CN115125617B - Method for preparing self-supporting gallium nitride bulk single crystal by setting temperature gradient - Google Patents
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- 239000013078 crystal Substances 0.000 title claims abstract description 89
- 229910002601 GaN Inorganic materials 0.000 title claims abstract description 74
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 44
- 239000007789 gas Substances 0.000 claims abstract description 35
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims abstract description 33
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims abstract description 33
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000002248 hydride vapour-phase epitaxy Methods 0.000 claims abstract description 25
- 238000000137 annealing Methods 0.000 claims abstract description 19
- 239000000758 substrate Substances 0.000 claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 claims abstract description 12
- UPWPDUACHOATKO-UHFFFAOYSA-K gallium trichloride Chemical compound Cl[Ga](Cl)Cl UPWPDUACHOATKO-UHFFFAOYSA-K 0.000 claims abstract description 11
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 22
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims description 16
- 229910052733 gallium Inorganic materials 0.000 claims description 15
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- 239000012159 carrier gas Substances 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 3
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000001816 cooling Methods 0.000 abstract 1
- 238000002017 high-resolution X-ray diffraction Methods 0.000 description 16
- 239000007788 liquid Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- XOYLJNJLGBYDTH-UHFFFAOYSA-M chlorogallium Chemical compound [Ga]Cl XOYLJNJLGBYDTH-UHFFFAOYSA-M 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- NWAIGJYBQQYSPW-UHFFFAOYSA-N azanylidyneindigane Chemical compound [In]#N NWAIGJYBQQYSPW-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000407 epitaxy Methods 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000000825 ultraviolet detection Methods 0.000 description 1
- 238000001429 visible spectrum Methods 0.000 description 1
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- C30B29/10—Inorganic compounds or compositions
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- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
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- C30B25/02—Epitaxial-layer growth
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Abstract
The invention discloses a method for preparing self-supporting gallium nitride bulk monocrystal by setting temperature gradient, which comprises the steps of fixing seed crystal on a substrate of an HVPE growth system and placing the seed crystal and NH in a high-temperature growth area 3 The distance between the gas outlets is 5-20 cm, and the temperature gradient between the seed crystal and the ammonia gas outlets is controlled; heating to a required temperature, introducing hydrogen chloride to react with Ga to generate gallium chloride, transporting to a high-temperature growth area, reacting with ammonia to epitaxially grow GaN, stopping introducing hydrogen chloride after reacting for 1-2 hours at a temperature gradient of-2 ℃, adjusting the temperature gradient to be-3~3 ℃/cm, annealing at a high temperature, continuing introducing hydrogen chloride, continuously epitaxially growing GaN for 1-2 h, adjusting the temperature gradient to be-3-3 ℃/cm, preserving heat for 1-2 hours, introducing hydrogen chloride again, epitaxially growing GaN for 2-48 hours, closing the hydrogen chloride, and cooling the system to room temperature. According to the method for forming different temperature gradient growth through temperature control of multiple temperature areas, the temperature gradient of the high temperature growth area is changed, the surface morphology and crystal quality of the grown GaN single crystal are changed, the time and production cost are saved, and the self-supporting GaN bulk single crystal is obtained.
Description
Technical Field
The invention belongs to the technical field of semiconductor synthesis, and particularly relates to a method for preparing self-supporting gallium nitride bulk single crystals by setting a temperature gradient.
Background
Gallium nitride (GaN) is used as a representative of a third-generation wide bandgap semiconductor material, is a direct bandgap semiconductor material, has the excellent characteristics of wide bandgap (3.44, eV), high breakdown field strength, high saturated electron mobility, small dielectric constant, large thermal conductivity, strong radiation resistance and the like, can greatly improve the high-voltage, high-frequency and high-power working performance of an electronic device, is widely applied to short-wavelength lasers, ultraviolet detectors and high-frequency high-power devices, and has great application prospects in the fields of military, new energy sources, electric automobiles and the like. In addition, gaN can be matched with indium nitride (InN) and aluminum nitride (AlN), and the regulation and control of the forbidden band width from 0.7 eV to 6.2 eV can be realized according to different proportions, so that the light-emitting range is not limited to blue light, and the complete coverage of the whole visible spectrum is realized. Therefore, LEDs with different wave bands can be prepared, and the LED-based solid-state lighting device is further applied to the aspects of lighting equipment such as white light lighting, full-color display equipment and the like, and meanwhile, the LED-based solid-state lighting device is more energy-saving, environment-friendly and efficient. Meanwhile, gaN has stronger resistance to the effect of ion radiation, so that the performance of electronic devices in the spacecraft can be effectively improved, and the service life of the spacecraft is prolonged; while GaN devices achieve miniaturization of the electron payload and provide higher power density and efficiency, thereby reducing the weight and volume of the spacecraft. GaN is therefore also an important material for electronics in spacecraft. GaN is a core of industries such as ultraviolet detection, high-frequency high-power devices, military devices, space electronics, and various energy-saving devices due to its excellent properties, and has been gaining attention internationally in recent years.
The hydride epitaxy production method (HVPE) is a mainstream growth technology for preparing a GaN monocrystal substrate at present, does not need ultrahigh temperature and ultrahigh pressure growth conditions, has low requirements on production equipment, and has the advantages of high growth speed, easy realization of doping and the like. The HPVE reactor mainly comprises two reaction zones, a low temperature zone and a high temperature reaction zone, wherein the temperature of the low temperature zone is usually 850 ℃, and the reaction of metal Ga and HCl mainly occurs to convert liquid-phase Ga metal into gas-phase GaCl so as to be transported to a substrate zone through carrier gas; the temperature of the high temperature area is 1040 ℃, and GaCl reacts with NH3 to realize the growth of GaN monocrystal on the substrate:
in order to obtain better self-supporting GaN, a plurality of researches develop various substrate pretreatment methods, including techniques of vacancy auxiliary separation, pattern masking, two-dimensional material coating and the like, so that the quality of crystal growth is effectively improved, and meanwhile, the self-supporting GaN single crystal is obtained. But pretreatment of the substrate does increase the cost and process of growth to some extent and some methods may even introduce some impurities. This is disadvantageous for obtaining a low cost homogenous substrate.
Thus, there is a need for a convenient, compact, easy to handle, low cost method of preparing self-supporting GaN bulk single crystals.
Disclosure of Invention
Aiming at the problems of poor surface morphology and crystal quality of GaN crystals prepared by an HVPE method in the prior art, the invention provides a method for preparing self-supporting GaN bulk single crystals by setting a temperature gradient, and the surface morphology and crystal quality of the grown GaN single crystals are effectively changed by changing the temperature gradient of a high-temperature growth area of an HVPE growth system, so that the method is a method for preparing the self-supporting GaN bulk single crystals, which is convenient, simple, easy to operate and low in cost.
The invention is realized by the following technical scheme:
a method for preparing a self-supporting bulk gallium nitride single crystal by setting a temperature gradient, comprising the steps of:
(1) Fixing seed crystal on substrate support of HVPE growth system and placing in high temperature growth zone to make seed crystal and NH 3 The distance between the air outlets is 5 cm to 20cm, the HPVE production system is heated to the required temperature, and the seed crystal and NH are controlled 3 The temperature gradient of the air outlet, continuously introducing nitrogen and ammonia in the heating process;
(2) After the temperature is stable, starting to introduce hydrogen chloride gas, reacting the hydrogen chloride gas with Ga in a low-temperature reaction zone to generate gallium chloride, transporting the gallium chloride to a high-temperature growth zone through carrier gas, reacting with ammonia gas, epitaxially growing GaN at a seed crystal, wherein the epitaxial growth temperature gradient is-2 ℃, and the reaction time is 1-2 hours;
(3) After reacting for 1-2 hours, stopping introducing hydrogen chloride gas, adjusting the temperature of the high-temperature growth area, enabling the annealing temperature gradient of the seed crystal and the ammonia gas outlet to be-3~3 ℃/cm, and preserving heat for 1-2 hours at the temperature to realize primary high-temperature annealing;
(4) After the primary high-temperature annealing is finished, continuously introducing hydrogen chloride gas to enable GaN to continue epitaxial growth of 1-2 h, and obtaining a GaN porous structure layer;
(5) Stopping introducing hydrogen chloride gas, adjusting the temperature of the high-temperature growth area, enabling the annealing temperature gradient of the seed crystal and the ammonia gas outlet to be-3-3 ℃/cm, and preserving heat for 1-2 h at the temperature to realize secondary high-temperature annealing;
(6) And after the secondary high-temperature annealing is finished, hydrogen chloride gas is introduced again, so that GaN epitaxially grows for 2-48 hours, the hydrogen chloride gas is closed, and the HVPE growth system is cooled to room temperature.
Further, the HVPE growth system is a vertical HVPE growth system, raw material gas is transported from bottom to top, a gallium source is located in a low-temperature reaction zone, a high-temperature growth zone comprises a first heating zone, a second heating zone and a third heating zone which are arranged from bottom to top, and seed crystals are located in the second heating zone of the high-temperature growth zone.
Further, the height of the first heating interval is 100-200mm, the height of the second heating interval is 200-350mm, and the height of the third heating interval is 100-200mm.
Further, the temperature of the first heating interval is set to 900-1100 ℃, the temperature of the second heating interval is set to 1000-1200 ℃, and the temperature of the third heating interval is set to 900-1200 ℃.
Further, the temperature of the low-temperature reaction zone is set to be 700-900 ℃.
Further, the time for heating to the desired temperature in the step (1) was 7 hours.
Further, the epitaxial growth temperature gradient and the annealing temperature gradient are not equal at the same time.
Further, the seed crystal is MOCVD-GaN/Al 2 O 3 The method comprises the steps of carrying out a first treatment on the surface of the The substrate support is connected with the rotatable seed rod.
Further, in the heating process, high-purity nitrogen is continuously introduced as atmosphere gas, and high-purity ammonia is simultaneously introduced.
The reaction principle of the preparation method is as follows:
the substrate hangs down on the upper part of the equipment and can rotate, the raw material gas is transported from bottom to top, and the whole growth process is carried out under normal pressure. The whole HPVE growing system is formed by five groups of heating modules, and the temperature is independently controlled in a resistance wire heating mode, so that the whole growing system has complete and controllable temperature field distribution and is independently stable, and the temperature gradient is adjusted by changing the length of each heating interval or setting different temperatures of the intervals.
The growth adopts high-purity N 2 As a carrier gas; metal Ga with purity of 7N is used as Ga source, and reacts with electronic grade HCl gas in low temperature reaction zone (set temperature is 850 ℃) to obtain GaCl, and is carried to high temperature zone by carrier gas, and NH with purity of 6N is provided for N source 3 The reaction, obtaining GaN, and growing GaN on a seed crystal (using GaN obtained by MOCVD growth as a seed crystal, on the seed crystal (or called substrate)) by HVPE method.
The growth process comprises the following steps: through a mass flow controller, nitrogen is continuously utilized to convey HCl gas (from bottom to top) into a quartz gallium boat, and HCl reacts with liquid gallium in the gallium boat in a low-temperature reaction zone to generate gallium chloride:
then gallium chloride generated by the reaction is conveyed out of the gallium boat through small holes in the gallium boat by nitrogen (from bottom to top) controlled by another route mass flow controller, so as to reach a high-temperature growth area; meanwhile, in the other path, the nitrogen is controlled by a mass flow controller to convey ammonia, a quartz conveying pipeline penetrates through a gallium boat and is directly conveyed to a high-temperature growth area, and when gallium chloride and ammonia just contact with each other at a substrate, the gallium chloride and the ammonia are subjected to further reaction.
The resulting GaN is continuously epitaxially grown to obtain a self-supporting GaN single crystal. The quality of GaN single crystal is further improved by controlling the temperature gradient of the high-temperature growth area, thereby changing the quality of GaN single crystal, and further improving the quality of HVPE (hydride vapor phase epitaxy) GaN single crystal, thereby obtaining high-quality self-supporting GaN single crystal. The whole growth process is carried out in a nitrogen environment continuously flowing from bottom to top. So as to ensure the growth atmosphere and ensure the gas flow direction from bottom to top.
Advantageous effects
According to the method for forming different temperature gradient growth through temperature control of multiple temperature areas, the surface morphology and crystal quality of the grown GaN single crystal are effectively changed through changing the temperature gradient of the high temperature growth area, time and production cost are saved, and the self-supporting GaN bulk single crystal is effectively obtained.
Drawings
FIG. 1 shows an HVPE growth system used in the present invention;
FIG. 2 is a Scanning Electron Microscope (SEM) image of a free-standing gallium nitride crystal prepared according to example 1;
FIG. 3 is a high resolution X-ray diffraction (HRXRD) rocking curve and full width at half maximum (FWHM) plot of the (002) and (102) planes of the free-standing gallium nitride crystal prepared in example 1;
FIG. 4 is a Scanning Electron Microscope (SEM) image of a free-standing gallium nitride crystal prepared in example 2;
FIG. 5 is a high resolution X-ray diffraction (HRXRD) rocking curve and full width at half maximum (FWHM) plot of the (002) and (102) planes of the free-standing gallium nitride crystal prepared in example 2;
FIG. 6 is a Scanning Electron Microscope (SEM) image of a free-standing gallium nitride crystal prepared in example 3;
FIG. 7 is a high resolution X-ray diffraction (HRXRD) rocking curve and full width at half maximum (FWHM) plot of the (002) and (102) planes of the free-standing gallium nitride crystal prepared in example 3;
FIG. 8 is a Scanning Electron Microscope (SEM) image of a free-standing gallium nitride crystal prepared according to example 4;
fig. 9 is a high resolution X-ray diffraction (HRXRD) rocking curve and full width at half maximum (FWHM) diagram of the (002) and (102) planes of the free-standing gallium nitride crystal prepared in example 4.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
As shown in figure 1, the HVPE growth system used in the invention is of a vertical structure, a substrate is hung downwards at the upper part of the equipment and can rotate (connected with a rotatable seed rod), the HVPE growth system comprises a low-temperature reaction zone and a high-temperature reaction zone, liquid gallium (7N) is added into a gallium boat at the lower part of the low-temperature reaction zone, raw material gas is transported from bottom to top, the high-temperature reaction zone comprises a first heating zone, a second heating zone and a third heating zone which are arranged from bottom to top, seed crystals are positioned in the second heating zone of the high-temperature growth zone, and the whole HVPE growth system is formed by five groups of heating modules through a resistance wire heating mode, and the temperature is independently controlled. Therefore, the whole growth system has complete and controllable temperature field distribution which is independent and stable, and the temperature gradient is adjusted by changing the length of each heating interval or setting different temperatures of the heating intervals. In the HVPE growth system, the height of the first heating interval is 200mm, the height of the second heating interval is 300mm, and the height of the third heating interval is 150mm;
the gallium metal in the example is 7N liquid gallium metal, the hydrogen chloride gas is electron-grade (5N) hydrogen chloride gas, and the nitrogen and ammonia are high-purity nitrogen and ammonia.
A free-standing bulk gallium nitride single crystal was prepared using the HVPE growth system shown in fig. 1.
Example 1
(1) MOCVD-GaN/Al 2 O 3 (Al with MOCVD GaN film) 2 O 3 ) Substrate as a substratePutting seed crystals into an HVPE growth system, fixing the seed crystals on a substrate support and connecting the seed crystals with a rotatable seed crystal rod, putting the fixed seed crystals into a second heating zone of a high-temperature growth zone, wherein the distance between the seed crystals and an ammonia gas outlet is 10 cm;
(2) Adding liquid gallium into a gallium boat, connecting an ammonia gas inlet pipeline, a nitrogen gas inlet pipeline and a hydrogen chloride inlet pipeline, heating the whole HVPE growing system for 7 hours to a growing temperature, wherein the temperature of a low-temperature reaction zone is 850 ℃, the temperature of an air outlet is 1060 ℃, the temperature of a substrate seed crystal is 1070 ℃, the temperature is uniformly changed, the temperature gradient (epitaxial growth) is 1 ℃/cm, and high-purity nitrogen is continuously introduced as atmosphere gas and high-purity ammonia gas is independently introduced in the heating process to prevent GaN from decomposing so as to ensure the integrity of the seed crystal before growing;
(3) After the temperature gradient of a 7h high-temperature growth area reaches the required condition, preserving heat for 1h until the temperature is stable, starting to introduce hydrogen chloride gas, enabling the hydrogen chloride gas to react with liquid Ga in a gallium boat in a low-temperature reaction area to generate gallium chloride, transporting the gallium chloride to the high-temperature growth area through carrier gas, reacting with ammonia gas, epitaxially growing GaN at a seed crystal, and obtaining a high-quality GaN single crystal epitaxial film with the epitaxial growth time of 1 h;
(4) After 1h of reaction, stopping introducing hydrogen chloride gas, and adjusting the three-stage temperature of the high-temperature growth zone to be: 1030. the temperature of 1070 ℃ and 1070 ℃ is 1060 ℃ at which the temperature gradient is 0 ℃/cm, and the temperature is kept for 1h to realize primary high-temperature annealing;
(5) After the primary high-temperature annealing is finished, adjusting the epitaxial growth temperature gradient in the step (2), and continuously introducing hydrogen chloride gas into an HVPE growth system to enable GaN to continuously grow epitaxially for 1h, so as to obtain a GaN porous structure layer;
(6) Stopping introducing hydrogen chloride gas, and adjusting the three-stage temperature of the high-temperature growth zone to be: 1030,1080,1070, changing the temperature gradient of the seed crystal and the air outlet to-1 ℃/cm, and preserving the temperature for 1h at the temperature to realize secondary high-temperature annealing;
(7) And (3) after the secondary high-temperature annealing is finished, adjusting the temperature gradient in the step (2), introducing hydrogen chloride gas again to enable GaN to epitaxially grow for 48 hours, closing the hydrogen chloride gas, and reducing the HVPE growth system to room temperature.
A free-standing 4 inch GaN single crystal was obtained, as shown in fig. 2 for Scanning Electron Microscopy (SEM), as shown in fig. 3 for high resolution X-ray diffraction (HRXRD) rocking curves and full width at half maximum (FWHM) for (002) and (102) crystal planes of the crystal, respectively, of 390,278 arcsec.
Example 2
Unlike example 1, example 2 did not set a temperature gradient, (substrate seed and gas outlet temperatures were 1060 ℃ C., temperature gradient was 0) GaN grown, and a Scanning Electron Microscope (SEM) image of the GaN was shown in FIG. 4, with more pits on the crystal surface; the high resolution X-ray diffraction (HRXRD) rocking curves and full width at half maximum (FWHM) patterns of the (002) and (102) crystal planes of the crystal are shown in fig. 5, and the (002) and (102) full widths are 699 and 746 arcsec, respectively.
Example 3
Unlike example 1, example 3 was conducted under such conditions that only a temperature gradient of 1 ℃/cm was set and no temperature adjustment was conducted, and a GaN crystal was grown, in which a Scanning Electron Microscope (SEM) chart was shown as a surface SEM chart in fig. 6, and high-resolution X-ray diffraction (HRXRD) rocking curves and full width at half maximum (FWHM) charts of (002) and (102) crystal planes were shown as fig. 7, and half maximum widths of (002) and (102) were 432, 486 arcsec, respectively.
Example 4
Unlike example 1, example 4 was conducted with only a temperature gradient of-1 ℃/cm, without temperature adjustment, a GaN crystal was grown, a Scanning Electron Microscope (SEM) image thereof was shown as a surface SEM image of fig. 6, high-resolution X-ray diffraction (HRXRD) rocking curves and full width at half maximum (FWHM) images of (002) and (102) crystal planes thereof were shown as fig. 7, and half peak widths (002) and (102) thereof were 524, 626 arcsec, respectively.
As can be seen from comparison of example 1, which uses different temperature gradients (examples 2,3, 4) and multi-step temperature gradient continuous growth, the presence of the temperature gradient is smaller than the half-width of the crystal in the absence of the temperature gradient, indicating that the growth quality of GaN single crystals is improved. And through multi-step continuous growth, in the growth process, the temperature gradient is continuously regulated, and the half-peak width of the crystal obtained by growth is obviously reduced to 390,278 arcsec, which indicates that the crystal quality is obviously improved.
Although the present invention has been described in detail by way of preferred embodiments with reference to the accompanying drawings, the present invention is not limited thereto. Various equivalent modifications and substitutions may be made in the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and it is intended that all such modifications and substitutions be within the scope of the present invention/be within the scope of the present invention as defined by the appended claims. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (8)
1. A method for preparing a bulk single crystal of self-supporting gallium nitride by setting a temperature gradient, comprising the steps of:
(1) Fixing seed crystal on substrate support of HVPE growth system and placing in high temperature growth zone to make seed crystal and NH 3 The distance between the air outlets is 5 cm to 20cm, the HPVE production system is heated to the required temperature, and the seed crystal and NH are controlled 3 The temperature gradient of the air outlet, continuously introducing nitrogen and ammonia in the heating process;
(2) After the temperature is stable, starting to introduce hydrogen chloride gas, reacting the hydrogen chloride gas with Ga in a low-temperature reaction zone to generate gallium chloride, transporting the gallium chloride to a high-temperature growth zone through carrier gas, reacting with ammonia gas, epitaxially growing GaN at a seed crystal, wherein the epitaxial growth temperature gradient is-2 ℃, and the reaction time is 1-2 hours;
(3) After reacting for 1-2 hours, stopping introducing hydrogen chloride gas, adjusting the temperature of the high-temperature growth area, enabling the annealing temperature gradient of the seed crystal and the ammonia gas outlet to be-3~3 ℃/cm, and preserving heat for 1-2 hours at the temperature to realize primary high-temperature annealing;
(4) After the primary high-temperature annealing is finished, continuously introducing hydrogen chloride gas to enable GaN to continue epitaxial growth of 1-2 h, and obtaining a GaN porous structure layer;
(5) Stopping introducing hydrogen chloride gas, adjusting the temperature of the high-temperature growth area, enabling the annealing temperature gradient of the seed crystal and the ammonia gas outlet to be-3-3 ℃/cm, and preserving heat for 1-2 h at the temperature to realize secondary high-temperature annealing;
(6) After the secondary high-temperature annealing is finished, hydrogen chloride gas is introduced again to enable GaN to epitaxially grow for 2-48 hours, the hydrogen chloride gas is closed, and the HVPE growth system is cooled to room temperature;
the HVPE growth system is a vertical HVPE growth system, raw material gas is transported from bottom to top, a gallium source is positioned in a low-temperature reaction zone, a high-temperature growth zone comprises a first heating zone, a second heating zone and a third heating zone which are arranged from bottom to top, and seed crystals are positioned in the second heating zone of the high-temperature growth zone.
2. The method for producing a bulk mono-crystal of self-supporting gallium nitride according to claim 1, wherein the first heating section has a height of 100 to 200mm, the second heating section has a height of 200 to 350mm, and the third heating section has a height of 100 to 200mm.
3. The method for producing a bulk mono-crystal of self-supporting gallium nitride according to claim 1, wherein the first heating zone temperature is set to 900-1100 ℃, the second heating zone temperature is set to 1000-1200 ℃, and the third heating zone temperature is set to 900-1200 ℃.
4. The method for producing a bulk mono-crystal of self-supporting gallium nitride according to claim 1, wherein the temperature of the low-temperature reaction zone is set to 700 to 900 ℃.
5. The method for producing a bulk mono-crystal of self-supporting gallium nitride according to claim 1, wherein the time for heating to the desired temperature in step (1) is 7 hours.
6. The method for producing a bulk mono-crystal of self-supporting gallium nitride according to claim 1, wherein the epitaxial growth temperature gradient and the annealing temperature gradient are not equal at the same time.
7. The method for preparing a bulk mono-crystal of self-supporting gallium nitride according to claim 1, wherein the seed crystal is MOCVD-GaN/Al 2 O 3 The method comprises the steps of carrying out a first treatment on the surface of the The substrate support is connected with the rotatable seed rod.
8. The method for producing a bulk mono-crystal of self-supporting gallium nitride according to claim 1, wherein in the heating process, high-purity nitrogen gas is continuously introduced as an atmosphere gas, while high-purity ammonia gas is introduced.
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Non-Patent Citations (4)
| Title |
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| Haixiao Hu et al..Growth of Freestanding Gallium Nitride (GaN) Through Polyporous Interlayer Formed Directly During Successive Hydride Vapor Phase Epitaxy (HVPE) Process.《Crystals》.2020,第1-9页. * |
| Qin Huo et al..High quality self-separated GaN crystal grown on a novel nanoporous template by HVPE.《SCIENTIFIC REPORTS》.2018,第1-8页. * |
| 张保国.GaN缓冲衬底的制备及其单晶生长研究.《中国博士学位论文全文数据库 工程科技I辑》.B014-206. * |
| 胡海啸.自支撑GaN单晶的HVPE生长及加工研究.《中国博士学位论文全文数据库 工程科技I辑》.2020,B014-166. * |
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