JP2003206200A - p-TYPE GaAs SINGLE CRYSTAL AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a p-type GaAs single crystal having an average dislocation density of ≤100/cm<SP>-2</SP>, and to provide a method for producing the same. <P>SOLUTION: The p-type GaAs single crystal has an average dislocation density of ≤100/cm<SP>-2</SP>and contains Si, Zn, B and In as dopants. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a low dislocation-type p-type G
The present invention relates to an aAs single crystal and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, a laser diode using a compound semiconductor material such as GaAs has been developed as an optical device for transmitting a large amount of information at high speed. Such an optical device is composed of a multi-layered thin film having a heterostructure, and the thin film is generally formed by a vapor phase epitaxial method or a molecular beam epitaxial method. Since optical devices are strongly required to have stable characteristics and long life, it is necessary that the defect density of the epitaxial layer is as low as possible. Therefore, it is required that the semiconductor substrate used as the base for forming the epitaxial layer has a low dislocation density. To be done.

Generally, a device substrate is cut out from a semiconductor single crystal. There are a vapor phase growth method, a liquid phase growth method and a solid phase growth method as a method for producing a semiconductor single crystal, but a liquid phase growth method is often used for producing a compound semiconductor single crystal. One of the liquid phase growth methods, the method of solidifying and growing the raw material melt from the seed crystal includes horizontal Bridgman method, vertical Bridgman method, gradient freezing method (GF method), and Czochralski method. (CZ method) and its improved methods (for example, liquid sealed Czochralski method (LEC method)) and the like.

[0004] In recent years, large size exceeding φ3 "(76.2 mm),
Moreover, as a method for obtaining a GaAs crystal with a low dislocation density, the vertical Bridgman method (V
The ertical Bridgman method (VB method) is drawing attention.
For example, when forming a GaAs-based compound semiconductor single crystal by the VB method, a raw material melt prepared by filling a raw material consisting of Ga and As or GaAs into a crystal growth container in which a GaAs seed crystal is placed below and melting it by heating. The growth container containing is moved in a space in which a temperature gradient is provided in the vertical direction, and crystallized from the bottom (seed crystal side) to the top. Therefore, a single crystal grows from the seed crystal in a direction perpendicular to its surface. In this way, VB
By this method, a high-quality compound semiconductor single crystal with few crystal defects can be manufactured. In addition to the VB method, there is also a vertical temperature gradient freezing method (VGF method). V
The GF method fixes the position of the container on which the single crystal is placed at the lower end, and lowers the temperature in the furnace at a constant rate while maintaining the temperature gradient in the furnace of the VB method, so that the surface of the seed crystal is perpendicular. This is essentially the same as the VB method, except that the single crystal is grown in the direction.

For compound semiconductor lasers and LEDs, low dislocation substrates are required in terms of device life and efficiency. The reason for this is that the above element operates at a high current density, and if dislocations are present in the substrate, heat is generated at the dislocation portions, leading to deterioration of the element. However, the average dislocation density of the p-type GaAs substrate by the conventional VB method is 1
It was about 000 cm ^-2 , and it was difficult to manufacture low dislocation single crystals with high yield.

As one of the methods for achieving a low dislocation of a p-type GaAs substrate, there is a method of realizing an average dislocation density of 500 cm ^-2 or less by doping Si and B in addition to Zn which is a p-type dopant. , JP 2000-86398 A. However, in the above method, it is difficult to achieve the average dislocation density of 100 cm ^-2 or less because only the effect of hardening the impurities of Si and B can be obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a p-type GaAs crystal having an average dislocation density of 100 cm ^-2 or less and a method for producing the same.

[0008]

As a result of earnest research in view of the above object, the present inventors have found that in addition to doping p-type GaAs crystals with one type of p-type dopant, n-type dopant, and one neutral atom respectively, It has been discovered that by doping In, which is an atom, it is possible to accelerate the impurity hardening action, and it is possible to easily obtain p-type GaAs with an average dislocation density of 100 cm ^-2 or less, which was difficult to achieve until now. Then, the present invention was conceived.

That is, the p-type GaAs single crystal of the present invention is a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less,
The dopant is characterized by containing Si, Zn, B and In.

As the dopant, a part of Si is S, T
It may be substituted with at least one selected from the group consisting of e, Sn and Se, and a part of Zn is C, Be, Cd, Li, G.
e, Mg and Mn may be substituted with at least one member selected from the group, and part of B may be substituted with at least one member selected from the group consisting of Al, Sb and P. , In may be partially substituted with at least one selected from the group consisting of Al, Sb and P.

As the dopant, Si atoms of 1.0 × 10
¹⁷~ 5.0 x 10¹⁹Pieces / cm³It is preferable to contain a Zn atom.
1.0 x 10¹⁸~ 1.0 x 10²⁰Pieces / cm³Preferably contained, B
1.0 x 10 atoms¹⁷~ 5.0 x 10¹⁹Pieces / cm³Like to contain
In addition, 1.0 × 10 In atoms ¹⁷~ 5.0 x 10¹⁹Pieces / cm³Including
It is preferable to have.

Carrier concentration n is 1.0 × 10 ^{17 to} 6.0 × 10 ¹⁹ cm
^-3 , mobility μ is 10 ~ 300 cm ² / V ・ sec, and specific resistance ρ is
It preferably has electrical properties of 0.001 to 1.0 Ω · cm.

A first production method of the present invention for producing a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less is a crystal growth in which a GaAs melt containing a dopant is contained and a seed crystal is placed below. In the vessel, by cooling the melt under a temperature gradient in which the temperature rises from the lower side to the upper side, the single crystal is grown upward from the seed crystal, and Si, Zn, B and It is characterized by using In.

A second production method of the present invention for producing a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less contains a GaAs melt containing a dopant and a seed crystal is installed at one end in the horizontal direction. A single crystal is grown from the seed crystal side by cooling the melt under a temperature gradient in which the temperature rises from the seed crystal side to the other end in the horizontal direction in the crystal growth container. , B and In are used.

A third manufacturing method of the present invention for manufacturing a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less is a pulling shaft having a seed crystal installed at the lower end of a GaAs melt containing a dopant and an As atmosphere. By pulling in, a single crystal is continuously grown from the melt, with Si, Zn, and
It is characterized by using B and In.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION [1] p-type GaAs single crystal p-type GaAs single crystal has a carrier concentration range n of 1.0
× 10 ^{17 to} 6.0 × 10 ¹⁹ m ^-3 , mobility μ is 10 to 300 cm ² / Vse
c and the specific resistance ρ are preferably 0.001 to 1.0 Ω · cm.

The p-type GaAs single crystal of the present invention comprises p-type dopant Zn, n-type dopant Si, neutral atom B, and
And a neutral atom In.

100 p in the electric characteristic range of the p-type GaAs single crystal
m^-2Percentage of dopants that can achieve the following average dislocation densities
Is shown in Table 1. Zn atom concentration is 1.0 × 10¹⁸~ 1.0 x 10²⁰Individual
/cm ³And the concentration of Si atoms is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Individual
/cm³And the concentration of B atoms is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Individual/
cm³And the concentration of In atoms is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Pieces / c
m³Is preferred. However, the concentration of In atoms is 1.0 × 10
¹⁹Pieces / cm³If it exceeds, impurities will be deposited and this will
Causes defects in the epitaxial layer. That
Therefore, the concentration of In atoms is usually 1.0 × 10¹⁷~ 1.0 x 10¹⁹Pieces / cm³
It is desirable that it is within the range.

The effect of lowering the dislocation is that the concentration of Si atoms is 0.3 × 1.
0 ¹⁸ / cm ³ or more, the concentration of B atoms is 0.3 × 10 ¹⁸ / cm ³ or more, and the concentration of In atoms is 0.3 × 10 ¹⁸ / cm ³ or more. However, when the total concentration of the above three types exceeds 1.5 × 10 ¹⁹ pieces / cm ³ , precipitates due to impurity atoms are generated.
Therefore, the carrier concentration range (n = 0.5
In the case of × 10 ^{19 to} 4.0 × 10 ¹⁹ cm ^-3 ), the concentration of each impurity is such that the concentration of Zn atoms is 0.5 × 10 ^{19 to} 6.0 × 10 ¹⁹ pieces / cm ³ , S
i atom concentration is 0.3 × 10 ^{18 to} 5.0 × 10 ¹⁸ atoms / cm ³ , B atom concentration is 0.3 × 10 ^{18 to} 5.0 × 10 ¹⁸ atoms / cm ³ , and In atom concentration is 0.3 × 10 ^{18 to} 5.0 It is more preferable that the number is × 10 ¹⁸ pieces / cm ³ .

[0020]

[Table 1]

Further, a part of the p-type dopant Zn is replaced with C, Be, C
The same effect can be obtained by substituting at least one selected from the group consisting of d, Li, Ge, Mg and Mn, and a part of the n-type dopant Si is composed of S, Te, Sn and Se. The same effect can be obtained by substituting at least one selected from Furthermore, the same effect can be obtained by substituting a part of the neutral atom B or In with at least one selected from the group consisting of Al, Sb, and P. However, as a neutral atom, at least B and I
It is desirable that two or more kinds of atoms including n are contained as impurities, and the total concentration of neutral atoms is 0.5 × 10 ¹⁸ atoms / cm ³ or more in order to obtain the effect of reducing dislocation.

[2] Manufacturing Method As a method for manufacturing a p-type GaAs single crystal having an average dislocation density of 100 cm ⁻² or less according to the present invention, a horizontal Bridgman method (HB method), a horizontal temperature gradient solidification method (GF method), etc. Horizontal boat method, vertical Bridgman method (VB method), vertical boat method such as vertical temperature gradient solidification method (VGF method), and VCZ method (Vapor Pressure Controlled)
Any of the Czochralski Method) can be preferably used. Among these, it is more preferable to use the VB method or the VGF method as the most effective growth method for obtaining the effect of reducing dislocation.

(1) First Manufacturing Method An example of the first method for manufacturing the p-type GaAs single crystal of the present invention will be described with reference to FIG. FIG. 1 shows an outline of a crystal growth furnace by the VB method. The crystal growth furnace is composed of a quartz glass growth container 1,
A quartz glass cap 2, a crystal growth container 3, a crystal pedestal 4, and a heating device 5 are provided. In order to produce a p-type GaAs single crystal, first, a seed crystal 6 is placed at the lower end of the crystal growth container 3, and GaAs (or Ga and A) which is a raw material for crystal growth is placed on the seed crystal 6.
s) 13 and Zn, Si and In (indicated by 10, 11 and 12 in the figure) as dopants are arranged. Further, boron oxide (B ₂ O ₃ ) 9 is arranged as a dopant on it. Next, the crystal growth container is heated by a heating device, and a GaAs melt containing a dopant is produced in the crystal growth container. At this time, a part of the seed crystal is melted to perform seeding, and then the quartz glass growth container 1 is moved to the low temperature side (downward) with respect to the heating device. This forms a temperature gradient in which the temperature rises from the bottom to the top and contains the dopant.
By gradually cooling the melt of GaAs, a p-type GaAs single crystal is grown from the lower side (seed crystal side) to the upper side.

On the other hand, in the VGF method, by fixing the position of the quartz glass growth container 1 and gradually lowering the temperature while maintaining the upper and lower temperature gradients, a thermal history similar to that of the VB method can be obtained. The single crystal is grown in the direction perpendicular to the surface of the seed crystal by supplying the raw material to solidify by cooling. Except for this, a p-type GaAs single crystal is produced in the same manner as the VB method.

(2) Second Manufacturing Method An example of the second method for manufacturing the p-type GaAs single crystal of the present invention will be described with reference to FIG. FIG. 2 shows an outline of the crystal growth furnace by the HB method. The crystal growth furnace includes a quartz reaction tube 21, a crystal growth container (quartz boat) 22, a diffusion barrier 23, and a heating device 25. Quartz boat with diffusion barrier 23 sandwiched in quartz reaction tube 21
22 and As, which is a raw material for crystal growth (indicated by 28 in the figure), are arranged. A seed crystal 26 is set on one end (shelf) in the horizontal direction of the quartz boat 22 and is used as a raw material for crystal growth in the quartz boat 22.
Ga (denoted by 29 in the figure), as well as Z as a dopant
Install n, Si, B ₂ O ₃ and In. Next, after the inside of the quartz reaction tube 21 is evacuated, the temperature of the quartz reaction tube 21 is raised by the heating device 25 to sublimate a part of As, and the As gas and Ga are reacted so that the seed crystal is not touched. A GaAs melt containing a dopant is prepared. Next, the seed crystal and the melt are brought into contact with each other, and the GaAs melt containing the dopant is gradually cooled under a temperature gradient in which the temperature rises from the seed crystal side toward the other end in the horizontal direction. To grow a p-type GaAs single crystal. Note that GaAs instead of Ga and As was used as the raw material for crystal growth.
A polycrystalline GaAs melt containing a dopant may be prepared.

(3) Third Manufacturing Method An example of the third method for manufacturing the p-type GaAs single crystal of the present invention will be described with reference to FIG. FIG. 3 shows an outline of a crystal growth furnace by the VCZ method (Czochralski method with vapor pressure control). The crystal growth furnace includes a crucible 31, a crucible shaft 32, a pulling shaft 33, an airtight container 34, a heating device 35, and a pressure resistant container 37. First, GaAs polycrystal (or Ga and As), B ₂ O ₃ , Zn, Si and In, which are raw materials for crystal growth, are added into the crucible 31, and the heating device 35 heats the crucible 31 and its vicinity to contain a dopant. GaAs
Create a melt. The airtight container 34 is a solid As
It is kept in a state of being filled with a mixed gas of As ₂ and As ₄ gas generated from the gas and an inert gas. Then seed crystals at the bottom
The pulling shaft 33 on which the 36 is installed is lowered to penetrate the surface B ₂ O ₃ and come into contact with the melt for seeding. Then, the p-type GaAs single crystal is continuously grown from the melt while moving the pulling shaft upward.

From the above, the method for producing the p-type GaAs single crystal of the present invention
The method uses p-type (Zn), n-type (Si) and neutral atoms (B)
In addition to doping one type of each, In, which is a neutral atom, is doped.
The average dislocation density is 100 cm^-2Low dislocation p-type G
It is characterized by producing an aAs crystal. The addition amount is Zn raw
Child is 1.0 × 10¹⁸~ 1.0 x 10²⁰Pieces / cm³, Si atom is 1.0 × 10 ¹⁷
~ 5.0 x 10¹⁹Pieces / cm³, B atom is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Individual
/cm³, In atom is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Pieces / cm³Will be
As described above, it is preferably placed in a crystal growth container.

[0028] In this way the p-type GaAs single crystal thus obtained is compared with the prior art, easily 100 cm ^{- 2} can be achieved average dislocation density follows will, among .phi.3 "free in the substrate Since a single crystal wafer with dislocations (up to 500 / φ3 "wafer conversion) can be obtained, high reliability (long life) can be obtained by using a substrate prepared from the p-type GaAs single crystal of the present invention as a compound semiconductor laser substrate. ) Laser can be obtained.

[0029]

The present invention will be described in more detail by the following examples, but the present invention is not limited thereto.

[0030]Example 1 (1) Fabrication of p-type GaAs single crystal As shown in FIG. 1, a seed crystal 6 is placed at the lower end of the crystal growth container 3.
It was installed, and 6500 g of GaAs as raw material and
As punt, 3.0g Zn, 1.0g Si, 100g B₂O ₃,as well as
2.0g of In was added. Next, put a quartz glass in the quartz glass growth container 1.
Place the lath cap 2 in a vacuum and seal, then vacuum seal
The quartz glass growth container 1 was placed on the lower bearing table 4.
After installing the quartz glass growth container, the crystal growth container 3 and
The quartz glass growth vessel 1 was heated by the heating device 5. Addition
The heat temperature was about 1200 ℃ for the seed crystal part 6 and about 1245 ℃ for the upper raw material.
It was adjusted. After melting the raw materials into a melt, the solid-liquid interface
Seeding is performed while adjusting the temperature gradient of the part to about 5 ° C / cm.
It was Quartz glass growth at a speed of 3 mm / hr after seeding is completed
The container 1 was lowered to crystallize and solidify. Solidified the whole
After that, the temperature of the heating device 5 is cooled to room temperature at a rate of about 30 ° C / hr.
And remove the quartz glass growth container 1 from the heating device 5.
It was Through the above process, the diameter is about 3 "and the length of the straight body is about 180 m.
A low dislocation GaAs single crystal of m was obtained.

(2) A wafer cut out from the obtained φ3 ″ p-type GaAs single crystal was
After etching for 15 minutes in a KOH solution at 450 ° C., the number of dislocations observed in a 1 mm ² visual field with an optical microscope was converted to 1 cm ² , and the in-plane measurement was conducted at 5 mm intervals. The results are shown in FIG. As a result of the average dislocation density calculation, the average dislocation density is 28 cm ^-2 ,
A dislocation density that is an order of magnitude lower than that of the prior art could be realized. The cut-out wafer was evaluated by the GDMS method. Table 2 shows the solidification rate, carrier concentration, Zn concentration, Si concentration, B concentration, In concentration, and average dislocation density.

Example 2 A p-type G was prepared in the same manner as in Example 1 except that 3.0 g of Zn, 0.5 g of Si, 50 g of B ₂ O ₃ and 1.0 g of In were added as dopants.
An aAs single crystal was prepared. The wafer cut out from the obtained single crystal was evaluated by the GDMS method. Solidification rate, carrier concentration,
Table 2 shows Zn concentration, Si concentration, B concentration, In concentration, and average dislocation density.

Example 3 A p-type G was prepared in the same manner as in Example 1 except that 3.0 g of Zn, 0.4 g of Si, 50 g of B ₂ O ₃ and 0.5 g of In were added as dopants.
An aAs single crystal was prepared. The wafer cut out from the obtained single crystal was evaluated by the GDMS method. Solidification rate, carrier concentration,
Table 2 shows Zn concentration, Si concentration, B concentration, In concentration, and average dislocation density.

Comparative Example 1 In the same manner as in Example 1 except that In was omitted from the dopant.
A p-type GaAs single crystal was prepared. A wafer cut out from the obtained single crystal was etched in a KOH solution at 450 ° C. for 15 minutes, and then the number of dislocations was measured by an optical microscope in the same manner as in Example 1, and the result is shown in FIG. The cut-out wafer was evaluated by the GDMS method. Solidification rate, carrier concentration, Zn concentration, Si concentration,
Table 2 shows the B concentration, the In concentration, and the average dislocation density.

Comparative Example 2 As a dopant, 3.0 g of Zn, 0.8 g of Si, and 50 g of B ₂ O ₃
A p-type GaAs single crystal was produced in the same manner as in Example 1 except that was added. The wafer cut from the obtained single crystal is GD
It was evaluated by the MS method. Solidification rate, carrier concentration, Zn concentration, Si
Table 2 shows the concentration, B concentration, In concentration, and average dislocation density.

[0036]

[Table 2]

In each of the examples, the average dislocation density was 10
Although the condition of 0 cm ⁻² or less is satisfied, the average dislocation density is 361 to 428 cm ^{−2 in the} comparative example, which shows that the average dislocation density is higher than that of the In-doped example.

[0038]

As described above, since the p-type GaAs single crystal of the present invention is doped with four or more kinds of atoms containing at least Si, Zn, B and In as a dopant, the average dislocation density is 100 cm ^-2. The following low-dislocation p-type GaAs single crystal can be obtained. Therefore, it is possible to manufacture a compound semiconductor laser, a light emitting diode and the like with high efficiency and long life.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a crystal growth furnace by a VB method.

FIG. 2 is a schematic cross-sectional view showing an example of a crystal growth furnace by the HB method.

FIG. 3 is a schematic sectional view showing an example of a VCZ crystal growth furnace.

FIG. 4 is a density measurement diagram showing a distribution of dislocation density of a p-type GaAs substrate in Example 1.

5 is a density measurement diagram showing a distribution of dislocation density of a p-type GaAs substrate in Comparative Example 1. FIG.

[Explanation of Codes] 1 ... Quartz glass growth container 2 ... Quartz glass cap 3 ... Crystal growth container 4 ... Crystal cradle 5, 25, 35 ... Heating device (heat generating part) 6, 26, 36 ・ ・ ・ Seed crystal 9,39 ・ ・ ・ Boron oxide (B ₂ O ₃ ) 10 ・ ・ ・ Zn 11 ・ ・ ・ Si 12 ・ ・ ・ In 13 ・ ・ ・ GaAs raw material 21 ・ ・ ・ Quartz reaction tube 22 ... Quartz boat 23 ... Diffusion barrier 28 ... As 29 ... Ga 31 ... Crucible 32 ... Crucible shaft 33 ... Lifting shaft 34 ... Airtight container 37 ... Pressure resistance container

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 27, 2003 (2003.3.2)
7)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: p-type GaAs single crystal and manufacturing method thereof

[Claims]

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a low dislocation-type p-type G
The present invention relates to an aAs single crystal and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, a laser diode using a compound semiconductor material such as GaAs has been developed as an optical device for transmitting a large amount of information at high speed. Such an optical device is composed of a multi-layered thin film having a heterostructure, and the thin film is generally formed by a vapor phase epitaxial method or a molecular beam epitaxial method. Since optical devices are strongly required to have stable characteristics and long life, it is necessary that the defect density of the epitaxial layer is as low as possible. Therefore, it is required that the semiconductor substrate used as the base for forming the epitaxial layer has a low dislocation density. To be done.

Generally, a device substrate is cut out from a semiconductor single crystal. There are a vapor phase growth method, a liquid phase growth method and a solid phase growth method as a method for producing a semiconductor single crystal, but a liquid phase growth method is often used for producing a compound semiconductor single crystal. One of the liquid phase growth methods, the method of solidifying and growing the raw material melt from the seed crystal includes horizontal Bridgman method, vertical Bridgman method, gradient freezing method (GF method), and Czochralski method. (CZ method) and its improved methods (for example, liquid sealed Czochralski method (LEC method)) and the like.

[0004] In recent years, large size exceeding φ3 "(76.2 mm),
Moreover, as a method for obtaining a GaAs single crystal with a low dislocation density, the vertical Bridgman method (VB method) is attracting attention in place of the liquid sealing pulling method (LEC method). For example, when forming a GaAs-based compound semiconductor single crystal by the VB method, a raw material melt prepared by filling a raw material consisting of Ga and As or GaAs into a crystal growth container in which a GaAs seed crystal is placed below and melting it by heating. The growth container containing is moved in a space in which a temperature gradient is provided in the vertical direction, and crystallized from the bottom (seed crystal side) to the top. Therefore, a single crystal grows from the seed crystal in a direction perpendicular to its surface. In this way, a high-quality, large-diameter compound semiconductor single crystal with few crystal defects can be produced by the VB method.

In addition to the VB method, the vertical temperature gradient solidification method (Vertic
High quality by al Gradient Freeze Method (VGF method)
With this, a large diameter compound semiconductor single crystal can be produced.
The VGF method fixes the position of the container on which the single crystal is placed at the lower end, and lowers the temperature in the furnace at a constant rate while maintaining the temperature gradient in the furnace of the VB method, so that the surface of the seed crystal becomes perpendicular. This is essentially the same as the VB method, except that the single crystal is grown in the direction.

For compound semiconductor lasers and LEDs, low dislocation substrates are required in terms of device life and efficiency. The reason for this is that the above devices operate at high current densities,
This is because if dislocations are present in the substrate, heat is generated at the dislocations and the element is deteriorated. However, the average dislocation density of the p-type GaAs substrate by the conventional VB method is 1000 cm.
^{It was} about ^-2 , and it was difficult to manufacture low dislocation single crystals with high yield.

As one of the methods for achieving a low dislocation in a p-type GaAs substrate, there is a method of realizing an average dislocation density of 500 cm ^-2 or less by doping Si and B in addition to Zn which is a p-type dopant. , JP 2000-86398 A. However, in the above method, it is difficult to achieve the average dislocation density of 100 cm ^-2 or less because only the effect of hardening the impurities of Si and B can be obtained.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less and a method for producing the same.

[0009]

As a result of earnest research in view of the above object, the present inventors have found that a p-type GaAs single crystal is doped with a p-type dopant and an n-type dopant.
In addition to doping one type of dopant and one type of neutral atom each, it is possible to accelerate the impurity hardening action by doping In, which is a neutral atom. The inventors have found that p-type GaAs having a size of 100 cm ⁻² or less can be easily obtained, and have conceived the present invention.

That is, the p-type GaAs single crystal of the present invention is a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less,
The dopant is characterized by containing Si, Zn, B and In.

As the dopant, a part of Si is S, T
It may be substituted with at least one selected from the group consisting of e, Sn and Se, and a part of Zn is C, Be, Cd, Li, G.
e, Mg and Mn may be substituted with at least one member selected from the group, and part of B may be substituted with at least one member selected from the group consisting of Al, Sb and P. , In may be partially substituted with at least one selected from the group consisting of Al, Sb and P.

As the dopant, Si atoms of 1.0 × 10
¹⁷~ 5.0 x 10¹⁹Pieces / cm³It is preferable to contain a Zn atom.
1.0 x 10¹⁸~ 1.0 x 10²⁰Pieces / cm³Preferably contained, B
1.0 x 10 atoms¹⁷~ 5.0 x 10¹⁹Pieces / cm³Like to contain
In addition, 1.0 × 10 In atoms ¹⁷~ 5.0 x 10¹⁹Pieces / cm³Including
It is preferable to have.

[0013] As the electrical characteristics of the p-type GaAs single crystal, a carrier concentration ^{n 1.0 × 10 17 ~6.0 × 10} 19 cm - is preferably from ³
The mobility μ is preferably 10 to 300 cm ² / V · sec.
Ku, the resistivity ρ preferably a 0.001~1.0Ω · cm.

The first production method of the present invention for producing a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less is a crystal growth in which a GaAs melt containing a dopant is contained and a seed crystal is placed below. In the vessel, by cooling the melt under a temperature gradient in which the temperature rises from the lower side to the upper side, the single crystal is grown upward from the seed crystal, and Si, Zn, B and It is characterized by using In.

A second production method of the present invention for producing a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less contains a GaAs melt containing a dopant and a seed crystal is installed at one end in the horizontal direction. A single crystal is grown from the seed crystal side by cooling the melt under a temperature gradient in which the temperature rises from the seed crystal side to the other end in the horizontal direction in the crystal growth container. , B and In are used.

A third production method of the present invention for producing a p-type GaAs single crystal having an average dislocation density of 100 cm ^-2 or less is a pulling shaft having a seed crystal at the lower end thereof and a pulling axis from a GaAs melt containing a dopant in an As atmosphere. By pulling in, a single crystal is continuously grown from the melt, with Si, Zn, and
It is characterized by using B and In.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION [1] p-type GaAs single crystal p-type GaAs single crystal has a carrier concentration range n of 1.0
× 10 ^{17 to} 6.0 × 10 ¹⁹ m ^-3 , mobility μ is 10 to 300 cm ² / Vse
c and the specific resistance ρ are preferably 0.001 to 1.0 Ω · cm.

The p-type GaAs single crystal of the present invention comprises p-type dopant Zn, n-type dopant Si, neutral atom B, and
And a neutral atom In.

100 p in the electric characteristic range of the p-type GaAs single crystal
m^-2Percentage of dopants that can achieve the following average dislocation densities
Is shown in Table 1. Zn atom concentration is 1.0 × 10¹⁸~ 1.0 x 10²⁰Individual
/cm ³And the concentration of Si atoms is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Individual
/cm³And the concentration of B atoms is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Individual/
cm³And the concentration of In atoms is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Pieces / c
m³Is preferred. However, the concentration of In atoms is 1.0 × 10
¹⁹Pieces / cm³If it exceeds, impurities will be deposited and this will
Causes defects in the epitaxial layer. That
Therefore, the concentration of In atoms is usually 1.0 × 10¹⁷~ 1.0 x 10¹⁹Pieces / cm³
It is desirable that it is within the range.

The effect of lowering the dislocation is that the concentration of Si atoms is 0.3 × 1.
0 ¹⁸ / cm ³ or more, the concentration of B atoms is 0.3 × 10 ¹⁸ / cm ³ or more, and the concentration of In atoms is 0.3 × 10 ¹⁸ / cm ³ or more. However, when the total concentration of the above three types exceeds 1.5 × 10 ¹⁹ pieces / cm ³ , precipitates due to impurity atoms are generated.
Therefore, the carrier concentration range (n = 0.5
In the case of × 10 ^{19 to} 4.0 × 10 ¹⁹ cm ^-3 ), the concentration of each impurity is such that the concentration of Zn atoms is 0.5 × 10 ^{19 to} 6.0 × 10 ¹⁹ pieces / cm ³ , S
i atom concentration is 0.3 × 10 ^{18 to} 5.0 × 10 ¹⁸ atoms / cm ³ , B atom concentration is 0.3 × 10 ^{18 to} 5.0 × 10 ¹⁸ atoms / cm ³ , and In atom concentration is 0.3 × 10 ^{18 to} 5.0 It is more preferable that the number is × 10 ¹⁸ pieces / cm ³ .

[0021]

[Table 1]

Further, part of the p-type dopant Zn is replaced with C, Be, C.
The same effect can be obtained by substituting at least one selected from the group consisting of d, Li, Ge, Mg and Mn, and a part of the n-type dopant Si is composed of S, Te, Sn and Se. The same effect can be obtained by substituting at least one selected from Furthermore, the same effect can be obtained by substituting a part of the neutral atom B or In with at least one selected from the group consisting of Al, Sb, and P. However, as a neutral atom, at least B and I
It is desirable that two or more kinds of atoms including n are contained as impurities, and the total concentration of neutral atoms is 0.5 × 10 ¹⁸ atoms / cm ³ or more in order to obtain the effect of reducing dislocations.

[2] Manufacturing Method As a method for manufacturing a p-type GaAs single crystal having an average dislocation density of 100 cm ⁻² or less according to the present invention, a horizontal Bridgman method (HB method), a horizontal temperature gradient solidification method (GF method), etc. Horizontal boat method, vertical Bridgman method (VB method), vertical boat method such as vertical temperature gradient solidification method (VGF method), and VCZ method (Vapor Pressure Controlled)
Any of the Czochralski Method) can be preferably used. Of these, the most effective growth method to obtain the effect of low dislocation is VB method or VGF method.

(1) First Manufacturing Method An example of the first method for manufacturing the p-type GaAs single crystal of the present invention will be described with reference to FIG. FIG. 1 shows an outline of a crystal growth furnace by the VB method. The crystal growth furnace is composed of a quartz glass growth container 1,
A quartz glass cap 2, a crystal growth container 3, a pedestal 4, and a heating device 5 on the lower temperature side are provided. To prepare a p-type GaAs single crystal, first, a seed crystal 6 is attached to the lower end of the crystal growth container 3.
GaAs as a raw material for crystal growth (or
Ga and As) 13 and Zn, Si and In as dopants
(Indicated by 10, 11 and 12 respectively in the figure). Furthermore, boron oxide (B
₂ O ₃ ) 9 is placed.

The crystal growth container 3 is heated by the heating device 5 to prepare a melt of GaAs containing a dopant in the crystal growth container 3 . Row seeding this time to melt the part of the seed crystal
U Next, the quartz glass growth container 1 is moved to the low temperature side (downward) of the heating device 5 . This causes the GaAs containing the dopant in a temperature gradient in which the temperature rises from the bottom to the top.
The melt is slowly cooled, and a p-type GaAs single crystal grows from the lower side (seed crystal 6 side) toward the upper side.

On the other hand, in the VGF method , the position of the quartz glass growth vessel 1 is fixed , and the temperature is gradually lowered while maintaining the upper and lower temperature gradients, so that a thermal history similar to that of the VB method is obtained inside the vessel . The single crystal is grown in the direction perpendicular to the surface of the seed crystal by supplying the raw material to solidify by cooling. Except for this, a p-type GaAs single crystal is produced in the same manner as the VB method.

(2) Second Manufacturing Method An example of the second method for manufacturing the p-type GaAs single crystal of the present invention will be described with reference to FIG. FIG. 2 shows an outline of the crystal growth furnace by the HB method. The crystal growth furnace includes a quartz reaction tube 21, a crystal growth container (quartz boat) 22, a diffusion barrier 23, and a heating device 25. Quartz boat with diffusion barrier 23 sandwiched in quartz reaction tube 21
22 and As as a raw material for crystal growth (indicated by 28 in the figure)
Place and. A seed crystal 26 is installed on one end (shelf) in the horizontal direction of the quartz boat 22 and used as a raw material for crystal growth in the quartz boat 22.
As Ga of Te (shown by 29 in the figure), and a dopant
Installing of Zn, Si, B ₂ O ₃ and In.

After evacuating the inside of the quartz reaction tube 21, a heating device
As the quartz reaction tube 21 was heated by 25 and sublimated from solid As
By reacting gas and Ga so as not to touch the seed crystal 26 to produce a GaAs melt containing a dopant. Then contacting the seed crystal 26 and the melt, by cooling gradually GaAs melt containing a dopant at a temperature gradient temperature increases toward the other horizontal end from the seed crystal 26 side, horizontally from the seed crystal 26 A p-type GaAs single crystal is grown toward the other end in the direction. A GaAs melt containing a dopant may be prepared by using GaAs polycrystal as a raw material for crystal growth instead of Ga and As.

(3) Third Manufacturing Method An example of the third method for manufacturing the p-type GaAs single crystal of the present invention will be described with reference to FIG. FIG. 3 shows an outline of a crystal growth furnace by the VCZ method (Czochralski method with vapor pressure control). Crystal growth furnace, a crucible 31, a crucible shaft 32, pulling shaft 33, the airtight container 34, the heating device 35 and the pressure vessel 37.
GaAs polycrystal as a crystal growth material in the crucible 31 (or Ga
And As), and B ₂ O ₃ , Zn, Si and In as dopants.
Placed, making by elevating the temperature of the crucible 31 and its vicinity of the GaAs melt containing a dopant by heating device 35. Airtight container 34
Is kept filled with a mixed gas of As ₂ and As ₄ gas generated from solid As placed in a container and an inert gas. Then, the pulling shaft 33 having the seed crystal 36 at the lower end is lowered to penetrate the B ₂ O ₃ on the surface and come into contact with the melt for seeding. After that, the p-type GaAs single crystal is continuously grown from the melt while moving the pulling shaft 33 upward.

From the aboveAs is clearOf the present inventionMethod
Is p-typeDopant(Zn), n typeDopant(Si) and
Neutral atom (B)With, Dope In, a neutral atom
Resulting in an average dislocation density of 100 cm^-2 Less thanLow dislocation p
Type GaAssingleCharacterized by producing crystals.Zn atom is 1.
0 x 10¹⁸~ 1.0 x 10²⁰Pieces / cm³, Si atom is 1.0 × 10¹⁷~ 5.0
× 10¹⁹Pieces / cm³, B atom is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Pieces / c
m³, In atom is 1.0 × 10¹⁷~ 5.0 x 10¹⁹Pieces / cm³So that
ToDopantIt is preferable to place it in the crystal growth container.
Yes.

Thus, according to the method of the present invention, the prior art
More easily p-type GaA with average dislocation density below 100 cm ^-2
s single crystal can be obtained , especially dislocation-free ( φ3 "
The number of dislocations in terms of E c is a single crystal wafer of less than 500)
Obtainable. By using the substrate manufactured from the p-type GaAs single crystal of the present invention as the substrate for compound semiconductor laser , a laser with high reliability ( long life) can be obtained.

[0032]

The present invention will be described in more detail by the following examples, but the present invention is not limited thereto.

[0033]Example 1 (1) Fabrication of p-type GaAs single crystal As shown in FIG. 1, a seed crystal 6 is placed at the lower end of the crystal growth container 3.
It was installed, and 6500 g of GaAs as raw material and
As punt, 3.0g Zn, 1.0g Si, 100g B₂O ₃,as well as
2.0g of In was added. Next, put a quartz glass in the quartz glass growth container 1.
Place the lath cap 2 in a vacuum and seal, then vacuum seal
Quartz glass growth container 1CradleI put it on top of 4.That
rear, The crystal growth container 3 and the quartz glass growth container 1 are heated.
The temperature was raised by the device 5. The heating temperature is about 1200 for the seed crystal part 6.
℃, the upper raw material was adjusted to about 1245 ℃. Melt raw materials
After making the melt in, the temperature gradient at the solid-liquid interface is set to about 5 ° C / cm.
Seeding was done while adjusting. 3 mm / hr after seeding is completed
The quartz glass growth vessel 1 is lowered at the speed of
went. After solidifying the whole, raise the temperature of the heating device 5 to about 30 ° C.
/ Hr speed to room temperatureLowering, Add quartz glass growth container 1
It was taken out of the heating device 5. Diameter of about φ
A low-dislocation GaAs single crystal with a length of 3 "and a straight body length of about 180 mm was obtained.

(2) 450 wafers cut out from the obtained φ3 ″ p-type GaAs single crystal were evaluated.
After etching for 15 minutes in KOH solution at ℃ ,
Dislocations were measured with an optical microscope at 5 mm intervals. 1 mm ²
The result of converting the number of dislocations in the field of view of the above into the number of dislocations in the field of view of 1 cm ² is shown in FIG. The average dislocation density obtained from this is 28 c
It was m ^-2 , which was one digit lower than that of the conventional technology. The cut-out wafer was evaluated by the GDMS method. Table 2 shows the solidification rate, carrier concentration, Zn concentration, Si concentration, B concentration, In concentration, and average dislocation density.

Example 2 A p-type G was prepared in the same manner as in Example 1 except that 3.0 g of Zn, 0.5 g of Si, 50 g of B ₂ O ₃ and 1.0 g of In were added as dopants.
An aAs single crystal was prepared. The wafer cut out from the obtained single crystal was evaluated by the GDMS method. Solidification rate, carrier concentration,
Table 2 shows Zn concentration, Si concentration, B concentration, In concentration, and average dislocation density.

Example 3 A p-type G was prepared in the same manner as in Example 1 except that 3.0 g of Zn, 0.4 g of Si, 50 g of B ₂ O ₃ and 0.5 g of In were added as dopants.
An aAs single crystal was prepared. The wafer cut out from the obtained single crystal was evaluated by the GDMS method. Solidification rate, carrier concentration,
Table 2 shows Zn concentration, Si concentration, B concentration, In concentration, and average dislocation density.

Comparative Example 1 In the same manner as in Example 1 except that In was omitted from the dopant ,
A p-type GaAs single crystal was prepared. The wafer cut from the obtained single crystal was etched in a KOH solution at 450 ° C. for 15 minutes, and then the number of dislocations was measured by an optical microscope in the same manner as in Example 1. Results are shown in FIG. The cut-out wafer was evaluated by the GDMS method. Table 2 shows the solidification rate, carrier concentration, Zn concentration, Si concentration, B concentration, In concentration, and average dislocation density.

Comparative Example 2 As a dopant, 3.0 g of Zn, 0.8 g of Si, and 50 g of B ₂ O ₃
A p-type GaAs single crystal was produced in the same manner as in Example 1 except that was added. The wafer cut from the obtained single crystal is GD
It was evaluated by the MS method. Solidification rate, carrier concentration, Zn concentration, Si
Table 2 shows the concentration, B concentration, In concentration, and average dislocation density.

[0039]

[Table 2]

In all the examples, the average dislocation density was 10
Although the condition of 0 cm ⁻² or less is satisfied, the average dislocation density is 361 to 428 cm ^{−2 in the} comparative example, which shows that the average dislocation density is higher than that of the In-doped example.

[0041]

As described above, since the p-type GaAs single crystal of the present invention contains four or more kinds of atoms containing at least Si, Zn, B and In as a dopant, the average dislocation density is 100.
It has a low dislocation of less than cm ^-2 . Therefore, it is possible to manufacture a compound semiconductor laser , a light emitting diode and the like with high efficiency and long life.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a crystal growth furnace by a VB method.

FIG. 2 is a schematic cross-sectional view showing an example of a crystal growth furnace by the HB method.

FIG. 3 is a schematic cross-sectional view showing an example of a crystal growth furnace by the VCZ method .

FIG. 4 shows the dislocation density of the p-type GaAs substrate in Example 1.
It is a figure which shows cloth .

FIG. 5 shows the dislocation density of the p-type GaAs substrate in Comparative Example 1.
It is a figure which shows cloth .

[Reference Numerals] 1 ... quartz glass growth vessel 2 ... quartz glass cap 3 ... crystal growth vessel 4 ... cradle 5,25,35 ... heating device (heating part) 6, 26 , 36 ・ ・ ・ Seed crystal 9,39 ・ ・ ・ Boron oxide (B ₂ O ₃ ) 10 ・ ・ ・ Zn 11 ・ ・ ・ Si 12 ・ ・ ・ In 13 ・ ・ ・ GaAs raw material 21 ・ ・ ・ Quartz reaction tube 22・ ・ ・ Quartz boat 23 ・ ・ ・ Diffusion barrier 28 ・ ・ ・ As 29 ・ ・ ・ Ga 31 ・ ・ ・ Crucible 32 ・ ・ ・ Crucible shaft 33 ・ ・ ・ Lifting shaft 34 ・ ・ ・ Airtight container 37 ・ ・ ・ Pressure resistant container

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinfumi Komata             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. (72) Inventor Seiji Mizuba             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. F-term (reference) 4G077 AA02 AB01 BE46 CD02 EA04                       FB01 FB05 MB04 MB35

Claims (17)

[Claims] 1. A p-type GaAs having an average dislocation density of 100 cm ^-2 or less.
A p-type GaAs single crystal which is a single crystal and contains Si, Zn, B and In as dopants. 2. The p-type GaAs single crystal according to claim 1, wherein a part of Si is substituted with at least one selected from the group consisting of S, Te, Sn and Se. p
Type GaAs single crystal. 3. The p-type GaAs single crystal according to claim 1 or 2, wherein a part of Zn is replaced with at least one selected from the group consisting of C, Be, Cd, Li, Ge, Mg and Mn. P-type GaAs single crystal characterized by being characterized. 4. The p-type GaA according to claim 1.
In the s single crystal, a part of B is substituted with at least one selected from the group consisting of Al, Sb and P, and a p-type GaAs single crystal. 5. The p-type GaA according to claim 1.
A p-type GaAs single crystal in which a part of In is replaced with at least one selected from the group consisting of Al, Sb, and P in the s single crystal. 6. The p-type GaA according to claim 1.
s single crystal, the concentration of Si atoms was 1.0 × 10 ^{17 to} 5.0 × 10
P-type GaAs single crystal characterized by ¹⁹ pieces / cm ³ . 7. The p-type GaA according to claim 1.
s single crystal, the concentration of Zn atoms was 1.0 × 10 ¹⁸ 〜 1.0 × 10
A p-type GaAs single crystal characterized by ²⁰ pieces / cm ³ . 8. The p-type GaA according to claim 1.
s single crystal, the concentration of B atoms was 1.0 × 10 ^{17 to} 5.0 × 10 ¹⁹
P-type GaAs single crystal characterized by the number of pieces / cm ³ . 9. The p-type GaA according to claim 1.
s single crystal, the concentration of In atoms is 1.0 × 10 ^{17 to} 5.0 × 10
P-type GaAs single crystal characterized by ¹⁹ pieces / cm ³ . 10. The p-type GaA according to claim 1.
s single crystal, carrier concentration n is 1.0
× 10 ^{17 to} 6.0 × 10 ¹⁹ cm ^-3 with mobility μ of 10 to 300 cm
A ² / V · sec, p-type GaAs single crystal having a specific resistance ρ is characterized in that it is a 0.001~1.0Ω · cm. 11. A p-type GaAs having an average dislocation density of 100 cm ^-2 or less.
A method of manufacturing a single crystal, comprising GaAs containing a dopant
In a crystal growth container containing a melt and a seed crystal installed in the lower part, by cooling the melt under a temperature gradient in which the temperature rises from the bottom to the top, from the seed crystal to the top A method for producing a p-type GaAs single crystal, wherein the single crystal is grown, and Si, Zn, B and In are used as the dopant at that time. 12. P-type GaAs having an average dislocation density of 100 cm ⁻² or less.
A method of manufacturing a single crystal, comprising GaAs containing a dopant
In a crystal growth container containing a melt and a seed crystal installed at one end in the horizontal direction, by cooling the melt under a temperature gradient in which the temperature increases from the seed crystal side to the other end in the horizontal direction, Growing the single crystal from the seed crystal side,
At that time, Si, Zn, B, and In are used as the dopant, and a method for producing a p-type GaAs single crystal. 13. P-type GaAs having an average dislocation density of 100 cm ⁻² or less.
A method for producing a single crystal, by pulling a pulling shaft having a seed crystal at the lower end from a GaAs melt containing a dopant in an As atmosphere to continuously grow the single crystal from the melt, In this case, Si, Z as the dopant
A method for manufacturing a p-type GaAs single crystal characterized by using n, B and In. 14. The p-type GaA according to any one of claims 11 to 13.
s In the method for producing a single crystal, the concentration of Si atoms was 1.0 × 10 ¹⁷
A method for manufacturing a p-type GaAs single crystal, characterized in that the concentration is up to 5.0 × 10 ¹⁹ pieces / cm ³ . 15. The p-type GaA according to claim 11.
s In the method for producing a single crystal, the concentration of Zn atoms is 1.0 × 10 ¹⁸
A method for manufacturing a p-type GaAs single crystal, characterized in that the concentration is up to 1.0 × 10 ²⁰ pieces / cm ³ . 16. The p-type GaA according to any one of claims 11 to 15.
s In the method for producing a single crystal, the concentration of B atoms is 1.0 × 10 ¹⁷
A method for manufacturing a p-type GaAs single crystal, characterized in that the concentration is up to 5.0 × 10 ¹⁹ pieces / cm ³ . 17. The p-type GaA according to claim 11.
s In the method for producing a single crystal, the concentration of In atoms was 1.0 × 10 ¹⁷
A method for manufacturing a p-type GaAs single crystal, characterized in that the concentration is up to 5.0 × 10 ¹⁹ pieces / cm ³ .