Group IIIA nitride growth systems and methods

Abstract

A system and method for growing gallium nitride (GaN) structures is provided. The system and method include: providing a mold; and growing at least a first GaN layer on the mold using a first sputtering process, the first sputtering process including: controlling the temperature of a sputtering target; and adjusting between a gallium-rich condition and a gallium-lean condition, the gallium-rich condition including a gallium-to-nitrogen ratio having a first value greater than 1 and the gallium-lean condition including a gallium-to-nitrogen ratio having a second value less than the first value. The system includes a load lock configured to load and remove substrate wafers into and from the system; and multiple deposition chambers, the multiple deposition chambers including GaN deposition chambers configured to grow at least a first GaN layer on the mold containing the substrate wafer.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a joint venture under 35 U.S.C. §119(e) with U.S. Provisional Patent Application No. 62 / 342,026, filed May 26, 2016, by Robbie J. Jorgenson, entitled "Low Temperature Gallium Nitride by Magnetron Sputtering / PVD Materials, Process and Equipment," and U.S. Provisional Patent Application No. 62 / 385,089, filed September 8, 2016, by Robbie J. Jorgenson, entitled "SYSTEM AND METHOD FOR DOPING GALLIUM NITRIDE DURING GROWTH BY PHYSICAL VAPOR DEPOSITION AND RESULTING MATERIALS AND DEVICES," and U.S. Provisional Patent Application No. 62 / 385,089, filed September 19, 2016, by Robbie J. Jorgenson, entitled "SYSTEM AND METHOD FOR DOPING GALLIUM NITRIDE DURING GROWTH BY PHYSICAL VAPOR DEPOSITION AND RESULTING MATERIALS AND DEVICES." This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 396,646, entitled "GALLIUM NITRIDE GROWTH BY SPUTTERING AND RESULTING MATERIALS AND DEVICES," filed on October 25, 2016 by Robbie J. Jorgenson et al., and U.S. Provisional Patent Application No. 62 / 412,694, entitled "GALLIUM NITRIDE GROWTH BY SPUTTERING AND RESULTING MATERIALS AND DEVICES," filed on February 22, 2017 by Robbie J. Jorgenson et al., each of which is incorporated herein by reference in its entirety.

[0002] This application is related to prior U.S. patent application Ser. No. 15 / 294,558, filed Oct. 14, 2016, entitled "SYSTEM AND METHOD FOR LIGHT-EMITTING DEVICES ON LATTICE-MATCHED METAL SUBSTRATES," and published Apr. 20, 2017 as Publication No. 2017 / 0110626; and U.S. Provisional Patent Application Ser. No. 62 / 242,604, filed Oct. 16, 2015, entitled "METHOD AND HYPER EMISSION GREEN LIGHT-EMITTING DIODE ON LATTICE-MATCHED METAL SUBSTRATES FOR ADVANCED OPTICAL FIBER NETWORKING," which applications are incorporated herein by reference in their entireties.

[0003] This application is also a continuation of U.S. Provisional Patent Application No. 60 / 835,934, filed August 6, 2006, entitled "III-NITRIDE LIGHT-EMITTING DEVICES WITH ONE OR MORE RESONANCE REFLECTORS AND REFLECTIVE ENGINEERED GROWTH TEMPLATES FOR SUCH DEVICES, AND METHODS"; U.S. Provisional Patent Application No. 60 / 821,588, filed August 7, 2006, entitled "III-NITRIDE LIGHT-EMITTING DEVICES WITH ONE OR MORE RESONANCE REFLECTORS AND REFLECTIVE ENGINEERED GROWTH TEMPLATES FOR SUCH DEVICES, AND METHODS"; and U.S. Provisional Patent Application No. 60 / 821,588, filed February 25, 2008, entitled "CURRENT-INJECTING / TUNNELING LIGHT EMITTING DEVICE AND U.S. Provisional Patent Application No. 61 / 066,960, entitled "Metallo-Semiconductor Structures for III-Nitride Devices," filed on March 14, 2012; U.S. Provisional Patent Application No. 61 / 610,943, entitled "Metallo-Semiconductor Structures for III-Nitride Devices," filed on April 13, 2012; U.S. Provisional Patent Application No. 61 / 623,885, entitled "Structures for III-Nitride Devices," filed on June 4, 2012; U.S. Provisional Patent Application No. 61 / 655,477, entitled "Metal-Based Transistors for III-Nitride Devices," filed on March 29, 2011; and U.S. Provisional Patent Application No. 61 / 655,477, entitled "Metal-Based Transistors for III-Nitride Devices," filed on March 29, 2011. U.S. Patent No. 7,915,624 entitled "TEMPLATES FOR SUCH DEVICES, AND METHODS";No. 8,253,157, issued on August 28, 2012, entitled "III-NITRIDE LIGHT-EMITTING DEVICES WITH REFLECTIVE ENGINEERED GROWTH TEMPLATES AND METHODS OF MANUFACTURE" (a division of the application now U.S. Pat. No. 7,915,624); U.S. Pat. No. 8,890,183, issued on November 18, 2014, entitled "III-NITRIDE LIGHT-EMITTING DEVICES WITH REFLECTIVE ENGINEERED GROWTH TEMPLATES AND MANUFACTURING METHOD" (a division of the application now U.S. Pat. No. 8,253,157); U.S. Pat. No. 8,890,183, issued on November 30, 2010, entitled "CURRENT-INJECTING / TUNNELING LIGHT-EMITTING DEVICE AND No. 7,842,939, entitled "METHOD OF FORMING CURRENT-INJECTING / TUNNELING LIGHT-EMITTING DEVICE," issued on October 21, 2014 (a division of the application that is now U.S. Pat. No. 7,842,939); and U.S. Pat. No. 8,865,492, entitled "METHOD OF FORMING CURRENT-INJECTING / TUNNELING LIGHT-EMITTING DEVICE," issued on October 21, 2014 (a division of the application that is now U.S. Pat. No. 7,842,939); and U.S. Pat. No. 9,608,145, entitled "MATERIALS, STRUCTURES, AND METHODS FOR OPTICAL AND ELECTRICAL III-NITRIDE SEMICONDUCTOR DEVICES," issued on March 28, 2017; each of which is incorporated herein by reference in its entirety.

[0004] There are multiple embodiments described herein, each of which can be combined with one or more of the other embodiments described herein and / or incorporated by reference. In some other embodiments, the invention provides subcombinations that incorporate most of the features of the various embodiments, but omit one or more features that are individually shown and described herein.

[0005] The present invention relates to the field of semiconductor devices and methods for fabricating semiconductor devices, and more particularly to materials, structures and methods for growing III-nitride devices. [Background technology]

[0006] Non-Patent Document 1 is incorporated herein by reference.

[0007] Non-Patent Document 2 is incorporated herein by reference.

[0008] Non-Patent Document 3 is incorporated herein by reference.

[0009] Non-Patent Document 4 is incorporated herein by reference.

[0010] Non-Patent Document 5 is incorporated herein by reference.

[0011] Non-Patent Document 6 is incorporated herein by reference.

[0012] Non-Patent Document 7 is incorporated herein by reference.

[0013] Non-Patent Document 8 is incorporated herein by reference.

[0014] Non-Patent Document 9 is incorporated herein by reference.

[0015] Non-Patent Document 10 is incorporated herein by reference.

[0016] Non-Patent Document 11 is incorporated herein by reference.

[0017] Non-Patent Document 12 is incorporated herein by reference.

[0018] US Patent Application Publication No. 2005 / 0129994 is incorporated herein by reference.

[0019] US Patent Application Publication No. 2005 / 0122994 is incorporated herein by reference.

[0020] US Patent Application Publication No. 2005 / 0129994 is incorporated herein by reference.

[0021] U.S. Patent No. 7,879,697 to PICohen, issued February 1, 2011, and entitled "GROWTH OF LOW DISLOCATION DENSITY GROUP-III NITRIDES AND RELATED THIN-FILM STRUCTURES," is incorporated herein by reference. [Prior art documents] [Patent documents]

[0022] [Patent Document 1] U.S. Patent No. 6,323,417, "METHOD OF MAKING I-III-VI SEMICONDUCTOR MATERIALS FOR USE IN PHOTOVOLTAIC CELLS," Timothy J. Gillespie et al., November 27, 2001 [Patent Document 2] U.S. Patent No. 6,692,568, "METHOD AND APPARATUS FOR PRODUCING MHIN COLUMNS AND MHIN MATERIALS GROWN THEREON," J.J. Cuomo, February 17, 2004 [Patent Document 3] U.S. Patent No. 6,784,085, "Mineral-Based Materials and Methods and Apparatus for Producing Same," J.J. Cuomo, August 31, 2004 [Non-patent literature]

[0023] [Non-Patent Document 1] "Magnetron Sputter Epitaxy of Gallium Nitride on (0001) Sapphire", Materials Science Forum, Vols. 264-268, pp. 1229-1234(1998), JBWebb, D.Northcott, S.Charbonneau, F.Yang, DJLockwood, O.Malvezin, P.Singh, J.Corbett

Non-patent document 2

Non-patent document 3

Non-patent document 4

Non-patented document 5

Non-Patent Document 10

Non-Patent Document 11

Non-Patent Document 12

Summary of the Invention

[0024] In some embodiments, the present invention utilizes a solid gallium target to provide epitaxial atomic layer sputtering (EALS) (in some such embodiments, EALS includes magnetron sputtering). In some embodiments, when columnar growth is avoided, the present invention produces films using two-dimensional (2D) step-wise growth. Such a process enables high-quality gallium nitride (GaN) films with low amounts of hydrogen and carbon. In some embodiments, no metalorganics are required, as is the case with metalorganic chemical vapor deposition (MOCVD). In some embodiments, a plasma used during the process reduces the required growth temperature (compared to MOCVD) and increases the growth rate (compared to molecular beam epitaxy (MBE)) while still maintaining high-quality films.

[0025] In some embodiments, the present invention provides systems and methods for growing high-quality, cost-effective epitaxial materials that push the envelope of current industry capabilities. In some embodiments, such materials have larger epitaxial regions before coalescence and have different densities of misfit dislocations.

[0026] In some embodiments, associated ion interactions self-annihilate (self-react) the density dislocations within thinner film thicknesses compared to the purely thermal environment of MOCVD.

[0027] Furthermore, because of the differential thermal contraction between the GaN and the substrate (e.g., due to different coefficients of thermal expansion (CTE)), in some embodiments, if GaN is grown on sapphire at temperatures lower than those used by MOCVD, the degree of subsequent wafer bow and wafer stress is reduced. This solves many problems of wafer cracking, epitaxy cracking, non-uniformity, the need for thicker sapphire substrates, and the need for processed wafer pockets in the MOCVD system for subsequent active area growth. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a flow chart of a method (101) for growing gallium nitride (GaN) based devices. [Figure 2] FIG. 2 is a schematic diagram of a system (201) for growing GaN-based devices. [Figure 3] Schematic diagram of a GaN structure (301). [Figure 4] FIG. 4 is a schematic diagram of a low temperature Group IIIA nitride sputtering system (401). [Figure 5A] 5 includes schematic diagrams of several growth modes (501) illustrating various epitaxial growth modes of some embodiments of the present invention. [Figure 5B] A set of atomic force microscope (AFM) images (502) of GaN growth. [Figure 6A] 6 is a table (601) of thicknesses (in nanometers) for the AlN and GaN layers identified in the GaN structure (301) of FIG. [Figure 6B] This is a continuation of Table (601). [Figure 7A] 7 is a table (701) showing ω rocking curve full width at half maximum (FWHM) X-ray diffraction (XRD) values (arcsec) for GaN produced according to some embodiments of the present invention. [Figure 7B] This is a continuation of Table (701). [Figure 8A]FIG. 8 is a schematic diagram of a mold and device epitaxy system (801) for electronics and solid state lighting (SSL). [Figure 8B] FIG. 8 is a schematic diagram of a template and device epitaxy system (802) for electronics and SSL. [Figure 9] FIG. 9 is a schematic diagram of a template and device epitaxy process (901) for electronics and SSL. [Figure 10] 10 is a graph (1001) illustrating n-type carrier concentration (per cubic centimeter) versus adatom mobility (cm 2 / V·s) for hafnium-doped gallium nitride produced in accordance with some embodiments of the present invention. [Figure 11] 11 is a graph (1101) showing X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention. [Figure 12] Schematic of a GaN template structure (1201) for subsequent LED epitaxial growth. [Figure 13] Schematic diagram of GEMM / GaN epitaxial stack structure (1301). [Figure 14A] 14 is a graph 1401 of X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention. [Figure 14B] 14 is a graph (1402) of X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention. [Figure 14C] 14 is a graph (1403) of X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention. [Figure 14D] 14 is a graph 1404 of X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention. [Figure 15] 15 is a chart (1501) of atomic force microscope (AFM) data for GaN on GEMM produced in accordance with some embodiments of the present invention. [Figure 16]16 is a graph (1601) illustrating a comparison of the reflectivity of a GEMM / GaN (solid line) produced in accordance with some embodiments of the present invention versus a conventional AlN / GaN distributed Bragg reflector (DBR) (dotted line). [Figure 17] 17 is a graph (1701) of estimated sputtering yield for gallium nitride (GaN) versus gallium target temperature. [Figure 18] FIG. 18 is a schematic diagram of a sputtering system (1801). DETAILED DESCRIPTION OF THE INVENTION

[0029] While the following details contain many specifics for purposes of illustration, those skilled in the art will recognize that many modifications and variations to the following details are within the scope of the present invention. Specific examples are used to illustrate particular embodiments; however, the invention as claimed is not intended to be limited to such examples alone, but rather encompasses the full scope of the appended claims. Accordingly, the following preferred embodiments of the present invention are set forth without loss of generality to, and without imposing limitations on, the inventive subject matter. Furthermore, in the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and which are shown for the purpose of illustrating specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. The embodiments shown in the figures and described herein may include features not included in all particular embodiments. In some cases, a particular embodiment may include only a subset of the described features, or in other cases, a particular embodiment may include all of the described features.

[0030] As the same reference number is used to refer to the same component that appears in multiple figures, the first digit of the reference number that appears in a figure corresponds to the number of the figure in which that component is first introduced. Signals and connections may also be referenced by the same reference number or label, with the actual meaning becoming clear from use in the context of the description.

[0031] As used herein, the term "substrate" means the material on which a process is performed, and includes silicon, sapphire, or other suitable materials.

[0032] As used herein, the term "template" refers to one or more layers that form a suitable base for epitaxial growth, and includes silicon, sapphire, GaN / silicon, GaN / sapphire, GaN / aluminum nitride (AlN), GaN / hafnium nitride (HfN), GaN / zirconium nitride (ZrN), or any other suitable material, structure, pattern template, or substrate.

[0033] As used herein, physical vapor deposition ("PVD") refers to deposition methods that can be used to produce thin films and coatings, and PVD includes cathodic arc deposition, electron beam PVD, evaporative deposition, pulsed laser deposition, and sputtering.

[0034] In some embodiments, sputtering includes one or more of the following: direct current (DC) sputtering, radio frequency (RF) sputtering, reactive sputtering, and magnetron sputtering.

[0035] It should be noted that many of the processes and methods described herein utilize numbered / lettered steps. While these processes and methods can be performed in the order defined by the numbers / letters, the present specification also contemplates performing these processes and methods in any other suitable order. Furthermore, the specification also contemplates performing the corresponding processes and methods using any one or more of the steps described, such that a given step(s) can be optionally omitted and / or additional step(s) can be optionally added.

[0036] FIG. 1 is a flowchart of a method (101) for growing gallium nitride (GaN)-based devices. In some embodiments, the method of flowchart (101) is performed in a single deposition chamber. In other embodiments, method (101) is performed in multiple separate deposition chambers. In some embodiments, method (101) includes any one or more of blocks (105-110) (e.g., in some embodiments, blocks (106) and (108) are optional). In some embodiments, in block (105), a substrate (e.g., sapphire or silicon) is positioned for subsequent deposition. In some embodiments, in block (106), substrate conditioning is performed. In some embodiments, in block (107), aluminum nitride (AlN) is sputtered onto the substrate, where X represents the thickness of the sputtered AlN. In some embodiments, in block (108), AlN conditioning is performed (e.g., in some embodiments, oxide removal). In some embodiments, GaN is sputtered in block (109), where Y represents the thickness of the sputtered GaN. In some such embodiments, the GaN sputtering includes doping (e.g., doping with silicon, magnesium, iron, carbon, or the like) and / or adatom mobility enhancement. In some embodiments, GaN is sputtered in block (110), where Z represents the thickness of the sputtered GaN. In some such embodiments, the GaN sputtering includes doping (e.g., doping with silicon, magnesium, iron, carbon, or the like) and / or adatom mobility enhancement (sometimes referred to herein as EALS). In some embodiments, the GaN is alloyed with scandium, zirconium, hafnium, indium, aluminum, or any other suitable element.

[0037] Figure 2 is a schematic diagram of a system (201) for growing GaN-based devices. In some embodiments, the system (201) is used to implement the method of flowchart (101) shown in Figure 1. In some embodiments, the system (201) includes a load lock (205) into which substrate wafers (298) are loaded and finished wafers (299) are removed from the system (201). In some embodiments, the system (201) includes a substrate conditioning module (206) (e.g., for performing block (106) of Figure 1), an AlN deposition module (207) (e.g., for performing block (107) of Figure 1), an AlN conditioning module (208) (e.g., for performing block (108) of Figure 1), a GaN deposition module (209) (e.g., for performing block (109) of Figure 1), and a doping module (210) for doped GaN deposition. In some embodiments, the modules (205-210) are housed within a single deposition chamber. In other embodiments, each of the modules (205-210) is a deposition chamber. In some embodiments, the system (201) includes a wafer handling robot (215) for moving wafers between modules within the system (201).

[0038] 3 is a schematic diagram of a GaN structure 301. In some embodiments, the GaN structure 301 is produced using the system 201 of FIG. 2 and / or the method 101 of FIG. In some embodiments, the GaN structure (301) includes a substrate layer (305), a sputtered aluminum nitride (AlN) layer (306) on the substrate layer (305) (in some such embodiments, the thickness of the AlN layer (306) = X), a sputtered GaN layer (307) on the AlN layer (306), the GaN layer (307) having a thickness of Y (in some such embodiments, the GaN layer (307) is doped (e.g., doped with silicon, magnesium, or the like)), and a sputtered GaN layer (308) on the GaN layer (307), the GaN layer (308) having a thickness of Z (in some such embodiments, the GaN layer (308) is doped (e.g., doped with silicon, magnesium, or the like).

[0039] Conventional industrial systems use metalorganic chemical vapor deposition (MOCVD) for the growth of GaN to produce GaN-based devices. In some embodiments, the present invention replaces the conventional MOCVD GaN process with sputtered GaN, which allows for: less wafer bow and therefore better wafer / device uniformity with sputtering; lower process temperatures; and the use of low-cost chemistries such as NH3 and Ga(CH3)3. In some embodiments, the sputtering process is easier to utilize, with less complex equipment requirements, and is less costly than the MBE process.

[0040] FIG. 4 is a schematic diagram of a low-temperature Group IIIA nitride sputtering system (401). In some embodiments, the sputtering system (401) includes a vacuum chamber (405). In some embodiments, the chamber (405) includes a wafer holder (406) and a sputtering gun (407). (For example, in some embodiments, the sputtering gun (407) is a gallium sputtering gun and includes a gallium target.) In some embodiments, the sputtering gun (407) includes a metal gasket and other appropriate components suitable for operation at low temperatures (e.g., below 0° C.). In some embodiments, the system (401) includes a cooling system (408) that cools the gallium target of the sputtering gun (407) so that the gallium target remains solid during sputtering. In some embodiments, the cooling system (408) is operably coupled to the sputtering gun (407) via a cold input line (409) and a hot output line (410). In some embodiments, cooling system (408) circulates one or more heat transfer fluids through wires (409) and (410) to maintain the solid state of the gallium target during sputtering. (For example, in some such embodiments, the heat transfer fluid is a cryogenic liquid such as liquid nitrogen and / or liquid hydrogen (in some embodiments, liquid nitrogen and / or liquid hydrogen are used when sputtering system (401) is used with large wafer and / or wafer platter production systems), one or more alcohols, or other suitable heat transfer fluids.) In some embodiments, system (401) includes a voltage source (415) connected to system (401) via wires (499). In some embodiments, the voltage is increased by voltage source (415) as wafer size increases. In some embodiments, system (401) includes an optical pathway (420) for in situ closed or open process monitoring (in some such embodiments, pathway (420) is operably coupled to a pyrometer and / or an optical reflectance system that is computer tuned for emissivity).

[0041] In some embodiments, the GaN growth process / system described herein is complementary to epitaxial atomic layer sputtering (EALS). In some embodiments, EALS is a process that effectively results in the stoichiometric epitaxial growth of a metal nitride composite on a substrate using sputtering or reactive sputtering, where the ratio of metal (e.g., gallium) to active nitrogen (N) atoms reaching the surface of the metal nitride being formed is periodically varied between metal-rich and N-rich conditions compared to the stoichiometric composition of the metal nitride compound. In some embodiments, this process of switching from metal-rich to metal-lean conditions is achieved by (1) decreasing the metal flux to the surface of the metal nitride being formed, or (2) increasing the active nitrogen flux, or (3) increasing the temperature of the substrate (or exposing the surface of the metal nitride being formed) to increase the evaporation rate of the metal adatoms (i.e., decreasing the residence time), or any combination of (1)-(3). In some embodiments, metal-rich conditions increase adatom mobility by reducing the effects of unsatisfactory bonds (or dangling bonds) at the surface and enhancing surface migration, which leads to non-columnar step growth and therefore results in higher quality, smoother films. Generally, in some embodiments, increased surface migration of adatoms improves the crystalline quality of the deposited material by promoting the incorporation of adatoms at low-energy sites on the growth front. Similarly, in some embodiments, increasing the surface temperature or applying low-energy ions can increase adatom surface migration to improve film quality. Thus, in some embodiments, the present invention provides EALS. In some embodiments, the process includes using a separate nitrogen plasma source (e.g., a radio frequency (RF) nitrogen source) or even ion-beam-assisted deposition.

[0042] FIG. 5A is a schematic diagram illustrating several different epitaxial growth modes (501) according to some embodiments of the present invention. In epitaxial film growth, the deposited material(s) ideally form regular crystals, with atomic arrangement and orientation dictated by the crystalline structure of the substrate (505). In some embodiments, various growth modes (510, 520, and / or 530) are obtained depending on the surface mobility of the arriving atoms and the properties of the substrate and epitaxial film. In some embodiments, depending on the surface mobility of the arriving atoms on the substrate surface and other factors such as the average terrace length of the surface steps, the crystal orientation and defect density of the substrate, the surface and interface energetics, and the lattice mismatch between the film and the substrate, the epitaxial growth process 1) initiates and progresses in one of the above modes, 2) is a combination of two or more modes, or 3) initiates in one mode and then transitions to other or combined growth modes.

[0043] In some embodiments, growth mode (510) (represented by the progression from (510a) to (510b)) is referred to as two-dimensional (2D) island growth. In some embodiments, in mode (510), small islands nucleate across the surface and grow laterally, coalescing into layers, resulting in many grain boundaries. In some embodiments, growth mode (520) (represented by the progression from (520a) to (520b)) is referred to as three-dimensional (3D) island growth. In some embodiments, in mode (520), small islands nucleate across the surface and grow, with additional islands forming on top of the initial islands before the underlying layer is finished, resulting in increased surface roughness (in some embodiments, mode (520) includes columnar growth). In some embodiments, growth mode (530) (represented by the progression from (530a) to (530b)) is referred to as step-flow growth. In some embodiments, in mode (530), atoms reaching the surface migrate and incorporate into the step edges, completing the layer in a step flow (in some embodiments, mode (530) occurs when surface diffusion is large compared to the average terrace length).

[0044] FIG. 5B is a set of atomic force microscope (AFM) images (502) of GaN growth. Image (540) shows smooth GaN with Ga droplets, which occurs in some embodiments when Ga-rich growth conditions are in place. In some embodiments, epitaxial atomic layer sputtering (EALS) is performed during GaN growth, such that there is a transition between Ga-rich and nitrogen-rich growth conditions shown in image (540). Image (545) shows the smooth GaN atomic steps, free of Ga droplets, that are present in the final state of the GaN film (after the transition between Ga-rich and nitrogen-rich conditions) prior to subsequent deposition. In some embodiments, the root-mean-square (RMS) roughness of image (540) is about 8 angstroms. In some embodiments, the RMS roughness of image (545) is about 2 angstroms.

[0045] In some embodiments, the present invention produces materials comprising GaN on two-dimensional (2D) photonic crystals using one or more of the processes described herein. In some embodiments, the GaN on the 2D photonic crystal comprises air / GaN repeating periods that are situated on a layer of GaN that is (optionally) situated on a layer of AlN that is situated on sapphire. In some embodiments, the GaN on the 2D photonic crystal comprises air / GaN repeating periods that are situated on a layer of GaN that is (optionally) situated on a layer of AlN that is situated on HfN. In some embodiments, the GaN on the 2D photonic crystal comprises air / GaN repeating periods that are situated on a layer of GaN that is (optionally) situated on a layer of AlN that is situated on ZrN. In some embodiments, the GaN on the 2D photonic crystal comprises air / GaN repeating periods that are situated on a layer of GaN that is (optionally) situated on a layer of AlN that is situated on other suitable Group IIIA nitrides. In some embodiments, any of the GaN structures are replaced by HfGaN. In some embodiments, any of the GaN structures are replaced by ZrGaN.

[0046] In some embodiments, the resulting material thickness of the air is expressed as: air gap thickness (T air )=(wavelength) * (1-2M) / 4, where M=an integer (0, 1, 2, 3, 4, 5).

[0047] In some embodiments, the resulting material thickness of GaN between air and sapphire (Al2O3) is expressed as: GaN thickness between air and Al2O3 (T GaN )=(wavelength) * (1-2M) / (4n), where M is an integer (e.g., 0, 1, 2, 3, 4, 5) and n is the refractive index.

[0048] In some embodiments, the GaN on the 2D photonic crystal is effectively carbon-free compared to GaN formed by MOCVD, hi some embodiments, the GaN on the 2D photonic crystal is effectively hydrogen-free compared to GaN formed by MOCVD.

[0049] In some embodiments, the GaN on 2D photonic crystals comprises effectively larger epitaxial grains or epi-islands compared to GaN formed by MOCVD and / or MBE. In some embodiments, the GaN on 2D photonic crystals comprises an epitaxial film with a substantially non-columnar structure. In some embodiments, the GaN on 2D photonic crystals comprises ultra-smooth surfaces due to improved 2D growth. In some embodiments, the GaN on 2D photonic crystals comprises smoother quantum wells than GaN formed by conventional processes. In some embodiments, compared to conventional methods of GaN growth, thinner GaN thickness is necessary due to dislocation self-annihilation and / or dislocation bending. In some embodiments, GaN sputtered at low temperatures on any material, mold, or substrate has a significantly different density of misfit dislocations than GaN grown at high temperatures. In some embodiments, the GaN on 2D photonic crystals comprises a substantially different point defect density than GaN formed by conventional processes. In some embodiments, the 2D photonic crystal GaN includes less wafer bow than GaN formed by conventional methods. In some embodiments, the 2D photonic crystal GaN includes a substantially different stress level in the film compared to GaN formed by conventional methods. In some such embodiments, the stress level in the film is detectable by Raman spectroscopy.

[0050] In some embodiments, subsequent epitaxial growth of the GaN material of the present invention results in any suitable light emitting device, light detecting device, light harvesting device, or transistor device (including transistors with vertical carrier flow). In some embodiments, the GaN material of the present invention is used in GaN-based displays (e.g., cell phones, tablets, etc.), GaN-based solar cells, GaN-based detector arrays, GaN-based very large scale integrated circuit applications, GaN coatings for windows, GaN-based high temperature indium tin oxide (ITO) replacements, etc. In some embodiments, wafers of the GaN material of the present invention have a diameter that is approximately 6 inches or less. In some embodiments, wafers of the GaN material of the present invention have a diameter that is greater than approximately 6 inches.

[0051] In some embodiments, the present invention provides a magnetron reactive sputtering system for producing the GaN material of the present invention. In some embodiments, other suitable sputtering techniques, such as direct current (DC) sputtering or radio frequency (RF) sputtering, are used. In some embodiments, the system for producing the GaN material of the present invention includes a nitrogen plasma source or an ion gun. In some embodiments, a solid-state gallium target is used, and an EALS process is performed to produce the GaN material of the present invention. In some such embodiments, the solid-state gallium allows for a sputter-up configuration, a sputter-down configuration, or a sputter-sideways configuration.

[0052] In some embodiments, the present invention provides a sputter GaN growth process that uses a solid gallium source located very close (e.g., less than about 8 inches) to a heated substrate. In some embodiments, the solid gallium source is located further away from the substrate. In some embodiments, the wafer substrate is heated to a range of 1100-1000 degrees Celsius (°C), in some embodiments to a range of 1000-900°C, in some embodiments to a range of 900-800°C, in some embodiments to a range of 800-700°C, in some embodiments to a range of 700-600°C, in some embodiments to a range of 600-500°C, in some embodiments to a range of 500-400°C, and in some embodiments to a range of 400°C to room temperature.

[0053] In some embodiments, the proximity and type of sputtering guns (e.g., balanced, unbalanced, and partially balanced) allows the process to achieve the desired add-atom energy through the plasma interaction of the sputtering guns while minimizing damage to the GaN film. In some embodiments, ionization caused by the proximity of the sputtering gun sources and types enables dislocation bending and / or dislocation self-breakdown.

[0054] In some embodiments, the sputtering gun used for the process of the present invention is fabricated with all-metal gasket seals, and / or the temperature of the N2 used with the sputtering gun is maintained below the melting point of gallium so that gallium can become solid. In some embodiments, heat transfer liquids such as various alcohols are used. In some embodiments, the characteristic dimensions of the sputtering target are larger than the 2-inch diameter of such a cooling system.

[0055] In some embodiments, there is an advantage to incorporating a gallium gun into a rotary magnet sputtering gun. In some embodiments, there is another advantage to using ring-shaped sputtering targets and / or multiple ring-shaped sputtering targets for the co-deposition of composite materials such as indium gallium nitride (InGaN) and / or aluminum gallium nitride (AlGaN). In some embodiments, hafnium, zirconium, or silicon are included as sputtering targets. In some embodiments, dilute SiH4 in nitrogen is provided, and the gas delivery system includes a dual dilution system. In some embodiments, the ring-shaped sputtering target allows for in-situ reflectivity measurements. In some embodiments, both radio frequency and direct current methods are applicable. In some embodiments, when EALS is used, variation between gallium-rich and gallium-lean conditions is achieved by varying temperature, pressure, argon, nitrogen, gallium source power, growth rate, or any other suitable variable.

[0056] In some embodiments, the present invention provides an epitaxial process for magnetron sputtering that includes any one or more of the following steps: (1) providing any combination of substrates, including any number and / or size of wafer substrates or wafer substrate cassettes that fit into a load lock; (2) the substrates are silicon, sapphire, GaN / sapphire, AlN / sapphire, GaN / silicon, AlN / silicon, or any other suitable mold such as any other Group IIIA nitride on sapphire or silicon; (3) transferring the wafer substrates to an epitaxial chamber by any suitable method or mechanism of manual or robotic transfer; (4) placing the wafer substrates into an AlN epitaxial sputtering (or other PVD), MOCVD, or MBE chamber, where AlN is grown to any thickness (columnar or non-columnar) on the wafer substrate; (5) transferring the AlN / wafer substrates by any suitable method or mechanism of manual or robotic transfer; (6) transferring the AlN / substrate wafers to an epitaxial chamber for GaN epitaxy. (6) placing the GaN / AlN / wafer substrate into a sputtering chamber, where GaN is grown to a desired thickness by sputtering on the AlN / wafer substrate (in some embodiments, the gallium is in the solid state during this process, an EALS process is performed, and in some embodiments, optional silicon (Si), hafnium (Hf), and / or zirconium (Zr) doping is included in the process); (7) transferring the sputtered GaN / AlN / wafer substrate by any suitable method or mechanism, either manual or robotic transfer; (8) depositing a Grown-Epitaxial Metal Mirror (Grown-Epitaxial Metal Mirror) on the AlN / wafer substrate; placing the sputtered GaN / AlN / wafer substrate into a Geometrically Mirrored Metal (GEMM) sputtering chamber, wherein GEMM growth occurs by sputtering on the sputtered GaN / AlN / wafer substrate (in some such embodiments, GEMM growth is performed as described in U.S. Pat. Nos. 7,915,624, 8,253,157, and / or 8,890,183, which are introduced above and incorporated herein by reference);In some embodiments, the process repeats steps 5, 6, and 7 in any order or combination as needed, (9) optionally growing a layer of AlN by sputtering on the GEMM to any suitable thickness, (10) transferring the sputtered GEMM / GaN / AlN / wafer substrate by any suitable method or mechanism of manual or robotic transfer, (11) covering the sputtered GEMM / GaN / AlN / wafer substrate with a final layer of sputtered GaN grown by sputtering to any suitable thickness, (12) transferring the sputtered GaN / GEMM / GaN / AlN / wafer substrate by any suitable method or mechanism of manual or robotic transfer, and (13) placing the sputtered GaN / GEMM / GaN / AlN / wafer substrate into an MOCVD, MBE, or sputtering (or other PVD) system for growth of quantum well(s) (also known as the active region) and p-type layer(s);

[0057] In some embodiments, the present invention provides a growth process for epitaxial materials that includes any one or more of the following steps: (1) providing any combination of substrates, including wafer substrates or wafer substrate cassettes of any number and / or size that fit into a load lock; (2) the substrates being silicon, sapphire, GaN / sapphire, AlN / sapphire, GaN / silicon, AlN / silicon, or any other suitable mold such as sapphire or any other Group IIIA nitride on silicon; (3) transferring the wafer substrates to an epitaxial chamber by any suitable method or mechanism of manual or robotic transfer; (4) placing the wafer substrates into an AlN epitaxial sputtering (or other PVD), MOCVD, or MBE chamber, where AlN can be grown to any thickness (columnar or non-columnar) on the wafer substrates; and (5) transferring the wafer substrates to an epitaxial chamber by any suitable method or mechanism of manual or robotic transfer. (6) placing the GaN / AlN / substrate wafer into a grown epitaxial metal mirror (GEMM) sputter chamber where GEMM growth occurs by sputtering on the AlN / wafer substrate (in some such embodiments, GEMM growth is performed as described in U.S. Pat. Nos. 7,915,624, 8,253,157, and / or 8,890,183, which are introduced above and incorporated herein by reference);In some embodiments, the process repeats steps 1-6 in any order or combination as needed; (7) growing a layer of AlN by sputtering on the GEMM to any suitable thickness; (8) transferring the sputtered GEMM / AlN / wafer substrate by any suitable method or mechanism, either manual or robotic transfer; and (9) covering the sputtered GEMM / AlN / wafer substrate with a final layer of sputtered Ga, grown by sputtering on the GEMM / AlN / wafer substrate to any suitable thickness (some embodiments may include the steps of: In such embodiments, the gallium is in the solid state, an EALS process is performed, and in some embodiments, doping with Si, Hf, Zr occurs), (10) transferring the sputtered GaN / GEMM / AlN / wafer substrate by any suitable method or mechanism, either manual or robotic, and (11) placing the sputtered GaN / GEMM / AlN / wafer substrate into an MOCVD, MBE, or sputtering (or other PVD) system for growth of the quantum well(s) (also known as the active region) and p-type layer(s);

[0058] In some embodiments, the present invention provides a growth process for epitaxial materials that includes any one or more of the following steps: (1) providing any combination of substrates, including wafer substrates or wafer substrate cassettes, of any number and / or size that fit into a load lock; (2) providing a substrate that is selected from the group consisting of silicon, sapphire, GaN / sapphire, AlN / sapphire, GaN / silicon, AlN / silicon, and the like; , sapphire, or any other suitable mold, such as any other Group IIIA nitride on silicon; (3) transferring the wafer substrate to an epitaxial chamber by any suitable method or mechanism, either manual or robotic, (4) placing the substrate wafer into a grown epitaxial metal mirror (GEMM) sputter chamber, where GEMM growth occurs by sputtering on the wafer substrate (in some such embodiments, GEMM growth is carried out as described in U.S. Pat. Nos. 7,915,624, 8,253,157, and / or 8,890,183, which are introduced above and incorporated herein by reference).), (5) transferring the GEMM / AlN / GEMM / wafer substrate to an epitaxial chamber by any suitable method or mechanism of manual or robotic transfer; (6) placing the GEMM / wafer substrate into an AlN epitaxial sputtering chamber where AlN is grown to any suitable thickness (columnar or non-columnar); in some embodiments, the process repeats steps 4-5 as needed; (7) optionally growing a layer of AlN by sputtering on the GEMM to any suitable thickness; (8) transferring the sputtered GEMM / AlN / GEMM / wafer substrate by any suitable method or mechanism of manual or robotic transfer; (9) sputtering the AlN grown to any suitable thickness on the GEMM / AlN / GEMM / wafer substrate. (10) covering the sputtered GEMM / AlN / GEMM / wafer substrate with a final layer of sputtered GaN (in some such embodiments, the gallium target used during sputtering is solid-state, an EALS process is performed, and in some embodiments, doping with Si, Hf, Zr occurs); (11) transferring the sputtered GaN / GEMM / AlN / GEMM / wafer substrate by any suitable method or mechanism, whether manual or robotic, and (12) placing the sputtered GaN / GEMM / AlN / GEMM / wafer substrate into an MOCVD, MBE, or sputtering (or other PVD) system for growth of quantum well(s) (also known as the active region) and p-type layer(s).

[0059] In some embodiments, the present invention provides a growth process for epitaxial materials that includes any one or more of the following steps: (1) providing any combination of substrates, including wafer substrates or wafer substrate cassettes of any number and / or size that fit into a load lock; (2) the substrates being silicon, sapphire, GaN / sapphire, AlN / sapphire, GaN / silicon, AlN / silicon, sapphire, or any other suitable mold such as any other Group IIIA nitride on silicon; (3) transferring the wafer substrates to a sputtering epitaxial chamber by any suitable method or mechanism of manual or robotic transfer; (4) growing any Group IIIA nitride material (columnar or non-columnar) on the wafer substrates to any suitable thickness; (5) transferring the Group IIIA nitride / wafer substrate by any suitable method or mechanism of manual or robotic transfer; (6) 1. Placing the Group IIIA nitride / wafer substrate into a GEMM sputtering chamber, where the GEMM growth occurs by sputtering on the Group IIIA nitride / wafer substrate. (In some such embodiments, the GEMM growth is carried out as described in U.S. Pat. Nos. 7,915,624, 8,253,157, and / or 8,890,183, which are introduced above and incorporated herein by reference.)In some embodiments, the process is repeated in any order or combination as desired, (7) optionally growing a layer of AlN or any other IIIA nitride by sputtering on the GEMM to any suitable thickness, (8) transferring the sputtered GEMM / IIIA nitride / wafer substrate by any suitable method or mechanism, either manual or robotic, and (9) covering the sputtered GEMM / IIIA nitride / wafer substrate with a final layer of sputtered Ga, grown by sputtering on the GEMM / IIIA nitride / wafer substrate to any suitable thickness. (10) transferring the sputtered GaN / GEMM / IIIA nitride / wafer substrate by any suitable method or mechanism, whether manual or robotic, and (11) placing the sputtered GaN / GEMM / IIIA nitride / wafer substrate into an MOCVD, MBE, or sputtering (or other PVD) system for growth of the quantum well(s) (also known as the active region) and p-type layer(s).

[0060] In some embodiments, the Group IIIA nitrides are replaced by any other Group IIIA nitride, or any combination of Group IIIA nitride layers and / or compounds. Additionally, in some embodiments, these materials include silicon (Si), Hf, Zr, and / or magnesium (Mg). In some embodiments, wafers and / or substrates are inserted, moved, or directly transferred by any suitable (manual or robotic) method or mechanism within or between any combination and / or number of material-specific or process-specific epitaxial sputtering (or other PVD), MOCVD, or MBE chambers or equipment. In some embodiments, the inventive process occurs within a material-specific sputtering (or other PVD), MOCVD, or MBE epitaxial chamber and / or with any combination of optional wafer transfer(s) within and between material-specific sputtering (or other PVD), MOCVD, or MBE chambers. In some embodiments, the process of the present invention occurs in a material-specific sputtering (or other PVD), MOCVD, or MBE epitaxial chamber without wafer transfer(s).

[0061] Growing gallium nitride (GaN) films by conventional sputtering techniques is typically considered unprofitable due to poor film quality (e.g., GaN films grown by conventional sputtering techniques typically have characteristic X-ray diffraction (XRD) rocking curve full width at half maximum values of 620 arcsec and / or higher). Because these sputtered epitaxially grown films are considered to be of lower quality than those that can be produced by MOCVD or MBE methods, conventional sputtered epitaxial growth techniques are not designed to include intentional doping.

[0062] In some embodiments, the present invention provides a method for manufacturing silicon-based nanotubes that are intentionally doped with a doping element such as silicon (or titanium (Ti), zirconium (Zr), hafnium (Hf), oxygen (O), sulfur (S), selenium (Se), and / or tellurium (Te)) and have a doping concentration of about 5×10 16 / cm 3 n-type doped GaN (which is known to be unintentionally doped as well) with a background electron concentration of 1×10 18 / cm 3 ~5x10 20 / cm 3 5x10 etc. 16 / cm 3 Achieving higher electron concentrations, or even higher, in some embodiments, these intentionally doped materials are used to create ohmic contacts and are used as conductive materials.

[0063] In some embodiments, the present invention provides methods for growing high quality GaN by sputtering with optional n-type doping, including one or more of the following: (1) degassing the wafer, chamber, and wafer holder; (2) GaN nucleation, where GaN nucleation includes (a) setting a temperature to provide adatom energy such that adatoms find energetically favorable positions on the surface of the template to initiate initial epitaxial growth; (b) setting a vacuum pressure in the chamber to allow for the formation of a plasma; (c) supplying plasma gas to the chamber; (d) supplying nitrogen gas to the chamber; and (e) providing power to a solid gallium (Ga) target gun to provide gallium and adatoms to the template to initiate initial epitaxial growth. (c) e-beam evaporation of dopants; (d) Ga mixing with dopants in the sputtering gun; and (e) dilute SiH, SiH, tetraethylsilane, and / or other reactants carrying dopants (Si) in a carrier gas (H, N, Ar, Xe, He, Kr, Rn, etc.). and (f) ion implant doping of silicon, wherein the method further includes (5) increasing the temperature to a temperature high enough to remove any potential gallium droplets and allowing to age until the gallium droplets are gone; and (6) turning off any of the above variables as needed and removing the wafer.

[0064] The GaN industry is interested in the full width at half maximum (FWHM) values of the ω rocking curves of both the X-ray diffraction (XRD) 002 (symmetric) and 102 (asymmetric) peaks as a measure of quality for the resulting devices. In some embodiments, the present invention provides sputtering GaN processes that enable FWHM values of both the 002 and 102 peaks to be less than 1000 arcsec, in some embodiments less than 600 arcsec, in some embodiments less than 300 arcsec, in some embodiments less than 200 arcsec, and in some embodiments less than 100 arcsec. In some embodiments of the present invention, the FWHM of the 002 peak is less than 500 arcsec, and the FWHM of the 102 peak is less than 1000 arcsec.

[0065] In some embodiments of the present invention, the FWHM of the 002 peak is less than 400 arcsec and the FWHM of the 102 peak is less than 800 arcsec. In some embodiments, the FWHM of the 002 peak is less than 300 arcsec and the FWHM of the 102 peak is less than 600 arcsec. In some embodiments, the FWHM of the 002 peak is less than 300 arcsec and the FWHM of the 102 peak is less than 500 arcsec. In some embodiments, the FWHM of the 002 peak is less than 300 arcsec and the FWHM of the 102 peak is less than 400 arcsec. In some embodiments, the FWHM of the 002 peak is less than 250 arcsec and the FWHM of the 102 peak is less than 350 arcsec.

[0066] In some embodiments, the present invention provides methods that include growing gallium nitride (GaN) by physical vapor deposition (PVD) (e.g., by sputtering) such that the grown GaN has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of both the 002 peak and the 102 peak of less than 1000 arcsec.

[0067] In some embodiments, the present invention provides a method for growing a GaN layer by sputtering, comprising: (1) co-sputtering any of Si, Ti, Zr, Hf, O, S, Se, and / or Te while growing GaN by sputtering; (2) thermally evaporating Si, Ti, Zr, Hf, O, S, Se, and / or Te while growing GaN by sputtering; and (3) co-sputtering Si, Ti, Zr, Hf, O, S, Se, and / or Te while growing GaN by sputtering. (4) growing n-type GaN by mixing Ga with Si, Ti, Zr, Hf, O, S, Se, and / or Te; (5) gas injection of dilute SiH, GeH, SiH, tetraethylsilane, and / or other reactants carrying the previously mentioned elements in a carrier gas (H, N, Ar, Xe, He, Kr, Rn...) during sputtering GaN growth; and (6) ion implantation doping with Si, Ti, Zr, Hf, O, S, Se, and / or Te during sputtering GaN growth. In some embodiments, the invention further includes (7) other Group IV element doping (e.g., Ge or Sn in some embodiments), (8) co-doping of any combination of the above elements, (9) n-doping enhanced with surfactants (e.g., In), (10) doping tailored to create a special doping profile or internal electric field, and / or (11) delta-doping of any of the above elements. In some embodiments, the invention includes the application of surfactants to modify or enhance growth.

[0068] In some embodiments, GaN grown using the methods described herein has a FWHM of 0-5 arcsec; in some embodiments, 5-10 arcsec; in some embodiments, 10-15 arcsec; in some embodiments, 15-20 arcsec; in some embodiments, 20-25 arcsec; in some embodiments, 25-30 arcsec; in some embodiments, 30-40 arcsec; in some embodiments, 40-50 arcsec. In some embodiments, a FWHM of 50-100 arcsec; in some embodiments, a FWHM of 100-150 arcsec; in some embodiments, a FWHM of 150-200 arcsec; in some embodiments, a FWHM of 200-250 arcsec; in some embodiments, a FWHM of 250-300 arcsec; in some embodiments, a FWHM of 300-400 arcsec; in some embodiments, a FWHM of 400-500 arcsec; in some embodiments, a FWHM of 500-600 arcsec. In some embodiments, the ω rocking curve has a full width at half maximum (FWHM) X-ray diffraction measurement (of the 002 peak and / or the 102 peak) of: M; in some embodiments, a FWHM of less than 620 arcsec; in some embodiments, a FWHM of less than 600 arcsec; in some embodiments, a FWHM of less than 500 arcsec; in some embodiments, a FWHM of less than 400 arcsec; in some embodiments, a FWHM of less than 300 arcsec; in some embodiments, a FWHM of less than 240 arcsec; in some embodiments, a FWHM of less than 200 arcsec; in some embodiments, a FWHM of less than 100 arcsec; in some embodiments, a FWHM of less than 50 arcsec; in some embodiments, a FWHM of less than 40 arcsec; in some embodiments, a FWHM of less than 30 arcsec; in some embodiments, a FWHM of less than 27 arcsec; in some embodiments, a FWHM of less than 25 arcsec; in some embodiments, a FWHM of less than 20 arcsec; in some embodiments, a FWHM of less than 10 arcsec; and in some embodiments, a FWHM of less than 5 arcsec.

[0069] In some embodiments, the present invention provides methods that include growing gallium nitride (GaN) by physical vapor deposition (PVD) (e.g., by sputtering) such that the grown GaN has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of less than 620 arcsec. In some embodiments, the grown GaN has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of less than 1000 arcsec. In some embodiments, the method further includes doping the GaN during the PVD of the GaN by co-sputtering at least one dopant selected from the group consisting of silicon (Si), titanium (Ti), zirconium (Zr), hafnium (Hf), oxygen (O), sulfur (S), selenium (Se), and tellurium (Te). In some embodiments, the method further includes doping the GaN during the PVD of the GaN by thermally evaporating at least one dopant selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the method further comprises doping the GaN by e-beam evaporation of at least one selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te to sustain the PVD of the GaN.

[0070] In some embodiments of the method, growing GaN includes doping the GaN to form n-type GaN using a mixture of Ga and at least one selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the method further includes doping the GaN by gas injection of at least one selected from the group consisting of dilute SiH, GeH, SiH, tetraethylsilane, and / or other reactants; and maintaining a carrier gas (H, N, Ar, Xe, He, Kr, Rn, or the like) and gas injection of at least one selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te; and sustaining the PVD of GaN. In some embodiments, the method further includes doping the GaN by ion implantation doping with at least one selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te to sustain the PVD of GaN.

[0071] In some embodiments of the method, the doping of the GaN uses at least one dopant selected from the group consisting of germanium (Ge) and tin (Sn) instead of, or in addition to, the elements detailed above. In some embodiments, the doping of the GaN includes surfactant-enhanced n-doping (e.g., In). In some embodiments, the doping of the GaN includes doping tailored to create a special doping profile or internal electric field. In some embodiments, the doping of the GaN includes delta doping with any of the elements detailed above.

[0072] In some embodiments, the present invention provides methods that include growing gallium nitride (GaN) by physical vapor deposition (PVD) (e.g., in some embodiments, by sputtering) such that the grown GaN has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement (in the 002 plane and / or the 102 plane) of less than 25 arcsec.

[0073] In some embodiments, the present invention provides methods that include growing gallium nitride (GaN) by physical vapor deposition (PVD) (e.g., in some embodiments, by sputtering), such that the grown GaN has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of both the 002 peak and the 102 peak of less than 1000 arcsec.

[0074] In some embodiments, the present invention provides a method comprising sputtering epitaxial GaN; and intentionally doping n-type GaN during sputtering. In some embodiments of the method, the doping comprises co-sputtering silicon (Si). In some embodiments, the doping comprises thermal evaporation of Si. In some embodiments, the doping comprises e-beam evaporation of Si. In some embodiments, the sputtering comprises using a target material comprising a mixture of Ga and Si. In some embodiments, the doping comprises gas injection of SiH, SiH, tetraethylsilane, and / or other reactants (in some embodiments, dilute portions) in a Si-carrying carrier gas (e.g., H, N, Ar, Xe, He, Kr, Rn, etc.).

[0075] In some embodiments, the doping comprises ion implantation doping of Si. In some embodiments, the doping comprises sputtering at least one selected from the group consisting of silicon (Si), titanium (Ti), zirconium (Zr), hafnium (Hf), oxygen (O), sulfur (S), selenium (Se), and tellurium (Te). In some embodiments, the doping comprises thermal evaporation of at least one selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the doping comprises e-beam evaporation of at least one selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the sputtering comprises using a target material comprising a mixture of Ga and at least one selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, doping comprises gas-pressuring SiH, 2H, tetraethylsilane, and / or other reactants with a carrier gas (e.g., H, N, Ar, Xe, He, Kr, Rn, etc.) carrying at least one selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te.

[0076] In some embodiments, the doping comprises ion implantation doping of at least one dopant selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the doping comprises tailored doping using at least one dopant selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te to create a specific doping profile or internal field. In some embodiments, the doping comprises delta doping with at least one dopant selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the doping comprises co-doping with at least one dopant selected from the group consisting of Si, Ti, Zr, Hf, O, S, Se, and Te. In some embodiments, the doping comprises surfactant (e.g., In) enhanced n-doping. In some embodiments, the method further comprises other Group IV element doping (e.g., Ge or Sn in some embodiments) instead of or in addition to the aforementioned elements.

[0077] 6A is a table (601) of thicknesses (in nanometers) for the AlN and GaN layers identified in the GaN structure (301) of FIG. 3. In some embodiments, each row of the table (601) refers to a range of thicknesses for the AlN layer (e.g., layer 306 of FIG. 3) and a corresponding range of thicknesses for at least one of the GaN layers (e.g., layer (307) and / or layer 308 of FIG. 3). In some embodiments, the thickness of the AlN layer ranges from about a monolayer thickness to 210 nanometers (nm), and the thickness of the GaN layer ranges from about 10 to 20,000 nm.

[0078] FIG. 6B is a continuation of table (601).

[0079] 7A is a table (701) showing ω rocking curve full width at half maximum (FWHM) X-ray diffraction (XRD) values (arcsec) for GaN produced according to some embodiments of the present invention. Table (701) includes rocking curve values for both the 002 (symmetric) and 102 (asymmetric) peaks. In some embodiments, the rocking curve values typically decrease with decreasing AlN thickness. In some embodiments, smaller rocking curve values are typically more preferable.

[0080] 7B is a continuation of Table (701). In some embodiments, the FWHM value of the GaN 002 peak ranges from approximately 14.4 to 619 arcsec, and the FWHM value of the GaN 102 peak ranges from approximately 0 to 2515 arcsec. In some embodiments, the present invention provides a combination of an 002 peak value of less than 250 arcsec and a 102 peak value of less than 550 arcsec at the AlN thicknesses indicated in Table (1201) and the sputtering process (see Table (1301) for some FWHM embodiments provided by the present invention; each row in Table (1301) refers to a range of FWHM values for the GaN 002 and 102 peaks).

[0081] In some embodiments, the present invention provides methods of producing gallium nitride (GaN)-based devices, the method including: providing a substrate; sputtering aluminum nitride (AlN) onto the substrate; and sputtering at least a first layer of GaN onto the AlN such that the first layer of GaN has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction (XRD) measurement of the 002 peak that is less than 250 arcsec, and a FWHM XRD measurement of the 102 peak that is less than 550 arcsec.

[0082] In some embodiments of the method, the first layer of GaN has a thickness in a range of approximately 10 to 20,000 nanometers (nm), wherein the AlN has a thickness in a range of approximately 5 to 210 nm.

[0083] In some embodiments, the present invention provides a gallium nitride (GaN)-based device, the device comprising: a substrate; a first layer of aluminum nitride (AlN) on the substrate; and at least a second layer of GaN on the first layer of AlN; wherein the second layer of GaN has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction (XRD) measurement of the 002 peak that is less than 250 arcsec, and a FWHM XRD measurement of the 102 peak that is less than 550 arcsec.

[0084] In some embodiments of the device, the first layer of GaN has a thickness in the range of approximately 10 to 20,000 nanometers (nm), wherein the AlN has a thickness in the range of approximately 1 monolayer to 210 nm.

[0085] In some embodiments, the present invention provides methods for growing gallium-polar (Ga-polar) gallium nitride (GaN) on sapphire (in some such embodiments, the sapphire is substantially c-plane oriented sapphire; in some embodiments, substantially r-plane oriented sapphire; in some embodiments, substantially m-plane oriented sapphire; in some embodiments, substantially a-plane oriented sapphire). In some embodiments, the method includes one or more of the following: (1) preparing a substrate (in some embodiments, step 1 is optional), where the substrate preparation comprises (a) chemical cleaning (epi-ready and / or degreasing, and / or chemical etching), and (b) a process using a pressure lower than air and a temperature higher than air (e.g., in some embodiments, 1e -6(2) surface nitridation, wherein the surface nitridation comprises: (a) providing a N radio frequency (RF) plasma at a RF power, N flow rate, and substrate temperature for a duration of 10-60 minutes (e.g., in some embodiments, RF power: 300-500 Watts (W), N flow rate: 2-9 standard cubic centimeters per minute (SCCM), substrate temperature: 300-900°C, and duration: 10-60 minutes); and (b) optionally monitoring reflection high energy electron diffraction (RHEED) during nitridation;forming an AlN buffer (in some embodiments, step 3 is optional), wherein the step of shaping the AlN buffer comprises: (a) depositing a layer of AlN (e.g., in some embodiments, 5 nanometers (nm) to 50 nm of AlN (or AlGaN)) by increasing RF power on a magnetron gun, nitrogen flow, substrate temperature, and Al / N flux ratio (e.g., in some embodiments, RF power: 300-800 W, N flow: 2-5 SCCM, substrate temperature: 700-850°C, Al / N flux slightly greater than 1:1); (b) in some embodiments, depositing Al for 5 seconds, then providing RF activated nitrogen plasma for 10 seconds (one or more times), then depositing AlN for 1 minute, followed by annealing for 30 seconds (one or more times), then a final N anneal (just enough to use up the excess Al on the surface), (c) optionally monitoring the change in RHEED pattern from sapphire to diffused AlN to streaked AlN, and (d) optionally using optical reflectivity measurements to monitor the number of excess metal anneals to form an AlN buffer. In some embodiments, when the template is AlN as described in steps (1) through (3) above, gallium is deposited and then evaporated to remove oxygen from the AlN surface. In some embodiments, the method further includes (4) GaN nucleation, wherein the GaN nucleation includes (a) providing 10-100 nm of high-temperature N-rich GaN (e.g., in some embodiments, RF power: 300-500 W, N flow: 2-5 SCCM, substrate temperature: 700-850° C., Ga / N flux ratio less than 1:1); (b) optionally monitoring RHEED patterns from streaky chevrons to extended chevrons (from two-dimensional (2D) diffraction to three-dimensional (3D) diffraction); and (c) optionally monitoring reflectometry intensity corresponding to the intended surface roughening;(5) forming a GaN smooth layer, wherein the step of forming the GaN smooth layer comprises: (a) providing 100-500 nm of high-temperature Ga-rich GaN (e.g., in some embodiments, RF power: 300-500 W, N2 flow: 2-5 SCCM, substrate temperature: 700-850°C, Ga / N flux ratio greater than 1:1); (b) removing excess Ga under N2 (RF plasma off) and at elevated substrate temperature (e.g., 700 to 800°C in some embodiments); (c) optionally monitoring RHEED patterns from elongated to striated peaks (3D to 2D diffraction); (6) forming a thick GaN defect reduction layer, where forming the GaN defect reduction layer (a) provides 1-5 μm of slightly Ga-rich GaN (e.g., in some embodiments, RF power: 300-500 W, N flow: 2-5 SCCM, substrate temperature: 400-800°C, Ga / N flux ratio greater than about 1:1, growth rate faster than 0.1 μm / hr); (b) removing excess Ga under N (RF plasma off) and increasing the substrate temperature (e.g., in some embodiments, 700 to 800°C) approximately every 15-30 minutes; and (c) an RHEED pattern showing clearer striations with increasing GaN thickness. (d) optionally using optical reflectivity measurements to monitor growth rate, changes in growth mode, and the number of extra Ga anneals; (e) optionally using defect reduction techniques such as epitaxial atomic layer sputtering (EALS), plasma enhanced epitaxy, glancing angle ion-enhanced growth, thin AlN interlayers, and AlN / GaN short period superlattices, or any other suitable defect reduction techniques; (f) forming a GaN defect reduction layer, including optionally using doping methods as described above (e.g., in some embodiments, dilute concentrations of SiH in nitrogen are injected into the chamber);

[0086] In some embodiments, the present invention provides Group IIIA nitride AlN / GaN and AlN / AlGaN superlattice (SL) structures used for threading dislocation (TD) density reduction (i.e., TD filtering) and / or for strain control and fabrication in GaN and AlGaN layers and structures grown on sapphire and silicon substrates. In some such embodiments, the sputtering techniques described herein (including, in some embodiments, epitaxial atomic layer sputtering (EALS)) are used to form high-quality TD filtering and strain-control structures at growth temperatures significantly lower than conventional methods. In some embodiments, the Group IIIA nitride SL structures include 50-100 periods of 3-5 nm AlN and 10-30 nm GaN or AlGaN grown under conditions that promote smooth interfaces. In some embodiments, the present invention provides SL structures that include periodic lattice-matched III-nitride / metal nitride layers, such as GaN / HfN and GaN / ZrN SLs. (In some such embodiments, the SL structures additionally have higher out-of-plane electrical conductivity compared to AlN / GaN SLs due to the very high resistivity of AlN.)

[0087] In some embodiments, the present invention provides methods for producing gallium nitride (GaN)-based devices, the methods including: providing a substrate mold comprising aluminum nitride; depositing one or more gallium nitride (GaN) nucleation layers on the substrate mold; depositing a GaN smoothing layer onto the one or more GaN nucleation layers; and depositing a thick GaN defect reduction layer onto the GaN smoothing layer.

[0088] In some embodiments, sputter epitaxy offers multiple benefits, including: (1) no metalorganic precursors; (2) lower process temperatures (compared to conventional epitaxy techniques); (3) larger wafers; and (4) superior thermal budgets that enable integration.

[0089] In some embodiments, the present invention provides systems and methods that include PVD (e.g., in some embodiments, sputtering) of an AlN nucleation layer (in some embodiments, 5 minutes of PVD can replace up to about 1.5 hours of MOCVD), PVD of a GaN:Hf template (in some embodiments, about 500 nm of GaN:Hf can replace up to about 5 μm of MOCVD GaN due to the very high conductivity of GaN:Hf), and PVD of a HfN / GaN:Hf distributed Bragg reflector (DBR) template (in some embodiments, PVD of a HfN / GaN:Hf DBR template is lattice matched to GaN, enabling optical microcavity devices with 99.99% reflectivity and high conductivity).

[0090] FIG. 8A is a schematic diagram of a mold and device epitaxy system (801) for electronics and solid-state lighting (SSL). In some embodiments, the system (801) performs processing on a bare wafer (850) to produce a metallic mirror device (860). In some embodiments, the system (801) includes multiple modules (805-810). (In some such embodiments, each one of the multiple modules (805-810) is a separate deposition chamber; in other embodiments, the multiple modules (805-810) are contained within a single deposition chamber.) In some embodiments, the system (801) includes an aluminum nitride (AlN) nucleation module (805) configured to produce a nucleation layer of AlN using one or more of the PVD processes described herein. (In some such embodiments, the thickness of the AlN nucleation layer is approximately 25 nanometers (nm).) In some embodiments, the system (801) further includes a grown epitaxial metal mirror (GEMM) module (806) configured to produce one or more GEMM layers (in some such embodiments, the GEMM layer(s) are produced as described in U.S. Pat. Nos. 7,915,624, 8,253,157, and / or 8,890,183, which are incorporated herein by reference). In some embodiments, the system (801) further includes GaN modules (807, 808, 809, and 810), which are configured to produce one or more GaN layers using one or more of the PVD processes described herein (e.g., in some embodiments, one or more layers of Hf:GaN are produced in the GaN modules (807, 808, 809, and / or 810)).

[0091] 8B is a schematic diagram of a mold and device epitaxy system (802) for electronics and SSL. In some embodiments, the system (802) performs processing on bare wafers (850) to produce LED-ready devices (870). In some embodiments, the system (802) includes multiple modules (805-808 and 820-821). (In some such embodiments, each one of the multiple modules (805-808 and 820-821) is a separate deposition chamber; in other embodiments, the multiple modules (805-808 and 820-821) are contained within a single deposition chamber.) In some embodiments, instead of the GaN modules (809 and 810), the system (802) includes MOCVD modules (821 and 822), which are configured to provide MOCVD processing.

[0092] 9 is a schematic diagram of a template and device epitaxy process (901) for electronics and SSL. In some embodiments, process (901) includes steps (A), (B), and (C). In some embodiments, step (A) includes producing a nucleation layer of AlN (906) on a sapphire substrate (905) using one or more of the PVD processes described herein (e.g., in some embodiments, sputtering), where the AlN nucleation layer (906) has a thickness of approximately 25 nm (in some such embodiments, step (A) is performed in module (805) of FIG. 8A). In some embodiments, step (B) includes producing a layer of Hf:GaN (907) on the AlN nucleation layer (906) using one or more of the PVD processes described herein (e.g., in some embodiments, sputtering). In some embodiments, step (B) is performed in modules (807, 808, 809, and / or 810) of Figure 8A. In some embodiments, step (C) includes producing N periods of alternating layers (e.g., distributed Bragg reflectors) of Hf:GaN and HfN (908) on layer (907) based on the GEMM descriptions in U.S. Patent Nos. 7,915,624, 8,253,157, and / or 8,890,183, introduced above and incorporated herein by reference (in some such embodiments, step (C) is performed in GEMM module (806) of Figure 8A). In some embodiments, one or more of steps (A), (B), and (C) include using an MOCVD process to produce an n-type GaN layer (920) and a p-type GaN / multiple quantum well (MQW) layer (921) (in some such embodiments, the thickness of layer (920) is approximately 5 micrometers (μm); in other such embodiments, the thickness of layer (920) is less than approximately 1 μm). In some embodiments, layers (920 and 921) are produced in modules (920 and / or 921) of FIG. 8B.

[0093] FIG. 10 shows the relationship between n-type carrier concentration (per cubic centimeter) and adatom mobility (cm ) for hafnium-doped gallium nitride produced in accordance with some embodiments of the present invention. 2 / V·s) (1001).

[0094] 11 is a graph 1101 showing X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention. In some embodiments, the ω rocking curve full width at half maximum (FWHM) value of the 002 peak is 300 arcsec.

[0095] 12 is a schematic diagram of a GaN template structure (1201) for subsequent LED epitaxial growth. In some embodiments, the structure (1201) includes one or more indium tin oxide (ITO) replacement layers for use with thin film and standard light emitting device applications. In some embodiments, the ITO replacement layer is patterned (e.g., pyramidal, dome, 2D photonic crystal, etc.) and includes GaN doped with a transition metal element to form patterned transition metal doped GaN, such as Hf:GaN, Hf:AlGaN, Hf:InGaN, Hf:InGaAlN, or the like. In some embodiments, for p-side-up devices, the replacement layer of ITO comprises a layer of Hf:GaN (1205) disposed directly on top of the p-type GaN / MQW layer(s) (921) and a layer of Si:GaN (1206) (in some such embodiments, less than 1 μm thick) disposed directly below the p-type GaN / MQW layer(s) (921). In some embodiments, for p-side-down devices, the replacement layer of ITO comprises a layer of Hf:GaN (1207) disposed directly on top of the AlN nucleation layer(s) (906). In some embodiments, the PVD processes (e.g., sputtering) for producing Hf:GaN described herein have low processing temperatures, which allows the layer of ITO to be used both pre- and post-epitaxy (thus, in some such embodiments, eliminating the need for tetrakisdimethylaminohafnium, as commonly used in MOCVD systems).

[0096] FIG. 13 is a schematic diagram of a GEMM / GaN epitaxial stack structure (1301). In some embodiments, the structure (1301) includes a sapphire (Al2O3) substrate layer (1305) and five periods of alternating GEMM and GaN layers (1306). In some embodiments, the structure (1301) is lattice-matched for epi-ready growth, highly conductive (low resistivity), and more reflective than an AlN / GaN distributed Bragg reflector (DBR). In some embodiments, the GEMM growth is performed as described in U.S. Patent Nos. 7,915,624, 8,253,157, and / or 8,890,183, which are incorporated herein by reference.

[0097] 14A is a graph 1401 of X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention. In some embodiments, the GaN is lattice-matched with a low rocking curve full width at half maximum (FWHM) value (e.g., in some embodiments, a mismatch of 0.35%).

[0098] FIG. 14B is a graph (1402) of X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention.

[0099] FIG. 14C is a graph (1403) of X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention.

[0100] FIG. 14D is a graph 1404 of X-ray diffraction (XRD) data for GaN produced in accordance with some embodiments of the present invention.

[0101] 15 is a chart 1501 of atomic force microscopy (AFM) data for GaN on GEMM produced in accordance with some embodiments of the present invention. In some embodiments, the GaN on GEMM has an ultra-smooth atomically stepped surface that allows for uniform growth of thin quantum wells.

[0102] 16 is a graph (1601) illustrating a comparison of the reflectivity of GEMM / GaN (solid line) produced in accordance with some embodiments of the present invention versus a conventional AlN / GaN distributed Bragg reflector (DBR) (dashed line). In some embodiments, the center wavelength λ is between 400 nanometers (nm) and 700 nm, depending on the choice of material and its thickness.

[0103] 17 is a graph (1701) of estimated sputtering rate for gallium nitride (GaN) versus gallium target temperature. Graph (1701) shows that, in some embodiments, the estimated sputtering rate is temperature sensitive when the gallium target temperature is in region (1705) (i.e., above approximately 14 degrees Celsius (°C)). Graph (1701) also shows that, in some embodiments, the estimated sputtering rate is temperature insensitive when the gallium target temperature is in region (1706) (i.e., below approximately 14°C). Graph (1701) further shows that, in some embodiments, the melting point of gallium (1799) (approximately 29°C) falls within the temperature-sensitive region (1705). In some embodiments, the present invention cools the gallium target so that it is within the temperature-insensitive region (1706). In some embodiments, cooling the gallium target includes providing a temperature gradient across a depth of the gallium target such that a first depth of the gallium target is at a first temperature and a second depth is at a second temperature.

[0104] In some embodiments, the temperature of the gallium target is kept low for reliable and repeatable production and high-quality films. In some embodiments, when gallium is liquid, gallium spitting on the wafer can interfere with production. In some embodiments, if the target is kept at a temperature close to the melting point (1799) of gallium (e.g., + / - 20°C or more above the melting point (1799)), the yield of ejected atoms will be highly dependent on small changes in process parameters, and the energies of the ejected atoms will have a wide distribution.

[0105] In some embodiments, lowering the temperature of the gallium sputtering target to 28 degrees Celsius (°C) or below improves the repetition rate and quality of the resulting gallium nitride (GaN) film. In some embodiments, the quality of the resulting GaN film improves down to -40°C, and in some embodiments, further lowering the temperature (e.g., to -200°C) results in further improvements in GaN crystal quality. In some embodiments, the improved film quality is due to refinement of gallium purity during the sputtering process, with impurities having a lower sputtering rate at lower target temperatures. Furthermore, in some embodiments, the improvement is due to a reduction in "gallium spitting," where the plasma gas (e.g., noble gas and optionally reactive gas) has shallower penetration into the gallium target. In some embodiments, the invention includes a noble gas and ion source for sputtering (e.g., in some embodiments, helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and / or oganesson (Og)).

[0106] In some embodiments of epitaxial atomic layer sputtering (EALS) provided by the present invention, the gallium sputtering target is kept solid and below its melting point at least 15 degrees Celsius (°C). In some embodiments, the temperature of the gallium sputtering target is , 0℃ or more and 15℃ or less and in some embodiments, the target temperature is , -15℃ or more and 0℃ or less and in some embodiments, the target temperature is , -40℃ or higher and -15℃ or lower and in some embodiments, the target temperature is , -100℃ or more and -40℃ or less and in some embodiments, the target temperature is , -200℃ or more and -100℃ or less in some embodiments, the target temperature is less than -200°C. In some embodiments, the target temperature for gallium sputtering is between 14°C and -273°C.

[0107] In some embodiments, the present invention provides methods for producing gallium nitride (GaN)-based devices, the methods comprising: providing a substrate mold comprising aluminum nitride; and depositing a patterned transition metal-doped GaN layer onto the substrate mold.

[0108] Conventional techniques avoid gallium deposition by sputtering due to the low melting point of gallium (approximately 29°C), especially when wafer temperatures are several hundred degrees higher than in most applications and when wafer-to-target distances are only a few centimeters.

[0109] In some embodiments, the present invention provides GaN growth by sputtering from a gallium target (solid or liquid) having an XRD 102 peak with a FWHM of less than about 3000 arcsec. In some embodiments, the present invention provides GaN for use with high electron mobility transistors, where the GaN has an XRD 102 peak with a FWHM of less than 1500 arcsec. In some embodiments, the present invention provides GaN for use with light emitting devices, where the GaN has an XRD 102 peak with a FWHM of less than 600 arcsec (e.g., 300 arcsec). In some embodiments, the present invention provides smooth, non-columnar step growth of GaN by PVD (e.g., sputtering). In some such embodiments, the gallium target is maintained below 14°C (in some embodiments, the gallium target is maintained at sub-zero Celsius temperatures and a non-aqueous heat transfer liquid such as an alcohol is used). In some embodiments, the present invention provides an EALS process to achieve commercial atomic force microscopy (AFM), optical diffraction, and X-ray diffraction (XRD) results.

[0110] In some embodiments, the present invention provides an epitaxial atomic layer sputtering (EALS) process (e.g., GaN growth on GaN, AlN, nucleation layers (described below), or similar templates) that includes any one or more of the following: (1) a high-temperature anneal; (2) growing Ga:N at a higher-than-standard temperature (e.g., 20°C to 50°C higher) for 5-20 minutes with a ratio of 1 or greater; (3) growing Ga:N in a standard growth mode (e.g., 700°C) for 20-40 minutes with a ratio of 1 or greater; (4a) stopping growth and annealing at 750°C (e.g., annealing for 5-10 minutes) until all excess gallium has evaporated and the film is smooth, or (4b) continuing growth to a Ga:N ratio less than 1 (in some such embodiments, the gallium may be shut off or shuttered); and (5) repeating steps 1 through 4. In some embodiments, RF nitrogen is used instead of N2 gas or NH3 gas while argon is supplied directly to the gallium target at any time during the above steps, and in some embodiments, an ion source from the gallium target or a separate ion source is used. In some embodiments, doping with hafnium (Hf), zirconium (Zr), silicon (Si), germanium (Ge), magnesium (Mg), copper (Cu), or any other transition metal is performed during the above steps. In some embodiments, alloying GaN with aluminum (Al), indium (In), or any other transition metal including Hf, Zr, or scandium (Sc) is performed during the above steps.

[0111] In some embodiments, the present invention provides a process for producing a nucleation layer on a foreign template (e.g., Si, sapphire, hafnium nitride (HfN), zirconium nitride (ZrN), zinc oxide (ZnO), glass, or the like), wherein the process comprises any one or more of the following: (1) chemically accelerated thermal cleaning, thermal texturing; (2) nitridation at high temperature by exposure to a nitrogen source, including N, nitrogen ions, NH, or the like; and (3) deposition of AlN (optionally GaN) to a thickness ranging from about 5 nanometers (nm) to 100 nm by sputtering. In some embodiments, RF nitrogen is used instead of N or NH gas while argon is supplied directly to the gallium target at any time during the above steps, and in some embodiments, an ion source from the gallium target or a separate ion source is used. In some embodiments, doping with either Hf, Zr, Si, Ge, Mg, Cu, or other transition metals is performed during the above steps. In some embodiments, alloying of the GaN with Al, In, or any of the other transition metals including, for example, Hf, Zr, or Sc, is performed during the above process.

[0112] 18 is a schematic diagram of a sputtering system (1801). In some embodiments, the system (1801) includes multiple gallium (Ga) guns, including a Ga gun (1810) (located at zero degrees from the mold (1805)), a Ga gun (1811) (located at 45 degrees from the mold (1805)), and a Ga gun (1812) (located at 90 degrees from the mold (1805)). In some embodiments, the system (1801) further includes multiple ion sources (1820 and / or 1821). In some embodiments, the mold (1805) rotates between the Ga guns (1810-1812) and the ion sources (1820 and / or 1821). In some embodiments, a sufficient supply of ions to the surface, either by the sputtering gun or the ion gun, is important for production stability and the quality of the Group IIIA nitride films. In some embodiments, the ion gun is replaced with a photon source (e.g., ultraviolet light) or an electron source. The ion source (e.g., ion source (1820) and / or ion source (1821)), whether from a dedicated ion source or a sputtering target, is best provided at an angle between shallow and 90 degrees relative to the surface of the mold (1805). In some embodiments, while these components are in place, argon is supplied to the sputtering gun and the amount of nitrogen interaction with the gallium target is minimized to run the process in a nitrogen poisoning-reduced regime.

[0113] In some embodiments, the present invention provides methods for epitaxy growing gallium nitride (GaN) structures, the method including: providing a substrate; and growing at least a first GaN layer on a surface of the substrate using a first physical vapor deposition (PVD) process (e.g., in some embodiments, sputtering), wherein the first PVD process includes: providing a solid gallium target; and maintaining the solid gallium target at a first temperature of less than approximately 29 degrees Celsius.

[0114] In some embodiments of the method, providing a substrate includes growing an aluminum nitride (AlN) layer on a base of the substrate using a second PVD process (e.g., in some embodiments, sputtering) such that the AlN layer forms a surface of the substrate. In some embodiments, the first PVD process further includes epitaxial atomic layer sputtering (EALS). In some embodiments, the first PVD process further includes EALS, where the EALS includes heating the substrate. In some embodiments, the first PVD process further includes magnetron sputtering. In some embodiments, the first temperature is less than approximately 15 degrees Celsius. In some embodiments, maintaining the solid gallium target at the first temperature includes fluid convection cooling the solid gallium target using an alcohol-based liquid. In some embodiments, the first GaN layer has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of both the 002 peak and the 102 peak of less than approximately 1000 arcsec.

[0115] In some embodiments, the present invention provides methods for growing gallium nitride (GaN) structures, the method comprising: providing a substrate; and growing at least a first GaN layer on a surface of the substrate using a first physical vapor deposition (PVD) process (e.g., in some embodiments, a first sputtering process), where the first PVD process comprises: providing a solid gallium target, where providing the solid gallium target comprises maintaining the solid gallium target at a first temperature; and performing epitaxial atomic layer sputtering (EALS) of the at least first GaN layer, such that growth of the at least first GaN layer comprises non-columnar step growth of the at least first GaN layer.

[0116] In some embodiments, the present invention provides a system for growing gallium nitride (GaN) structures, the system including: a load lock configured to load and remove substrate wafers into and from the system; and a plurality of deposition modules; wherein the plurality of deposition modules includes a GaN deposition module configured to grow at least a first GaN layer on a surface of the substrate wafer via a first physical vapor deposition (PVD) process (e.g., in some embodiments, a first sputtering process), wherein the GaN deposition module includes a solid gallium target maintained at a first temperature, and wherein the first PVD process includes epitaxial atomic layer sputtering (EALS) of the at least first GaN layer, such that non-columnar step growth of the at least first GaN layer occurs.

[0117] In some embodiments, the present invention provides methods for growing gallium nitride (GaN) structures, the method comprising: providing a substrate; and growing at least a first GaN layer on a surface of the substrate using a first sputtering process, wherein the first sputtering process comprises: providing a gallium target; and performing epitaxial atomic layer sputtering (EALS) such that the growth of the at least first GaN layer comprises non-columnar step growth of at least the first GaN layer.

[0118] In some embodiments, performing MEE includes controlling the ratio of nitrogen to gallium to be greater than 1 to 1 for at least a first time period of the first sputtering process. In some embodiments of the method, performing MEE includes introducing nitrogen via a radio frequency (RF) nitrogen source.

[0119] In some embodiments of the method, the first sputtering process further comprises doping at least the first GaN layer with silicon (Si). In some embodiments, the first sputtering process further comprises doping at least the first GaN layer by gas pumping reactants with a carrier gas that carries silicon (Si).

[0120] In some embodiments of the method, the gallium target is a solid gallium target, and wherein the first sputtering process further comprises maintaining the solid gallium target at a first temperature that is less than approximately 15 degrees Celsius. In some embodiments, the gallium target is a solid gallium target, and wherein the first sputtering process further comprises maintaining the solid gallium target at the first temperature, and wherein maintaining the solid gallium target at the first temperature comprises fluid convection cooling the solid gallium target using an alcohol-based liquid.

[0121] In some embodiments of the method, providing a substrate includes growing an aluminum nitride (AlN) layer on a base of the substrate using a second sputtering process, such that the AlN layer forms a surface of the substrate. In some embodiments, the method further includes growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer. In some embodiments, the method further includes growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer, where the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN). In some embodiments, the method further includes growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer, where the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); and growing at least a first quantum well on a surface of the GEMM using a metalorganic chemical vapor deposition (MOCVD) process. In some embodiments, the first sputtering process further comprises magnetron sputtering. In some embodiments, at least the first GaN layer has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of both the 002 peak and the 102 peak of less than approximately 1000 arcsec. In some embodiments, at least the first GaN layer has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of the 002 peak in the range of about 10 arcsec to about 2500 arcsec.

[0122] In some embodiments, the present invention provides a system for growing gallium nitride (GaN) structures, the method comprising: a load lock configured to load and remove substrate wafers into and from the system; and a plurality of deposition chambers; wherein the plurality of deposition chambers comprises a GaN deposition chamber configured to grow at least a first GaN layer on a surface of the substrate wafer by a first sputtering process, wherein the first sputtering process comprises epitaxial atomic layer sputtering (EALS) of the at least first GaN layer such that non-columnar step growth of the at least first GaN layer occurs.

[0123] In some embodiments, the system further includes a wafer handling mechanism configured to automatically move the substrate wafer between the multiple deposition chambers. In some embodiments, the multiple deposition chambers include an aluminum nitride (AlN) deposition chamber configured to grow an AlN layer on a base of the substrate wafer by a second sputtering process, such that the AlN layer forms a surface of the substrate wafer. In some embodiments, the multiple deposition chambers include a grown epitaxial metal mirror (GEMM) deposition chamber configured to grow a GEMM on at least the first GaN layer. In some embodiments, the GaN deposition chamber includes a solid gallium target maintained at a first temperature, where the first temperature is less than approximately 15 degrees Celsius. In some embodiments, the GaN deposition chamber further includes a solid gallium target maintained at the first temperature; and a fluid convection cooler configured to cool the solid gallium target with an alcohol-based liquid.

[0124] In some embodiments, the GaN deposition chamber is further configured to dope the at least first GaN layer with silicon (Si). In some embodiments, the GaN deposition chamber is further configured to grow the at least first GaN layer such that the at least first GaN layer has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of both the 002 peak and the 102 peak of less than approximately 1000 arcsec. In some embodiments, the GaN deposition chamber is further configured to grow the at least first GaN layer such that the at least first GaN layer has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of the 002 peak in the range from about 10 arcsec to about 2500 arcsec.

[0125] In some embodiments, the plurality of deposition chambers further include: an aluminum nitride (AlN) deposition chamber configured to grow an AlN layer on the base of the substrate wafer by a second sputtering process, such that the AlN layer forms a surface of the substrate wafer; a grown epitaxial metal mirror (GEMM) deposition chamber configured to grow a GEMM on at least the first GaN layer, wherein the GEMM includes alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); and a metalorganic chemical vapor deposition (MOCVD) chamber configured to grow at least a first quantum well on the surface of the GEMM.

[0126] In some embodiments, the present invention provides a gallium nitride structure, the structure comprising: a substrate; and at least a first gallium nitride (GaN) layer grown on a surface of the substrate; wherein the at least the first GaN layer has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of both the 002 peak and the 102 peak of less than approximately 1000 arcsec (in some embodiments, the at least the first GaN layer has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of the 002 peak in the range of from about 10 arcsec to about 2500 arcsec).

[0127] In some embodiments, the structure further comprises an aluminum nitride (AlN) layer grown on the base of the substrate, such that the AlN layer forms the surface of the substrate. In some embodiments, the structure further comprises a grown epitaxial metal mirror (GEMM) grown on the surface of at least the first GaN layer. In some embodiments, the substrate comprises sapphire, and the structure further comprises: an aluminum nitride (AlN) layer on the base of the substrate, such that the AlN layer forms the surface of the substrate; a grown epitaxial metal mirror (GEMM) grown on the surface of at least the first GaN layer; where the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); a layer of n-type GaN grown on the surface of the GEMM; and a layer of p-type GaN / multiple quantum well (MQW) grown on the layer of n-type GaN.

[0128] In some embodiments, the present invention provides a system for growing gallium nitride (GaN) structures, the system including: means for loading a substrate wafer into the system; and means for sputtering at least a first GaN layer on a surface of the substrate wafer, wherein the means for sputtering the at least first GaN layer includes means for performing epitaxial atomic layer sputtering (EALS) such that non-columnar step growth of the at least first GaN layer occurs.

[0129] In some embodiments of the system, the means for sputtering includes means for doping at least the first GaN layer with silicon (Si). In some embodiments, the system further includes means for growing an aluminum nitride (AlN) layer on the base of the substrate, such that the AlN layer forms a surface of the substrate. In some embodiments, the system further includes means for growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer, wherein the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN). In some embodiments, the system further includes means for growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer, wherein the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); and means for growing at least a first quantum well on the surface of the GEMM.

[0130] In some embodiments, the present invention provides methods for growing gallium nitride (GaN) structures, the method comprising: providing a template; and growing at least one first GaN layer on the template using a first sputtering process, wherein the first sputtering process comprises: controlling a temperature of a sputtering target and repeatedly adjusting between gallium-rich and gallium-lean conditions, wherein the gallium-rich condition comprises a gallium-to-nitrogen ratio having a first value greater than 1, and wherein the gallium-lean condition comprises a gallium-to-nitrogen ratio having a second value less than 1.

[0131] In some embodiments, the first sputtering process includes introducing nitrogen via a radio frequency (RF) nitrogen source. In some embodiments, the first sputtering process further includes doping at least the first GaN layer with silicon (Si). In some embodiments, the first sputtering process further includes doping at least the first GaN layer by gas-pressuring the reactants with a carrier gas that carries silicon (Si). In some embodiments, the sputtering target is a solid gallium target, and wherein controlling the temperature of the solid gallium target includes maintaining its temperature at a first temperature value that is less than approximately 14°C. In some embodiments, the sputtering target is a solid gallium target, and wherein maintaining the temperature of the solid gallium target includes fluid convection cooling the solid gallium target using alcohol as a heat transfer fluid.

[0132] In some embodiments, providing the mold comprises growing an aluminum nitride (AlN) layer on the mold. In some embodiments, providing the mold comprises growing an aluminum nitride (AlN) layer on the mold using a second sputtering process. In some embodiments, providing the mold comprises growing a first aluminum nitride (AlN) layer on the mold using a second sputtering process, wherein the method further comprises growing a second aluminum nitride (AlN) layer on at least the first GaN layer using the second sputtering process; and growing a second GaN layer on the second AlN layer using the first sputtering process.

[0133] In some embodiments, the method further includes growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer, where the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN). In some embodiments, the method further includes growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer, where the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); and growing at least a first quantum well on a surface of the GEMM using a metalorganic chemical vapor deposition (MOCVD) process. In some embodiments, the first sputtering process further includes magnetron sputtering. In some embodiments, the at least first GaN layer has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of the 002 peak in the range of about 10 arcsec to about 2500 arcsec.

[0134] In some embodiments, the present invention provides a system for growing gallium nitride (GaN) structures, the method comprising: a load lock configured to load and remove substrate wafers into and from the system; and a plurality of deposition chambers; wherein the plurality of deposition chambers includes a GaN deposition chamber configured to grow at least a first GaN layer on a mold comprising the substrate wafer by a first sputtering process, wherein the first sputtering process comprises repeatedly adjusting between gallium-rich conditions and gallium-lean conditions, wherein the gallium-rich conditions comprise a gallium-to-nitrogen ratio between the gallium-rich conditions and the gallium-lean conditions having a first value greater than 1, and wherein the gallium-lean conditions comprise a gallium-to-nitrogen ratio having a second value less than 1.

[0135] In some embodiments, the system further includes a wafer handling mechanism configured to automatically move the mold between the plurality of deposition chambers. In some embodiments, the plurality of deposition chambers includes an aluminum nitride (AlN) deposition chamber configured to grow an AlN layer on the substrate wafer by a second sputtering process to form the mold. In some embodiments, the plurality of deposition chambers includes a grown epitaxial metal mirror (GEMM) deposition chamber configured to grow a GEMM on at least the first GaN layer. In some embodiments, the GaN deposition chamber includes a solid gallium target maintained at a first temperature, where the first temperature is less than approximately 14 degrees Celsius. In some embodiments, the GaN deposition chamber further includes a solid gallium target maintained at the first temperature; and a fluid convection cooler configured to cool the solid gallium target with an alcohol heat transfer fluid. In some embodiments, the GaN deposition chamber is further configured to dope at least the first GaN layer with silicon (Si). In some embodiments, the GaN deposition chamber is further configured to grow at least a first GaN layer, wherein the at least first GaN layer has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of the 002 peak in the range from about 10 arcsec to about 2500 arcsec. In some embodiments, the plurality of deposition chambers further include an aluminum nitride (AlN) deposition chamber configured to grow an AlN layer on the substrate wafer to form the mold by a second sputtering process; a grown epitaxial metal mirror (GEMM) deposition chamber configured to grow a GEMM on the at least first GaN layer, where the GEMM includes alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); and a metalorganic chemical vapor deposition (MOCVD) chamber configured to grow at least a first quantum well on a surface of the GEMM.

[0136] In some embodiments, the present invention provides a gallium nitride structure, the gallium nitride structure comprising: a template; and at least a first gallium nitride (GaN) layer grown on the template; wherein the at least the first GaN layer has an ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of a 002 peak in the range from about 10 arcsec to about 2500 arcsec.

[0137] In some embodiments, the template comprises an aluminum nitride (AlN) layer grown on the substrate. In some embodiments, the structure further comprises a grown epitaxial metal mirror (GEMM) grown on a surface of at least the first GaN layer. In some embodiments, the template is a gallium nitride structure comprising an aluminum nitride (AlN) layer grown on a sapphire substrate, the structure further comprising a grown epitaxial metal mirror (GEMM) on a surface of at least the first GaN layer, where the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); a layer of n-type GaN grown on the surface of the GEMM; and a layer of p-type GaN / multiple quantum well (MQW) grown on the layer of n-type GaN.

[0138] In some embodiments, the present invention provides a system for growing gallium nitride (GaN) structures, the system comprising: means for loading a substrate wafer into the system; and means for sputtering at least a first GaN layer on a mold containing the substrate wafer; wherein the means for sputtering the at least first GaN layer comprises means for repeatedly adjusting between gallium-rich and gallium-lean conditions, wherein the gallium-rich condition comprises a gallium-to-nitrogen ratio having a first value greater than 1, and wherein the gallium-lean condition comprises a gallium-to-nitrogen ratio having a second value less than 1.

[0139] In some embodiments of the system, the means for sputtering includes means for doping at least the first GaN layer with silicon (Si). In some embodiments, the system further includes means for growing an aluminum nitride (AlN) layer on the substrate wafer to form the mold. In some embodiments, the system further includes means for growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer, where the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN). In some embodiments, the system further includes means for growing a grown epitaxial metal mirror (GEMM) on at least the first GaN layer, where the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); and means for growing at least a first quantum well on a surface of the GEMM.

[0140] In some embodiments, the present invention provides methods for growing gallium nitride (GaN) structures, the method comprising: providing a template; and growing at least one first GaN layer on the template using a first sputtering process, wherein the first sputtering process comprises: providing a gallium sputtering target, wherein the gallium sputtering target has a depth; and maintaining a temperature of the gallium sputtering target at a first temperature value that is less than approximately 14° C. In some embodiments, maintaining the temperature of the gallium sputtering target comprises providing a temperature gradient across the depth of the gallium sputtering target.

[0141] In some embodiments, the present invention provides a method for growing gallium nitride (GaN) structures, the method comprising: providing a template having a surface; and growing at least one first GaN layer on the template using a first sputtering process, wherein the first sputtering process comprises: repeatedly adjusting, for at least a first oscillation, gallium-rich conditions on the surface of the template and gallium-lean conditions on the surface of the template, wherein the gallium-rich conditions include a gallium-to-nitrogen ratio having a first value greater than 1, and wherein the gallium-lean conditions include a gallium-to-nitrogen ratio having a second value less than the first value. In some embodiments, the repeatedly adjusting comprises repeatedly adjusting for a plurality of amplitudes, including the first oscillation. In some embodiments, the at least first GaN layer has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of a 102 peak ranging from about 10 arcsec to about 2500 arcsec.

[0142] In some embodiments, the present invention provides a method for growing a gallium nitride (GaN) structure, the method comprising: providing a template; and growing at least one first GaN layer on the template using a first sputtering process, wherein the first sputtering process comprises: providing a gallium sputtering target, wherein the gallium sputtering target has a depth; and maintaining a temperature of the gallium sputtering target at a first temperature value that is less than approximately 14°C. In some embodiments, at least the first GaN layer has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of a 102 peak in the range of about 10 arcsec to about 2500 arcsec. In some embodiments, maintaining the temperature of the gallium sputtering target comprises providing a temperature gradient across the depth of the gallium sputtering target.

[0143] In some embodiments, the present invention provides a method for growing a gallium nitride (GaN) structure, the method comprising: providing a template; growing a first aluminum nitride (AlN) layer on the template using a first sputtering process; and growing a first GaN layer on the first AlN layer using a second sputtering process. In some embodiments, the method further comprises growing a second AlN layer on the first GaN layer using the first sputtering process; and growing a second GaN layer on the second AlN layer using the second sputtering process. In some embodiments, the first GaN layer has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of a 102 peak ranging from about 10 arcsec to about 2500 arcsec.

[0144] In some embodiments, the present invention provides methods for growing gallium nitride (GaN) structures, the method comprising: providing a template having a surface; and growing at least a first GaN layer on the template using a first sputtering process, wherein the first sputtering process comprises: growing the at least first GaN layer under at least two conditions, the two conditions comprising a gallium-rich condition and a gallium-lean condition, wherein the gallium-rich condition comprises a gallium-to-nitrogen ratio having a first value greater than 1, and wherein the gallium-lean condition comprises a gallium-to-nitrogen ratio having a second value less than the first value; and alternating between the two conditions for at least a first growth under one of the two conditions, a second growth under the second of the two conditions after the first growth, and a third growth under the first of the two conditions after the second growth. In some embodiments, the step of alternating between the two conditions further includes a fourth growth under a second of the two conditions after the third growth, and a fifth growth under the first of the two conditions after the fourth growth. In some embodiments, the first value of the gallium to nitrogen ratio is at least 10 percent greater than the second value of the gallium to nitrogen ratio. In some embodiments, the first value of the gallium to nitrogen ratio is at least 50 percent greater than the second value of the gallium to nitrogen ratio. In some embodiments, the first value of the gallium to nitrogen ratio is at least two times greater than the second value of the gallium to nitrogen ratio.

[0145] In some embodiments, the present invention provides a method for growing a gallium nitride (GaN) structure, the method comprising: providing a template; growing a first aluminum nitride (AlN) layer on the template using a first sputtering process; and growing a first GaN layer on the first AlN layer using a second sputtering process. In some embodiments, the method further comprises growing a second AlN layer on the first GaN layer using the first sputtering process; and growing a second GaN layer on the second AlN layer using the second sputtering process. In some embodiments, the first GaN layer has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of a 102 peak ranging from about 10 arcsec to about 2500 arcsec. In some embodiments, the method further includes growing a second AlN layer on the first GaN layer using a first sputtering process; growing a second GaN layer on the second AlN layer using a second sputtering process; and growing an AlN layer on the second GaN layer using a second sputtering process. x Ga (1-x) growing one or more layers of N, where x is Between 0 and 1 (inclusive) In some embodiments, the method further includes growing a second AlN layer on the first GaN layer using a first sputtering process; growing a second GaN layer on the second AlN layer using a second sputtering process; and growing an AlN layer on the second GaN layer using a second sputtering process. x Ga (1-x) growing one or more layers of N, where x varies with depth; Between 0 and 1 (inclusive)In some embodiments, the method further comprises growing a second AlN layer on the first GaN layer using a first sputtering process; growing a second GaN layer on the second AlN layer using a second sputtering process; and growing one or more layers of a compound on the second GaN layer, wherein the compound comprises one or more selected from the group consisting of hafnium nitride (HfN), zirconium nitride (ZrN), aluminum nitride (AlN), gallium nitride (GaN), and scandium nitride (ScN). In some embodiments, the method further comprises growing one or more layers of Al on the first GaN layer. x Ga (1-x) N, wherein x is 0 or more and 1 or less In some embodiments, the first sputtering process further comprises doping at least the first GaN layer with silicon (Si). In some embodiments, the method further comprises doping Al on the first GaN layer. x Ga (1-x) N, wherein x is 0 or more and 1 or less In some embodiments, the method further comprises depositing Al on the first GaN layer. x Ga (1-x) N, where x varies with depth; 0 or more and 1 or less In some embodiments, the method further comprises growing one or more layers of a compound on the first GaN layer, wherein the compound comprises one or more selected from the group consisting of hafnium nitride (HfN), zirconium nitride (ZrN), aluminum nitride (AlN), gallium nitride (GaN), and scandium nitride (ScN).

[0146] In some embodiments, the present invention provides a system for growing gallium nitride (GaN) structures, the system including: a load lock configured to load and remove substrate wafers into and from the system; and a plurality of deposition chambers, wherein the plurality of deposition chambers includes a first GaN deposition chamber configured to grow at least a first GaN layer by a first sputtering process on a mold including the substrate wafer, wherein the first GaN deposition chamber includes a gallium sputtering target, wherein the gallium sputtering target has a depth, and wherein the GaN deposition chamber is further configured to maintain a temperature of the gallium sputtering target at a first temperature value that is less than approximately 14°C.

[0147] In some embodiments, the system further includes a wafer handling mechanism configured to automatically move the mold between the multiple deposition chambers. In some embodiments, the multiple deposition chambers include an aluminum nitride (AlN) deposition chamber configured to grow an AlN layer by a second sputtering process on the substrate wafer to form the mold. In some embodiments, the multiple deposition chambers include a grown epitaxial metal mirror (GEMM) deposition chamber configured to grow a GEMM on at least the first GaN layer. In some embodiments, the system further includes a fluid convection cooler configured to cool the gallium sputtering target with an alcohol heat transfer fluid. In some embodiments, the GaN deposition chamber is further configured to maintain a temperature gradient across the depth of the gallium sputtering target. In some embodiments, the multiple deposition chambers include a metalorganic chemical vapor deposition (MOCVD) chamber. In some embodiments, the GaN deposition chamber is further configured to dope at least the first GaN layer with silicon (Si).

[0148] In some embodiments, the present invention provides a gallium nitride structure comprising: a template; and at least a first gallium nitride (GaN) layer grown on the template; wherein the at least first GaN layer has a ω rocking curve full width at half maximum (FWHM) X-ray diffraction measurement of a 102 peak ranging from about 10 arcsec to about 2500 arcsec. In some embodiments, the template comprises an aluminum nitride (AlN) layer grown on a sapphire substrate, and the structure further comprises a grown epitaxial metal mirror (GEMM) grown on a surface of at least the first GaN layer, wherein the GEMM comprises alternating layers of hafnium (Hf):GaN and hafnium nitride (HfN); a layer of n-type GaN grown on the surface of the GEMM; and a layer of p-type GaN / multiple quantum well (MQW) grown on the layer of n-type GaN.

[0149] It is expressly contemplated that the present invention includes embodiments having combinations and subcombinations of the various embodiments and features individually described herein (i.e., rather than describing every combination of elements, the specification includes descriptions of representative embodiments and contemplates embodiments including some features from one embodiment combined with some features of another embodiment). Furthermore, some embodiments include fewer than all of the components described as part of any one of the embodiments described herein. Also, it is expressly contemplated that the present invention includes embodiments having combinations and subcombinations of the various embodiments described herein, as well as various embodiments described by related applications and publications incorporated by reference in paragraphs of this application.

[0150] It should be understood that the above features are intended to be illustrative and not limiting. While numerous features and benefits of the various embodiments as described herein have been set forth in the foregoing description, many other embodiments and variations on the details, as well as details of the structure and function of the various embodiments, will become apparent to those skilled in the art upon reviewing the above description. Therefore, the scope of the present invention should be determined with reference to the appended claims, along with the full scope to which the claims are entitled. In the appended claims, the terms "including" and "in which" are used as the plain English equivalents of the respective terms "comprising" and "wherein," respectively. Terms such as "first," "second," and "third" are used merely as labels and are not intended to impose numerical requirements on their objects.

Claims

1. 1. A method for growing a nitride compound structure comprising one or more Group IIIA metals, wherein the Group IIIA metal-containing nitride compound comprises a nitride compound selected from gallium (Ga)-containing GaN, AlGaN, and InGaN, the method comprising: (a) providing a template; (b) growing a first layer of a nitride compound comprising at least said Group IIIA metal on the template using a first sputtering process; wherein the first sputtering process comprises: (i) providing a gallium sputtering target, wherein the gallium sputtering target has a depth; (ii) heating the substrate to less than 800 degrees Celsius; and (iii) maintaining the gallium sputtering target in a frozen state substantially throughout its depth by maintaining the temperature of the gallium sputtering target at a first temperature value of −40 degrees Celsius or less; A method comprising:

2. 10. The method of claim 1, wherein the first layer of nitride compound containing at least the Group IIIA metal has an ω rocking curve full width at half maximum (FWHM) x-ray diffraction measurement of 102 peaks ranging from 10 arcsec to 2500 arcsec.

3. 10. The method of claim 1, wherein the first sputtering process further comprises doping the first layer of nitride compound containing at least the Group IIIA metal with silicon (Si).

4. 10. The method of claim 1, wherein maintaining the temperature of the gallium sputtering target comprises fluid convection cooling the solid gallium target using a cryogenic heat transfer fluid comprising liquid nitrogen or liquid hydrogen.

5. 10. The method of claim 1, wherein the first sputtering process further comprises: (e) doping the first layer of nitride compound containing at least the Group IIIA metal with silicon (Si).

6. 10. The method of claim 1, wherein the first sputtering process further comprises doping the first layer of nitride compound containing at least the Group IIIA metal with germanium (Ge).

7. 10. The method of claim 1, wherein the first sputtering process further comprises doping the first layer of nitride compound containing at least the Group IIIA metal with hafnium (Hf).

8. 10. The method of claim 1, wherein the first sputtering process further comprises doping the first layer of nitride compound containing at least the Group IIIA metal with magnesium (Mg).

9. The method of claim 1 , wherein growing the first layer of nitride compound containing at least the Group IIIA metal comprises step-flow growth.

10. 10. The method of claim 1, wherein growing the first layer of nitride compound containing at least the Group IIIA metal comprises two-dimensional (2D) island growth.

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