JP2009057247A - Method for growing group iii nitride crystal, and group iii nitride crystal substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for growing a group III nitride crystal which has a nonpolar surface as its principal surface, and has a low dislocation density; and the group III nitride crystal substrate. <P>SOLUTION: The method for growing a group III nitride crystal comprises a step of preparing a ground substrate 10 which includes a group III nitride seed crystal 10a at least at the principal surface 10m side and of which the principal surface 10m has an inclination angle of ≥0.5° to ≤10° with respect to the ä1-100} surface 10c of the group III nitride crystal layer 10a and a step of growing a group III nitride crystal 20 on the principal surface 10 m of the ground substrate 10. When the group III nitride crystal 20 is grown, at least one portion of the dislocation remaining in the group III nitride crystal 20 is propagated in a direction substantially parallel to the ä1-100} surface 10c and discharged to the outer peripheral part of the group III nitride crystal 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for growing a group III nitride crystal having a low dislocation density and a group III nitride crystal substrate, which are preferably used as substrates for various semiconductor devices such as light-emitting elements, electronic elements, and semiconductor sensors.

Group III nitride crystals such as Al _x Ga _y In _1-xy N crystal (0 ≦ x, 0 ≦ y, x + y ≦ 1, and so on) are substrates for various semiconductor devices such as light emitting elements, electronic elements, and semiconductor sensors. It is very useful as a material for forming. Here, in order to improve the characteristics of various semiconductor devices, a group III nitride crystal having a low dislocation density and good crystallinity is required.

  As a method of growing such a group III nitride crystal, a liquid phase method such as an ultrahigh temperature ultrahigh pressure solution method, a flux method, a gas phase such as an HVPE (hydride vapor phase epitaxy) method, and a MOCVD (metal organic chemical vapor deposition) method. A law has been proposed.

For example, Japanese Unexamined Patent Application Publication No. 2004-244307 (hereinafter referred to as Patent Document 1) includes a substrate, a semiconductor layer formed on the substrate, and a group III nitride crystal formed above the semiconductor layer. A group III nitride substrate, wherein the semiconductor layer is made of a semiconductor represented by a composition formula Al _u Ga _v In _1-uv N (0 ≦ u ≦ 1, 0 ≦ v ≦ 1), The surface is a (0001) plane step inclined in one direction arranged stepwise, the angle between the inclined plane and the (0001) plane is 0.05 ° or more, and A group III nitride substrate is disclosed in which the in-plane variation of the carrier concentration of the group III nitride crystal formed on the semiconductor layer is 1/5 or more and 5 times or less of the average value of the carrier concentration.

Here, in Patent Document 1, as a method for producing such a group III nitride crystal substrate, a composition formula Al _u Ga _v In _1-uv N (0 ≦ u ≦ 1, 0 ≦ v ≦ 1) is formed on the substrate. Forming a semiconductor layer having a (0001) plane on the surface, and treating the surface of the semiconductor layer so as to be inclined with respect to the (0001) plane of the semiconductor layer And bringing the surface of the semiconductor layer into contact with a melt containing at least one group III element selected from gallium, aluminum, and indium and a solvent in an atmosphere containing nitrogen, and at least one group III And a step of causing a group III nitride crystal to grow on the semiconductor layer by reacting the element with nitrogen.

  In the method of Patent Document 1, the surface of the semiconductor layer is processed into a stepped shape with the (0001) plane exposed. Therefore, abnormal growth during crystal growth can be prevented. In addition, a crystal having high surface flatness can be obtained as compared with the case where a normal seed crystal substrate is used. In particular, by using a tilted substrate in the liquid phase growth, it is possible to improve the growth rate and the uniformity of the concentration of impurities incorporated into the crystal as compared with the case where the tilted substrate is not used.

  Here, when a group III nitride crystal is grown on a group III nitride substrate whose principal surface is the (0001) plane, the dislocation of the group III nitride substrate is the growth direction of the group III nitride crystal [0001] ] To the growth surface of the group III nitride crystal. When a group III nitride crystal is grown thickly, dislocations having the same sign of the Burgers vector but having the same magnitude merge by attraction and disappear, thereby reducing the dislocation density of the group III nitride crystal.

However, when the dislocation density of the crystal is less than 1 × 10 ⁷ cm ⁻² , the distance between the dislocations is increased, so that the possibility of the above-described dislocation coalescence is extremely reduced. That is, when a group III nitride crystal is grown on a group III nitride crystal substrate having a dislocation density of less than 1 × 10 ⁷ cm ⁻² , the group III has a lower dislocation density than the group III nitride crystal substrate that is the base substrate. It was difficult to grow nitride crystals.

Further, since the conventional group III nitride crystal is usually obtained by epitaxial growth on the (0001) plane which is the main surface of the group III nitride crystal substrate which is the base substrate, its crystal growth surface is also The (0001) plane becomes the principal plane of the crystal. The (0001) plane is a polar plane having a polarity in the direction perpendicular to the plane. For this reason, a semiconductor device obtained by forming at least one semiconductor crystal layer on the (0001) plane, which is the main surface of a group III nitride crystal, generates a decomposition electric field, and electrons and holes are spatially generated. In order to isolate | separate, there existed a problem that device characteristics, such as luminous efficiency, fell. For this reason, there has been a demand for a crystal whose main surface is a nonpolar surface having no polarity in the direction perpendicular to the surface.
JP 2004-244307 A

  An object of the present invention is to provide a method for growing a group III nitride crystal having a nonpolar plane as a main surface and a low dislocation density, and a group III nitride crystal substrate.

  The present invention provides a base substrate that includes a group III nitride seed crystal at least on the main surface side, and the main surface has an inclination angle of 0.5 ° to 10 ° with respect to the {1-100} plane of the group III nitride seed crystal. And a step of growing a group III nitride crystal on the main surface of the base substrate, and at the time of growing the group III nitride crystal, at least a part of dislocations existing in the group III nitride crystal Is a method for growing a group III nitride crystal that propagates in a direction substantially parallel to the {1-100} plane and is discharged to the outer periphery of the group III nitride crystal.

In the method for growing a group III nitride crystal according to the present invention, the dislocation density on the main surface of the base substrate is less than 1 × 10 ⁷ cm ^−2, and the dislocation density on the crystal growth surface after the growth of the group III nitride crystal is mainly used. The dislocation density in the plane can be 1/10 or less. Here, a liquid phase method can be used as a method for growing a group III nitride crystal. Moreover, nitrogen-containing gas can be supplied in the melt containing a group III element as a liquid phase method.

  In addition, the present invention is a group III nitride crystal substrate obtained by cutting out from a group III nitride crystal obtained by the above growth method.

  According to the present invention, it is possible to provide a group III nitride crystal growth method and a group III nitride crystal substrate having a nonpolar plane as a main surface and a low dislocation density.

(Embodiment 1)
One embodiment of a method for growing a group III nitride crystal according to the present invention, as shown in FIG. 1, includes a group III nitride seed crystal 10a at least on the main surface 10m side, and the main surface 10m is a group III nitride seed crystal 10a. A step of preparing the base substrate 10 having an inclination angle θ of 0.5 ° or more and 10 ° or less with respect to the {1-100} surface 10c, and a group III nitride crystal 20 on the main surface 10m of the base substrate 10 And at least a part of the dislocations existing in the group III nitride crystal 20 is substantially parallel to the {1-100} plane 10c when the group III nitride crystal 20 is grown. Propagated in the direction and discharged to the outer periphery of the group III nitride crystal 20. Thereby, a group III nitride crystal having a low dislocation density is obtained, in which the {1-100} plane which is a nonpolar plane is a grown crystal growth plane (this plane corresponds to the main plane of the crystal).

  In the method for growing a group III nitride crystal of the present embodiment, first, at least the main surface side includes a group III nitride seed crystal 10a, and the main surface 10m is relative to the {1-100} plane of the group III nitride seed crystal 10a. A base substrate having an inclination angle θ of 0.5 ° or more and 10 ° or less is prepared (base substrate preparation step). Base substrate 10 includes a group III nitride seed crystal 10a on the main surface 10m side. That is, the group III nitride seed crystal 10a has a main surface 10m. Therefore, the group III nitride crystal 20 can be epitaxially grown on the main surface 10 m of the base substrate 10. Therefore, group III nitride crystal 20 grown on main surface 10m having a {1-100} plane of base substrate 10 or a plane orientation close thereto inherits the crystal orientation of group III nitride seed crystal 10a of base substrate 10. The crystal growth plane becomes the {1-100} plane. Main surface 10m has an inclination angle θ of 0.5 ° or more and 10 ° or less with respect to {1-100} surface 10c of group III nitride seed crystal 10a.

  Here, the manufacturing method of the base substrate 10 as described above is not particularly limited, and for example, the following method is possible. That is, a group III nitride bulk crystal whose principal surface is the (0001) plane is grown thick by a conventional ordinary vapor phase method or liquid phase method. The obtained group III nitride bulk crystal was obtained by slicing with {1-100} planes parallel to each other, and polishing and / or grinding the sliced surface to obtain a mirror surface. There is no restriction | limiting in particular in the slicing method, A wire saw, an inner peripheral blade, an outer peripheral blade, a laser beam etc. are used.

  In the method for growing a group III nitride crystal of the present embodiment, the group III nitride crystal 20 is then grown on the main surface 10 m of the base substrate 10 (group III nitride crystal growth step). When the group III nitride crystal 20 is grown on the main surface 10 m of the base substrate 10, at least of dislocations inherited from the base substrate 10 or generated during crystal growth and existing in the group III nitride crystal 20. A part of the light propagates in a direction substantially parallel to the {1-100} surface 10c and is discharged to the outer peripheral portion of the group III nitride crystal 20, thereby reducing the dislocation density of the group III nitride crystal 20. be able to.

Such a reduction method is different from the reduction in dislocation density in which dislocations having the same sign of the Burgers vector but having the same magnitude are merged together by attraction and disappear, and the dislocation density of the crystal is 1 × 10 ⁷ cm ^−2. Even if it is less than this, the dislocation density can be further reduced. The dislocation density on the surface of the crystal can be measured by a cathodoluminescence method.

  Here, the {hkil} plane and the <hkil> direction of the crystal can be specified by X-ray diffraction of the crystal. Here, i = − (h + k), and h, k, and l are all integers, and may be the same or different. The state of dislocation propagation (dislocation propagation line 20d) in the crystal can be observed by a light scattering tomography method. The {hkil} plane is a generic name including a (hkil) plane and a crystal plane that is crystal geometrically equivalent to the (hkil) plane. The <hkil> direction is a generic name including a [hkil] direction and a direction geometrically equivalent to the [hkil] direction.

  The mechanism for reducing the dislocation density of the group III nitride crystal in this embodiment will be described below. Referring to FIG. 2, the main surface 10 m of the base substrate 10 in the present embodiment is at a certain angle with respect to each of a plurality of {1-100} surfaces 10 mc and those {1-100} surfaces 10 mc. And a plurality of step surfaces 10t each having a plurality of steps 10s.

  When the group III nitride crystal 20 is grown on such a main surface 10m, the group III nitride crystal 20 has a direction perpendicular to the {1-100} surface 10c of the main surface 10m and a step surface of the main surface 10m. Grows in a direction perpendicular to 10t. For this reason, the crystal growth surfaces 20a and 20b during the growth of the group III nitride crystal 20 have a plurality of {1-100} surfaces 20ac and 20bc and their {1-100} surfaces 20ac and 20bc, respectively. A plurality of steps 20as and 20bs each formed by a plurality of step surfaces 20at and 20bt having a certain angle are formed.

  Here, the crystal growth in the direction perpendicular to the step faces 20at and 20bt is superior to the crystal growth in the direction perpendicular to the {1-100} faces 20ac and 20bc. Dislocations propagate in the crystal growth direction. For this reason, it is inherited from the main surface of the base substrate 10 or is generated during crystal growth, and dislocations existing in the crystal are propagated substantially parallel to the {1-100} direction (FIG. 1B). ) And the dislocation propagation line 20d in FIG. 2 (b)), it is considered that the crystal can be discharged to the outer periphery of the crystal. Here, the dislocation propagation line 20 refers to a line indicating a trajectory of dislocation propagation.

  Here, the direction substantially parallel to the {1-100} plane, which is the direction in which dislocations existing in the crystal propagate, is a crystal perpendicular to the step faces 20at and 20bt in the growth of the group III nitride crystal. Since the growth rate is about twice or more the crystal growth rate in the direction perpendicular to the {1-100} planes 20ac, 20bc, the tilt angle φ with respect to the {1-100} planes 10c, 20ac, 20bc (this is , The dislocation propagation angle φ formed by the dislocation propagation line 20d and the {0001} planes 10c, 20c, 20ac, and 20bc) means a direction of about 26 ° or less.

  As the group III nitride crystal 20 grows, the step surfaces 20at and 20bt move to the outer periphery of the crystal together with dislocations, and the step surface disappears at a certain crystal growth surface 20e. Furthermore, the crystal grows in a direction perpendicular to the {1-100} plane, and a group III nitride crystal 20 having a {1-100} plane as the crystal growth plane 20s is obtained. In this way, a group III nitride crystal having a reduced dislocation density at the crystal growth surface 20s is obtained.

  If the inclination angle θ of the main surface 10m with respect to the {1-100} surface 10c of the group III nitride seed crystal 10a in the base substrate 10 is smaller than 0.5 °, the number of steps 10s existing on the main surface 10m of the base substrate 10 Therefore, dislocations cannot be efficiently propagated in a direction substantially parallel to the {1-100} plane, and if it is larger than 10 °, the number of steps 10 s existing on the main surface 10 m increases, and the crystal is growing. Steps 20as and 20bs are combined into a macro step (not shown). When the macro step occurs, the melt is caught in the macro step and a vacuole is easily generated in the crystal. From this viewpoint, the inclination angle θ is more preferably 0.5 ° or more and 5 ° or less.

  Further, the direction 10h of the inclination of the main surface 10m with respect to the {1-100} surface 10c is not particularly limited, but from the viewpoint of crystal symmetry, the <0001> direction, the <000-1> direction, and the <11-20> The direction is preferred.

In the group III nitride crystal growth method of this embodiment, in addition to the tilt angle θ described above, the growth is performed on the main surface 10 m of the base substrate having a dislocation density of less than 1 × 10 ⁷ cm ⁻² on the main surface 10 m. A group III nitride crystal in which the dislocation density on the subsequent crystal growth surface 20 s is 1/10 or less of the dislocation density on the main surface 10 m of the base substrate 10 can be grown. In this embodiment, dislocation density of the base substrate is 1 × 10 ⁷ cm ⁻² , unlike dislocation density reduction in which dislocations having the same sign of the Burgers vector but having the same size are combined and disappeared by attractive force. Even if it is less, the dislocation density of the crystal to be grown can be further reduced, and the dislocation density on the crystal growth surface 20s after the growth can be reduced to 1/10 or less of the dislocation density on the main surface 10m of the base substrate 10.

  In the group III nitride crystal growth method of this embodiment, the growth method is not particularly limited, and either a liquid phase method or a gas phase method can be used. Here, in the liquid phase method, the crystal growth rate in the direction perpendicular to the step surfaces 20at and 20bt in FIG. 2B is higher than that in the gas phase method in the direction perpendicular to the {1-100} surfaces 20ac and 20bc. Easy to increase compared to speed. Therefore, the liquid phase method is easier to perform step flow crystal growth in which crystal growth is performed so that dislocations propagate substantially parallel to the {1-100} plane in the initial stage of crystal growth, compared with the vapor phase method. In particular, it is advantageous in that it is easy to reduce dislocations.

  Here, the liquid phase method is not particularly limited, but from the viewpoint of efficiently growing a crystal having a low dislocation density, a base substrate is disposed in the melt 32 containing a group III element with reference to FIG. A method of growing a group III nitride crystal 20 on the main surface 10 m of the base substrate 10 by supplying a nitrogen-containing gas 34 into the melt 32 is preferable. If it is the melt 32 containing group III nitride, there will be no restriction | limiting in particular, The metal element (Na, Li which becomes a solvent (flux) of a group III element and a group III element melt (self-flux method) and a group III element For example, a melt (flux method) with an alkali metal element such as Ca, an alkaline earth metal element such as Ca, or a transition metal element such as Cu, Ti, Fe, Mn, or Cr is used. In particular, from the viewpoint of reducing the concentration of intrinsic defects contained in the crystal and / or controlling electrical characteristics such as carrier concentration, a melt having a high purity of the group III element is preferable. For example, the purity of the group III element is 99 mol% or more. Is preferable, more preferably 99.99 mol% or more, and still more preferably 99.9999 mol% or more.

(Embodiment 2)
One embodiment of a group III nitride crystal substrate according to the present invention is obtained by cutting out from a group III nitride crystal 20 obtained by the growth method of embodiment 1 with reference to FIG. Such a group III nitride crystal substrate has a reduced dislocation density on its main surface.

  Here, the method of cutting out the substrate from the group III nitride crystal 20 is not particularly limited, and a wire saw, an inner peripheral blade, an outer peripheral blade, laser light, or the like is used. Moreover, it is preferable that the cut main surfaces 20q and 20r of the group III nitride crystal substrate 20p are mirror-finished by polishing and / or grinding.

(Example 1)
Referring to FIG. 1A, first, a wurtzite GaN crystal substrate having a size of 5 mm × 10 mm × thickness 350 μm was prepared as a base substrate 10. In this GaN substrate (underlying substrate 10), the main surface 10m has an inclination angle θ of 1 ° in the [0001] direction (inclination direction 10h) with respect to the (1-100) surface ({1-100} surface 10c). The main surface 10m is mirror-finished by polishing. When the dislocation density on the main surface of the base substrate was detected and measured as a dark spot by the cathodoluminescence method, the in-plane average dislocation density was 9 × 10 ⁶ cm ⁻² .

  Here, the GaN substrate (underlying substrate 10) is a GaN bulk crystal having a (0001) plane as the main surface grown thick by a conventional normal vapor phase method or liquid phase method, and is parallel to the (1-100) plane. It was obtained by slicing with a wire saw on a flat surface and polishing the slice surface.

  Referring to FIG. 1B, next, 400 μm of a GaN crystal was grown on the main surface 10 m of the base substrate 10 by a liquid phase method using high-purity Ga as a solvent. Specifically, referring to FIG. 3, the base substrate 10 is placed on the bottom of the crucible with the main surface 10m facing up in an alumina crucible 30, and the purity is 7N (99.99999 mol%). 40 g of pure metal Ga was weighed and put together in a crucible and heated to 950 ° C. to form a high-purity Ga melt (melt 32 containing a group III element) in contact with the base substrate 10. Nitrogen gas (nitrogen-containing gas 34) having a pressure of 8 MPa was supplied to the high-purity Ga melt (melt 32) for 4000 hours to grow a GaN crystal (Group III nitride crystal 20) to an average growth thickness of 400 μm. . The plane orientation of the growth surface of the GaN crystal after crystal growth was (1-100).

Next, the grown GaN crystal was taken out of the crucible, and its surface was polished to make a mirror surface. When the in-plane average dislocation density of the mirror-finished GaN crystal surface was examined by the cathodoluminescence method in the same manner as the base substrate, the dislocation density was 7 × 10 ⁵ cm ⁻² . When the dislocation propagation of the GaN crystal was observed by a light scattering tomography method, the dislocation propagated in a direction substantially parallel to the (1-100) plane in the early growth stage close to the base substrate, It has been confirmed that Further, when the inside of the crystal was observed with a fluorescence microscope, no vacuole was observed.

(Example 2)
A GaN crystal is grown in the same manner as in Example 1 except that the main surface 10m of the base substrate 10 has an inclination angle θ of 3 ° in the [0001] direction with respect to the (1-100) plane. The surface was mirrored. For this GaN crystal, the average dislocation density on the surface is 3.0 × 10 ⁵ cm ⁻² , and the dislocation propagates in a direction substantially parallel to the (1-100) plane in the early growth stage near the base substrate. It was confirmed that the crystal had reached the outer peripheral side surface of the crystal, and no vacuole was observed inside the crystal.

(Example 3)
A GaN crystal is grown in the same manner as in Example 1 except that the main surface 10m of the base substrate 10 has an inclination angle θ of 6 ° in the [0001] direction with respect to the (1-100) plane. The surface was mirrored. For this GaN crystal, the average dislocation density on the surface is 1.0 × 10 ⁵ cm ⁻² , and the dislocation propagates in a direction substantially parallel to the (1-100) plane in the early growth stage close to the base substrate. It was confirmed that the crystal had reached the outer peripheral side surface of the crystal, and no vacuole was observed inside the crystal.

Example 4
A GaN crystal is grown in the same manner as in Example 1 except that the main surface 10m of the base substrate 10 has an inclination angle θ of 9 ° in the [0001] direction with respect to the (1-100) plane. The surface was mirrored. For this GaN crystal, the average dislocation density on the surface is 8.0 × 10 ⁴ cm ⁻² , and the dislocation propagates in a direction substantially parallel to the (0001) plane in the early growth stage close to the base substrate. It was confirmed that it reached the outer peripheral side surface, and no vacuoles were observed inside the crystal. Virtually no problem was observed, but a very small amount of vacuoles were observed inside the crystal.

(Comparative Example 1)
A GaN crystal was grown in the same manner as in Example 1 except that the main surface 10m of the base substrate 10 was a (1-100) plane (inclination angle θ was 0 °), and its surface was mirrored. For this GaN crystal, the average dislocation density at the surface was 9.5 × 10 ⁶ cm ⁻² , and it was confirmed that the dislocation propagated in a direction substantially perpendicular to the (1-100) plane. No vacuoles were found inside.

(Comparative Example 2)
A GaN crystal is grown in the same manner as in Example 1 except that the main surface 10m of the base substrate 10 has an inclination angle θ of 12 ° in the [0001] direction with respect to the (1-100) plane. The surface was mirrored. For this GaN crystal, the average dislocation density at the surface is 5.0 × 10 ⁴ cm ⁻² , and the dislocation propagates in a direction substantially parallel to the (1-100) plane in the early growth stage near the base substrate. However, although it was confirmed that the crystal reached the outer peripheral side surface, a vacuole was observed inside the crystal.

(Example 5)
Referring to FIG. 5, base substrate 10 similar to that in Example 2 was prepared, GaN crystal 20 was grown on main surface 10m of base substrate 10 by HVPE, and the surface was mirror-finished. Specifically, a base substrate is placed in a crystal growth furnace of an HVPE apparatus, and gallium monochloride (GaCl) gas is used as a Ga raw material under conditions of a crystal growth furnace pressure of 9.31 kPa (70 Torr) and a crystal growth temperature of 1020 ° C. , Using ammonia (NH ₃ ) gas as the N raw material and hydrogen gas as the carrier gas, the molar ratio of ammonia gas to gallium chloride gas (V / III ratio) is 30 and the GaN crystal 20 has an average thickness of 420 μm. Grown up. The crystal growth surface of the GaN crystal 20 was polished to obtain a GaN crystal 20 having a thickness H of 400 μm with the surface 20u mirrored.

When the dislocation density on the mirror-finished surface 20u of the GaN crystal 20 was examined, the average dislocation density was 3.0 × 10 ⁵ cm in the region where the distance L from the upper edge of the tilt direction 10h of the base substrate 10 was 400 μm. ^{-2 was} a low dislocation density region 20v, but the other regions were high dislocation density regions 20w having an average dislocation density of 9.0 × 10 ⁶ cm ^-2 (FIG. 5 (a)). When the dislocation propagation state of this GaN crystal was observed by the light scattering tomography method, the dislocation propagated in the direction where the dislocation propagation angle φ was 45 ° with respect to the (1-100) plane (FIG. 5B). . Therefore, it was confirmed that the majority of dislocations propagated from the base substrate penetrated the crystal surface and part of the GaN crystal reached the side surface of the crystal outer periphery. No vacuole was observed inside the crystal.

  From Examples 1 to 5 and Comparative Examples 1 and 2, a group III nitride crystal is grown on a base substrate whose main surface has an inclination angle of 0.5 ° to 10 ° with respect to the {1-100} plane By doing so, at least some of the dislocations present in the group III nitride crystal propagate in a direction substantially parallel to the {1-100} plane and are discharged to the outer periphery of the group III nitride crystal. It was found that a group III nitride crystal having a reduced dislocation density on the crystal growth surface after growth was obtained. However, from the viewpoint of eliminating the presence of vacuoles in the crystal, it is more preferable that the tilt angle be 0.5 ° or more and 5 ° or less. Further, from the viewpoint of easy step-flow crystal growth in which crystals grow so that the dislocations propagate substantially parallel to the {1-100} plane in the initial stage of crystal growth, and the dislocations can be effectively reduced. It is preferable to grow by the phase method.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic sectional drawing which shows one Embodiment of the growth method of the group III nitride crystal concerning this invention. Here, (a) shows a step of preparing a base substrate, and (b) shows a step of growing a group III nitride crystal on the base substrate. It is a general | schematic fragmentary expanded sectional view which shows one Embodiment of the growth method of the group III nitride crystal concerning this invention. Here, (a) shows what expanded the IIA part in Fig.1 (a), (b) shows what expanded the IIB part in FIG.1 (b). It is a schematic sectional drawing which shows an example which grows a group III nitride crystal by a liquid phase method. It is a schematic sectional drawing which shows one Embodiment of the group III nitride crystal substrate concerning this invention. It is the schematic which shows an example of the group III nitride crystal obtained by the growth method of the group III nitride crystal concerning this invention. Here, (a) shows a schematic plan view, and (b) shows a schematic cross-sectional view in the VB direction in (a).

Explanation of symbols

  10 base substrate, 10a group III nitride seed crystal, 10c, 10mc, 20c, 20ac, 20bc {1-100} plane, 10h tilt direction, 10m, 20q, 20r main surface, 10s, 20as, 20bs step, 10t, 20at , 20 bt step plane, 20 group III nitride crystal, 20a, 20b, 20e, 20s crystal growth plane, 20d dislocation propagation line, 20p group III nitride crystal substrate, 20u surface, 20v low dislocation density region, 20w high dislocation density region , 30 crucible, 32 melt, 34 nitrogen-containing gas.

Claims (5)

A base substrate is prepared that includes a group III nitride seed crystal at least on the main surface side, and the main surface has an inclination angle of 0.5 ° to 10 ° with respect to the {1-100} plane of the group III nitride seed crystal. And a process of
And growing a group III nitride crystal on the main surface of the base substrate,
During the growth of the group III nitride crystal, at least some of the dislocations present in the group III nitride crystal propagate in a direction substantially parallel to the {1-100} plane, and A method for growing a group III nitride crystal discharged to the outer periphery of a group III nitride crystal. A dislocation density in the main surface of the base substrate is less than 1 × 10 ⁷ cm ⁻² ;
2. The method for growing a group III nitride crystal according to claim 1, wherein a dislocation density on a crystal growth surface after the growth of the group III nitride crystal is 1/10 or less of a dislocation density on the main surface.   The method for growing a group III nitride crystal according to claim 1 or 2, wherein a liquid phase method is used as a method for growing the group III nitride crystal.   The method for growing a group III nitride crystal according to any one of claims 1 to 3, wherein a nitrogen-containing gas is supplied into a melt containing a group III element as the liquid phase method.   A group III nitride crystal substrate obtained by cutting out from a group III nitride crystal obtained by the growth method according to any one of claims 1 to 4.

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