JP4168115B2 - Method for producing Si-doped GaAs single crystal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a Si-doped GaAs single crystal used as a material for a light emitting / receiving element or the like.
[0002]
[Prior art]
An n-type conductive GaAs (gallium arsenide) single crystal used as a material for a light emitting / receiving element, a high-speed arithmetic element, a microwave element or the like generally uses Si (silicon) as a dopant to reduce the dislocation density in the crystal. It is manufactured using the horizontal boat method and the vertical boat method. In particular, the vertical boat method has the advantage that not only crystal growth of (100) orientation can be grown, but also a circular and large-diameter crystal can be obtained. The vertical temperature gradient method (VGF method) and the vertical bridge Crystal growth is performed by the Mann method (VB method).
[0003]
[Problems to be solved by the invention]
By the way, as the V group element As, which is one of the raw materials of the GaAs single crystal, is a volatile component, B ₂ O ₃ (oxidation) is used as a liquid sealant for the purpose of preventing dissociation and decomposition from the crystal. Boron) is used. However, when B ₂ O ₃ is used as the liquid sealant, Si as a dopant reacts with B ₂ O ₃ to form silicon oxide (SiO ₂ or SiO), making it difficult to control the Si concentration in the crystal. . For this reason, it is difficult to always stably produce a Si-doped GaAs single crystal having a desired preferable carrier concentration distribution. In order to eliminate this defect, the present inventors proposed a method of growing a Si-doped GaAs single crystal having a desired carrier concentration distribution with good reproducibility using B ₂ O ₃ previously doped with Si oxide ( (See Japanese Patent Publication No. 3-57079).
[0004]
However, even in the invention according to the above proposal, it is difficult to manufacture a crystal having a predetermined carrier concentration distribution in a predetermined range with a high yield. The present inventors, using two or more kinds of B ₂ O ₃ of B ₂ O ₃ not doped with B ₂ O ₃ and Si oxides doped with previously Si oxide to improve the yield, these A method of controlling the carrier concentration distribution by stirring at an appropriate time has been proposed (see Japanese Patent Application No. 9-96799). FIG. 7 shows the solidification rate of the Si-doped GaAs single crystal manufactured by the conventional manufacturing method according to this proposal as g, the logarithmic value of (1-g) is taken on the horizontal axis, and the logarithm of the carrier concentration in the single crystal is taken on the vertical axis It is the figure which was taken. As shown in FIG. 7, the curve indicating the relationship between the carrier concentration and the solidification rate changes with a minimum value or maximum value, and the carrier concentration distribution changes with a minimum value or maximum value in the crystal growth direction. is doing. Such a distribution is extremely undesirable as a crystal.
[0005]
The present invention has been made under the above-mentioned background, and an object thereof is to provide a method for producing a Si-doped GaAs single crystal having a good carrier concentration distribution.
[0006]
[Means for Solving the Problems]
As means for solving the above problems, the first invention provides:
A Si-doped GaAs single crystal produced by a vertical boat method using a liquid sealant,
The position in the single crystal is represented by the solidification rate g of the crystal in the crystal growth process, the logarithmic value of (1-g) is taken on the horizontal axis, and the logarithmic value of the carrier concentration in the single crystal at the position specified by each solidification rate. The curve represented by the graph with the vertical axis representing 1 in the range of the solidification rate g of 0.1 to 0.8 has a negative slope and the absolute value of the slope is greater than 0.6. Or a curve that can be regarded as two or more straight lines or straight lines and a curve that can be regarded as one or two or more straight lines or straight lines having an absolute slope value of 0.6 or less. Si-doped GaAs single crystal. However, the gradient here is the value of a when y = ax + b represents a straight line or a curve that can be regarded as a straight line in the orthogonal coordinates with the horizontal axis in the graph as the x-axis and the vertical axis as the y-axis. And
[0007]
The second invention is
In the Si-doped GaAs single crystal according to the first invention,
The curve may be regarded as a first straight line or a straight line having a solidification rate g of 0.1 to 0.4 and a second straight line having a solidification rate g of 0.4 to 0.8. Alternatively, a straight line and a curve that can be regarded as being connected, and the first and second straight lines or the straight line and the curve that can be regarded as both have a negative slope, and the first straight line or the straight line Si-doped GaAs, characterized in that the absolute value of the slope of the curve that can be regarded is larger than 0.6 and the absolute value of the slope of the curve that can be regarded as the second straight line or the straight line is 0.6 or less. Single crystal.
[0008]
The third invention is
In the Si-doped GaAs single crystal according to the first invention,
The curve may be regarded as a first straight line or a straight line having a solidification rate g of 0.1 to 0.6, and a second straight line having a solidification rate g of 0.6 to 0.8. Alternatively, a straight line and a curve that can be regarded as being connected, and the first and second straight lines or the straight line and the curve that can be regarded as both have a negative slope, and the first straight line or the straight line Si-doped GaAs, characterized in that the absolute value of the slope of the curve that can be regarded is larger than 0.6 and the absolute value of the slope of the curve that can be regarded as the second straight line or the straight line is 0.6 or less. Single crystal.
[0009]
The fourth invention is:
In the Si-doped GaAs single crystal according to the first invention,
The curve may be regarded as a first straight line or a straight line having a solidification rate g of 0.1 to 0.4 and a second straight line having a solidification rate g of 0.4 to 0.75. Alternatively, a curve that can be regarded as a straight line and a third straight line or a straight line that has a solidification rate g in the range of 0.75 to 0.8 are connected to each other and a curve that can be regarded as a straight line. 3 straight lines or curves that can be regarded as straight lines have a negative slope, and the absolute values of the slopes of the first and third straight lines or straight lines that can be regarded as straight lines are larger than 0.6, The Si-doped GaAs single crystal is characterized in that the absolute value of the slope of a straight line of 2 or a curve that can be regarded as a straight line is 0.6 or less.
[0010]
The fifth invention is:
A method for producing a Si-doped GaAs single crystal by a vertical boat method using a liquid sealant, wherein a seed crystal, a GaAs raw material, a Si raw material for dopant, and a Si oxide are pre-doped in a crucible In a method for producing a Si-doped GaAs single crystal having a predetermined crystal growth step, after storing a raw material for use and melting the raw material so that a liquid sealant is disposed on the GaAs raw material layer,
A reaction involving the movement of Si is performed between the liquid sealant layer and the GaAs raw material melt layer, and this reaction is performed when the concentration of Si contained in the liquid sealant layer is the liquid sealant. In the crystal growth process, using the phenomenon that has a property of being balanced in a state where it is high in the lower part near the interface between the layer and the GaAs raw material melt layer and becomes rapidly lower as it goes away from this interface and goes to the upper part, The amount of Si taken into the liquid sealant is controlled by forcibly changing the Si concentration distribution of the liquid sealant layer, thereby controlling the Si concentration in the GaAs raw material melt layer. Thus, a Si-doped GaAs single crystal having a good carrier concentration distribution is obtained.
[0011]
The sixth invention is:
In the method for producing a Si-doped GaAs single crystal according to the fifth invention,
The operation for forcibly changing the Si concentration distribution of the liquid sealant layer is to stir the liquid sealant layer at an appropriate time after the start of the crystal growth process. This is a method for producing a single crystal.
[0012]
The seventh invention
In the method for producing a Si-doped GaAs single crystal according to the sixth invention,
The proper time is a method for producing a Si-doped GaAs single crystal, wherein the solidification rate g of the GaAs raw material is in the range of 0.3 to 0.5.
[0013]
The eighth invention
In the method for producing a Si-doped GaAs single crystal according to the sixth invention,
The proper time is a method for producing a Si-doped GaAs single crystal, wherein the solidification rate g of the GaAs raw material is in the range of 0.5 to 0.6.
[0014]
The ninth invention
In the method for producing a Si-doped GaAs single crystal according to the sixth invention,
The liquid sealant agitation step includes two times, a time when the solidification rate g of the GaAs raw material is in the range of 0.3 to 0.5 and a time when the solidification rate g is in the range of 0.5 to 0.7. This is a method for producing a Si-doped GaAs single crystal, which is performed at each of the two times.
[0015]
The tenth invention is
In the method for producing a Si-doped GaAs single crystal according to any of the sixth to ninth inventions,
The liquid sealing agent is a method for producing a Si-doped GaAs single crystal, which contains B ₂ O ₃ as a main component.
[0016]
The eleventh invention is
In an apparatus for producing a Si-doped GaAs single crystal by a vertical boat method using a liquid sealant,
A crucible containing a seed crystal, GaAs raw material, Si raw material for dopant and raw material for liquid sealant;
Heating means for melting these raw materials so that a liquid sealant layer is disposed on the GaAs raw material melt layer;
Stirring means for stirring the liquid sealant layer;
An apparatus for producing a Si-doped GaAs single crystal, comprising control means for controlling the timing of stirring and the degree of stirring by the stirring means.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 is a graph showing the carrier concentration distribution of the Si-doped GaAs single crystal according to the first embodiment of the present invention, and FIGS. 2 to 4 show the production of the single crystal used in the method for producing the Si-doped GaAs single crystal according to the present invention. It is explanatory drawing of an apparatus. Hereinafter, a Si-doped GaAs single crystal and a manufacturing method thereof according to Embodiment 1 of the present invention will be described with reference to these drawings.
[0018]
The Si-doped GaAs single crystal according to this embodiment is manufactured by the vertical temperature gradient method in the vertical boat method. FIG. 2 is a cross-sectional view showing a schematic configuration of a single crystal manufacturing apparatus that performs the vertical temperature gradient method. In FIG. 2, reference numeral 4 denotes a crucible, and the raw material is accommodated in the crucible 4 and crystal growth is performed. The crucible 4 is substantially cylindrical and has an upper side opened and a lower side formed with a tapered cross section so that the diameter gradually decreases. The seed crystal 5 is accommodated in a small diameter portion at the lowermost end. It is like that.
[0019]
The crucible 4 is accommodated in a cylindrical crucible storage container 3 having a bottom, and the crucible storage container 3 is supported by the lower rod 1. The lower rod 1 can be moved up and down and rotated by a drive mechanism (not shown) so that the crucible storage container 3 and the crucible 4 stored in the crucible storage container 3 can be driven up and down and rotated. .
[0020]
The crucible storage container 3 is installed in a cylindrical heater 17. The heater 17 is composed of a plurality of heaters that can set the temperature independently, and can form a desired temperature gradient and temperature distribution in the crucible storage container 3. A cylindrical heat insulating material 16 is disposed outside the heater 17, and these are housed in an airtight container 11.
[0021]
A through hole that allows the lower rod 1 to pass therethrough is formed in the lower portion of the hermetic container 11, and a seal ring 11 a is fitted into the through hole, and the lower rod 1 can move up and down and rotate while maintaining the hermetic container 11 hermetic. It can be done. Further, a through hole is formed through the upper rod 12 in the upper portion, and a seal ring 11b is fitted into the through hole so that the upper rod 12 can move up and down and rotate while maintaining the hermetic container 11 airtight. It has become.
[0022]
The upper rod 12 can be moved up and down and rotated by a drive mechanism (not shown), and a stirring plate 10 is attached to the tip of the upper rod 12. The stirring plate 10 is a substantially rectangular plate body attached to a mounting portion at the tip of the upper rod 12 substantially vertically. The plate body of the stirring plate 10 has a horizontal width that is 1/2 or more of the inner diameter of the crucible 4 and a vertical width that is 1/2 or more of the thickness of the liquid sealant layer described later. Two or more plates may be provided. Furthermore, the stirring plate 10 may be of any shape in principle as long as it can stir the melt. Of course, the crucible 4 and the stirring plate 10 are made of a material having necessary heat resistance and hardly reacting with the raw material melt, such as carbon (C) or pBN.
[0023]
The Si-doped GaAs single crystal is manufactured by the above-described single crystal manufacturing apparatus as follows. First, as shown in FIG. 4, the crucible 4 is filled with a seed crystal 5, a GaAs raw material 13, a Si raw material 14 as a dopant, and a B ₂ O ₃ raw material as a liquid sealant raw material.
[0024]
Here, the amount of the raw material filled in the crucible 4 is as follows.
* GaAs raw material 13 ... 4000g
* Si raw material 14 as dopant: 0.02 to 0.03% by weight based on GaAs raw material
* As a liquid sealant material B ₂ O ₃ raw material (B ₂ O ₃ was added Si oxide to be 3% by weight Si equivalent concentration) ... 240 g
[0025]
Next, the crucible 4 filled with these raw materials is set in the apparatus, and the raw materials are dissolved in accordance with the vertical temperature gradient method, and solidification is started. Solidification is performed from a portion in contact with the seed crystal 5 at the lower part of the crucible 4 where the temperature of the heater 17 is lowered, and gradually progresses upward. This solidification is also a process in which crystals grow from the seed crystal 5. The ratio of the weight of the solidified part to the weight of the entire GaAs raw material is called solidification rate g. The solidification rate g increases from 0 to 1 as the solidification progresses and the crystal grows. Therefore, the solidification rate g being a specific value means that the interface between the solidified portion and the melt portion is in a specific position corresponding to the value of g on a one-to-one basis. . The position specified by this is naturally the same even after the whole is solidified and the crystal is completed. Therefore, the position of the completed single crystal in the crystal growth direction can be specified by the solidification rate g.
[0026]
In FIG. 2, the portion indicated by reference numeral 6 in the crucible 4 is a portion where GaAs is solidified, and the portion indicated by reference numeral 7 is a melt portion. The position of the interface between the solidified part 6 and the melt part 7 is a position represented by the solidification rate g at this time. A melted B ₂ O ₃ layer 8 as a liquid sealant is formed on the upper surface of the melt 7. In this embodiment, in the process of crystal growth, when the solidification rate g is 0.4, the upper rod 12 is moved downward as shown in FIG. _It is immersed in the ₂ O ₃ layer 8, the upper rod 12 is driven to rotate and the stirring plate 8 is rotated to stir the B ₂ O ₃ layer 8. This stirring is performed for 20 hours with the rotation speed of the stirring plate 8 set to 1 rpm.
[0027]
When the carrier concentration distribution at each position of the Si-doped GaAs single crystal thus obtained was measured by the Van der Pauw method, results as shown in the graph of FIG. 1 were obtained. In the graph of FIG. 1, the horizontal axis represents the position of the single crystal in terms of the solidification rate g of the crystal during the crystal growth process, and the logarithmic value of (1-g) is taken, and the vertical axis is specified by each solidification rate. This is a logarithmic value of the carrier concentration in the single crystal at the position to be measured. As shown in the graph of FIG. 1, the curve indicating the carrier concentration distribution is such that two straight lines having a negative gradient are connected at a solidification rate g of 0.4, and a smooth increasing tendency is obtained. Is shown. Moreover, the slope of the straight line when the solidification rate g is 0.1 to 0.4 is about -0.85, and the slope of the straight line when the solidification rate g is 0.4 to 0.8 is about -0.3. there were. This result can be said to have a sufficiently good carrier concentration distribution that has not been obtained in the past. Here, the gradient is the value of a when the straight line is expressed as y = ax + b in the orthogonal coordinates in which the horizontal axis in the graph is the x-axis and the vertical axis is the y-axis. This gradient has a certain correspondence with the segregation coefficient of Si in GaAs.
[0028]
Obtaining such a good carrier concentration distribution is based on the discovery of a new fact that the present invention has not previously recognized. Hereinafter, this point will be described. In general, the carrier concentration distribution corresponds to the Si concentration distribution as a dopant. Further, for GaAs, the Si concentration, which is also an impurity, increases as the solidification rate g increases and does not become uniform. Accordingly, various attempts have been made to control the Si concentration distribution by utilizing the fact that the liquid sealant takes in Si. That is, the following reaction is performed between the B ₂ O ₃ melt layer, which is a liquid sealant in contact with the raw material melt, and the GaAs melt layer containing Si until the next reaction is in an equilibrium state.
3Si (in GaAs Melt) + 2B ₂ O ₃ = 3SiO ₂ (to B ₂ O ₃ )
+ 4B (To GaAs Melt)
[0029]
Therefore, by the B ₂ O ₃ layer into two layers, the lower layer of SiO ₂ in advance appropriate amounts in addition to the B ₂ O ₃ layer (GaAs layer side), left without added SiO ₂ in the upper layer. While the solidification rate g is small (the Si concentration is also small), Si taken in from the GaAs layer is decreased so that the lower layer in this state is in the equilibrium state. When the solidification rate g reaches a predetermined value (the Si concentration of the GaAs layer also increases), the upper layer and the lower layer are mixed to reduce the lower SiO ₂ concentration, and the Si incorporated into the B ₂ O ₃ layer from the GaAs layer To increase. This is intended to make the Si concentration distribution uniform (for details, see Japanese Patent Application No. 9-96799).
[0030]
However, although it has been found that the Si concentration distribution can be made uniform to some extent by the above method, even if the amount of SiO ₂ added to the two layers of B ₂ O ₃ is variously changed, the theoretically assumed uniformity can be obtained. I couldn't. In particular, when an amount that should improve the uniformity is added based on trial and error results, the Si concentration distribution may show a discontinuous distribution as shown in FIG. I understood it.
[0031]
The present invention is based on new facts discovered in the process of investigating this cause. That is, conventionally, it has been premised on common sense knowledge that the Si concentration in the melt is substantially uniform. In order to investigate the cause, the present inventors examined the Si concentration in the B ₂ O ₃ layer, which is a liquid sealant, and found that the B ₂ O ₃ layer had a lower portion near the interface with the GaAs melt layer. It was found that the Si concentration was high, and the Si concentration decreased rapidly as it moved away from the interface and moved upward.
[0032]
As a result of this fact, the reason why the conventional method of forming a liquid sealant in two layers does not necessarily achieve the effect as theoretically assumed, and at the same time, the present invention can be made. It is a thing.
[0033]
(Embodiment 2)
Since this embodiment is the same as Example 1 except that the timing of stirring is performed from the time point when the solidification rate g is about 0.55, detailed description thereof is omitted.
[0034]
FIG. 5 is a graph showing the carrier concentration distribution at each position of the obtained Si-doped GaAs single crystal. The horizontal axis and vertical axis of the graph in FIG. 5 are the same as those in the first embodiment. As shown in the graph of FIG. 5, the curve indicating the carrier concentration distribution includes a first straight line having a solidification rate g of 0.1 to 0.55 and a solidification rate g of 0.55 to 0.8. Two straight lines having a negative gradient together with the second straight line in the range are connected to each other, indicating a smooth increasing tendency. Moreover, the slope of the straight line when the solidification rate g is 0.1 to 0.55 is about -0.85, and the slope of the straight line when the solidification rate g is 0.55 to 0.8 is about -0.3. there were. This result can be said to have a sufficiently good carrier concentration distribution that has not been obtained in the past.
[0037]
(Comparative example)
In this comparative example, a B ₂ O ₃ layer (50 g) to which no Si oxide is added is arranged on the B ₂ O ₃ layer 8 in the first embodiment, so that two liquid sealant layers are provided. Other than that, the crystal growth was performed under the same conditions as in the first embodiment, including the stirring conditions. The carrier concentration distribution at each position of the obtained Si-doped GaAs single crystal was as shown in the graph of FIG. As shown in FIG. 7, the curve indicating the relationship between the carrier concentration and the solidification rate is discontinuous, and the carrier concentration distribution changes discontinuously in the crystal growth direction. Such a distribution is extremely undesirable as a crystal.
[0038]
In each of the embodiments described above, the case where the timing and conditions of stirring are specific is shown. However, the present invention is not limited to this, and in the crystal growth process, the liquid sealant layer and the GaAs raw material melt A reaction involving the movement of Si is carried out between the layer and the reaction, and the concentration of Si contained in the liquid sealant layer is lower in the vicinity of the interface between the liquid sealant layer and the GaAs raw material melt layer. In the crystal growth process, the Si concentration distribution in the liquid sealant layer is forcibly changed by utilizing the phenomenon of having an equilibrium property in a state of being high and low and abruptly lowering as it goes away from this interface and moves upward. The amount of Si taken into the liquid sealant is controlled by performing the operation, thereby controlling the Si concentration in the GaAs raw material melt layer to obtain a Si-doped GaAs single crystal having a good carrier concentration distribution. Including the case of That.
[0039]
That is, for example, the timing of stirring may be other than the timing shown in the above embodiment as long as the carrier concentration distribution of GaAs is within a predetermined range. The stirring conditions may be other than the conditions shown in the above embodiment as long as the carrier concentration distribution of GaAs is within a predetermined range. Accordingly, in some cases, as long as the stirring conditions satisfying the above conditions can be selected, stirring may be performed continuously to constantly change the Si concentration distribution of the liquid sealant.
[0040]
Further, the stirring may be performed by rotating the lower rod 1 while the stirring plate 10 is immersed and fixed in the liquid sealant. Of course, both the stirring plate 10 and the lower rod 1 may be rotated. Further, the Si concentration distribution of the liquid sealing agent layer may be forcibly changed by stirring the GaAs by immersing the stirring plate 10 in the GaAs melt without stirring the liquid sealing agent. .
[0041]
The present invention also relates to a Si-doped GaAs single crystal produced by a vertical boat method using a liquid sealant, wherein the position in the single crystal is represented by the crystal solidification rate g in the crystal growth process ( A curve represented by a graph in which the logarithmic value of 1-g) is taken on the horizontal axis and the logarithmic value of the carrier concentration in the single crystal at the position specified by each solidification rate is taken on the vertical axis is a solidification rate g of 0. In the range of 1 to 0.8, the gradient has a negative value, and the absolute value of the gradient is 0 or more, and the absolute value of the gradient is 0. It includes all Si-doped GaAs single crystals characterized in that one or two or more straight lines or straight lines of .6 or less are connected to an assumed curve.
[0042]
In the embodiment, an example in which two and three straight lines are connected has been described. However, the number of the straight lines may be four or more, and may be innumerable in principle.
[0043]
Moreover, although the case where the vertical temperature gradient method is used is shown in the embodiment, this may be a vertical Bridgman method.
[0044]
【The invention's effect】
As described above, the Si-doped GaAs single crystal according to the present invention is a Si-doped GaAs single crystal produced by a vertical boat method using a Si-doped GaAs single crystal liquid sealant, Is represented by the solidification rate g of the crystal in the crystal growth process, the logarithm of (1-g) is taken on the horizontal axis, and the logarithm of the carrier concentration in the single crystal at the position specified by each solidification rate is taken on the vertical axis. The curve represented by the graph shows that when the solidification rate g is in the range of 0.1 to 0.8, the gradient has a negative value, and the absolute value of the gradient is 1 or 2 or greater than 0.6. A straight line or a curve that can be regarded as a straight line and one or two or more straight lines or straight lines that have an absolute value of gradient of 0.6 or less and a curved line that can be regarded as a straight line are connected. . Further, in the method for producing a Si-doped GaAs single crystal according to the present invention, in the crystal growth process, a reaction involving the movement of Si is performed between the liquid sealant layer and the GaAs raw material melt layer. In a state where the concentration of Si contained in the liquid sealant layer is high in the lower part near the interface between the liquid sealant layer and the GaAs raw material melt layer, and rapidly decreases as the distance from the interface increases to the upper part. Controlling the amount of Si taken into the liquid sealant by performing an operation of forcibly changing the Si concentration distribution of the liquid sealant layer in the crystal growth process, utilizing a phenomenon having an equilibrium property, Thus, a Si-doped GaAs single crystal having a good carrier concentration distribution is obtained by controlling the Si concentration in the GaAs raw material melt layer. As a result, an Si-doped GaAs single crystal having a good carrier concentration distribution and a method for producing the same are obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing a carrier concentration distribution of a Si-doped GaAs single crystal according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of a single crystal manufacturing apparatus for performing a vertical boat method used in a method for manufacturing a Si-doped GaAs single crystal according to the present invention.
FIG. 3 is an explanatory diagram of a single crystal manufacturing apparatus used in the method for manufacturing a Si-doped GaAs single crystal according to the present invention.
FIG. 4 is an explanatory diagram of a single crystal manufacturing apparatus used in the method for manufacturing a Si-doped GaAs single crystal according to the present invention.
FIG. 5 is a graph showing a carrier concentration distribution of a Si-doped GaAs single crystal according to a second embodiment of the present invention.
FIG. 6 is a graph showing a carrier concentration distribution of a Si-doped GaAs single crystal according to a conventional example.
[Explanation of symbols]
1 ... lower rod 3 ... crucible container, 4 ... crucible, 5 ... seed crystal, 6 ... solidified portion, 7 ... molten portion, 8 ... liquid sealant serving B ₂ O ₃ layer, 10 ... stir plate, 11 DESCRIPTION OF SYMBOLS ... Airtight container, 12 ... Upper rod, 11a, 11b ... Seal ring, 16 ... Heat insulating material, 17 ... Heater.

Claims (4)

  A method for producing a Si-doped GaAs single crystal by a vertical boat method using a liquid sealant, in which a seed crystal, a GaAs raw material, a Si raw material for a dopant and a raw material for a liquid sealant are housed in a crucible. After the raw material is melted and one liquid sealant layer is disposed on the GaAs raw material melt layer, the solidification rate g of the Si-doped GaAs single crystal is in the range of 0.1 to 0.8. A method for producing an Si-doped GaAs single crystal, wherein the Si concentration in the GaAs raw material melt layer is controlled by stirring the liquid sealant layer. A method for producing a Si-doped GaAs single crystal by a vertical boat method using a liquid sealant, in which a seed crystal, a GaAs raw material, a Si raw material for a dopant and a raw material for a liquid sealant are housed in a crucible. After the raw material is melted so that one liquid sealant layer is disposed on the GaAs raw material melt layer, after the start of the crystal growth process, the solidification rate g of the GaAs raw material is 0.3. The Si-doped GaAs single crystal having a good carrier concentration distribution by stirring the one liquid sealant layer and controlling the Si concentration in the GaAs raw material melt layer at a time in the range of ˜0.5. A method for producing a Si-doped GaAs single crystal. A method for producing a Si-doped GaAs single crystal by a vertical boat method using a liquid sealant, in which a seed crystal, a GaAs raw material, a Si raw material for a dopant and a raw material for a liquid sealant are housed in a crucible. After the raw material is melted so that one liquid sealant layer is disposed on the GaAs raw material melt layer, after the start of the crystal growth process, the solidification rate g of the GaAs raw material is 0.5. The Si-doped GaAs single crystal having a good carrier concentration distribution by stirring the one liquid sealant layer and controlling the Si concentration in the GaAs raw material melt layer at a time in the range of ~ 0.6. A method for producing a Si-doped GaAs single crystal. 4. The method for producing a Si-doped GaAs single crystal according to claim 2 , wherein the liquid sealant contains B ₂ O ₃ as a main component. .

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