectrum due to the bandgap of the semiconductor is also generated (for example, in the case of GaP, yellow green), and a dopant (S
A spectrum resulting from the transition from the donor level to the acceptor level related to i) is also generated (light red in the case of GaP), so that the emission intensity ratio according to the present invention can be obtained by photoluminescence measurement.

As described above, for one wafer, n
After obtaining the carrier concentration and R / G ratio of the type epitaxial layer, the same process is performed for a plurality of wafers having different carrier concentrations to create a calibration curve. Specifically, as shown in FIG. 4, the relationship between the R / G ratio and the carrier concentration is plotted on the graph, and a calibration curve is prepared from the scattered state.

After preparing the calibration curve as described above, FIG.
In the step (ii), Ru determine the carrier concentration of the n-type buffer layer 11 in the actual evaluation subject to GaP wafer W '. That is, the photoluminescence measurement is performed on the n-type buffer layer 11 of the GaP wafer W ′ having the n-type buffer layer 11 with an unknown carrier concentration as the uppermost layer by using the same device as in FIG. Then, based on the obtained photoluminescence spectrum (see FIG. 3), R
If the ratio of the R and G components (R / G ratio) is obtained and the carrier concentration corresponding to the R / G ratio is read from the calibration curve (see FIG. 4) created in the step (i), the carrier concentration of the evaluation target a can therefore be found by the non-destructive.

As described above, the step (i) includes a step of CV measurement for measuring the carrier concentration in the step (i), and a metal electrode is formed on the III-V group compound semiconductor wafer. Or, the III-V compound semiconductor wafer may be destroyed, but once the above calibration curve is obtained, it is not necessary to perform such a step thereafter. Then, if they have the calibration curve can be determined to continue step by performing only, without performing destructive inspection, such as C-V measurements, the carrier concentration of (ii). Furthermore, in creating the calibration curve, a more precise calibration curve can be determined by investigating the relationship between the carrier concentration and the R / G ratio for a larger number of wafers. The carrier concentration converted from the / G ratio is also more accurate.

In the method for producing a III-V group compound semiconductor wafer, a desired R / G ratio is not obtained III-V
The group compound semiconductor wafer (GaP wafer W ′) is not supplied to the next step (meltback step).
FIG. 7 shows the relationship between the carrier concentration of the buffer layer and the brightness of the manufactured light emitting device when the GaP epitaxial wafer W is used as the substrate for the GaP light emitting device. In order to obtain a light emitting device having good brightness, the carrier concentration of the buffer layer is set to 4 × 10 ¹⁷ / cm ^3.
It will be understood that the ratio is more preferably 2 × 10 ¹⁷ / cm ³ or less. Also, from the viewpoint of light emission drive voltage,
The carrier concentration of the buffer layer 2 × ^{10 1} 6 / cm ³ or more, and more preferably to a 6 × ¹⁰ 16 / cm ³ or more. It can be seen from FIG. 4 that the R / G ratio range corresponding to the above carrier concentration range is 0.01 or more and 0.055 or less, and more preferably 0.021 or more and 0.035 or less. Therefore, the R / G ratio of the buffer layer is managed so as to be kept within this range. When the R / G ratio of the buffer layer obtained in the step (ii) is out of the above range, the III-V compound semiconductor wafer to be evaluated is regarded as a nonstandard product and supplied to the subsequent steps. To stop.

Further, based on the R / G ratio obtained by the photoluminescence measurement, Ga used in the subsequent manufacturing
The amount of dopant (Si) added to the solution 20a can also be adjusted. That is, it is considered that when the obtained R / G ratio is low, the carrier concentration in the n-type GaP buffer layer 11 is low and the dopant concentration in the Ga solution 20a is low. Therefore, a predetermined amount of Si is added to the Ga solution 20a. The amount of Si to be added is appropriately selected based on the obtained R / G ratio value.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating a method of the present invention.

FIG. 2 is a schematic diagram illustrating an outline of a photoluminescence spectrum measuring apparatus.

FIG. 3 is a diagram showing an example of a photoluminescence spectrum.

FIG. 4 is a diagram showing an example of a calibration curve.

FIG. 5 is a conceptual diagram showing an example of a III-V group compound semiconductor wafer according to the present invention.

6 is a conceptual diagram illustrating a method for manufacturing the III-V compound semiconductor wafer of FIG.

FIG. 7 is a diagram showing a relationship between carrier concentration of a buffer layer and light emission luminance of a manufactured light emitting element.

[Explanation of symbols]

W GaP epitaxial wafer (III-V group compound semiconductor wafer) W'GaP wafer 11 n-type GaP buffer layer (buffer layer) 15 Light emitting region

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2G043 AA01 BA07 CA05 EA01 FA06                       GA25 GB21 GB28 HA01 HA02                       HA12 JA01 JA03 KA02 KA05                       KA09 NA01 NA11                 4M106 AA01 BA04 CA12 CA70 CB01                 5F041 AA04 CA37 CA53 CA55 CA57                 5F053 AA01 DD07 FF02 GG01 HH04                       JJ01 JJ03 KK04 KK10 LL02                       RR03

Claims (9)

[Claims] 1. In a photoluminescence spectrum emitted from a III-V group compound semiconductor containing a dopant, the carrier concentration of the III-V group compound semiconductor is based on the emission intensity ratio of a pink spectrum and a yellow-green spectrum. A method for measuring carrier concentration, which comprises: 2. The carrier concentration measuring method according to claim 1, wherein the dopant is Si. 3. The carrier concentration measuring method according to claim 1, wherein the III-V compound semiconductor is GaP. 4. A calibration curve showing the relationship between the carrier concentration obtained by CV measurement and the emission intensity ratio is obtained in advance, and the carrier concentration is measured based on the calibration curve. Item 4. The method for measuring carrier concentration according to any one of Items 1 to 3. 5. The carrier concentration and the emission intensity ratio of the same III-V group compound semiconductor are determined by measuring the carrier concentration by CV measurement and performing photoluminescence measurement to obtain the emission intensity ratio. A calibration curve is prepared in advance, and photoluminescence measurement is performed on the III-V group compound semiconductor to be evaluated, and the emission intensity ratio obtained from the photoluminescence spectrum is compared with the calibration curve. The carrier concentration measuring method according to any one of claims 1 to 4, wherein the carrier concentration corresponding to the emission intensity ratio is read from the calibration curve. 6. A growth solution for melting a dopant is brought into contact with a substrate to cause a buffer layer of a III-V compound semiconductor to undergo liquid phase growth on the substrate, and a photoluminescence spectrum emitted from the buffer layer After measuring the emission intensity ratio between the red spectrum and the yellow green spectrum, the buffer layer is melted back, and a new epitaxial layer is subjected to liquid phase growth using this as a raw material, thereby forming a III-V group compound semiconductor. Wafer manufacturing method. 7. The III-V according to claim 6, wherein the amount of the dopant melted in the growth solution is adjusted based on the emission intensity ratio obtained from the photoluminescence spectrum emitted from the buffer layer. Method for manufacturing group compound semiconductor wafer. 8. The method for producing a III-V group compound semiconductor wafer according to claim 6, wherein the dopant is Si. 9. The method for producing a III-V compound semiconductor wafer according to claim 6, wherein the III-V compound semiconductor is GaP.