KR20160122863A - Hexagonal wurtzite single crystal - Google Patents

Abstract

Techniques for growing high-quality bulk hexagonal single crystals using a solvo-thermal method and techniques for achieving high quality and fast speeds are disclosed. Crystal quality is strongly dependent on the growth plane, where the nonpolar or semi-polar seed surface results in a higher quality crystal compared to the c-plane seed surface. Also, the growth rate strongly depends on the growth plane, where the semi-polar seed surface results in a faster growth rate. High crystal quality and fast growth rates can be achieved at the same time by selecting an appropriate growth plane. High quality crystals are achievable when the non-polar or semi-polar seed surface RMS roughness is less than 100 nm; On the other hand, even if grown from an atomically smooth surface, crystals grown from Ga-plane or N- plane result in poor crystal quality.

Description

Hexagonal wurtzite single crystal < RTI ID = 0.0 >

Cross reference of related application

This application is a continuation-in-part of co-pending U. S. Patent Application No. Assume the benefit of 119 (e):

TZITE SINGLE CRYSTAL AND HEXAGONAL W

RTZITE SINGLE CRYSTAL SUBSTRE,"표제의 미국 특허 출원 번호 61/056,797(상기 출원은 인용에 의하여 본 명세서에 통합된다)."HEXAGONAL W " filed on May 28, 2008 by Makoto Saito et al.

TZITE SINGLE CRYSTAL AND HEXAGONAL W

RTZITE SINGLE CRYSTAL SUBSTRE, entitled "U.S. Patent Application Serial No. 61 / 056,797, the application of which is incorporated herein by reference.

This application is related to the following co-pending and commonly assigned US patent applications:

Tadao Hashimoto et al., Entitled " A METHOD FOR GROWING LARGE SURFACE AREA GALLIUM NITRIDE CRYSTALS IN SUPERCRITICAL AMMONIA AND LARGE SURFACE AREA GALLIUM NITRIDE CRYSTALS "filed April 7, 2006, entitled " US Patent Application No. 60 / 790,310, 30794.0179USP1;

Tadao Hashimoto, Hitoshi Sato, and Shuji Nakamura et al., U.S. Patent Application No. 11 / 765,629, entitled " OPTO-ELECTRONIC AND ELECTRONIC DEVICES USING N-FACE GaN SUBSTRATE PREPARED WITH AMMONOTHERMAL GROWTH, "filed on June 20, Attorney Docket No. 30794.184-US-P1 (2006-666);

Quot; HYDROTHERMAL SYNTHESIS OF TRANSPARENT CONDUCTING ZINO HETEROEPITAXIAL FILMS ON GAIN IN WATER AT 90C, "filed on August 4, 2006, by Frederick F. Lange, Jin Hyeok Kim, Daniel B. Thompson and Steven P. DenBaars, Patent Application No. 60 / 821,558, Attorney Docket No. 30794.192-US-P1 (2007-048-1);

Quot; HYDROTHERMAL SYNTHESIS OF TRANSPARENT CONDUCTING ZINO HETEROEPITAXIAL FILMS ON GAIN IN WATER AT 90C, "filed April 11, 2007 by Frederick F. Lange, Jin Hyeok Kim, Daniel B. Thompson and Steven P. DenBaars, Patent Application No. 60 / 911,213, Attorney Docket No. 30794.192-US-P2 (2007-048-2);

US Provisional Patent Application No. 61 / 112,560, Attorney Docket No. 30794.296-US-P1, filed November 7, 2008 by Siddha Pimputkar et al., Entitled "REACTOR DESIGNS FOR USE IN AMMONOTHERMAL GROWTH OF GROUP-III NITRIDE CRYSTALS, 283-1);

Siddha Pimputkar et al., Entitled " NOVEL VESSEL DESIGNS AND RELATIVE PLACEMENTS OF THE SOURCE MATERIAL AND SEED CRYSTALS WITH RESPECT TO THE VESSEL FOR THE AMMONOTHERMAL GROWTH OF GROUP-III NITRIDE CRYSTALS, 61 / 112,552, Attorney Docket No. 30794.297-US-P1 (2009-284-1);

Siddha Pimputkar et al., "ADDITION OF HYDROGEN AND / OR NITROGEN-CONTAINING COMPOUNDS TO THE NITROGEN-CONTAINING SOLVENT USED DURING THE AMMONOTHERMAL GROWTH OF GROUP- III NITRIDE CRYSTALS TO OFFSET THE DECOMPOSITION OF THE NITROGEN-CONTAINING SOLVENT US Patent Application No. 61 / 112,558, Attorney Docket No. 30794.298-US-P1 (2009-286-1), entitled " AND / OR MASS LOSS DUE TO DIFFUSION OF HYDROGEN OUT OF THE CLOSED VESSEL,

Siddha Pimputkar et al., Entitled " CONTROLLING RELATIVE GROWTH RATES OF DIFFERENT EXPOSED CRYSTALLOGRAPHIC FACETS OF A GROUP-III NITRIDE CRYSTAL DURING THE AMMONOTHERMAL GROWTH OF A GROUP-III NITRIDE CRYSTAL, / 112,545, Attorney Docket No. 30794.299-US-P1 (2009-287-1);

US Provisional Patent Application No. 61 / 112,550 entitled " USING BORON-CONTAINING COMPOUNDS, GASSES AND FLUIDS DURING AMMONOTHERMAL GROWTH OF GROUP-III NITRIDE CRYSTALS, "filed November 7, 2008 by Siddha Pimputkar et al., Attorney Docket No. 30794.300-US -P1 (2009-288-1); And

U.S. Patent Application No. 61 / 855,591 entitled " HEXAGONAL WURTZITE TYPE EPITAXIAL LAYER POSSESSING A LOW ALKALI-METAL CONCENTRATION AND METHOD OF CREATING THE SAME, "filed May 28, 2008 by Makoto Saito et al.

All of the above applications are incorporated herein by reference.

The present invention relates to hexagonal wurtzite type bulk single crystals, and more particularly to high-speed and high-quality solvent-to-solvo-thermal growth of hexagonal wurtzite type single crystals. .

(Note: The present application cites many other documents as parentheses, for example, [X], as indicated throughout the specification, with one or more quotation numbers, for example. Each of these documents is incorporated herein by reference.)

The availability of gallium nitride (GaN), its ternary compounds including aluminum and indium and its four elemental compounds (AlGaN, InGaN, AlInGaN) is well established in the production of visible and ultraviolet optoelectronic devices and high power electronic devices. These devices typically include molecular beam epitaxy (MBE), metalorganic chemical vapor deposition (MOCVD), and hydride vapor phase epitaxy (HVPE). Lt; RTI ID = 0.0 > epitaxially < / RTI >

GaN and its alloys are most stable in the hexagonal-wurtzite crystal structure, wherein all of the structures are two (or three) equivalents of the crystal structure, which are all perpendicular to the unique c-axis and rotated 120 degrees relative to each other Described as base axes. Group III and nitrogen atoms occupy the alternating c-planes along the c-axis of the crystal. The symmetry elements contained in the wurtzite structure are such that the group III-nitride has bulk spontaneous polarization along the c-axis and the wurtzite structure exhibits piezoelectric polarization. do.

Current nitride techniques in electronic devices and optoelectronic devices use nitride films grown along the polar c-direction. However, due to the presence of strong piezoelectric and spontaneous polarization, conventional c-plane quantum well structures in III-nitride-based optoelectronic devices and electronic devices have an undesirable quantum-confined Stark effect (QCSE) Receive. The strong built-in electric field along the c-direction causes spatial separation of electrons and holes, which in turn leads to limited carrier recombination efficiency, reduced oscillator strength, And red-shifted emission.

One approach to removing or reducing spontaneous and piezoelectric polarization effects in GaN optoelectronic devices is to grow the device on a non-polar plane or a semi-polar plane of the crystal. Recently, several reports have been published confirming the advantages of non-polar and semi-polar devices. Most of them point out that high quality substrates are essential for the manufacture of these devices. Historically, there have been many efforts to use foreign substrates such as SiC, spinel, sapphire, etc. to fabricate devices; However, device quality was poor due to high defect density due to hetero-epitaxy.

In this situation, high quality and high cost-performance GaN substrates for homo-epitaxy are key materials for the industrialization of non-polar and semipolar devices. The use of HVPE in conjunction with GaN substrates is an approach for realizing high quality non-polar or semi-polar devices, but wafer size is limited and fabrication costs are very high.

In addition, the growth of Group III nitride crystals in supercritical ammonia has been proposed. This method has advantages, such as no deformation, no bow, lower defect density, cost effective process, etc., compared with conventional HVPE-grown, GaN substrates. However, this method still has problems such as low growth rate, poor crystal quality and the like.

Thus, there remains a need in the art for improved techniques for growing high-quality, bulk, hexagonal-wurtzite single crystals. The present invention satisfies this need.

And a bulk monocrystal including a hexagonal wurtzite structure.

And a method of growing a bulk single crystal with a hexagonal wurtzite structure.

In order to overcome the limitations in the above-mentioned prior art and to overcome other limitations which will become apparent upon reading and understanding the present specification, the present invention provides a high-quality, bulk, hexagonal Describes a technique for growing a hexagonal wurtzite single crystal. The technology achieves both high quality and fast growth rates at the same time.

Crystal quality is strongly dependent on the growth plane. In the present invention, {10-10}, {10-11}, {10-1-1}, {10-12}, {10-1-2}, {11-20}, {11-22} Or a non-polar or semi-polar seed surface such as {11-2-2} leads to better crystal quality compared to the c-plane seed surface, i.e., (0001) and (000-1). Also, the growth rate strongly depends on the growth plane. Semi-polar seed surfaces such as {10-12}, {10-1-2}, {11-22}, or {11-2-2} lead to faster growth rates. Both high quality and fast growth rates can be achieved at the same time by selecting a suitable growth plane.

The crystal quality also depends on the seed surface roughness. High quality crystals can be obtained when the mean root mean square (RMS) roughness of the non-polar or semi-polar seed surface is less than 100 nm. On the other hand, a crystal grown from a Ga-plane or an N-plane becomes a crystal of poor quality even if grown from an atomically smooth surface.

The term "non-polar planes" can be used to refer to a wide range of planes having two non-zero h, i, or k miller indices and one Miller index of zero.

The term "semi-polar planes" can be used to refer to a wide range of planes with two nonzero h, i, or k miller indices and one non-zero Miller index.

The growth rate strongly depends on the off-orientation from the on-axis m-plane. The present invention examined the following off-orientations from the axial m-plane (10-10) and the axial m-plane (10-10): two degrees toward c + / c-, five degrees toward c + / c- , c + / c- (10-12) / (10-1-2) toward the c + / c- (10-11) / (10-1-1) 90 degrees toward (0001) / (000-1). A faster growth rate was observed using a seed with a larger off orientation from the axial m-plane (10-10).

In addition, the crystal quality strongly depends on the off-orientation from the axial plane. The off-oriented seed crystal of 2 degrees showed the narrowest FWHM value of the XRD rocking curve measurement. On the other hand, (0001) / (000-1) seed crystals with 90 degrees off-orientation showed the largest FWHM.

High quality crystals and fast growth rates can be achieved at the same time by selecting an appropriate off-orientation angle.

The present invention discloses a method for growing crystals and crystals. A single bulk crystal according to the present invention comprises a hexagonal wurtzite structure wherein the bulk monocrystalline is subjected to solvent-thermal growth (solvo) using a seed having a non- -thermal growth.

Such crystals optionally further comprise a bulk monocrystal, which is a group III-nitride, wherein the seed for crystal having a growth surface comprises one or more of the following planes: {10-10}, {10- 11}, {10-1-1}, {10-12}, {10-1-2}, {11-20}, {11-22}, or {11-2-2} Wherein the off-orientation angle is in the [0001] direction, the off-orientation angle is in the range of greater than 0.5 degrees and less than 48 degrees, and the off-orientation angle is in the [0001] direction (RMS) roughness of the growth surface of the seed is less than 100 nm, and the orientation angle is in the range of greater than 0.5 degrees and less than 90 degrees. , The x-ray diffraction (XRD) rocking curve half width (FWHM) for the bulk crystal is less than 500 arcsec, the bulk monocrystalline is gallium nitride, The substrate can be obtained by cutting the crystal.

A method of growing a bulk monocrystal having a hexagonal wurtzite structure in accordance with one or more embodiments of the present invention includes performing solvent-thermal crystal growth on a seed crystal phase having a growth surface comprising a nonpolar plane or a semi- .

Such a method optionally further comprises a bulk monocrystal, which is a group III nitride,

The growth surface comprises at least one of the following planes: {10-10}, {10-11}, {10-1-1}, {10-12}, {10-1-2}, {11 -20}, {11-22}, or {11-2-2}, the growth surface includes an m-plane having an off orientation angle, the off orientation angle is toward the [0001] direction, And the off-orientation angle is greater than 0.5 degrees and less than 48 degrees, the off-orientation angle is greater than 0.5 degrees and less than 4.5 degrees, the off-orientation angle is toward the [000-1] (RMS) roughness of the growth surface is less than 100 nm, the x-ray diffraction (XRD) rocking curve half width (FWHM) of the bulk crystal is less than 500 arcsec, the bulk crystal is gallium nitride, To obtain a substrate.

Another method of fabricating a Group III nitride bulk crystal or device according to one or more embodiments of the present invention includes growing a Group III nitride bulk crystal or device on a growth surface of the seed wherein the growth surface comprises one or more non- Or semi-polar plane, or one or more off-orientations of the non-polar planar or semipolar plane, and growth in a non-polar, semi-polar or off-oriented direction, the quality of the group III nitride bulk crystal or device, Growth rate, or both quality and growth rate.

Another method of making Group-III nitride crystals in accordance with one or more embodiments of the present invention includes growing Group-III nitride bulk crystals by a solvent-thermal process wherein the Group-III nitride bulk crystals are grown on a substrate other than the c- Wherein the growth plane is selected based on at least one of a growth rate in the growth plane and a quality of growth in the growth plane.

The present invention describes a technique for growing high-quality, bulk, hexagonal wurtzite single crystals using a solvo-thermal method. The technology achieves both high quality and fast growth rates at the same time.

The same reference numerals in the figures refer to the corresponding parts to the end:
1 is a diagrammatic view of an autoclave according to one embodiment of the present invention.
Fig. 2 is a table showing the thickness of the obtained crystal and the growth rate data calculated for each plane of the seed crystal.
3 is a table showing XRD rocking curve FWHM (full width at half maximum) data for each of the planar crystals.
Figure 4 is a graph showing the correlation between the on-axis XRD FWHM data of each seed surface and the axial XRD FWHM data of the resulting crystals.
Figure 5 is a graph showing the correlation between the RMS roughness of each seed surface and the axial XRD FWHM data of the resulting crystal.
6 is a graph showing the off orientation dependency of the growth rate.
7 is a graph showing the XRD rocking curve FWHM data of each off-oriented seed crystal.
8 is an enlarged view of the range of 0 to 5 in FIG.
FIG. 9 is an enlarged view of the range of 0 to 5 in FIG.
10 is a diagram illustrating growth according to one or more embodiments of the present invention.

The following description of the preferred embodiments illustrates specific embodiments in which the invention may be practiced, with reference to the accompanying drawings, which form a part hereof. It is needless to say that other embodiments may be used and structural changes may be made without departing from the scope of the present invention.

survey

The present invention describes a technique for growing high-quality, bulk, hexagonal-wurtzite single crystals using a solvent-heat method. The present invention also describes a technique for simultaneously achieving high quality and fast growth rates.

Prior to the present invention, a method of growing Group III nitride crystals in supercritical ammonia has been proposed. The method has been expected to produce a GaN substrate that is bow-free, has a lower defect density, and is cost effective. However, there are still problems such as slow growth rate and poor crystal quality.

C-plane seed crystals have been used with this method. In the present invention, however, nonpolar and semipolar seed crystals were first introduced, and the high performance of these faces has been successfully demonstrated.

The present invention utilizes various planes of seed crystals, including polar planes (N-plane and Ga-plane), non-polar planes (m-plane and a-plane) and semi-polar planes in the growth process.

Technical description

The present invention includes a method for growing high quality GaN bulk crystals at a high growth rate. In particular, the present invention utilizes various planar seed crystals in the growth process. For example, it is crucial to choose a suitable growth plane.

Figure 1 is a schematic diagram of an autoclave that may be used in one embodiment of the present invention. The autoclave 1 includes an autoclave lid 2, an autoclave screw 3, a gasket 4, an ammonia discharge port 5, and a baffle plate 6.

Preferably, the autoclave 1 is an internal diameter 1-inch autoclave made of a Ni-Cr superalloy, although other vessels may also be used. The baffle plate 6 defines and separates the higher temperature zone of the autoclave and the lower temperature zone of the autoclave. The aforementioned seed crystals are mounted in the higher temperature region (growth region) of the autoclave and the baffle plate 6 is placed in the middle of the autoclave and is placed in a Ni-Cr mesh basket, The polycrystalline GaN crystal is located in the lower temperature region (nutrient region) of the autoclave. Nutrient polycrystalline crystals were synthesized by the HVPE method. Next, a mineralizer, sodium amide or sodium metal, was introduced into the autoclave. The autoclave lid (2) was closed and tightened with the required torque. These loading processes were all performed in a nitrogen glove box to avoid oxygen contamination.

Next, the autoclave was cooled using liquid nitrogen. Next, ammonia was introduced into the autoclave. The amount of ammonia was monitored by the flow meter and the required amount of ammonia was condensed inside the autoclave and then closed the autoclave high pressure valve. The amount of ammonia was strictly controlled to obtain the required pressure at the growth temperature of 500 to 600 ° C, in this case ~ 200 MPa. Next, the autoclave is placed in a resistive heater system, where the heating system is divided into a lower region and an upper region, each corresponding to a growing region and a nutrient region of the autoclave.

The temperature was raised using a speed of ~ 2 ° C per minute and maintained at 500-550 ° C for 1-2 days to etch the seed surface. Next, the temperature of the growth region of the autoclave was increased again to 550 to 600 ° C. This temperature gradient causes a difference in solubility between the two regions of the autoclave and also improves the convection inside the autoclave for nutrient transfer. The autoclave was maintained at growth temperature for 13-23 days (4 growths were performed, for example, the maximum was 23 days and the minimum was 13 days). Next, the autoclave was turned to room temperature, and ammonia was released. Finally, crystals were taken from the autoclave.

Growth rate of crystal obtained by micrometer = growth rate was investigated, and crystals obtained by X-ray diffractometer were examined for crystal quality evaluation. The surface roughness of the seed crystal was investigated by a step height measurement. The experimental results are described in more detail below.

Experiment result

Fig. 2 is a table showing the thickness of the crystals obtained and the estimated growth rate data for each plane of the seed crystal. The growth rate depends strongly on the growth plane. The semi-polar (11-22) / (11-2-2) plane seed showed the fastest growth rate. Semi-polar (10-12) / (10-1-2) plane seeds also showed fast growth rates; However, the (10-12) plane was unstable during the growth process in that (10-11) the facet appeared partially. On the other hand, the non-polar (10-10) / (10-10) seed showed a slower growth rate, indicating the stability of this plane. During growth, the (11-20) a-plane disappeared and changed to (10-10) m-plane. Ga-face / N-face grown crystals showed relatively fast growth rates; However, poor crystal quality was confirmed by XRD (x-ray diffraction) measurement. In addition, an extremely rough surface of the Ga-face grown crystal can be observed with an optical microscope.

FIG. 3 is a table showing XRD rocking curve FWHM (full width width) data for each crystal grown on the seed crystal. All seed crystals referred to herein are polished and have an atomically smooth surface with an RMS roughness of less than 1 nm. The non-polar / semi-polar planes showed evidence of good crystal quality; However, despite growing from an atomically smooth surface, c-planar crystals showed evidence of poor crystal quality (multiple grains and wider XRD curves FWHM are evidence of poorer crystal quality). Moreover, the roughness of 2771 arcseconds in (0001) planar growth, and the large number of grains present in both the (0001) and (000-1) growth planes, for example, as in the ammonothermal method , Indicating that growth of these planes using the solvent heating method is likely to create unacceptable surfaces in device fabrication for mechanical, electrical, and / or other reasons. However, the present invention is based on the fact that the semi-polar growth rate obtained by the same solvent heating method as the unacceptable polarity film and the relative smoothness of the semi-polar film surface are, for example, " Quality "semi-polar surface.

Figure 4 is a graph showing the correlation between the on-axis XRD FWHM data of each seed surface and the axial XRD FWHM data of the resulting crystals. A seed with a small FWHM does not necessarily make a small FWHM crystal. Also, the sliced and etched seed surface results in a worse FWHM value for the crystals being produced.

Figure 5 is a graph showing the correlation between the RMS roughness of each seed surface and the axial XRD FWHM data of the resulting crystal. RMS roughness is measured with a step height measurement system. A smooth seed surface results in better crystal quality. Microscopically, multiple directional growth occurs on the rough seed surface and the FWHM is widened.

In some bulk crystal growth, etching off the seed surface slightly before growth is common and effective. The purpose of the etching is to remove the damaged layer, to make the seed surface smoother, or " clean " impurities from the seed surface. However, this does not appear to be effective in supercritical ammonia and GaN; At least, etching with supercritical ammonia can not smooth the rough GaN surface.

Experimental results on off orientation

In one embodiment of the invention, several off-oriented seed crystals were mounted with the same growth process. The present invention relates to a process for preparing seed crystals having off-orientation from the axial (10-10) m-plane seed crystal (on-axis (10-10) C + / c- (direction) toward the c + / c- direction, 5 degrees toward the c + / c- direction, 28 degrees toward the c + / c- (10-11) / 10 degrees) / (10-1-2) direction, and 90 degrees toward c + / c- (0001) / (000-1).

The seed crystal was grown in the [0001] direction using the HVPE method and sliced into a wafer shape with the required off orientation as described above. The off-orientation permissible limit of the seed wafer was +0.5 / -0.5 degrees.

This embodiment of the invention performed a four-fold growth experiment under similar conditions as described above.

Figure 6 shows the off orientation dependence of growth rate. The growth rate strongly depends on the off orientation angle. Larger off-oriented seed crystals show faster growth rates, up to eight times faster than axial (10-10) m-plane seeds.

Figure 7 shows the XRD locking curve FWHM data for each off-oriented seed crystal. Seed crystals of -90 to 48 degrees off-orientation showed similar crystal quality. On the other hand, (0001) crystals showed a much larger FWHM.

Faster growth rates can be achieved without sacrificing crystal quality by using off-oriented seed crystals.

8 is an enlarged view of the range of 0 to 5 degrees in Fig. This shows that even a small off-orientation of about 2 or 5 degrees can result in growth rates about three times faster.

9 is an enlarged view of the range of 0 to 5 degrees in Fig. This shows that the crystal quality is highest when the off-orientation is between 0 and 5 degrees.

The best crystal quality can be achieved by using slightly off-oriented seed crystals.

Possible variations

In addition to GaN growth in supercritical ammonia as described above, the techniques of the present invention are applicable to other Group III nitride crystallites such as AlN, InN, and the like. Also, the technique of the present invention is applicable to hexagonal crystals such as ZnO grown by a hydro-thermal method.

Even though axial nonpolar and semi-polar seed crystals are used, any misoriented wafer from these planes is also applicable. The present invention uses an m-plane seed crystal having an off orientation toward the c + / c-direction, but an off orientation oriented toward the a-direction or another direction is also applicable.

It is reasonable to assume that poorer quality determinations contain more impurities as compared to higher quality crystals produced under the same / similar growth conditions as poorer quality determinations. A lower impurity incorporation rate is expected when using non-polar / semi-polar seed crystals compared to Ga-face or N-face seed crystals.

It has been found that non-polar / semi-polar flat crystals are of higher quality compared to c-planar crystals. The present invention also finds that crystals grown on slightly off-oriented m-plane seeds are of higher quality than crystals grown on axial m-plane seeds. The reason for this is not the growth method, but the nature of the hexagonal crystal structure. Therefore, the present invention can be widely applied to other growth techniques such as vapor phase growth and the like.

Solvothermal growth is growth by supercritical fluid. Solvent thermal growth includes, for example, hydrothermal growth and ammonthermal growth. The present invention also anticipates hydrothermal growth of, for example, ZnO crystals.

Benefits and Improvements

High-quality crystalline c-plane crystals have been reported using supercritical ammonia at a slow growth rate [1]. It has been found in the present invention that the same or better XRD FWHM can be achieved at a growth rate of more than 10 times faster using nonpolar / semi-polar flat seed crystals. At the higher growth rate conditions, as shown in the XRD-FWHM data, the c-plane grown crystal quality was worse. It has been confirmed that a fast growth rate can be achieved simultaneously with high-quality crystals by selecting a suitable growth plane.

In the present invention, by using slightly off-oriented m-plane seed crystals, excellent XRD FWHMs with about 5 times faster growth rate than those using m-plane seed crystals that are not off- Can be achieved. As shown in the XRD-FWHM data, the quality of c-plane grown crystals is worse. It was confirmed that a fast growth rate and a high quality crystal can be achieved at the same time by selecting an appropriate off orientation angle.

Figure 10 illustrates growth according to one or more embodiments of the present invention.

A seed crystal 1000 having a growth surface 1002 is shown. The seed crystal 1000 is typically a hexagonal wurtzite crystal, typically a Group III nitride structure. As discussed above, the growth surface 1002 is a nonpolar plane or a semi-polar plane of the seed crystal 1000. In addition, the growth surface 1002 may be an off-oriented m-plane of the seed crystal 1000, or a plane off-oriented from any plane of the seed crystal 1000. The layer 1004 is grown on the growth surface 1002 by a solvent-thermal process, typically a dark-heat process. Since the growth planes grow at different growth rates, the materials grown on each plane have different properties, for example, in electrical properties, surface smoothness, etc., and the growth planes are determined by device requirements, time available, and Cost, and so on. Thus, for example, and not limitation, growth surface 1002 on seed crystal 1000 can be selected to maximize growth rate of layer 1004, maximize surface smoothness of layer 1004, Any other property required in layer 1004 may be designed by selecting another growth surface 1002 on crystal 1000. [

references

The following references are incorporated herein by reference: < RTI ID = 0.0 >

[1] Hashimoto et al., Nat. Mater. 6 (2007) 568.

European Patent Application Publication No. EP 1 816 240 A1 entitled " Hexagonal Wurtzite Single Crystal, Process for Producing the Same, and Hexagonal Wurtzite Single Crystal Substrate, " filed September 21, 2005.

conclusion

The present invention discloses a crystal and crystal growth method. A bulk monocrystal according to the present invention comprises a hexagonal wurtzite structure wherein the bulk monocrystal is grown via solvent-thermal growth using a seed having a nonpolar plane or a semi-polar plane.

Such crystals also include a bulk monocrystal, optionally a Group III nitride, and the seed for crystal having a growth surface comprises one or more of the following planes: {10-10}, {10-11}, {10-1- 1}, {10-12}, {10-1-2}, {11-20}, {11-22}, or {11-2-2}, the seed for crystal having a growth surface has an off- plane, and the off-orientation angle is greater than 0.5 degrees and less than 48 degrees, the off-orientation angle is greater than 0.5 degrees and less than 4.5 degrees with respect to the [0001] (RMS) roughness of the growth surface of the seed is less than 100 nm, and the x-ray diffraction intensity of the bulk crystal is in the range of < RTI ID = 0.0 & Ray diffraction (XRD) rocking curve half width (FWHM) is less than 500 arcsec, the bulk monocrystal is gallium nitride, Obtained.

A method of growing a bulk monocrystal having a hexagonal wurtzite structure according to one or more embodiments of the present invention comprises performing solvent-thermal crystal growth on a seed crystal having a growth surface comprising a nonpolar plane or a semi-polar plane .

Such a method also optionally includes a bulk monocrystal, which is a group III nitride,

The growth surface includes one or more of the following planes: {10-10}, {10-11}, {10-1-1}, {10-12}, {10-1-2}, {11- 20}, {11-22}, or {11-2-2}, the growth surface includes an m-plane having an off orientation angle, the off orientation angle toward the [0001] The off-orientation angle is greater than 0.5 degrees and less than 4.5 degrees, the off-orientation angle is toward the [000-1] direction, is greater than 0.5 degrees and less than 48 degrees, Wherein the average surface roughness (RMS) of the growth surface is less than 100 nm, the x-ray diffraction (XRD) rocking curve half width (FWHM) of the bulk crystal is less than 500 arcsec, the bulk crystal is gallium nitride, And a substrate is obtained by cutting.

Another method of fabricating a Group III nitride bulk crystal or device according to one or more embodiments of the present invention includes growing a Group III nitride bulk crystal or device on a growth surface of the seed, Polarity plane, or at least one off-orientation of the nonpolar planar or semi-polar plane, and growing in a non-polar, semi-polar or off-oriented direction, the quality of the group III nitride bulk crystal or device, Growth rate, or both quality and growth rate.

Another method of making Group-III nitride crystals in accordance with one or more embodiments of the present invention includes growing Group-III nitride bulk crystals through a solvent-and-heat process wherein the Group-III nitride bulk crystals are grown in a non- Wherein the growth plane is selected based on at least one of a growth rate in the growth plane and a quality of growth in the growth plane.

This concludes the description of the preferred embodiment of the present invention. The foregoing description of one or more embodiments of the invention has been presented for the purposes of illustration and description. This is not intended to be exhaustive of the invention or to limit the invention to the precise form disclosed. Many variations and modifications are possible without departing from the essence of the present invention in light of the above teachings. The scope of the invention is not to be limited by this detailed description, but rather by the full scope of equivalents of the claims appended hereto and the appended claims below.

1 autoclave
2 Autoclave lid
3 Autoclave screws
4 gaskets
5 Ammonia outlet
6 Baffle plate
1000 seed crystal
1002 growth surface
1004 floor

Claims (17)

1. A method for growing a group III nitride bulk single crystal having a hexagonal wurtzite structure,
Solvo-thermal crystal growth on a Group III nitride seed crystal having a growth surface comprising a non-polar planar or semi-polar plane with an off-orientation angle greater than 0.5 degrees and less than 48 degrees, thermal crystal growth to produce a group III nitride bulk single crystal,
Wherein growth on a growth surface of a Group III nitride seed crystal comprising a nonpolar plane or a semi-polar plane having an off orientation angle greater than 0.5 degrees and less than 48 degrees comprises growing a Group III nitride seed crystal phase with a growth surface comprising a polar plane To produce a smoother surface compared to the surface. The method according to claim 1,
Wherein the growth surface comprises one or more of the following planes:
{10-10}, {10-11}, {10-1-1}, {10-12}, {10-1-2}, {11-20}, {11-22}, or {11-2 -2}. The method according to claim 1,
Wherein the growth surface comprises an m-plane having the off-orientation angle. The method of claim 3,
Wherein the off-orientation angle is directed to the [0001] direction. 5. The method of claim 4,
Wherein the off-orientation angle is in the [0001] direction and is greater than 0.5 degrees and less than 4.5 degrees. The method of claim 3,
Wherein a higher crystal quality is obtained using a growth surface comprising an m-plane having an off-orientation angle greater than 0.5 degrees and less than 48 degrees. The method according to claim 6,
Wherein the higher crystal quality is obtained using a growth surface comprising an m-plane with an off-orientation angle greater than 0.5 degrees and less than 5 degrees. The method of claim 3,
Wherein the growth surface comprising an m-plane having an off-orientation angle greater than 0.5 degrees and less than 48 degrees has a higher growth rate than a growth surface comprising an axial m-plane. The method of claim 3,
Wherein the growth surface comprising an m-plane with an off-orientation angle greater than 0.5 degrees and less than 48 degrees has a higher growth rate without reducing crystal quality, compared to a growth surface comprising a polar plane. The method according to claim 1,
Wherein a growth surface comprising a non-polar planar or semi-polar plane having an off-orientation angle greater than 0.5 degrees and less than 48 degrees produces a smoother surface with a higher growth rate than a growth surface comprising said polar plane . The method of claim 3,
Wherein the off-orientation angle is directed toward the [000-1] direction. The method according to claim 1,
Wherein the average surface roughness (RMS) roughness of the growth surface is less than 100 nm. The method according to claim 1,
Wherein the x-ray diffraction (XRD) rocking curve half-width (FWHM) of the bulk crystal is less than 500 arcsec. The method according to claim 1,
Wherein the bulk crystal is gallium nitride. The method according to claim 1,
Wherein the crystal is cut to obtain a substrate. CLAIMS What is claimed is: 1. A method of making a Group III nitride bulk crystal or device,
(a) growing the Group III nitride bulk crystal or device on a growth surface of a Group III nitride seed using a solvent-thermal crystal growth technique, wherein the growth surface of the Group III nitride seed is grown on one or more semi- Wherein said off orientation is greater than 0.5 degrees and less than 48 degrees, and wherein said off-orientation is at least one of said semi-polar planes, or said III Growth on the growth surface of the group nitride seed comprises creating a smoother surface relative to growth on the growth surface of the group III nitride seed comprising the polar planes;
(b) the growing step is performed in a semi-polar or off-oriented non-polar direction selected to enhance both the crystal quality, growth rate, or crystal quality and growth rate of the Group III nitride bulk crystal or device. A method for producing a Group III nitride crystal,
Growing a Group III nitride bulk crystal by a solvent-thermal method, wherein the Group III nitride bulk crystal has a growth plane that includes a non-polar planar or semi-polar plane having an off orientation angle that is greater than 0.5 degrees and less than 48 degrees Wherein the growth plane is selected based on at least one of a growth rate in a growth plane and a crystal quality in a growth plane, and wherein the nonpolar plane or half plane having an off orientation angle greater than 0.5 degrees and less than 48 degrees Wherein growing in a growth plane comprising a polar plane produces a smoother surface than growth in a growth plane being a c-plane.

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