WO2004067814A1

WO2004067814A1 - Method for preparing single crystal of iii group element nitride and transparent single crystal of iii group element nitride prepared thereby

Info

Publication number: WO2004067814A1
Application number: PCT/JP2004/000688
Authority: WO
Inventors: Takatomo Sasaki; Yusuke Mori; Masashi Yoshimura; Fumio Kawamura; Kunimichi Omae; Tomoya Iwahashi; Masanori Morishita
Original assignee: Osaka Industrial Promotion Organization
Priority date: 2003-01-28
Filing date: 2004-01-27
Publication date: 2004-08-12
Also published as: TW200419016A

Abstract

In an embodiment, gallium, lithium and sodium are placed in a BN crucible and are molten in a nitrogen atmosphere at a temperature of 800°C, under a low pressure as well as 30 atm (ca. 0.3 MPa), and then a single crystal is grown for 96 hours. The resultant gallium nitride single crystal is colorless and transparent with no blackening, exhibits almost no dislocation and has high quality, as shown in a photomicrograph of Fig. 2, and has a maximum diameter of 2 cm or more. An alkali metal other than sodium (except Li and Na) or an alkaline earth metal can be added in place of sodium or in addition to sodium.

Description

Specification

Method for producing group III element nitride single crystal and group III element nitride transparent single crystal obtained thereby

The present invention relates to a method for producing a single crystal of a Group III element nitride such as gallium nitride (GaN). Background art

Group III element nitride semiconductors are used in fields such as heterojunction high-speed electronic devices and optoelectronic devices (semiconductor lasers, light-emitting diodes, sensors, etc.), and gallium nitride (GaN) in particular is attracting attention. Have been. Conventionally, in order to obtain a single crystal of gallium nitride, direct reaction between gallium and nitrogen gas has been performed (for example, J. Phys. Chem. Solids, 1995, 56, 639). However, in this case, 130 ° C. to 160 ° C. C, requires an ultrahigh temperature and pressure of 800 atm to 170 atm (0.81 MPa to l.72 MPa). In order to solve this problem, a technique for growing gallium nitride single crystals in sodium (Na) flux (hereinafter, also referred to as “Na flux method”) has been developed (for example, US Pat. 8 3 7). According to this method, the heating temperature can be greatly reduced to 600 to 800, and the pressure can be reduced to about 50 atm (about 5 MPa). However, this method has a quality problem because the resulting single crystal is blackened. Although this method can greatly reduce the temperature and pressure as compared with the case of direct synthesis, it is still a condition. Strict. Therefore, there is a particular need for lower pressure manufacturing methods. Furthermore, the conventional technology cannot produce a high-quality gallium nitride single crystal that is transparent, has a low dislocation density and a high quality, and has a poor yield. In other words, in the conventional technology, the growth rate is extremely slow, for example, a growth rate of about several / im / hour, so that only 100 g of growth can provide only gallium nitride having a maximum diameter of about several millimeters. . Even the largest single crystal of gallium nitride reported so far has a maximum diameter of about 1 cm, which does not lead to practical use of gallium nitride. Also, for example, a method has been reported in which gallium nitride single crystal is grown by reacting lithium nitride (Li ₃ N) with gallium (eg, Journal of Crystal Growth 247 (2003) 275-278). The size of the obtained crystal is about 1 mm to 4 mm. These problems apply not only to gallium nitride but also to other Group III nitride semiconductors. Disclosure of the invention

The present invention has been made in view of such circumstances, and is directed to a manufacturing method capable of manufacturing a single crystal of a large group III element nitride which is transparent, has a low dislocation density, is high in quality, and is large in bulk. Provision is its purpose. In order to achieve the above object, a manufacturing method of the present invention is a method for manufacturing a group III element nitride single crystal, comprising lithium (L i), alkali metal (excluding Li), and alkali earth metal. Gallium (Ga) and aluminum (A) in a mixed flux (F1ux) with at least one of

1) and at least one element selected from the group consisting of indium (In) and a group III element by reacting the element with nitrogen (N). This is a manufacturing method for growing an element nitride single crystal. As described above, the dislocation is achieved by reacting a group III element nitride such as gallium with nitrogen in a mixed flux of lithium, at least one of an alkali metal (except Li) and an alkaline earth metal. Large, transparent bulk single crystals with low density and high quality can be manufactured. In addition, the pressure during the reaction can be reduced as compared with the conventional case. BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1 (A) and 1 (B) are schematic diagrams showing the configuration of an example of an apparatus for producing a single crystal of gallium nitride.

FIG. 2 is an optical micrograph of a single crystal of gallium nitride obtained by one example of the production method of the present invention.

FIG. 3 is a cross-sectional view showing an example of the field-effect transistor of the present invention.

FIG. 4 is a sectional view showing an example of the LED of the present invention.

FIG. 5 is a sectional view showing an example of the LD of the present invention.

FIG. 6 is a sectional view showing an example of the semiconductor optical sensor of the present invention. FIG. 7 shows the ratio of L i and the ratio in another example of the production method of the present invention.

4 is a graph showing the relationship with the ratio of the yield of GaN single crystals.

FIG. 8 is an optical micrograph of a GaN single crystal in another example of the production method of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail by way of examples. In the present invention, the group III elements are gallium (Ga), aluminum (A1), and indium (In), of which gallium is preferable. Further, the group III element nitride single crystal is preferably a gallium nitride (G a N) single crystal. The conditions shown below are particularly preferable for producing a single crystal of gallium nitride, but can be similarly applied to the production of other Group IV element nitride single crystals. In the present invention, the alkali metals are sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and Francium (Fr), and the alkaline earth metal is calcium. (C a), strontium (S r), barium (B a) and radium (R a). These may be used alone or in combination of two or more. Among them, preferred are Na, Ca, K, Rb and Cs, and more preferred are Na and Ca. The addition ratio of the alkali metal and the alkaline earth metal is, for example, 0.001 mol% to the total of lithium (L i), alkali metal (excluding L i) and alkaline earth metal. It is in the range of 9.9.99 mo 1%, preferably in the range of 0.01 mol% to 99.9 mo 1%, and more preferably in the range of 50 mo 1% to 99.5 mo. It is in the range of 1%. When lithium (L i) and sodium (Na) are used in combination, the ratio of Na to the total of the two is, for example, 0.001 mol% to 99.99 mol %, Preferably from 0.01 mol% to 99.9 mol%, more preferably from 50 mol% to 99.5 mol%. The ratio (mo 1) of sodium (Na) to the sum of gallium (Ga) and lithium (Li) is, for example, 0.001 mol% to 99.99 mol It is in the range of 1%, preferably in the range of 0.01 mol% to 99.9mo1%, more preferably in the range of 50mo1% to 99.5mo1%. . The molar ratio of Ga: Li: Na is particularly preferably 2.7: 0.18: 7.1. In addition, as shown in Examples described later, in the case of a mixed flux of Li and Na, when the growing pressure is 15 atm, the larger the Li, the higher the GaN yield. In the present invention, the melting conditions include, for example, a temperature of 100 ° C. to 1 ° C.

500 ° C, pressure 100 Pa to 20 MPa, preferably, temperature 300 ° 0 to 120 ° 0, pressure 0.01 MPa to 10 MPa More preferably, the temperature is 500 ° C. to 110 ° C. and the pressure is 0.1 MPa to

6 MPa. In the present invention, as the nitrogen (N) source, for example, a nitrogen (N) -containing gas can be used. The nitrogen (N) -containing gas is, for example, nitrogen (N ₂ ) gas, ammonia (NH ₃ ) gas or the like, and these may be used as a mixture, and the mixing ratio is not limited. In particular, it is preferable to use ammonia gas as the nitrogen (N) -containing gas because the reaction pressure can be reduced. In the production method of the present invention, a group III element nitride (for example, gallium nitride) is prepared in advance, and the mixed flux is brought into contact with the nitride.

It is preferable to grow a new group III element nitride single crystal (for example, gallium nitride single crystal) using the group III element nitride as a nucleus. The most important feature of this manufacturing method is that large single crystals can be manufactured quickly. In other words, in this method, the core of the Group III element The larger the number, the faster a large single crystal can be obtained. For example, when a thin film of gallium nitride is used as a nucleus, a gallium nitride single crystal grows in the thickness direction in an area equivalent to this. Specifically, the maximum diameter

When the thin film of 5 cm is used as a nucleus, a gallium nitride single crystal having the same area as this grows from several / xm to several mm in the thickness direction, so that a sufficiently large bulk gallium nitride can be obtained. The group III element nitride serving as a nucleus may be a single crystal or amorphous (amorphous). The form of the group III element nitride serving as a nucleus is not particularly limited, but for example, a thin film form is preferable. This thin film may be formed on a substrate. Examples of the substrate material include amorphous gallium nitride (GaN), amorphous aluminum nitride (A1N), sapphire, silicon (Si), and gallium arsenide (GaAs). , gallium nitride (G a N), aluminum nitride (A 1 N), carbide Kei element (S i C), boron nitride (BN), oxide Richiumugariu beam _{(L i G a 0 2)} , boron, zirconium (Z r B _2), zinc oxide (Z n 0), various types of glass, various metals, boron phosphide _{(BP), Mo S 2,} L aA l 〇 _{3, n b n, Mn F} e 2 0 4, Z n F e ₂ 〇 _{4, Z r N, T i} N, gallium phosphide (G a P), MgA l 2 〇 _{_{4, N d G a 0 3}} , L i A 1 O 2 S c A l Mg 0 4, C a ₈ L a ₂ (P_〇 ₄₎ there are ₆ 0 _2. The thickness of the group I II element nitride thin film serving as a nucleus is not particularly limited, and is, for example, 0.0 005 _im to 100 000 m, preferably 0.0 001 m to 500 000 0 m, more preferably in the range of 0.01 m to 500 m. The thin film can be formed on a substrate by, for example, metal organic chemical vapor deposition (MOCVD), halide vapor deposition (HVPE), molecular beam epitaxy (MBE), or the like. Also, the substrate Since a thin film of gallium nitride or the like is formed on the market, it may be used. The maximum diameter of the thin film is, for example, 2 cm or more, preferably 3 cm or more, more preferably 4 cm or more, and particularly preferably 5 cm or more. The larger the maximum diameter of the thin film, the better, and the upper limit is not limited. In addition, since the standard of the bulk compound semiconductor is 2 inches, from this viewpoint, the maximum diameter is preferably 5 cm, but may be larger or smaller, and is not particularly limited. The range of the maximum diameter is, for example, 2 cm to 5 cm, preferably 3 cm to 5 cm, and more preferably 4 cm to 5 cm. The maximum diameter is a line connecting a point on the outer periphery of the thin film surface and another point, and refers to the length of the longest line. In the manufacturing method, the group III element nitride prepared in advance may be dissolved by the flux before the nitrogen concentration increases. In order to prevent this, it is preferable that a nitride is present in the flux at least at the beginning of the reaction. Examples of the nitride include Ca ₃ N ₂ , Li ₃ N, Na N ₃ , BN, Si ₃ N ₄ , In N and the like, and these may be used alone. More than one kind may be used together. Further, the ratio of the nitride in the flux is, for example, 0.0001 mol% to 99 mol%, and preferably, 0.001 mol% to 50 mol 1%. , More preferably 0.005 mo 1% to 1 O mo 1%. In the production method of the present invention, it is possible that impurities are present in the mixed flux. In this way, the impurity-containing III A group III nitride single crystal can be produced. The impurities are, for example, calcium © beam (Ca), a compound containing calcium (Ca), silicon (S i), alumina (A1 ₂ 0 _3), indium (I n), aluminum (A1), nitride Print © beam (InN), silicon oxide (S i 0 _2), oxide Injiumu (I n ₂ 0 _3), zinc (Zn), magnesium (Mg), zinc oxide (ZnO), magnesium oxide (MgO), germanium (Ge) Etc. The production method of the present invention is carried out, for example, using the apparatus shown in FIG. As shown in FIG. 1 (A), this apparatus has a gas cylinder 1, an electric furnace 4, and a heat-resistant and pressure-resistant container 3 arranged in the electric furnace 4. A gas cylinder 1 is connected to a pipe 21, which is provided with a gas pressure regulator 5 and a pressure control valve 25, and a leak pipe is attached from the middle. The leak valve 24 is located ahead of it. The pipe 21 is connected to the pipe 22, and the pipe 22 is connected to the pipe 23, which enters the electric furnace 4 and is connected to the pressure- and heat-resistant vessel 3. Further, as shown in FIG. 1 (B), a crucible 6 is arranged in the pressure-resistant and heat-resistant container 3, and contains gallium and lithium, and alkali metals (excluding Li) and alkaline earth metals. Either or both are arranged. As the crucible, for example, a BN crucible can be used. The production of a single crystal of a Group III element nitride using this apparatus is performed, for example, as follows. First, materials such as a group III element such as gallium, lithium, and sodium are put into the crucible 6 and placed in the pressure- and heat-resistant container 3. The pressure- and heat-resistant container 3 is placed in the electric furnace 4 with the end of the pipe 23 connected. In this state, from gas cylinder 1, The nitrogen-containing gas is fed into the pressure-resistant and heat-resistant vessel 3 through the pipes (2 1, 2, 2, 23), and is heated in the electric furnace 4. The pressure in the pressure- and heat-resistant container 3 is adjusted by the pressure regulator 5. Then, by applying pressure and heating for a certain period of time, the material (indicated by 7 in FIG. 1B) is melted to grow a single crystal of a Group III element nitride. Then, the obtained single crystal is taken out of the crucible.

When a group III element nitride is prepared in advance and a group III element nitride single crystal is grown using the nucleus as a nucleus, for example, a thin film of a group III element nitride formed on a substrate is placed in a crucible 6 in advance. In this case, a single crystal may be grown in the mixed flux as described above. Although a single crystal of a Group III element nitride of the present invention can be manufactured by the above-described manufacturing method, the single crystal of the present invention is not limited to these manufacturing methods, and may be manufactured by another manufacturing method. Is also good. As described above, gallium nitride is preferable as the group III element nitride of the present invention. In the gallium nitride of the present invention, dislocation density, for example, 1 0 ⁵ ZCM ² or less, preferably 1 0 ⁴ Z cm ² or less, more preferably 1 0 ³ Zc m ² or less, particularly preferably 1 0 ² / cm ² or less, particularly preferably almost no dislocation (e.g., 1 0 ¹ cm ² or less) is of. The dislocation density can be determined by, for example, an etching method. The maximum diameter is, for example, 2 cm or more, preferably 3 cm or more, more preferably 4 cm or more, and particularly preferably 5 cm or more. The larger the better, the better, and the upper limit is not limited. In addition, since the standard of a bulk compound semiconductor is 2 inches, from this viewpoint, it is preferable that the maximum diameter is 5 cm. It may be below and is not particularly limited. The range of the maximum diameter is, for example, 2 cm to 5 cm, preferably 3 cm to 5 cm, and more preferably 4 cm to 5 cm. Note that the maximum diameter is a line connecting a point on the outer periphery of the single crystal and another point, and refers to the length of the longest line. Further, according to the manufacturing method of the present invention, the growth in the horizontal direction (vertical direction to the c-axis direction) is promoted rather than the growth in the vertical direction (c-axis direction) for growing GaN on the substrate. As a result, the resulting single crystal often has a plate shape. Therefore, it can be expected that the dislocation of the obtained crystal will be further reduced. Next, a semiconductor device using the group III element nitride transparent single crystal of the present invention will be described with reference to examples. The following devices are a field effect transistor, a light emitting diode (LED) and a semiconductor laser (LD), but the device of the present invention is not limited to these. Other than these, there is a semiconductor device using the single crystal of the present invention, for example, a semiconductor device having a simple structure in which a p-type semiconductor layer and an n-type semiconductor layer are simply joined, and A layer using the single crystal of the present invention (for example, ρηρ transistor, npn transistor, npnp thyristor, etc.), a conductive layer, a conductive substrate or a conductive semiconductor, an insulating layer, There is a semiconductor device using the single crystal of the present invention as an insulating substrate or an insulating semiconductor. The semiconductor device of the present invention can be manufactured by combining the manufacturing method of the present invention with a conventional method. For example, a GaN substrate may be manufactured by the manufacturing method of the present invention, and a semiconductor layer may be stacked on the GaN substrate by MOCVD or the like. The original GaN thin films grown by MOCVD or the like on GaN substrates manufactured by the above-mentioned manufacturing method have excellent characteristics because of their high quality. Alternatively, a semiconductor layer can be formed by the manufacturing method of the present invention. That is, first, a predetermined material is put in a crucible, an n-type GaN layer is formed by a manufacturing method of the present invention in a nitrogen-containing gas atmosphere, and the material is changed on the n-type GaN layer in the same manner as described above. By forming the p-type GaN layer, a pn junction semiconductor device can be manufactured. In this way, the following field-effect transistors, LEDs, LDs, semiconductor optical sensors, and other semiconductor devices can be manufactured. However, the semiconductor device of the present invention is not limited to the manufacturing method described above, but can be manufactured by other manufacturing methods. FIG. 3 shows an example of a field-effect transistor using the group III element nitride transparent single crystal of the present invention. As shown in the figure, the field-effect transistor 30 has a conductive semiconductor layer 32 formed on an insulating semiconductor layer 31 and a source electrode 33, a gate electrode 34, and a drain electrode 35 formed thereon. Is formed. In the figure, 37 indicates a highly concentrated two-dimensional electron. In this field-effect transistor, at least one of the insulating semiconductor layer 31 and the conductive semiconductor layer 32 is formed of a group III element nitride transparent single crystal of the present invention. Since the transparent single crystal of the present invention has few defects and has excellent insulating properties unless doped with impurities, the insulating semiconductor layer 31 may be formed of the single crystal of the present invention. For example, GaN single crystals are theoretically excellent in high-frequency characteristics, but conventional GaN single crystals have defects, making it difficult to realize a field-effect transistor with excellent high-frequency characteristics. However, since the G a N single crystal of the present invention has almost no dislocation and high quality, If this is used, a field effect transistor having excellent high frequency characteristics as expected can be obtained. The field effect transistor of the present invention may further include a substrate, and the field effect transistor element may be formed on the substrate. In this case, the substrate may be formed from the group III element nitride transparent single crystal of the present invention, or may be a substrate made of another material such as a SiC substrate, an A1N substrate, and sapphire. Good. Next, a light emitting diode (LED) using the single crystal of the present invention is a light emitting diode (LED) formed by stacking an n-type semiconductor layer, an active region layer, and a p-type semiconductor layer in this order. At least one of the three layers is formed from the group III element nitride transparent single crystal of the present invention. An n-type or p-type semiconductor can be obtained by doping an appropriate impurity and manufacturing a single crystal by the manufacturing method of the present invention. FIG. 4 shows an example of the LED of the present invention. As shown, the LED 40 has an InGaN layer 42 as an active layer formed between an n-type GaN layer 41 and a p-type GaN layer 43. I have. Further, an n-electrode 44 is arranged below the n-type GaN layer 41, and a p-electrode 45 is arranged above the p-type GaN layer 43, so that a compact structure is obtained. On the other hand, in the conventional structure, since the material used for the substrate is an insulator, it is necessary to form the n-type semiconductor layer in an L-shape and to form the n-electrode on the portion protruding sideways. Therefore, a compact structure could not be obtained. The LED of the present invention may further include a substrate, and the light emitting diode element may be formed on the substrate. In this case, the substrate is It may be formed from the group III element nitride transparent single crystal of the present invention, or may be a substrate made of another material such as a SiC substrate, an A1N substrate, and sapphire. However, when a substrate is formed from the single crystal of the present invention, conductivity can be imparted, and as a result, electrodes can be arranged below the substrate. In the LED of the present invention, the p-type semiconductor layer, the active region layer, and the n-type semiconductor layer may have a single-layer structure or a stacked structure. For example, in the semiconductor device of FIG. 4, instead of the p-type GaN layer 43, a laminate of a p-type AIGN layer and a p-type GaN layer may be formed. Next, the semiconductor laser (LD) using the single crystal of the present invention is a semiconductor laser (LD) having an n-type semiconductor layer, an active region layer, and a p-type semiconductor layer laminated in this order. In addition, at least one of the three layers is formed of the group III element nitride transparent single crystal of the present invention. An example of this is shown in FIG. As shown in the figure, this LD 50 has an InGaN layer 52 as an active layer formed between an n-type GaN layer 51 and a p-type GaN layer 53. . In addition, an n-electrode 54 is disposed below the n-type GaN layer 51, and a p-electrode 55 is disposed above the p-type GaN layer 53, resulting in a compact structure. I have. In contrast, in the conventional structure, the material used for the substrate was an insulator, so it was necessary to form the n-type semiconductor layer in an L-shape and to form the n-electrode on the part protruding sideways. However, it was not possible to take a compact structure. The LD of the present invention may further include a substrate, and the semiconductor laser device may be formed on the substrate. In this case, the substrate is It may be formed of a transparent group III element nitride transparent single crystal, or may be a substrate made of another material such as a SiC substrate, an A1N substrate, or sapphire. However, when a substrate is formed from the single crystal of the present invention, conductivity can be imparted, and as a result, electrodes can be arranged below the substrate. In the LD of the present invention, the p-type semiconductor layer, the active region layer, and the n-type semiconductor layer may have a single-layer structure or a stacked structure. For example, in the semiconductor device of FIG. 5, instead of the p-type GaN layer 53, a p-type A 1 G a N capping layer, a p-type GaN waveguiding layer, and a p-type Al GaN / G a N MD—SLS c 1 adding layer and p-type GaN layer are laminated in this order to form a laminate, and n-type GaN layer is substituted for n-type GaN layer. -You may form the laminated body which laminated | stacked the SLS cladding layer and the n-type GaN waveguiding layer in this order. Next, a semiconductor optical sensor according to the present invention is a semiconductor optical sensor element in which a p-type semiconductor layer and an n-type semiconductor layer are joined, and at least one of the two semiconductor layers is a group III element nitride according to the present invention. It is formed from a transparent single crystal. FIG. 6 shows an example of this semiconductor optical sensor. As shown in the figure, the semiconductor optical sensor 60 has an n-type GaN layer 61 and a p-type GaN layer 62 on each protrusion of a GaN substrate 65 having three protrusions. The layers are stacked in this order, and at least one of them is formed of the single crystal of the present invention. An n electrode (Au / Ti electrode) 64 is formed below the substrate 65, and a P electrode (AuZT i electrode) 63 is formed above the p-type GaN layer 62. Have been. The semiconductor optical sensor of the present invention may further include a substrate, and the semiconductor optical sensor may be formed on the substrate. In this case, the substrate may be formed from the group III element nitride transparent single crystal of the present invention, or may be a substrate of another material such as a SiC substrate, an A1N substrate, and sapphire. . Since the electrode can be arranged below the substrate as a result of imparting conductivity to the substrate, it is preferable to form the substrate using the single crystal of the present invention among them. Example

Next, examples of the present invention will be described together with comparative examples. The following example is an example of a gallium nitride single crystal, but other III group element nitride single crystals can be manufactured in the same manner.

(Example 1)

A single crystal of gallium nitride was manufactured using the apparatus shown in Figs. 1 (A) and (B). That is, gallium, lithium, and sodium are put into a BN crucible, and heated and melted under a nitrogen (N ₂ ) gas atmosphere under the following conditions to grow a single crystal of gallium nitride. After the growth, ethanol and water are added. The residue was treated with. As a result, as shown in the optical micrograph of FIG. 2, a transparent gallium nitride single crystal was obtained, and the yield was 38.6%. The maximum diameter of the obtained single crystal was 2 cm or more, and as a result of examination by an etching method, it was almost free from dislocation. (Manufacturing conditions)

Growth temperature: 800 ° C Growth pressure (N ₂ ): 30 atm (3.0 4 MPa)

Training time: 9 6 hours

Crucible used: BN crucible

G a: flu (molar ratio) = 2.7: 7.3

L i: N a (molar ratio) = 0.25: 9.75

(Comparative Example 1)

A single crystal of gallium nitride was produced in the same manner as in Example 1 except that a single elemental Na flux was used as the flux. As a result, the yield was as low as 9.7%, and the obtained single crystal was blackened and had poor quality, and the maximum diameter was as small as several mm.

(Comparative Example 2)

A single crystal of gallium nitride was produced in the same manner as in Example 1 except for using the Li single flux as the flux. As a result, the yield was as low as 4.5%, and the obtained single crystal was often blackened, of poor quality, and had a small maximum diameter of only a few mm.

(Example 2, Comparative Example 3)

A single crystal of gallium nitride was produced in the same manner as in Example 1 except that the molar ratio between Li and Na was set to Li: Na = 5: 95 and the growing pressure was set to 15 atm. (Example 2). In Comparative Example 3, a single crystal of gallium nitride was produced in the same manner as in Example 2 except that a single flux of Na was used as the flux. As a result, in Example 2, a transparent gallium nitride single crystal was obtained, and the yield was 13%. The maximum diameter of the obtained single crystal was 2 cm or more. As a result of examination by the Ching method, it was almost dislocation-free. On the other hand, in Comparative Example 3, a single crystal of gallium nitride could not be obtained. (Example 3)

The weighed value of Ga was fixed at 1.0 g. The molar ratio between Ga and the flux is fixed at Ga: flux = 2.7: 7.3, and the molar ratio (Li / Na) between the fluxes Li and Na is defined as Weighing was performed continuously from 0 to 1. The weighed material was put into a BN crucible, and nitrogen gas was introduced into the BN crucible and heated and pressurized by the apparatus shown in FIG. The heating temperature was 800 ° C., the pressure was 15 atm of nitrogen gas, and this was maintained for 96 hours. After the growth was completed, G a N generated by treating the residue with ethanol and water was taken out, and the yield was calculated. The results are shown in the graph of FIG. As shown in the figure, the yield is low in the region where the proportion of Li is small, but the yield sharply increases when the proportion of Li exceeds 40%, and when the proportion of Li is 70%, The yield reached 84%. In addition, in both cases where Li was 0% and Na was 0%, the yield was 0%. The obtained GaN single crystal was transparent as shown in the optical micrograph of Fig. 8, and the maximum diameter of the single crystal was 2 cm or more. It was hot. Industrial applicability

As described above, according to the production method of the present invention, a high-quality, large and transparent bulk group III element nitride single crystal can be produced in high yield. The group III element nitride single crystal obtained by the production method of the present invention has a very high practical value. It can be used for various semiconductor devices such as photodiodes (LEDs) and semiconductor lasers (LDs).

Claims

The scope of the claims

1. A method for producing a Group 111 element nitride single crystal, comprising a mixed flux (F 1 ux) of lithium (L i) and at least one of an alkali metal (except Li) and an alkaline earth metal. A group III element nitride by reacting at least one group III element selected from the group consisting of gallium (Ga), aluminum (A1) and indium (In) with nitrogen (N). Manufacturing method for growing crystals. 2. The production method according to claim 1, wherein the group III element is gallium (Ga), and the group III element nitride single crystal is gallium nitride (GaN).

3. the alkali metal is at least one selected from the group consisting of sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr); The production method according to claim 1, wherein the metal is at least one selected from the group consisting of calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). 4. The production method according to claim 1, wherein the mixed flux is a mixed flux of sodium (Na) and lithium (Li).

5. In the mixed flux, the ratio of lithium (Na) to the sum of sodium (Na) and lithium (Li) is from 0.01 mol% to 99.9 mol 1%. The method according to claim 1, which is a range.

6. The production method according to claim 1, wherein the reaction conditions are a temperature of 100 ° (: up to 150 ° C., a pressure of 100 Pa to 20 MPa) 7. A nitrogen (N) source 2. The production method according to claim 1, wherein a nitrogen (N) -containing gas is used.

8. The method according to claim 7, wherein the nitrogen (N) -containing gas is at least one of a nitrogen (N ₂ ) gas and an ammonia (NH ₃ ) gas.

9. The method according to claim 7, wherein the nitrogen (N) -containing gas is ammonia (NH ₃ ) gas or a mixed gas of the ammonia (NH ₃ ) gas and nitrogen (N) gas.

10. The production according to claim 1, wherein a group III element nitride is prepared in advance, and the mixed flux is brought into contact with the group III element nitride to grow a new group III element nitride single crystal with the group III element nitride as a nucleus. Method. 1 1. The production method according to claim 10, wherein the core element III nitride is single crystal or amorphous.

12. The method according to claim 10, wherein the group III nitride serving as a nucleus is in the form of a thin film.

13. The product according to claim 12, wherein the thin film is formed on a substrate. Construction method.

14. The production method according to claim 10, wherein the maximum diameter of the core group III element nitride is 2 cm or more.

1 5. The production method according to claim 10, wherein the maximum diameter of the core group III element nitride is 3 cm or more.

1 6. The production method according to claim 10, wherein the maximum diameter of the core group III element nitride is 4 cm or more.

17. The production method according to claim 10, wherein the maximum diameter of the core group III element nitride is 5 cm or more. 18. The production method according to claim 10, wherein a nitride is present in the mixed flux at least at an early stage of the reaction.

1 9. The nitride is C a ₃ N ₂ , L i ₃ N, N a N ₃ , BN, S

1 ₃ N ₄ and a method for producing at least one Der Ru claim 1 8, wherein selected from the group consisting of I n N.

20. The production method according to claim 1, wherein impurities to be doped are present in the mixed flux. 2 1. The impurity, calcium (Ca), including compounds of calcium (Ca), silicon (Si), alumina (A1 ₂ 0 _3), indium (In), § Ruminiumu (Al), there are indium nitride (InN), silicon oxide (Si0 _2), acid indium (In ₂ 0 _3), zinc (Zn), magnesium (Mg), oxidized zinc (ZnO), magnesium oxide (MgO) 21. The production method according to claim 20, which is at least one selected from the group consisting of: and germanium (Ge).

2 2. The production method according to claim 1, wherein a transparent single crystal is grown.

2 3. A group III element nitride transparent single crystal obtained by the production method according to claim 22.

2. Dislocation density is at 1 0 ⁵ / cm ² or less, the maximum diameter of 2 cm or more, III group element nitride transparent single crystal bulk claim 2 3 wherein. 2 5. The dislocation density is 1 0 ⁴ Z cm ² or less is claims 2 4 III group element nitride transparent single crystal according.

26. The group III element nitride transparent single crystal according to claim 24, wherein the dislocation density is 10 ³ / cm ² or less.

27. The group III element nitride transparent single crystal according to claim 24, wherein the dislocation density is 10 ² / cm ² or less.

28. The transparent group III element nitride single crystal according to claim 24, wherein the dislocation density is 10 i / cm ² or less.

29. The group III element nitride transparent single crystal according to claim 24, wherein the maximum diameter is 3 cm or more.

30. The group III element nitride transparent single crystal according to claim 24, wherein the maximum diameter is 4 cm or more.

31. The group III element nitride transparent single crystal according to claim 24, wherein the maximum diameter is 5 cm or more. 3 2. dislocation density is at 1 0 ⁴ / cm ² or less, and a maximum diameter of 5 cm or more, Paiiota group elements nitrides transparent single crystal bulk claim 2 3 wherein.

33. The transparent group III element nitride single crystal according to claim 32, wherein the dislocation density is 10 ³ Z cm ² or less. '

34. The group III element nitride transparent single crystal according to claim 32, wherein the dislocation density is 10 ² Z cm ² or less.

3 5. The group III element nitride transparent single crystal according to claim 32, wherein the dislocation density is 10 e / cm ² or less.

3 6. A semiconductor comprising the group III element nitride transparent single crystal according to claim 23

3 7. A semiconductor device including a semiconductor layer, wherein the semiconductor layer is formed from the group III element nitride transparent single crystal according to claim 23.

38. A semiconductor device in which a p-type semiconductor layer and an n-type semiconductor layer are joined, and at least one of the two semiconductor layers is formed of the group III element nitride transparent single crystal according to claim 23. .

3 9. In at least one semiconductor element selected from an npn transistor element, a pnp transistor element and an npnp thyristor element, at least one of the semiconductor layers used in the semiconductor element is defined in claim 23. A semiconductor device formed from the group III element nitride transparent single crystal described in the above.

40. A semiconductor device including a field-effect transistor element in which a conductive semiconductor layer is formed on an insulating semiconductor layer, and a source electrode, a gate electrode, and a drain electrode are formed on the conductive semiconductor layer. The semiconductor device according to claim 23, wherein at least one of a semiconductor layer and the conductive semiconductor layer is formed from the group III element nitride transparent single crystal.

4 1. A substrate further comprising a substrate, wherein the field-effect transistor is formed on the substrate, and wherein the substrate is formed from the group III element nitride transparent single crystal according to claim 23. Item 41. The semiconductor device according to Item 40.

4 2. A semiconductor device including a light-emitting diode (LED) element in which an n-type semiconductor layer, an active region layer, and a p-type semiconductor layer are stacked in this order, wherein at least one of the three layers is provided. A semiconductor device formed from the group III element nitride transparent single crystal according to claim 23.

43. The method according to claim 43, further comprising a substrate, wherein the light emitting diode element is formed on the substrate, and the substrate is formed from the group III element nitride transparent single crystal according to claim 23. 42. The semiconductor device according to 2. 44. A semiconductor device including a semiconductor laser (LD) element in which an n-type semiconductor layer, an active region layer, and a p-type semiconductor layer are stacked in this order, and at least one of the three layers includes: A semiconductor device formed from the group III element nitride transparent single crystal according to claim 23. 45. A substrate further comprising a substrate, wherein the semiconductor laser device is formed on the substrate, and wherein the substrate is formed from the group III element nitride transparent single crystal according to claim 23. 13. The semiconductor device according to claim 1.

46. A semiconductor device including a semiconductor optical sensor element in which a p-type semiconductor layer and an n-type semiconductor layer are joined, wherein at least one of the two semiconductor layers is a group III element nitride transparent unit according to claim 23. A semiconductor device formed from crystals.

47. A substrate further comprising a substrate, wherein the optical sensor element is formed on the substrate, and wherein the substrate is formed of the group III element nitride transparent single crystal according to claim 43. 46. The semiconductor device according to 6.

4.8. The semiconductor device according to claim 36, comprising a group III element nitride grown using the transparent group III element nitride single crystal according to claim 23 as a substrate.

4 9. The grown Group III element nitride is in the form of a thin film Item 48. The semiconductor device according to Item 8.

50. The semiconductor device according to claim 48, wherein the group III element nitride grown on the substrate is grown by MOCVD.