KR20130112903A - Iii-nitride layer grown on a substrate - Google Patents

Abstract

는 1% 이하이고, 여기서 a_substrate는 기판의 면내 격자 상수이고 a_layer는 III-질화물층의 벌크 격자 상수이다. 본 발명의 실시예들에 따른 다른 방법에서, III-질화물층이 기판 위에 성장된다. 기판은 비-III-질화물 재료이다. III-질화물층은 3원, 4원, 또는 5원 합금이다. III-질화물층은 기계적으로 자기 지지하기에 충분히 두껍고 낮은 결함 밀도를 갖는다.In a method according to embodiments of the present invention, a III-nitride layer is grown over the substrate. The substrate is RAO ₃ (MO) _n , wherein R is selected from Sc, In, Y, and lanthanide based elements; A is selected from Fe (III), Ga, and Al; M is selected from Mg, Mn, Fe (II), Co, Cu, Zn and Cd; n is an integer of 1 or more. In some embodiments,

Is less than or equal to 1%, where a _substrate is the in-plane lattice constant of the substrate and a _layer is the bulk lattice constant of the III-nitride layer. In another method according to embodiments of the present invention, a III-nitride layer is grown over the substrate. The substrate is a non-III-nitride material. III-nitride layers are ternary, quaternary, or pentamembered alloys. The III-nitride layer is thick enough to mechanically self-support and has a low defect density.

Description

III-nitride layer grown on substrate {III-NITRIDE LAYER GROWN ON A SUBSTRATE}

The present invention relates to growing a III-nitride layer on a substrate. The III-nitride layer can be used as a growth substrate for semiconductor light emitting device structures.

Semiconductor light emitting devices including light emitting diodes (LEDs), resonant cavity light emitting diodes (RCLEDs), vertical cavity laser diodes (VCSELs), and edge emitting lasers are among the most efficient light sources currently in use. Material systems currently of interest in the manufacture of high-brightness light emitting devices capable of operating across the visible spectrum are binary, tertiary, group III-V semiconductors, especially gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. And ternary alloys. Typically, III-nitride light emitting devices have different compositions and dopants on sapphire, silicon carbide, III-nitride, or other suitable substrates by organometallic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. It is prepared by epitaxially growing a stack of semiconductor layers of concentration. The stack is usually one or more n-type layers formed on the substrate, for example doped with Si, one or more light emitting layers in the active region formed on the n-type layer or layers, and one or more doped, for example, Mg formed on the active regions. a p-type layer. Electrical contacts are formed in the n-type and p-type regions.

Because natural III-nitride substrates are generally expensive and not widely available, III-nitride devices are usually grown on sapphire or SiC substrates. These non-III-nitride substrates are less than optimal because sapphire and SiC have different lattice constants than the III-nitride layers grown on them, resulting in strain and crystal defects in the III-nitride device layer, and poor Can cause performance and reliability problems.

US Pat. No. 6,086,673 states that "a nitride layer is created on a growth substrate. Independent GaN layers are preferred for many applications. GaN growth is a mechanical failure along that side, parallel to the prevailing growth surface. And intentionally designed to exhibit mechanical weaknesses of sufficient size to cause delamination of the epitaxial nitride layers due to thermal stresses generated as the substrate and nitride layers cool after nitride growth. It can be carried out on a growth substrate. The cooling and peeling mechanism not only allows for the formation of thick and crack-free but also independent GaN layers. Suitable external substrates that promote automatic GaN layer peeling are, for example, For example, containing mica, such as ScMgAlO ₄ , that is, a layered or graphite material, and a species of mica material.

It is an object of the present invention to provide a III-nitride alloy film grown on a substrate. In some embodiments, the III-nitride light emitting device structure can be grown over the III-nitride alloy film.

는 1% 이하이고, 여기서 a_substrate는 기판의 면내 격자 상수이고 a_layer는 III-질화물층의 벌크 격자 상수이다.In a method according to embodiments of the present invention, a III-nitride layer is grown over the substrate. The substrate is RAO ₃ (MO) _n , wherein R is selected from Sc, In, Y, and lanthanide based elements; A is selected from Fe (III), Ga, and Al; M is selected from Mg, Mn, Fe (II), Co, Cu, Zn and Cd; n is an integer of 1 or more. In some embodiments,

Is less than or equal to 1%, where a _substrate is the in-plane lattice constant of the substrate and a _layer is the bulk lattice constant of the III-nitride layer.

In a method according to embodiments of the present invention, a III-nitride layer is grown over the substrate. The substrate is a non-III-nitride material. III-nitride layers are ternary, quaternary, or pentamembered alloys. The III-nitride layer is thick enough to mechanically self-support and has a low defect density.

The III-nitride alloy film described herein can be used as a growth substrate for III-nitride light emitting devices. The III-nitride light emitting device grown on such an alloy film has less strain than the conventionally grown III-nitride light emitting device, and thus may have better performance.

1 shows an alloy film grown on a substrate.
2 illustrates a semiconductor device structure grown on an alloy film.
3 illustrates a thin film flip chip light emitting device.
4 illustrates a vertical light emitting device.

One method of creating a thick layer of ternary or quaternary III-nitride alloy film on which a III-nitride device can be grown is HVPE (water) on a binary semiconductor template film, such as GaN, formed on a conventional substrate such as sapphire. The alloy film is formed by a high growth rate film forming technique such as digested gas phase epitaxy). The lattice mismatch between the substrate (sapphire in this example) and the template film (GaN in this example) is generally large (> 1%), and GaN will contain many defects. Since the alloy film (InGaN in this example) is also significantly inconsistent with the binary film (> 1% lattice mismatch), additional defects or nonuniformities are included in the alloy film during its growth. A device grown on an alloy film produced by this method may exhibit poor performance due to defects caused by lattice mismatch. Moreover, the thickness of the alloy film is generally at most several micrometers, in order to minimize the density of additional defects, so that it is not mechanically self supporting. Therefore, device growth is performed on a composite substrate comprising sapphire, GaN, and InGaN in this example, all of which have different coefficients of thermal expansion that can cause significant wafer warpage or other geometric distortions.

In embodiments of the present invention, a substrate is provided that is hexagonally symmetrical and identical in lattice match (or nearly match) with a desired alloy film. Since the substrate is lattice match, fewer defects or non-uniformities will be included in the alloy film during growth, and the film may be grown thicker to mechanically self-support (eg, in some embodiments, a thickness of 50 μm). Larger, in some embodiments greater than 100 μm, in some embodiments greater than 200 μm). The substrate can be removed from the thick alloy film and later reused.

는 어떤 실시예들에서는 1% 이하이고, 어떤 실시예들에서는 0.5% 이하이다.1 illustrates an alloy film 12 grown over a substrate 10 in accordance with embodiments of the present invention. The layer of semiconductor material can be characterized by a bulk lattice constant and an in-plane lattice constant. The bulk lattice constant is the lattice constant of the theoretical, fully relaxed layer of the same composition as the semiconductor layer. The in-plane lattice constant is the lattice constant of the grown semiconductor layer. When the semiconductor layer is strained, the bulk lattice constant is different from the in-plane lattice constant. If the semiconductor layer is grown on a substantially lattice matched substrate, the bulk lattice constant of the semiconductor layer will be approximately equal to the in-plane lattice constant of the semiconductor layer and will be the same as the in-plane lattice constant of the substrate, and there will be no cracking or other strain relief. For substrates grown as bulk ingots and sliced into wafers, the in-plane lattice constant of the substrate may be equal to the bulk lattice constant of the substrate. In a substrate grown with strain or a composite substrate, the in-plane lattice constant of the substrate may be different from the bulk lattice constant of the substrate. Alloy film 12 is 0.5 in some embodiments the substrate 10, the in-plane having a lattice constant of a _substrate bulk lattice constant of a _layer within 1% of, certain embodiments of the in-plane lattice constant of a _substrate of the substrate 10 in It has a bulk lattice constant a _layer in%. In other words,

Is 1% or less in some embodiments, and 0.5% or less in some embodiments.

Substrate 10 is a non-III-nitride material. In some embodiments, the substrate 10 has hexagonal fibrous zinc symmetry similar or identical to the alloy film 12. In some embodiments, the substrate 10 is substantially immune to attack by the chemical and thermal environment experienced during the formation of the alloy film 12. In some embodiments, the substrate 10 has an in-plane thermal expansion coefficient within 30% of the in-plane thermal expansion coefficient of the formed alloy film 12. In some embodiments, the substrate 10 may or may not be transparent to near UV rays. In some embodiments, the substrate 10 is a monocrystalline or substantially monocrystalline material.

In some embodiments, the substrate 10 is a material of the general composition RAO ₃ (MO) _n , where R is usually a trivalent cation selected from Sc, In, Y, and lanthanide series elements (atoms 57-71) ; A is also usually a trivalent cation selected from Fe (III), Ga, and Al; M is usually a divalent cation selected from Mg, Mn, Fe (II), Co, Cu, Zn and Cd; n is an integer of 1 or more. In some embodiments n ≦ 9 and in some embodiments n ≦ 3. In certain embodiments, the RAMO ₄ (ie, n = 1) compound is of the YbFe ₂ O ₄ structure type and the RAO ₃ (MO) _n (n ≧ 2) compound is of the InFeO ₃ (ZnO) _n structure type.

The following table lists examples of suitable materials for substrate 10 and compositions of InGaN alloys having the same in-plane lattice constant as each substrate:

These and related substrate materials are described in "Strutrual Classification of RAO ₃ (MO) _n Compounds (R = Sc, In) by Kimizuka and Mohri, published in Journal of Solid State Chemistry 78, 98 (1989), incorporated herein by reference. , Y, or Lanthanides; A = Fe (III), Ga, Cr, or Al; M = Divalent Cation; n = 1-11).

In some embodiments, the alloy film 12 is grown over the surface of the substrate 10 "miscut" or angled to the major crystallographic side of the substrate. In some embodiments, the surface of the substrate 10 on which the alloy film 12 is grown may be oriented away between -10 degrees and +10 degrees from the base (0001) face. In some embodiments, a miscut between -0.15 degrees and +0.15 degrees inclined from the (0001) plane can cause a large atomic terrace over the substrate surface that can preferably reduce the number of defects formed at the terrace edge.

Alloy film 12 is formed over substrate 10 by any means known in the art, including, for example, organometallic chemical vapor deposition (MOCVD), HVPE, or molecular beam epitaxy (MBE). Complete lattice matching between the alloy film 12 and the substrate 10 is not necessary, but lattice matching within 0.1% may allow the formation of a high quality alloy film 12 of at least 50 μm thick. For the purposes of embodiments of the present invention, the bulk lattice constant of the ternary or quaternary AlInGaN layer is a _AlInGaN = x (a _AlN ) + y (a _AlN ) + z (a _GaN for Al _x In _y Ga _z N. ), (Where x + y + z = 1, and the variable "a" indicates the bulk a-lattice constant of each binary material), which can be evaluated according to Vegaard's law. have. AlN has a bulk a-lattice constant of 3.111 Å, InN has a bulk a-lattice constant of 3.544 Å, and GaN has a bulk a-lattice constant of 3.1885 Å.

Alloy film 12 may be any material from which a III-nitride device structure can be grown. Alloy film 12 is usually a ternary (such as InGaN or AlGaN), ternary (such as AlInGaN), or quinine (such as BAInGaN) alloy of III-nitride or other III-V material. As illustrated in the table above, in some embodiments, the proportion of InN in InGaN alloy film 12 may be between 14% and 48%. III-nitride device structures having active regions capable of emitting visible light in the blue to red-orange portions of the visible spectrum can be grown on the substrates listed in the table above. Alloy film 12 may be grown such that the defect density is less than 5 × 10 ⁸ cm ^{−2 in} some embodiments and less than 10 ⁷ cm ⁻² in some embodiments.

In some embodiments, the alloy film 12 may include one or more n-type dopants, such as, for example, Si, Ge, or Sn, or one or more p-type dopants, such as, for example, Mg, Be, Zn, or Cd. Doped with. The doped alloy film 12 can be used, for example, in a vertical device in which contact is made to the surface of the alloy film 12 opposite the device structure. In some embodiments, alloy film 12 is doped with one or more dopants that insulate the alloy film, such as Fe and / or C. An insulating alloy film can be used when several devices such as LEDs are monolithically formed on a single alloy film 12. The insulating alloy film can electrically insulate adjacent devices. One example of several devices monolithically formed on a single alloy film is an array of LEDs that can be connected to an AC power source. In some embodiments, alloy film 12 is semi-insulated without intentionally doping or replenishing. In some embodiments, one or more dopants are used to fine tune the lattice constant of the alloy film 12 in order to reduce the lattice mismatch with the substrate 10, eventually reducing the amount of indium required in the alloy film 12. And / or thicker alloy film 12 may be grown.

In some embodiments, alloy film 12 is removed from substrate 10.

If the substrate 10 is transparent, in some embodiments the alloy film 12 is removed by laser lift-off where a laser beam is irradiated through the substrate. The first layer of III-nitride material grown on the substrate 10 absorbs and melts the laser light to separate the alloy film 12 from the substrate. Laser lift-off may be facilitated by an optional low-gap alloy semiconductor layer 14 between the thick alloy film 12 and the substrate 10. The composition of the low energy-gap layer 14 may be selected such that the layer 14 absorbs more incident light than the thick alloy film 12, thereby melting the interface between the substrate 10 and the semiconductor material. It may reduce the incident flux required to cause and cause less scattered damage throughout the alloy film 12.

In some embodiments, layer 14 is a discontinuous patterned film of a non-III-nitride material, such as SiN _x or SiO ₂ , provided on substrate 10 prior to formation of alloy film 12, so that the alloy film is formed of the substrate. The nucleation grows preferentially over the exposed portion and then merges over the discontinuous pattern after a sufficient thickness has been formed. The patterned layer preferentially absorbs incident laser light, causing localized melting and cracking of the alloy film / substrate interface.

In some embodiments, an optional zone of weakness at or near the interface to facilitate cracking of the interface of the alloy film 12 and the substrate 10 and thereby to facilitate removal of the alloy film from the substrate. weakness) 16 is provided. The fragile zone may be provided to the substrate 10 or alloy film 12 by implantation of one or more of H or N or other atoms before or after the formation of all or part of the alloy film or patterned film. Weak zone 16 in alloy film 12 firstly with a higher mole fraction InN (at a predetermined growth temperature) and subsequently with a lower mole fraction InN (at a predetermined higher growth temperature, preferentially with the substrate). By lattice matched composition). Alloy films containing higher InN can be transformed into regions of much higher and lower indium composition at higher growth temperatures, depending on the phase diagram. The region of highest indium composition absorbs more of the incident laser light, and mechanical stresses due to the spatially varying indium composition will create a mechanically weak layer in the alloy film.

Weak zone 16 may also be formed by patterning the surface of the substrate prior to formation of alloy film 12 (eg, into a ridge of a rectangular or triangular lattice of substrate material). May be provided at the interface.

Vulnerable zone 16 may also be formed by exposing the wafer to a pattern of a strongly focused pulsed laser beam of sufficient intensity and photon energy to create a plurality of micron-scale crystal defects or voids within the crystal structure. 10) may be provided at the interface. Patterns of crystal damage can be generated by rasterizing one or more laser beams across the wafer, or by generating a large number of spots from a single high power laser, such as an excimer laser, using diffractive optics. The laser beam can be strongly converged with pulses of less than 1 microsecond short and can cause very localized damage. This exposure can occur through the epitaxy stack after growth to a sufficiently low dose that additional wafer processing can be done after exposure. In some embodiments, the substrate is removed after subsequent wafer processing in a die level process, for example, rather than a wafer level process. In addition, the total exposure power can be less than that required in conventional laser lift-off, which can result in less mechanical impact.

In some embodiments, the substrate 10 is removed by etching, such as a wet chemical etch. For example, ScMgAlO ₄ has been added to H ₃ PO ₄ , as reported by CDBrandle et al. In “Dry and Wet Etching of ScMgAlO ₄ ” published in Solid-State Electronics, 42,467 (1998), incorporated herein by reference. It is easily attacked by an aqueous mixture of H ₂ O _2, an aqueous mixture of H ₂ SO ₄ : H ₂ O ₂ : H ₂ O, and HF. In some embodiments, all or part of the growth substrate 30 is removed by reactive ion etching using a gas mixture of Cl ₂ and Ar at an applied power of 800 watts.

The substrate material shown in the above table has mica characteristics, and the (0001) base face of the crystal (that is, the plane parallel to the surface of the substrate when the substrate orientation is (0001)) is preferentially cracked. Substrate 10 may be removed from alloy film 12 by mechanical methods. Suitable methods include, for example, mechanical polishing with a polishing slurry; Applying rotational force between the substrate and the alloy film; Bonding the adhesive coated plastic film to the substrate and the second adhesive coated plastic film to the alloy layer and separating the substrate and the alloy film; Using a sharp blade to break the interface between the substrate and the alloy film; Applying a pulse of acoustic energy; Applying one or more laser pulses focused at a small point (<1 mm 2) of the interface to generate a shock wave initiating the crack; Applying a non-uniform temperature distribution across the surface of the substrate 10 and the alloy film 12; Applying a temperature gradient across the surface perpendicular to the alloy film 12 and the substrate 10 (eg, a higher temperature is applied to one side of the alloy film and a lower temperature is applied to one side of the substrate) ), But not limited to these.

Once the substrate 10 is removed from the alloy film 12, the substrate 10 can be surface retreated and another alloy film 12 is formed thereon.

After the substrate 10 is removed, the semiconductor device structure can be grown over the alloy film 12, as shown in FIG. In the examples below, the semiconductor device structure is a III-nitride LED that emits blue or UV light, but other electronic and optoelectronic devices such as laser diodes, high electron mobility transistors, and heterojunction bipolar transistors may be formed over the substrate described herein. Can be.

As shown in FIG. 2, a semiconductor structure 22 is grown over the alloy film 12. The semiconductor structure 22 includes a light emitting or active region 23 sandwiched between the n-type region 21 and the p-type region 25. The n-type region 21 is typically grown first and for example preparative layers, such as a buffer layer or nucleation layer, which may be n-type or intentionally not doped, and certain optical which is desirable for the light-emitting region to emit light efficiently. Or multiple layers of different composition and dopant concentration, including n-type or even p-type device layers designed for electrical properties. The light emitting or active region 23 is grown over the n-type region 21. Examples of suitable light emitting regions 23 include multiple quantum well light emitting regions comprising one thick or thin light emitting layer, or multiple thin or thick light emitting layers separated by a barrier layer. The p-type region 25 is grown over the light emitting region 23. Like the n-type region 21, the p-type region 25 may comprise multiple layers of different composition, thickness, and dopant concentration, including intentionally undoped layers, or n-type layers. In one example, ScMgAlO ₄ comprises a substrate (10), and the alloy film 12 is an In _{0 .14} Ga _{0 .86} N. In the present example, n-type layer, a light emitting layer, and a p-type layer, respectively, In _{0 .14 0 .86} N Ga, In _{0 .16 0 .84} N Ga, In, and _{0 .12 0 .88} Ga is formed in a N . The structure shown in FIG. 2 can be processed with any suitable device design, including but not limited to the thin film flip chip device shown in FIG. 3 and the vertical device shown in FIG.

In the device shown in FIG. 3, a p contact metal 26 is disposed above the p-type region 25, and then a portion of the p-type region 25 and the active region 23 are n-type layers for metallization. Etched off to expose. p contact 26 and n contact 24 are on the same side of the device. The p contact 26 is electrically separated from the n contact 24 by a gap 27 that can be filled with an electrically insulating material such as a dielectric. As shown in FIG. 3, p contact 26 may be disposed between multiple n contact regions 24, but need not be. In some embodiments either or both of n contact 24 and p contact 26 are reflective and the device is mounted such that light is extracted through the top of the device in the orientation shown in FIG. 3. In some embodiments, the contact can be limited in size or made transparent, and the device can be mounted so that light is extracted through the surface on which the contact is formed. The semiconductor structure is attached to mount 28. The alloy film on which the semiconductor structure 22 is grown may be removed as shown in FIG. 3, or may remain as part of the device. In some embodiments, the alloy film itself may be patterned or roughened in embodiments that remain as part of the exposed semiconductor layer, or device by removing the alloy film, to improve light extraction from the device.

In the vertical implantation LED shown in FIG. 4, n contacts are formed on one side of the semiconductor structure 22 and p contacts are formed on the other side of the semiconductor structure. For example, p contact 26 may be formed over p-type region 25 and the device may be attached to mount 28 via p contact 26. All or part of the alloy film may be removed and an n contact 24 may be formed on the surface of the exposed n-type region 21 by removing a portion of the alloy film. The electrical contact with the n contact may be made of a wire bond or metal bridge as shown in FIG. 4. In some embodiments, all or part of the alloy film remains in the device and electrical contact is made with the alloy film.

The LED may be combined with one or more wavelength converting materials such as phosphorus, quantum dots, or pigments to produce monochromatic light of white light or other color. All or part of the light emitted by the LED may be converted by the wavelength converting material. The unconverted light emitted by the LED need not be, but may be part of the final spectrum of light. Examples of typical combinations include blue light emitting LEDs combined with yellow light emitting phosphors, blue light emitting LEDs combined with green and red light emitting phosphorus, UV light emitting LEDs combined with blue and yellow light emitting phosphorus, and UV light emitting combined with blue, green and red light emitting phosphorus. It includes an LED. Wavelength converting materials that emit light of different colors may be added to match the spectrum of light emitted from the device.

The wavelength converting element may be, for example, a preformed ceramic phosphor layer bonded or bonded to or separated from the LED, or a stencil, screen print, spray, precipitate, deposit, sputtered, or otherwise dispensed or formed over the LED. It may be powdered phosphorus or quantum dots disposed in an organic or inorganic encapsulant.

Ternary, quaternary, or ternary semiconductor alloy films may have several advantages over available basic and binary semiconductor substrates. For example, the crystal structure and in-plane lattice constant of the alloy film described above may better match the III-nitride device structure. This results in higher crystal quality (e.g. fewer defects) and less stress on the active layer, which can improve the optoelectronic properties of the material and improve device performance and match thermal expansion properties of the substrate and device layer. Becomes more favorable, and the manufacturing yield of an apparatus can be improved.

Although the present invention has been described in detail, those skilled in the art will appreciate that modifications may be made to the invention in accordance with the present disclosure without departing from the spirit of the inventive concept described herein. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.

Claims (20)

Growing a III-nitride layer on a substrate
Lt; / RTI &gt;
The substrate is RAO ₃ (MO) _n , where R is selected from Sc, In, Y and lanthanide based elements,
A is selected from Fe (III), Ga and Al, M is selected from Mg, Mn, Fe (II), Co, Cu, Zn and Cd, n is an integer of 1 or more,
The substrate has an in-plane lattice constant a _substrate ,
The III-nitride layer has a bulk lattice constant a _layer ,

Is less than or equal to 1%. The method of claim 1, wherein the substrate is one of ScMgAlO ₄ , ScGaMgO ₄ , ScAlMnO ₄ , InAlMnO ₄ . The method of claim 1, wherein the III-nitride layer is one of InGaN and AlInGaN. The method of claim 1, wherein the III-nitride layer has a thickness greater than 50 μm. The method of claim 1, further comprising removing the substrate. 6. The method of claim 5, further comprising growing a structure on the III-nitride layer comprising a III-nitride light emitting layer disposed between an n-type region and a p-type region. The method of claim 6, wherein the n-type region is In _{0 .14} Ga _{0 .86} N and at least comprising a layer, of the light-emitting layer comprises an In _{0 .16} Ga _{0 .84} N, the p-type region In _{0 .12} Ga _{0 .88} N at least one layer. 6. The method of claim 5, wherein the removing comprises melting a sacrificial layer disposed between the substrate and the III-nitride layer. The method of claim 8, wherein the sacrificial layer is one of a patterned non-III-nitride film and a III-nitride material having a lower band gap than the III-nitride layer. 6. The method of claim 5, wherein the removing comprises one of removing by a mechanical method and breaking the interface between the III-nitride layer and the substrate using a blade. 6. The method of claim 5, wherein said removing comprises said III-nitride in a zone of weakness disposed in said substrate, in said III-nitride layer, or at an interface between said substrate and said III-nitride layer. Separating the substrate from the layer. The method of claim 11, wherein the fragile zone comprises a patterned layer. The method of claim 11, wherein the fragile zone comprises a region implanted with one of H atoms and N atoms. The method of claim 11, wherein said III-nitride layer is InGaN and said fragile zone comprises a region having a higher InN composition than said III-nitride layer. 12. The method of claim 11, wherein the zone of weakness comprises a plurality of micron scale crystal defects or voids generated by irradiation of a focused laser beam. Growing a III-nitride layer on a substrate
Lt; / RTI &gt;
The substrate is a non-III-nitride material,
The III-nitride layer is a three-, four- or five-membered alloy,
The III-nitride layer is thick enough to be mechanically self-supporting,
Wherein said III-nitride layer has a defect density of less than 5 × 10 ⁸ cm ⁻² . The method of claim 16 further comprising removing the substrate from the III-nitride layer. 18. The method of claim 17, further comprising growing a light emitting layer on the III-nitride layer after removing the substrate. The method of claim 16, wherein the substrate is one of ScMgAlO ₄ , ScGaMgO ₄ , ScAlMnO ₄ , InAlMnO ₄ . 17. The method of claim 16,
The substrate has an in-plane lattice constant a _substrate ,
The III-nitride layer has a bulk lattice constant a _layer ,

Is less than or equal to 1%.

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