Ultrawide bandgap semiconductor with p-type conductivity and methods of making and use thereof

Abstract

Disclosed herein are ultrawide bandgap semiconductors with p-type conductivity and methods of making and use thereof. For example, disclosed herein are compositions comprising ultrawide bandgap oxide semiconductor with p-type conductivity comprising LixGayOz, wherein Li and Ga have an atomic ratio (e.g., x:y) of from 0.0001 to 1.0; Li and O have an atomic ratio (e.g., x:z) of from 0.0001 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0. In some examples, Li and Ga have an atomic ratio (e.g., x:y) of from 0.01 to 1.0; Li and O have an atomic ratio (e.g., x:z) of from 0.00625 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

Description

[0001] ULTRAWIDE BANDGAP SEMICONDUCTOR WITH P-TYPE CONDUCTIVITY AND METHODS OF MAKING AND USE THEREOF

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 531,083 filed August 7, 2023, which is hereby incorporated herein by reference in its entirety.

[0004] STATEMENT OF GOVERNMENT SUPPORT

[0005] This invention was made with government support under Grant / Contract No. FA9950- 23-1-0142 awarded by the Air Force Office of Scientific Research. The government has certain rights in the invention.

[0006] BACKGROUND

[0007] Ultrawide bandgap semiconductors with improved p-type conductivity are needed. The compositions, methods, and devices discussed herein addresses these and other needs.

[0008] SUMMARY

[0009] In accordance with the purposes of the disclosed compositions, methods, and devices as embodied and broadly described herein, the disclosed subject matter relates to ultrawide bandgap semiconductors with p-type conductivity, and methods of making and use thereof.

[0010] For example, disclosed herein are compositions comprising ultrawide bandgap oxide semiconductor with p-type conductivity comprising:

[0011] LixGayOzwherein Li and Ga have an atomic ratio (e.g., x:y) of from 0.0001 to 1.0; Li and O have an atomic ratio (e g., x:z) of from 0.0001 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

[0012] In some examples, Li and Ga have an atomic ratio (e g., x:y) of from 0.01 to 1.0; Li and O have an atomic ratio (e.g., x:z) of from 0.00625 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

[0013] Also disclosed herein are compositions comprising ultrawide bandgap oxide semiconductor with p-type conductivity comprising:

[0014] LixGayOzwherein Li and Ga have an atomic ratio (e.g., x:y) of from 0.01 to 1.0; Li and O have an atomic ratio (e.g., x:z) of from 0.00625 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

[0015] In some examples, Li, Ga, and O have an atomic ratio (e.g., x:y:z) of 1:5:8.

[0016] In some examples, the composition comprises β-LixGayOz. In some examples, the composition comprises LiGa5O8.

[0017] In some examples, the composition comprises Li rich LiGa5O8

[0018] In some examples, the composition comprises Li poor LiGa5O8.

[0019] In some examples, the composition comprises O poor LiGa5O8.

[0020] In some examples, the composition comprises O rich LiGa5O8.

[0021] In some examples, the composition further comprises a dopant, such as a p-type dopant.

[0022] In some examples, the composition is substantially free of any dopants.

[0023] In some examples, the composition has a carrier concentration (e.g., a hole concentration) of from 1 x 1014per cubic centimeter to 1 x 1021cm'3. In some examples, the composition has a carrier concentration (e.g., a hole concentration) of from 1 x 1014to 1 5 x 1019cm'3, such as from 1 x 1017to 5 x 1018cm'3.

[0024] In some examples, the composition has a mobility, such as a hole mobility, of from 0.01 to 100 cm2 / Vs. In some examples, the composition has a mobility, such as a hole mobility, of from 0.1 to 10 cm2 / Vs, such as from 0.35 to 2 cm2 / Vs.

[0025] In some examples, the composition exhibits high p-type conductivity.

[0026] Also disclosed herein are device comprising any of the compositions disclosed herein. In some examples, the devices further comprise a substrate, wherein the composition is deposited on the substrate as a layer.

[0027] In some examples, the substrate comprises LiGa5O8, free standing GaN, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga2O3, AIN, AlGaN, diamond, or a combination thereof. In some examples, the substrate comprises LiGa5O8, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga2O3, or a combination thereof.

[0028] In some examples, the layer has a surface roughness with an RMS value of 20 nm or less. In some examples, the layer has a surface roughness with an RMS value of 15 nm or less, 10 nm or less, 5 nm or less, 2.5 nm or less, 1.75 nm or less, or 1.5 nm or less.

[0029] In some examples, the layer has an average thickness of from 10 to 2000 nm. In some examples, the layer has an average thickness of from 25 nm to 1000 nm, such as from 50 to 100 nm.

[0030] In some examples, the device comprises a vertical PN diode, a MOSFET device such as a power MOSFET or a trench MOSFET, a MESFET device, a MODFET device, a Current Aperture Vertical Electron Transistor (CAVET) device, or a combination thereof. In some examples, the device comprises a vertical PN diode, a MOSFET device such as a power MOSFET or a trench MOSFET, a Current Aperture Vertical Electron Transistor (CAVET) device, or a combination thereof. In some examples, the device comprises a vertical power device. In some examples, the device comprises an optical device, an electronic device, an optoelectronic device, or a combination thereof In some examples, the device comprises a diode. In some examples, the device comprises a n-Ga2O3 / p-LixGayOz(e.g., a n-Ga2O3 / p- LiGa5O8) heterojunction. In some examples, the device comprises n-GaN / p-LixGayOz, n-AlN / p-

[0031] LixGayOz, n-diamond / p-LixGayOz, or a combination thereof.

[0032] Also disclosed herein are methods of use of any of the compositions disclosed herein.

[0033] Also disclosed herein are methods of making any of the compositions disclosed herein, the methods comprising contacting a gallium containing precursor and a lithium containing precursor at a temperature in the presence of oxygen or an oxygen containing precursor to thereby react the gallium containing precursor, the lithium containing precursor, and the oxygen or the oxygen containing precursor to form the composition.

[0034] In some examples, the gallium containing precursor comprises a metalorganic Ga containing precursor. In some examples, the gallium containing precursor comprises Ga(acac)s ([CH3COCH=C(O-)CH3]3Ga).

[0035] In some examples, the lithium containing precursor comprises a metalorganic Li containing precursor. In some examples, the lithium containing precursor comprises lithium acetoacetate (CLH5LiO3).

[0036] In some examples, the gallium containing precursor and / or the lithium containing precursor independently comprise(s) a fluid.

[0037] In some examples, the gallium containing precursor and / or the lithium containing precursor are independently provided with a carrier gas. In some examples, the carrier gas comprises argon, helium, N2, and the like, or combinations thereof. In some examples, the carrier gas comprises argon.

[0038] In some examples, the temperature is from 300°C to 1200°C. In some examples, the temperature is from 800°C to 1000°C, such as from 800°C to 950°C, or from 850°C to 950°C. In some examples, the temperature is 900°C.

[0039] In some examples, the method comprises metal organic chemical vapor deposition (MOCVD), molecular-beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), pulsed laser deposition (PLD), low pressure chemical vapor deposition (LPCVD), mist-CVD, or a combination thereof. In some examples, the method comprises mist-CVD.

[0040] In some examples, the method comprises depositing the composition on a substrate. In some examples, the substrate comprises LiGa5O8, free standing GaN, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga2O3, AIN, AlGaN, diamond, or a combination thereof. In some examples, the substrate comprises LiGa5O8, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c- plane sapphire), Ga2O3, or a combination thereof.

[0041] Additional advantages of the disclosed compositions, devices, and methods will be set forth in part in the description which follows, and in part will be obvious from the description. The advantages of the disclosed compositions, devices, and methods will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed devices and methods, as claimed.

[0042] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

[0043] BRIEF DESCRIPTION OF THE FIGURES

[0044] The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects of the disclosure, and together with the description, serve to explain the principles of the disclosure.

[0045] Figure 1A. Plan-view SEM image of LiGa5O8sample grown on GaN on sapphire template at a growth temperature (TG) of 800°C.

[0046] Figure IB. Plan-view SEM image of LiGa5O8sample grown on GaN on sapphire template at a growth temperature (TG) of 850°C.

[0047] Figure 1C. Plan-view SEM image of LiGa5O8sample grown on GaN on sapphire template at a growth temperature (TG) of 900°C.

[0048] Figure ID. Plan-view SEM image of LiGa5O8sample grown on GaN on sapphire template at a growth temperature (TG) of 950°C.

[0049] Figure 2A. 5 pm x 5 pm AFM image of LiGa5O8samples grown on GaN on sapphire template at a growth temperature (TG) of 800°C.

[0050] Figure 2B. 5 pm x 5 pm AFM image of LiGa5O8samples grown on GaN on sapphire template at a growth temperature (TG) of 850°C.

[0051] Figure 2C. 5 pm x 5 pm AFM image of LiGa5O8samples grown on GaN on sapphire template at a growth temperature (TG) of 900°C.

[0052] Figure 2D. 5 pm x 5 pm AFM image of LiGa5O8samples grown on GaN on sapphire template at a growth temperature (TG) of 950°C. Figure 3 A. Cross-sectional TEM image of LiGa5O8sample grown on GaN on sapphire template at 900°C. The interfaces are marked with red dash-dot lines.

[0053] Figure 3B Atomic resolution HAADF STEM image of LiGa5O8sample grown on GaN on sapphire template at 900°C. The interfaces are marked with red dash-dot lines.

[0054] Figure 4. XRD 20-ro scan of LiGa5O8sample grown on GaN-on-sapphire substrate at temperature 900°C. The corresponding LiGa5O8peaks are marked with red arrows.

[0055] Figure 5A. Plan view SEM image of LiGa5O8sample grown on on-axis c-sapphire substrate at 850°C.

[0056] Figure 5B. Plan view SEM image of LiGa5O8sample grown on 6° offcut c-sapphire substrate at 850°C.

[0057] Figure 5C. 5 pm x 5 pm AFM image of LiGa5O8sample grown on on-axis c-sapphire substrate at 850°C.

[0058] Figure 5D. 5 pm x 5 pm AFM image of LiGa5O8sample grown on 6° offcut c-sapphire substrate at 850°C.

[0059] Figure 6A. Cross-sectional TEM image of LiGa5O8sample grown on on-axis c-sapphire substrate at 850°C. The interfaces are marked with red dash-dot lines.

[0060] Figure 6B. Atomic resolution HAADF STEM image of LiGa5O8sample grown on on- axis c-sapphire substrate at 850°C. The interfaces are marked with red dash-dot lines.

[0061] Figure 7A. XPS spectrum near the Li Is peaks from a Li -rich LiGa5O8film grown on GaN on sapphire template at 900°C.

[0062] Figure 7B. XPS spectrum near the Ga 3s peaks from a Li-rich LiGa5O8film grown on GaN on sapphire template at 900°C.

[0063] Figure 7C. XPS spectrum near the O ls peaks from a Li-rich LiGa5O8film grown on GaN on sapphire template at 900°C.

[0064] Figure 7D. XPS spectrum near the Li Is peaks from a Li -poor LiGa5O8film grown on GaN on sapphire template at 900°C.

[0065] Figure 7E. XPS spectrum near the Ga 3 s peaks from a Li -poor LiGa5O8film grown on GaN on sapphire template at 900°C.

[0066] Figure 7F. XPS spectrum near the O Is peaks from a Li-poor LiGa5O8film grown on GaN on sapphire template at 900°C.

[0067] Figure 8A. Example design structure of vertical PN diodes based on n'-Ga2O3 drift layer, n+-Ga?03 substrate and p-LiGa5O8layer.

[0068] Figure 8B. Example design structure of LiGa5O8-Ga2O3 MOSFET.

[0069] Figure 8C. Example design structure of LiGa5O8-Ga2O3 trench MOSFET. Figure 8D. Example design structure of LiGa5O8-Ga2O3 current aperture vertical electron transistor (CAVET).

[0070] Figure 9A-Figure 9D Cross-sectional STEM images showing (Figure 9A) low magnification and (Figure 9B) high magnification view of LiGa5O8sample grown on (010) Fe doped β-Ga2O3substrate. The interfaces are marked with gray dash lines and the zone axis is marked within the figure. The inset (Figure 9C) shows

[0110] LiGa5O8with the atomic model (Figure 9D) overlaid showing the structural match for

[0110] LiGa5O8.

[0071] Figure 10. XRD 29-co scan of LiGa5O8sample grown on (010) Fe doped |3-Ga2O3 substrate. The LiGa5O8peaks are marked with black arrows.

[0072] Figure 1 lA-Figure 11C. The XPS spectra of (Figure 11 A) Li Is, (Figure 1 IB) Ga 3s, and (Figure 11C) Ols peaks obtained from LiGa5O8sample grown on (010) Fe doped β-Ga2O3substrate. The black circles represent the original data points. The solid curves represent fitted peaks obtained assuming a Voigt shape and Shirley background. The background is shown by the grey dashed lines.

[0073] Figure 12. The bandgap energies of the LiGa5O8sample grown on (010) Fe doped P- Ga2O3 substrate determined by the energy difference of the O Is core level peak and the onset of the energy loss spectrum. Inset shows the zoomed-in spectrum in the boxed region.

[0074] Figure 13A-Figure 13C. Li Is and Ga 3s core-level and valence band spectra of (Figure 13A) 50 nm thick LiGa5O8sample grown on (010) Fe doped β-Ga2O3substrate, (Figure 13B) (010) Fe doped β-Ga2O3substrate and (Figure 13C) LiGa5O8 / p-Ga2O3 interface sample. The original data are shown by the black circles. The solid curves are the fitted peaks obtained assuming a Voigt shape and Shirley background. The background is shown by the grey dashed lines.

[0075] Figure 14. Experimentally measured valence band alignment at the LiGa5O8 / p-Ga2O3 hetero-interface.

[0076] Figure 15A-Figure 15B. (Figure 15A) Plan view SEM and (Figure 15B) 2 pm x 2 pm AFM image of LiGa5O8film grown on (010) Fe doped β-Ga2O3substrate.

[0077] Figure 16A-Figure 16B. XRD (Figure 16A) 29-co scan of LiGa5O8sample grown on (010) Fe doped β-Ga2O3substrate with film thickness of -400 nm. The corresponding β-Ga2O3and LiGa5O8peaks are marked with black arrows. (Figure 16B) rocking curve scan of (440) peak. DETAILED DESCRIPTION

[0078] The compositions, methods, and devices described herein may be understood more readily by reference to the following detailed description of specific aspects of the disclosed subject matter and the Examples included therein.

[0079] Before the present compositions, methods, and devices are disclosed and described, it is to be understood that the aspects described below are not limited to specific synthetic methods or specific reagents, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0080] Also, throughout this specification, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which the disclosed matter pertains. The references disclosed are also individually and specifically incorporated by reference herein for the material contained in them that is discussed in the sentence in which the reference is relied upon.

[0081] In this specification and in the claims that follow, reference will be made to a number of terms, which shall be defined to have the following meanings.

[0082] Throughout the description and claims of this specification the word “comprise” and other forms of the word, such as “comprising” and “comprises,” means including but not limited to, and is not intended to exclude, for example, other additives, components, integers, or steps.

[0083] As used in the description and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a composition” includes mixtures of two or more such compositions, reference to “an agent” includes mixtures of two or more such agents, reference to “the component” includes mixtures of two or more such components, and the like.

[0084] “Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0085] Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. By “about” is meant within 5% of the value, e.g., within 4, 3, 2, or 1% of the value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0086] Values can be expressed herein as an “average” value. “Average” generally refers to the statistical mean value.

[0087] By “substantially” is meant within 5%, e.g., within 4%, 3%, 2%, or 1%.

[0088] “Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal embodiment. “Such as” is not used in a restrictive sense, but for explanatory purposes.

[0089] It is understood that throughout this specification the identifiers “first” and “second” are used solely to aid in distinguishing the various components and steps of the disclosed subject matter. The identifiers “first” and “second” are not intended to imply any particular order, amount, preference, or importance to the components or steps modified by these terms.

[0090] References in the specification and concluding claims to parts by weight of a particular element or component in a composition denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.

[0091] A weight percent (wt. %) of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.

[0092] The term “or combinations thereof’ as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof’ is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.

[0093] Disclosed herein are ultrawide bandgap semiconductors with p-type conductivity and methods of making and use thereof.

[0094] For example, disclosed herein are compositions comprising ultrawide bandgap oxide semiconductor with p-type conductivity comprising LixGayOz, wherein Li and Ga have an atomic ratio (e g., x:y) of from 0.0001 to 1.0; Li and O have an atomic ratio (e g., x:z) of from 0.0001 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0. In some examples, the composition comprises β-LixGayOz.

[0095] For example, Li and Ga have an atomic ratio (e.g., x:y) of 0.0001 or more (e.g., 0.0005 or more, 0 001 or more, 0.005 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, 0.5 or more, 0.55 or more, 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0 8 or more, 0 85 or more, or 0.9 or more). In some examples, Li and Ga have an atomic ratio (e.g., x:y) of 1.0 or less (e.g., 0.95 or less, 0.9 or less, 0.85 or less, 0.8 or less, 0.75 or less, 0.7 or less, 0.65 or less, 0.6 or less, 0.55 or less, 0.5 or less, 0.45 or less, 0.4 or less, 0.35 or less, 0.3 or less, 0.25 or less, 0.2 or less, 0.15 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less, 0.005 or less, or 0.001 or less). The atomic ratio of Li to Ga (e.g., x:y) can range from any of the minimum values described above to any of the maximum values described above. For example, Li and Ga can have an atomic ratio (e.g., x:y) of from 0.0001 to 1.0 (e.g., from 0.0001 to 0.5, from 0.5 to 1, from 0.0001 to 0.2, from 0.2 to 0.4, from 0.4 to 0.6, from 0.6 to 0.8, from 0.8 to 1.0, from 0.0001 to 0.8, from 0.0001 to 0.6, from 0.0001 to 0.4, from 0.0001 to 0.1, from 0.0005 to 1.0, from 0.001 to 1.0, from 0.005 to 1.0, from 0.01 to 1.0, from 0.01 to 0.5, from 0.5 to 1, from 0.01 to 0.2, from 0.01 to 0.8, from 0.01 to 0.6, from 0.01 to 0.4, from 0.01 to 0.1, from 0.05 to 1.0, from 0.1 to 1.0, from 0.4 to 1.0, from 0.6 to 1.0, from 0.0005 to 0.95, from 0.1 to 0.9, from 0.2 to 0.8, from 0.2 to 0.5, or from 0.2 to 0.3). In some examples, Li and Ga have an atomic ratio of 0.01 or more. In some examples, Li and Ga have an atomic ratio of from 0.01 to 1.0. In some examples, Li and Ga have an atomic ratio of from 0.1 to 0.3. In some examples, Li and Ga have an atomic ratio of 0.2 to 0.3. In some examples, Li and Ga have an atomic ratio of 0.2.

[0096] In some examples, Li and O have an atomic ratio (e.g., x:z) of 0.0001 or more (e.g., 0.0005 or more, 0.001 or more, 0.005 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, or 0.45 or more). In some examples, Li and O have an atomic ratio (e.g., x:z) of 0.5 or less (e.g., 0.45 or less, 0.4 or less, 0.35 or less, 0.3 or less, 0.25 or less, 0.2 or less, 0.15 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less, 0.005 or less, or 0.001 or less). The atomic ratio of Li to O (e.g., x:z) can range from any of the minimum values described above to any of the maximum values described above. For example, Li and O can have an atomic ratio (e.g., x:z) of from 0.0001 to 0.5 (e.g., from 0.0001 to 0.25, from 0.25 to 0.5, from 0.0001 to 0.1, from 0.1 to 0.2, from 0.2 to 0.3, from 0.3 to 0.4, from 0.4 to 0.5, from 0.0001 to 0.4, from 0.0001 to 0.3, from 0.0001 to 0.2, from 0.0001 to 0.1, from 0.0001 to 0.05, from 0.00625 to 0.25, from 0.00625 to 0.1, from 0.00625 to 0.4, from 0.00625 to 0.3, from 0.00625 to 0.2, from 0.00625 to 0.1, from 0.00625 to 0.05, from 0.00625 to 0.5, from 0.01 to 0.5, from 0.05 to 0.5, from 0.1 to 0.5, from 0.2 to 0.5, from 0.3 to 0.5, from 0.01 to 0.45, from 0.05 to 0.4, or from 0.05 to 0.2). In some examples, Li and O have an atomic ratio (e.g., x:z) of 0.00625 or more In some examples, Li and O have an atomic ratio (e g., x:z) of from 0.00625 to 0.5. In some examples, Li and O have an atomic ratio (e.g., x:z) of from 0.05 to 0.2. In some examples, Li and O have an atomic ratio (e.g., x:z) of from 0.125 to 0.25. In some examples, Li and O have an atomic ratio (e g., x:z) of 0.125.

[0097] In some examples, Ga and O have an atomic ratio (e.g., y:z) of 0.5 or more (e g., 0.525 or more, 0.55 or more, 0.575 or more, 0.6 or more, 0.625 or more, 0.65 or more, 0.675 or more, 0.7 or more, 0.725 or more, 0.75 or more, 0.775 or more, 0.8 or more, 0.825 or more, 0.85 or more, 0.875 or more, 0.9 or more, 0.925 or more, or 0.95 or more). In some examples, Ga and O have an atomic ratio (e g., y:z) of 1.0 or less (e.g., 0.975 or less, 0.95 or less, 0.925 or less, 0.9 or less, 0.875 or less, 0.85 or less, 0.825 or less, 0.8 or less, 0.775 or less, 0.75 or less, 0.725 or less, 0.7 or less, 0.675 or less, 0.65 or less, 0.625 or less, 0.6 or less, 0.575 or less, or 0.55 or less). The atomic ratio of Ga to O (e.g., x:z) can range from any of the minimum values described above to any of the maximum values described above. For example, Ga and O can have an atomic ratio (e.g., y:z) of from 0.5 to 1.0 (e.g., from 0.5 to 0.75, from 0.75 to 1.0, from 0.5 to 0.6, from 0.6 to 0.7, from 0.7 to 0.8, from 0.8 to 0.9, from 0.9 to 1.0, from 0.5 to 0.9, from 0.5 to 0.8, from 0.5 to 0.7, from 0.6 to 1.0, from 0.7 to 1.0, from 0.8 to 1.0, from 0.6 to 0.9, or from 0.625 to 0.8). In some examples, Ga and O have an atomic ratio (e.g., y:z) of from 0.625 to 0.8. In some examples, Ga and O have an atomic ratio (e.g., y:z) of from 0.65 to 0.75. In some examples, Ga and O have an atomic ratio (e g., y:z) of 0.625.

[0098] In some examples, the compositions comprises LixGayOzwherein Li and Ga have an atomic ratio (e.g., x:y) of from 0.01 to 1.0; Li and O have an atomic ratio (e.g., x:z) of from 0.00625 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

[0099] In some examples, Li, Ga, and O can have an atomic ratio (e.g., x:y:z) or 1:5:8.

[0100] In some examples, the composition comprises LiGa5O8.

[0101] In some examples, the composition comprises Li rich LiGa5O8.

[0102] In some examples, the composition comprises Li poor LiGa5O8.

[0103] In some examples, the composition comprises O poor LiGa5O8.

[0104] In some examples, the composition comprises O rich LiGa5O8.

[0105] In some examples, the composition further comprises a dopant, such as a p-type dopant. In some examples, the composition is substantially free of any dopants.

[0106] In some examples, the composition has a carrier concentration (e.g., a hole concentration) of 1 x 1014per cubic centimeter (cm’3) or more (e g., 5* 1014cm’3or more, 1 x

[0107] 1015cm’3or more, 5 x 1015cm-3or more, 1 x 1016cm-3or more, 5 x 1016cm-3or more, 1 x 1017cm’3or more, 5 x 1017cm'3or more, 1x1018cm’3or more, 5 x 1018cm’3or more, 1x1019cm’3or more, 5 * 10 cm’ or more, 1 x 10 cm’ or more, or 5 x 10 cm’ or more). In some examples, the composition has a carrier concentration (e g., a hole concentration) of 1 x 1021cm’3or less (e.g., 5 x 1O20cm’3or less, 1xIO20cm'3or less, 5 x 1019cm'3or less, 1x1019cm'3or less, 5 x 1018cm'3or less, 1 x 1018cm'3or less, 5 x 1017cm'3or less, 1x1017cm'3or less, 5 x

[0108] 1016cm’3or less, 1x1015cm'3or less, 5 x 1015cm'3or less, 1x1015cm'3or less, or 5 x 1014cm'

[0109] 3or less). The carrier concentration (e.g., hole concentration) can range from any of the minimum values described above to any of the maximum values described above. For example, the composition can have a carrier concentration (e.g., hole concentration) of from 1 x 1014per cubic centimeter to 1x1021cm'3(e.g., from 1x1014to 1x1017cm'3, from 1x1017to 5 x 1019cm'3, from 5x1019to 1x1021cm'3, from 1 x 1014to 1x1015cm'3, from 1x1015to 1x1016cm'3, from 1 x 1016to 1x1017cm’3, from 1 x 1017to 1x1018cm'3, from 1 x 1018to 1 x 1019cm’3, from 1x1019to 1x102° cm'3, from 1xio20to 1x1021cm'3, from 1x1014to 5x1019cm'3, from 1x1014to 1 x 1018cm'3, from 1 x 1015to 1x1021cm'3, from 1x1015to 5x1019cm'3, from 1 x 1018to 5 x 1019cm'3, from 1 x 1015to 1 x 1018cm'3, or from 1 x 1017to 5 x 1018cm'3).

[0110] In some examples, the composition has a carrier concentration (e.g., a hole concentration) of 5x1019cm'3or less. In some examples, the composition can have a carrier concentration (e.g., hole concentration) of from 1 x 1014per cubic centimeter to 5 x 1019cm'3. In some examples, the dopant has a concentration of from 1x1017to 5x1018cm'3.

[0111] In some examples, the composition has a mobility, such as a hole mobility, of 0.01 cm2 / Vs or more (e.g., 0.05 cm2 / Vs or more, 0.1 cm2 / Vs or more, 0.25 cm2 / Vs or more, 0.5 cm2 / Vs or more, 0.75 cm2 / Vs or more, 1 cm2 / Vs or more, 1.5 cm2 / Vs or more, 2 cm2 / Vs or more, 2.5 cm2 / Vs or more, 3 cm2 / Vs or more, 3.5 cm2 / Vs or more, 4 cm2 / Vs or more, 4.5 cm2 / Vs or more, 5 cm2 / Vs or more, 5.5 cm2 / Vs or more, 6 cm2 / Vs or more, 6.5 cm2 / Vs or more, 7 cm2 / Vs or more, 7.5 cm2 / Vs or more, 8 cm2 / Vs or more, 8.5 cm2 / Vs or more, 9 cm2 / Vs or more, 10 cm2 / Vs or more, 15 cm2 / Vs or more, 20 cm2 / Vs or more, 25 cm2 / Vs or more, 30 cm2 / Vs or more, 40 cm2 / Vs or more, 50 cm2 / Vs or more, or 75 cm2 / Vs or more). In some examples, the composition has a mobility, such as a hole mobility, of 100 cm2 / Vs or less (e.g., 90 cm2 / Vs or less, 80 cm2 / Vs or less, 70 cm2 / Vs or less, 60 cm2 / Vs or less, 50 cm2 / Vs or less, 40 cm2 / Vs or less, 30 cm2 / Vs or less, 25 cm2 / Vs or less, 20 cm2 / Vs or less, 15 cm2 / Vs or less, 10 cm2 / Vs or less, 9.5 cm2 / Vs or less, 9 cm2 / Vs or less, 8.5 cm2 / Vs or less, 8 cm2 / Vs or less, 7.5 cm2 / Vs or less, 7 cm2 / Vs or less, 6.5 cm2 / Vs or less, 6 cm2 / Vs or less, 5.5 cm2 / Vs or less, 5 cm2 / Vs or less, 4.5 cm2 / Vs or less, 4 cm2 / Vs or less, 3.5 cm2 / Vs or less, 3 cm2 / Vs or less, 2.5 cm2 / Vs or less, 2 cm2 / Vs or less, 1.5 cm2 / Vs or less, 1 cm2 / Vs or less, 0.75 cm2 / Vs or less, or 0.5 cm2 / Vs or less). The mobility (e.g. the hole mobility) of the composition can range from any of the minimum values described above to any of the maximum values described above. For example, the composition can have a mobility, such as a hole mobility, of from 0.01 to 100 cm2 / Vs (e.g., 0.01 to 50 cm2 / Vs, from 50 to 100 cm2 / Vs, from 0.01 to 20 cm2 / Vs, from 20 to 40 cm2 / Vs, from 40 to 60 cm2 / Vs, from 60 to 80 cm2 / Vs, from 80 to 100 cm2 / Vs, from 0.01 to 75 cm2 / Vs, from 0.01 to 25 cm2 / Vs, from 0.1 to 100 cm2 / Vs, from 10 to 100 cm2 / Vs, from 25 to 100 cm2 / Vs, from 75 to 100 cm2 / Vs, from 0.05 to 75 cm2 / Vs, from 0.1 to 10 cm2 / Vs, from 0.1 to 5 cm2 / Vs, from 5 to 10 cm2 / Vs, from 0.1 to 4 cm2 / Vs, from 4 to 7 cm2 / Vs, from 7 to 10 cm2 / Vs, from 0.1 to 8 cm2 / Vs, from 0.1 to 6 cm2 / Vs, from 0.1 to 3 cm2 / Vs, from 0.1 to 1 cm2 / Vs, from 1 to 10 cm2 / Vs, from 2 to 10 cm2 / Vs, from 4 to 10 cm2 / Vs, from 6 to 10 cm2 / Vs, from 8 to 10 cm2 / Vs, from 1.5 to 9.5 cm2 / Vs, or from 0.35 to 2 cm2 / Vs).

[0112] In some examples, the composition has a mobility, such as a hole mobility, of 0.1 cm2 / Vs or more. In some examples, the composition has a mobility, such as a hole mobility, of 10 cm2 / Vs or less. In some examples, the composition can have a mobility, such as a hole mobility, of from 0.1 to 10 cm2 / Vs. In some examples, , the composition can have a mobility, such as a hole mobility, of from 0.35 to 2 cm2 / Vs.

[0113] In some examples, the composition exhibits high p-type conductivity.

[0114] Also disclosed herein are devices comprising any of the compositions disclosed herein. In some examples, the device further comprises a substrate, wherein the composition is deposited on the substrate as a layer. The substrate can comprise any suitable substate. For example, the substrate can comprise LiGa5O8, free standing GaN, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga2O3, AIN, AlGaN, diamond, or a combination thereof. In some examples, the substrate can comprise LiGa5O8, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°- offcut c-plane sapphire), Ga2Ox, or a combination thereof.

[0115] In some examples, the layer has a surface roughness with a RMS value of 20 nm or less (e.g., 19 nm or less, 18 nm or less, 17 nm or less, 16 nm or less, 15 nm or less, 14.5 nm or less, 14 nm or less, 13.5 nm or less, 13 nm or less, 12.5 nm or less, 12 nm or less, 11.5 nm or less, 11 nm or less, 10.5 nm or less, 10 nm or less, 9.5 nm or less, 9 nm or less, 8.5 nm or less, 8 nm or less, 7.5 nm or less, 7 nm or less, 6.5 nm or less, 6 nm or less, 5.5 nm or less, 5 nm or less, 4.5 nm or less, 4 nm or less, 3.5 nm or less, 3 nm or less, 2.5 nm or less, 2 nm or less, 1.75 nm or less, 1.5 nm or less, 1.25 nm or less, 1 nm or less, 0.75 nm or less, or 0.5 nm or less). In some examples, the layer has a surface roughness with an RMS value of 15 nm or less. In some examples, the layer has a surface roughness with an RMS value of 10 nm or less. In some examples, the layer has a surface roughness with an RMS value of 5 nm or less. In some examples, the layer has a surface roughness with an RMS value of 2.5 nm or less. In some examples, the layer has a surface roughness with an RMS value of 1.75 nm or less, In some examples, the layer has a surface roughness with an RMS value of 1 .5 nm or less.

[0116] In some examples, the layer has an average thickness of 10 nanometers (nm) or more (e.g., 15 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, 50 nm or more, 55 nm or more, 60 nm or more, 65 nm or more, 70 nm or more, 75 nm or more, 80 nm or more, 85 nm or more, 90 nm or more, 95 nm or more, 100 nm or more, 125 nm or more, 150 nm or more, 175 nm or more, 200 nm or more, 225 nm or more, 250 nm or more, 275 nm or more, 300 nm or more, 325 nm or more, 350 nm or more, 375 nm or more, 400 nm or more, 425 nm or more, 450 nm or more, 475 nm or more, 500 nm or more, 525 nm or more, 550 nm or more, 575 nm or more, 600 nm or more, 625 nm or more, 650 nm or more, 675 nm or more, 700 nm or more, 725 nm or more, 750 nm or more, 775 nm or more, 800 nm or more, 825 nm or more, 850 nm or more, 875 nm or more, 900 nm or more, 925 nm or more, 950 nm or more, 975 nm or more, 1000 nm or more, 1050 nm or more, 1100 nm or more, 1150 nm or more, 1200 nm or more, 1250 nm or more, 1300 nm or more, 1400 nm or more, 1500 nm or more, or 1750 nm or more). In some examples, the layer has an average thickness of 2000 nm or less (e.g., 1900 nm or less, 1800 nm or less, 1700 nm or less, 1600 nm or less, 1500 nm or less, 1450 nm or less, 1400 nm or less, 1350 nm or less, 1300 nm or less, 1250 nm or less, 1200 nm or less, 1150 nm or less, 1100nm or less, 1050 nm or less, 1000 nm or less, 975 nm or less, 950 nm or less, 925 nm or less, 900 nm or less, 875 nm or less, 850 nm or less, 825 nm or less, 800 nm or less, 775 nm or less, 750 nm or less, 725 nm or less, 700 nm or less, 675 nm or less, 650 nm or less, 625 nm or less, 600 nm or less, 575 nm or less, 550 nm or less, 525 nm or less, 500 nm or less, 475 nm or less, 450 nm or less, 425 nm or less, 400 nm or less, 375 nm or less, 350 nm or less, 325 nm or less, 300 nm or less, 275 nm or less, 250 nm or less, 225 nm or less, 200 nm or less, 175 nm or less, 150 nm or less, 125 nm or less, 100 nm or less, 95 nm or less, 90 nm or less, 85 nm or less, 80 nm or less, 75 nm or less, 70 nm or less, 65 nm or less, 60 nm or less, 55 nm or less, 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, or 20 nm or less). The average thickness of the layer can range from any of the minimum values described above to any of the maximum values described above. For example, the layer can have an average thickness of from 10 to 2000 nm (e.g., from 10 to 1000 nm, from 1000 to 2000 nm, from 10 to 500 nm, from 500 to 1000 nm, from 1000 to 1500 nm, from 1500 to 2000 nm, from 10 to 1750 nm, from 10 to 1500 nm, from 25 to 2000 nm, from 100 to 2000 nm, from 20 to 1750 nm, from 25 to 1000 nm, from 25 to 500 nm, from 500 to 1000 nm, from 25 to 200 nm, from 200 to 400 nm, from 400 to 600 nm, from 600 to 800 nm, from 800 to 1000 nm, from 25 to 800 nm, from 25 to 600 nm, from 25 to 400 nm, from 25 to 100 nm, from 50 to 1000 nm, from 100 to 1000 nm, from 200 to 1000 nm, from 400 to 1000 nm, from 600 to 1000 nm, from 35 to 950 nm, from 50 to 900 nm, or from 50 to 100 nm). In some examples, the layer has an average thickness of 25 nanometers (nm) or more. In some examples, the layer has an average thickness of 1000 nm or less. In some examples, the layer can have an average thickness of from 25 to 1000 nm. In some examples, the layer can have an average thickness of from 50 to 100 nm.

[0117] The device can comprise any suitable device. In some examples, the device comprises a vertical PN diode, a MOSFET device such as a power MOSFET or a trench MOSFET, a MESFET device, a MODFET device, a Current Aperture Vertical Electron Transistor (CAVET) device, or a combination thereof. In some examples, the device comprises a vertical PN diode, a MOSFET device such as a power MOSFET or a trench MOSFET, a Current Aperture Vertical Electron Transistor (CAVET) device, or a combination thereof. In some examples, the device comprises a vertical power device. In some examples, the device comprises an optical device, an electronic device, an optoelectronic device, or a combination thereof. In some examples, the device comprises a diode. In some examples, the device comprises a n-Ga2O3 / p-LixGayOz (e.g., a n-Ga2O3 / p-LiGa5O8) heterojunction. In some examples, the device comprises n-GaN / p-

[0118] LixGayOz, n-AlN / p-LixGayOz, n-diamond / p-LixGayOz, or a combination thereof.

[0119] Also disclosed herein are methods of use of any of the compositions disclosed herein.

[0120] Also disclosed herein are methods of making any of the compositions or devices disclosed herein. In some examples, the methods comprising contacting a gallium containing precursor and a lithium containing precursor at a temperature in the presence of oxygen or an oxygen containing precursor to thereby react the gallium containing precursor, the lithium containing precursor, and the oxygen or the oxygen containing precursor to form the composition.

[0121] In some examples, the gallium containing precursor comprises Ga(acac)3 ([CH3COCH=C(O-)CH3]3Ga), a metalorganic Ga containing precursor, or a combination thereof. In some examples, the gallium containing precursor comprises a metalorganic Ga containing precursor. In some examples, the gallium containing precursor comprises Ga(acac)3([CH3COCH=C(O-)CH3]3Ga).

[0122] In some examples, the lithium containing precursor comprises lithium acetoacetate (C4HsLiO3), a metalorganic Li containing precursor, or a combination thereof. In some examples, the lithium containing precursor comprises a metalorganic Li containing precursor. In some examples, the lithium containing precursor comprises lithium acetoacetate (C4H5LiO3).

[0123] In some examples, the gallium containing precursor and / or the lithium containing precursor independently comprise(s) a fluid.

[0124] In some examples, the gallium containing precursor and / or the lithium containing precursor are independently provided with a carrier gas. In some examples, the carrier gas comprises argon, helium, N2, and the like, or combinations thereof. In some examples, the carrier gas comprises argon.

[0125] In some examples, the temperature is 300°C or more (e.g., 350°C or more, 400°C or more, 450°C or more, 500°C or more, 550°C or more, 600°C or more, 650°C or more, 700°C or more, 750°C or more, 800°C or more, 825°C or more, 850°C or more, 875°C or more, 900°C or more, 925°C or more, 950°C or more, 975°C or more, 1000°C or more, 1050°C or more, or 1100°C or more). In some examples, the temperature is 1200°C or less (e.g., 1150°C or less, 1100°C or less, 1050°C or less, 1000°C or less, 975°C or less, 950°C or less, 925°C or less, 900°C or less, 875°C or less, 850°C or less, 825°C or less, 800°C or less, 750°C or less, 700°C or less, 650°C or less, 600°C or less, 550°C or less, 500°C or less, 450°C or less, or 400°C or less). The temperature can range from any of the minimum values described above to any of the maximum values described above. For example, the temperature can be from 300°C to 1200°C (e.g., from 300°C to 750°C, from 750°C to 1200°C, from 300°C to 600°C, from 600°C to 900°C, from 900°C to 1200°C, from 300°C to 1000°C, from 300°C to 800°C, from 400°C to 1200°C, from 600°C to 1200°C, from 800°C to 1200°C, from 400°C to 1100°C, from 600°C to 1000°C, from 800°C to 1000°C, from 800°C to 900°C, from 900°C to 1000°C, from 800°C to 850°C, from 850°C to 900°C, from 900°C to 950°C, from 950°C to 1000°C, from 800°C to 950°C, from 850°C to 1000°C, or from 850°C to 950°C). In some examples, the temperature is 800°C or more. In some examples, the temperature is 1000°C or less. In some examples, the temperature is from 800°C to 1000°C. In some examples, the temperature is from 800°C to 950°C. In some examples, the temperature is from 850°C to 950°C. In some examples, the temperature is 900°C.

[0126] The method can, for example, comprise metal organic chemical vapor deposition (MOCVD), molecular-beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), pulsed laser deposition (PLD), low pressure chemical vapor deposition (LPCVD), mist-CVD, or a combination thereof. In some examples, the method comprises mist-CVD.

[0127] In some examples, the method comprises depositing the composition on a substrate. Examples of substrates include, but are not limited to, LiGa5O8, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga2O3, or a combination thereof.

[0128] A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

[0129] The examples below are intended to further illustrate certain aspects of the devices and methods described herein, and are not intended to limit the scope of the claims.

[0130] EXAMPLES

[0131] The following examples are set forth below to illustrate the methods and results according to the disclosed subject matter. These examples are not intended to be inclusive of all aspects of the subject matter disclosed herein, but rather to illustrate representative methods and results. These examples are not intended to exclude equivalents and variations of the present invention which are apparent to one skilled in the art.

[0132] Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric. There are numerous variations and combinations of measurement conditions, e.g., component concentrations, temperatures, pressures and other measurement ranges and conditions that can be used to optimize the described process.

[0133] Example 1 - Ultra-wide bandgap oxide semiconductors with p-type conductivity

[0134] Beta-Gallium oxide (P-Ga2O3) has emerged as a promising material for future power devices due to its ultrawide bandgap (~4.9eV), high critical electric field (EC), controllable doping, and availability of high quality, large-diameter wafers [1], While n-type β-Ga2O3can be readily obtained through Si or Sn doping, the existence of p-type P-Ga2O3remains undocumented. One potential approach to create P-Ga2O3devices with a p-n junction involves using a heterojunction between β-Ga2O3and another p-type semiconductor. An oxide material is preferred as the p-type semiconductor in this scenario, as it prevents interfacial oxidation reactions that would occur with non-oxide materials, enabling more efficient device fabrication methods. Recent developments have employed p-type nickel oxide (with a bandgap of 3.4-4 eV) to form p-n junction diodes with β-Ga2O3[2], Since the initial report, NiO / Ga2O3 p-n diodes have achieved multi-kilovolt breakdown voltage (BV) and low differential specific on-resistance (RON,SP) [3-5], However, the performance of these devices is significantly limited by the comparatively smaller bandgap ofNiO.

[0135] Recently, there has been renewed interest in LiGaO2as a potential ultra-wide bandgap semiconductor material LiGaO2is a transparent ceramic material that has previously been explored for its applications in piezoelectric and nonlinear optical fields [6-10], It can be grown as a bulk single crystal, making it suitable as a lattice-matched substrate for GaN epitaxial growth [11-16], LiGaO2possesses a wurtzite-based crystal structure and can be viewed as an I- III- VI2 analog of the II- VI material ZnO. The crystal structure features an ordered arrangement of Li and Ga atoms on the cation sublattice of the wurtzite, with the ground state represented by the Pna2i space group ( β-LiGaO2). Furthermore, studies have examined mixed alloy systems of ZnO and LiGaO2, as well as ZnO / LiGaO2 heterojunctions [17-19], Recent studies suggest that LiGaO2 can be doped n-type with Si or Ge, which holds promise for ultrawide-gap semiconductor applications [20-24], From this perspective, LiGaO2 may offer certain advantages compared to β-Ga2O3, such as its simpler tetrahedrally coordinated crystal structure and potentially even wider bandgap.

[0136] Herein, an ultra-wide bandgap semiconductor called LixGayOz, which exhibits high p- type conductivity, is described. The materials were obtained using a customized mist chemical vapor deposition (CVD) technique. Unintentionally doped LixGayOzthin films can be deposited on GaN-on-sapphire templates, as well as on on-axis and offcut c-sapphire substrates using the mist-CVD chamber. To prepare the source solutions, Gallium acetyl acetonate (Ga(acac)3, [CH3COCH=C(O-)CH3]3Ga, 99.99%) and lithium acetoacetate (C4H5LiO3, 99.95%) are dissolved in deionized (DI) water, with a Ga / Li molar ratio of approximately 1. The solutions are used to generate atomized particles via an ultrasonic generator operating at 1.7 MHz. The atomized particles are then delivered into a growth chamber using Argon (Ar) as the carrier gas. Growth substrates are loaded in the growth chamber and the growth temperature can be tuned widely between 800 - 1000 °C. Through a series of material characterization techniques, it was confirmed that the films grown on the respective substrates exhibited a spinel-cubic structure known as LiGa5O8. The p-type conductive films were found to have a wide range of Li compositions, including both Li-poor and Li-rich conditions. LiGa5O8is a complex oxide compound that belongs to the spinel family of compounds and has an isostructural relationship with the MgAhCh spinel. Its crystal structure is characterized by a lattice constant of a = 8.203 A and space group P4_332. In this structure the Li+ions in LiGa5O8are coordinated to six equivalent O2ions, resulting in the formation of LiOe octahedra. These octahedra share corners with six equivalent GaO4tetrahedra and edges with six equivalent GaO6 octahedra, giving rise to the overall crystalline structure of LiGa5O8.

[0025] LiGa5O8has been the subject of considerable research interest due to its intriguing luminescent properties, particularly when doped with transition metals (MT) or rare earth (RE) impurities. [26-28] For instance, when doped with Cr3+, it exhibits persistent luminescence properties and holds promise for biomedical imaging applications. The structural, electronic, and optical properties of both undoped and Cr3+-doped LiGa5O8have been investigated via density functional theory (DFT). [28, 29] Theoretical calculations suggest a bandgap of approximately 5.7 eV, which renders LiGa5O8a potential ultra- wide bandgap semiconductor. However, to date, there have been no experimental reports on thin film growth of undoped LiGa5O8.

[0137] Herein, the CVD growth of LiGa5O8that is either Li-poor or Li-rich and exhibits p-type conductivity is demonstrated. This is an important discovery as there does not exist an ultrawide bandgap oxide semiconductor that has been demonstrated with p-type conductivity.

[0138] Figure lA-Figure ID show the surface morphology of LiGa5O8samples grown on GaN on sapphire templates at different growth temperatures. It is confirmed with the corresponding AFM images as shown in Figure 2A-Figure 2D that at the growth temperature of 900°C, the smoothest surface is achieved. The surface roughness RMS is determined to be around 1.60 nm. The thickness of the as-grown film at 900°C is measured by cross-sectional TEM image to be around 60 nm, as shown in Figure 3A. A sharp interface between the grown film and GaN layer can be observed. The spinel cubic structure of the as-grown film is also shown by the atomic resolution HAADF STEM image in Figure 3B. Figure 4 shows the XRD spectrum of the same sample. The XRD peaks at around 34.55°, 41.68° and 72.86° are attributed to the GaN and sapphire peaks from the substrate, while possible LiGa5O8peaks at around 58.46° can be observed. Note that other peaks at around 18.74° and 38.01° are also noticeable, indicating the existence of possible rotated crystal domains in the as-grown film.

[0139] Similar surface morphology can be observed on LiGa5O8samples grown on co-loaded c- sapphire substrates. Figure 5A-Figure 5D shows the plan-view SEM images of the LiGa5O8sample grown at 850°C on on-axis and 6°-offcut c-plane sapphire substrates as well as the corresponding AFM images. It is worth noticing that with the use of offcut angles, better surface morphology can be achieved for the films grown on sapphire substrates. Cross-sectional TEM imaging and atomic resolution HAADF STEM image of the sample grown on on-axis c-sapphire substrate, as is shown in Figure 6A-Figure 6B, confirm a film thickness of around 96 nm and the same spinel cubic structure as the samples grown on GaN templates. More importantly, Hall measurement suggests a robust p-type conductivity for this sample, as is shown in Table 1.

[0140] Table 1. Hall measurement results of both Li-poor and Li-rich LiGa5O8samples grown on on- axis c-sapphire substrate at 850°C.

[0141] The atomic compositions of the as-grown films were examined using X-ray photoemission spectroscopy (XPS). The acquired Li Is, Ga 3 s and O ls peaks from LiGa5O8film grown on GaN on sapphire template at 900°C are shown in Figure 7A-Figure 7F as two examples (Figure 7A - Figure 7C for Li -rich condition; Figure 7D - Figure 7F for Li-poor condition). The curves are fitted with a Voigt peak shape and a Shirley background is assumed. The atomic ratio of Li / Ga, Li / O and Ga / O are then derived using the fitting peak areas. As is shown in Table 2, the samples grown on all three substrates show a ratio of -1:5:8 for Li / Ga / O with Li being either compositionally rich or poor.

[0142] Table 2. Li / Ga, Li / O, and Ga / O ratio estimated from XPS measurement results using the peak areas of Li Is, Ga 3 s, and O ls peaks for LiGa5O8samples grown with different conditions (Li rich and Li poor).

[0143] With the successful demonstration of p-type conductivity of Li rich and Li poor LiGa5O8, multiple device designs are proposed for power device applications. Figure 8A represents a vertical PN diodes based on n -Ga2O3 drift layer, n -GazO? substrate and p-LiGa5O8layer. Figure 8B represents a LiGa5Os-Ga2O3 MOSFET. Figure 8C represents a LiGa5Os-Ga2O3 trench MOSFET. Figure 8D represents a LiGa5O8-Ga2O3 current aperture vertical electron transistor (CAVET). In these designs, a key structure is based on the n-Ga2O3 / p-LiGa5O8 heterojunctions.

[0144] References

[0145] 1. S.J. Pearton et al. “A review of Ga2O3materials, processing, and devices,” Appl. Phys. Rev. 5(1), 011301 (2018).

[0146] 2. Y. Kokubun et al. “All-oxide p-n heterojunction diodes comprising p-type NiO and n-type β-Ga2O3,” Appl. Phys. Express 9(9), 091101 (2016).

[0147] 3. X. Lu et al. “1-kV Sputtered p-NiO / n-Ga2O3 Heterojunction Diodes With an Ultra-Low Leakage Current Below 1 uA / cm2,” IEEE Electron Device Lett. 41(3), 449-452 (2020).

[0148] 4. Y. Wang et al. “2.41 kV Vertical P-NiO / n-Ga2O3 Heterojunction Diodes With a Record Baliga’s Figure-of-Merit of 5.18 GW / cm2,” IEEE Trans. Power Electron. 37(4), 3743- 3746 (2022).

[0149] 5. B. Wang et al. “2.5 kV Vertical Ga2O3Schottky Rectifier With Graded Junction Termination Extension,” IEEE Electron Device Lett. 44(2), 221-224 (2023).

[0150] 6. A. Boonchun et al. “First-principles study of the elasticity, piezoelectricity, and vibrational modes in LiGaO2compared with ZnO and GaN,” Phys. Rev. B 81(23), 235214 (2010).

[0151] 7. S.N. Gupta et al. “Surface acoustic wave properties of lithium gallium oxide,” J. Appl. Phys. 47(3), 858-860 (1976).

[0152] 8. S. Nanamatsu et al. “Piezoelectric, elastic and dielectric properties of LiGaO2,” Jpn. J. Appl. Phys. 11(6), 816 (1972).

[0153] 9. P. Knoll, and H. Kuzmany, “Nonlinear-optical properties and signs of the Raman tensor for LiGaO2,” Phys. Rev. B 29(4), 2221-2226 (1984).

[0154] 10. S.N. Rashkeev et al. “Theoretical evaluation of LiGaO2for frequency upconversion to ultraviolet,” JOSA B 16(12), 2217-2222 (1999).

[0155] 11. T. Ishii et al. “Single-crystal growth of LiGaO2for a substrate of GaN thin films,” J. Cryst. Growth 186(3), 409-419 (1998).

[0156] 12. M. Marezio, “The crystal structure of LiGaO2,” Acta Crystallogr. 18(3), 481-484 (1965).

[0157] 13. A. Christensen et al. “Heat dissipation in high-power GaN electronics on thermally resistive substrates,” IEEE Trans. Electron Devices 52(8), 1683-1688 (2005).

[0158] 14. W.A. Doolittle et al. “MBE growth of high quality GaN on LiGaO2for high frequency, high power electronic applications,” Solid-State Electron. 44(2), 229-238 (2000). 15. K. Sakurada et al. “Low temperature epitaxial growth of GaN films on LiGaO2substrates,” Appl. Phys. Lett. 90(21), 211913 (2007).

[0159] 16. C Chen et al. “Growth and characterization of β-LiGaO2single crystal,” J. Cryst Growth 402, 325-329 (2014).

[0160] 17. I. Ohkubo et al. “Heteroepitaxial growth of β-LiGaO2thin films on ZnO,” J. Appl. Phys. 92(9), 5587-5589 (2002).

[0161] 18. T. Omata et al. “Wide band gap semiconductor alloy: x(LiGaO2)1 / 2-(1-x)ZnO,” J. Appl. Phys. 103(8), 083706 (2008).

[0162] 19. T. Omata et al. “Zn2LiGaO4 , Wurtzite-Derived Wide Band Gap Oxide,” Jpn. J. Appl. Phys. 50(3R), 031102 (2011).

[0163] 20. A. Boonchun et al. “First-principles study of point defects in LiGaO2,” J. Appl. Phys. 126(15), 155703 (2019).

[0164] 21. A. Boonchun et al. in Oxide-Based Mater. Devices II (SPIE, 2011), pp. 129-134.

[0165] 22. K. Dabsamut et al. “First-principles study of n-and p-type doping opportunities in LiGaO2,” J. Phys. Appl. Phys. 53(27), 274002 (2020).

[0166] 23. C.A. Lenyk et al. “Lithium and gallium vacancies in LiGaO2 crystals,” J. Appl. Phys. 124(13), 135702 (2018).

[0167] 24. D. Skachkov et al. “Computational study of electron paramagnetic resonance spectra for Li and Ga vacancies in LiGaO2,” J. Phys. Appl. Phys. 53(17), 17LT01 (2020).

[0168] 25. J. Ahman et al. “Structure of LiGa5O8,” Acta Chem. Scand. 50(5), 391-394 (1996).

[0169] 26. F. Liu et al. “Photostimulated near-infrared persistent luminescence as a new optical read-out from Cr3+-doped LiGa5O8,” Sci. Rep. 3(1), 1554 (2013).

[0170] 27. L. Ao et al. “Structure characterization and microwave dielectric properties of LiGa5O8ceramic with low-εr and low loss,” J. Eur. Ceram. Soc. 40(15), 5498-5503 (2020).

[0171] 28. O.M. Sousa et al. “Theoretical study of the structural, energetic, electronic and magnetic properties of the host matrix LiGa5O8doped with Cr3+,” J. Solid State Chem. 289, 121472 (2020).

[0172] 29. O.M. De Sousa, “Study of the structural, electronic, and optical properties of the host matrices of LiA5O8and LiGa5O8via DFT,” Comput. Theor. Chem. 1123, 96-101 (2018). Example 2 - Experimental Determination of the Band Offsets at the UWBG p- LiGasOg / GaiOs Interface

[0173] Abstract. LiGa5O8, a recently discovered ultrawide bandgap semiconductor exhibiting p- type conductivity at room temperature, is grown on (010) β-Ga2O3substrate. Utilizing a mist chemical vapor deposition (M-CVD) method, LiGa5O8thin film grown on insulating Ga2O3substrate exhibits hole concentration ~ 2 3 lx 1018cm'3and hole mobility ~ 2 07 cm2 / V s The resulting heterostructure is characterized comprehensively. A smooth, uniform film growth was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging. Cross-sectional scanning transmission electron microscopy (STEM) and X-ray diffraction (XRD) confirm the growth of spinel cubic crystal structure of LiGa5O8along the

[0110] direction. Moreover, the valence and conduction band offsets at β- LiGa5O8 / β-Ga2O3heterointerface were determined via x-ray photoelectron spectroscopy (XPS). The determined band alignments at LiGa5O8 / β-Ga2O3 interface reveal the formation of a type-II (staggered) heterojunction. The experimental measurements provide valuable parameters of the band offsets at the heterointerface, addressing an aspect for future power electronic device design and fabrication based on β-Ga2O3ultrawide bandgap semiconductors.

[0174] Introduction. Over the last decade, the remarkable high-power switching capabilities of diodes and transistors [A1-A3] based on beta-phase gallium oxide (P-Ga2O3) have been prominently demonstrated, emphasizing their potential in advanced power electronics [Al, A4- A13], Despite these strides, a notable impediment in the widespread adoption of β-Ga2O3lies in its inherent inability to support effective p-type conductivity. This limitation arises from the flat nature of its valence band and the self-trapping of holes, leading to polaron formation [A14, A15], To overcome this challenge, various p-type semiconductors have been combined with n- Ga2O3 to establish pn-junctions [A16-A23], These materials include SiC, GaN, SnO, CU2O, Cui, and notably NiO. NiO, distinguished by its relatively wide bandgap ranging between 3.6 and 4.0 eV and compatibility with β-Ga2O3, stands out as a robust candidate [A20-A22, A26], Recent advancements in p-NiO / n- Ga2O3-based pn diodes have demonstrated impressive breakdown voltages and specific on-resistances [Al 8, A20, A24, A25], However, the overall performance of these devices is currently constrained by the thermal instability of the sputtered NiO layer [A26] and the comparatively smaller bandgap of NiO in comparison to Ga2O3. This presents the compelling need to explore alternative p-type semiconductors with ultrawide bandgaps.

[0175] In a recent development, LiGa5O8, characterized by an ultrawide bandgap semiconductor with an experimentally measured bandgap of approximately 5.36 eV, has demonstrated p-type conductivity at room temperature. This breakthrough positions LiGa5O8as the widest bandgap p- type oxide semiconductor identified to date [A27], LiGa5O8, belonging to the spinel family of compounds, shares an isostructural relationship with the MgAhCU spinel. Both pure and Cr3+- doped LiGa5O8have been investigated using density functional theory (DFT) with a full potential augmented plane wave (FP-LAPW) method [A28, A29], suggesting an indirect bandgap of approximately 5.7 eV and a direct bandgap about 0.1 eV higher. The recently reported CGA / QSGW methods show closely matched bandgap values and suggest Si as potential n-type dopant [A30], Using the mist chemical vapor deposition (M-CVD) method, high crystalline quality LiGa5O8thin films were grown on c-plane sapphire and GaN-on-sapphire substrates. These films exhibited robust p-type conductivity with hole concentrations ranging from 1015cm'3to 1018cm'3[A27], This discovery shows a great potential of employing p- LiGa5O8in Ga2O3based device designs for future power electronics. Herein, the M-CVD growth of p-type LiGa5O8thin films on Ga2O3substrates and the experimental measurements of the band offsets at the LiGa5O8 / Ga2O3 heterointerface via X-ray photoemission spectroscopy (XPS) are reported.

[0176] Results and Discussion. LiGa5O8thin films were synthesized utilizing a specially engineered mist-CVD system on semi-insulating Fe-doped (010) Ga2O3substrates. Gallium acetylacetonate (Ga(acac)3, [CH3COCH=C(O-)CH3]3Ga) served as the source material for Ga, while lithium acetoacetate (C4H5LiO3) was employed as the source for Li. The oxygen source comprised pure O2, and argon (Ar) gas was utilized as the carrier gas during the deposition process. The growth temperature was consistently maintained at 850 °C and the growth pressure was kept at atmospheric pressure. The detailed description on growth conditions has been published elsewhere [A27], For the XPS measurements discussed later, two LiGa5O8samples were grown with targeted thicknesses of —50 nm and —2 nm on (010) Fe doped Ga2O3substrates with varying growth time. The 50 nm-thick film was used to probe the bulk LiGa5O8, and the 2 nm-thick sample was used to probe the LiGa5O8 / Ga2O3 heterostructure interface.

[0177] X-ray diffraction (XRD) analysis was conducted using a Bruker Advanced D8 Discover XRD system. Scanning transmission electron microscopy (STEM) was performed with a Thermofisher probe-corrected Themis STEM. Surface morphologies were examined through scanning electron microscopy (SEM) using the FEI Apreo LoVac analytical SEM. Atomic force microscopy (AFM) was employed for surface roughness measurements using a Bruker Icon 3 AFM. X-ray photoelectron spectroscopy (XPS) evaluations were performed using a ThermoFisher Nexsa G2 XPS system. Additionally, measurements of the net carrier concentration at room temperature and the associated electron Hall mobility were carried out using the Ecopia HMS-3000 Hall measurement system. Details of the instruments used for characterizing has been reported elsewhere [A27], The room temperature Hall measurement was performed to characterize the conductivity of the LiGa5O8thin film grown on (010) Fe doped 0- Ga2O3substrate. The measured hole concentration was around 2.3 IxlO18cm'3with the hole mobility around 2.07 cm2 / V s. The detailed measurements about the p-type conductivity in LiGa5O8films can be found elsewhere [A27], The surface morphology and roughness of the LiGa5O8sample grown on (010) Fe doped [l-GajOs substrate were characterized and shown in the supplementary materials. Figure 15A shows the plan view SEM image of the film surface and Figure 15B shows the corresponding 2pm x 2pm AFM image. A smooth and uniform surface can be observed from the SEM image. The root mean square (RMS) value of the surface roughness obtained from AFM is ~ 1.27 nm, confirming the smooth and high-quality surface. Furthermore, stripe-like surface features can be found with the AFM image shown in Figure 9B. The similar groove structures along the

[0001] direction have been reported for 0-Ga2O3 films grown on the same substrate [A31],

[0178] The thickness and crystalline quality of the as-grown LiGa5O8film were probed using cross-sectional STEM. In Figure 9A, high-angle annular dark-field STEM image is presented. Continuous film growth can be observed along the cross section. The as-grown film thickness was estimated to be around 160 nm, giving a growth rate of - 1.8 nm / min. There is a clear interface between the grown film and the (010) Fe doped 0-Ga2O3 substrate. The atomic resolution image in Figure 9B reveals the film's spinel cubic structure. Further characterization identifies the cross-sectional view as corresponding to the

[0110] zone, as corroborated through the atomic models and XRD analysis. The lattice mismatch between the determined (110) LiGa5O8and (010) 0-Ga2O3is estimated to be -4.8%. Moreover, signs of dislocations are found present in the LiGa5O8film, which could be responsible for relaxing the strain within the film. The local structure of the LiGa5O8is affected by the dislocations as well.

[0179] The crystalline quality and film orientation of the as-grown sample was analyzed with XRD measurements. As shown in Figure 10, the XRD peaks at approximately 30.85° and 61.44° are attributed to the (010) Ga2O3peaks arising from the substrate. Importantly, the LiGa5O8(440) peak, evident at around 63.88°, further confirms the growth of (110) LiGa5O8film, which is perpendicular to the (110) orientation observed from the cross-section. Although the peak intensity is relatively low due to the thin film thickness, the well-defined peaks demonstrate high-quality, single-crystalline growth of the LiGa5O8thin films. To better understand the crystalline quality and film orientation of the LiGa5O8film, a separate sample with increased film thickness have been grown and analyzed using XRD. Figure 16A-Figure 16B shows the XRD 20-oj scan of the LiGa5O8film grown on (010) Fe doped 0-Ga2O3substrate with a film thickness of -400 nm and the rocking curve scan of the (440) peak. Lower order peaks become observable with enhanced XRD signal intensities.

[0180] The atomic compositions of the LiGa5O8films were probed using XPS measurements. Figure 1 lA-Figure 11C shows the acquired Li Is, Ga 3s, and O ls peaks from the LiGa5O8sample grown on (010) β-Ga2O3substrate. The peaks were fitted with a Voigt peak shape and Shirley background was assumed. The atomic ratio of the Li / Ga, Li / O and Ga / O were then derived to be - 0.15, 0.11, and 0.72, respectively, using the ratio of the fitted peak areas. The sample can be determined to be a slight Li- and O- poor in stoichiometry.

[0181] The bandgap of the as-grown LiGa5O8film was determined by the inelastic energy loss spectrum of the O Is core level XPS peak. The onset of the inelastic loss spectrum at lower kinetic energy (higher binding energy) relative to the core level peak corresponds to the bandgap energy [A32], Figure 12 shows the O ls core level spectrum of the LiGa5O8film. The bandgap estimated by measuring the onset of energy loss peak is 5.4 ± 0.12 eV, which matches well with the value obtained from optical transmission measurements

[0027] ,

[0182] To experimentally assess the band offsets between mist-CVD grown LiGa5O8and P- Ga2O3, XPS measurements were undertaken on two LiGa5O8samples with specific thicknesses: approximately 2 nm and 50 nm, serving as the interface and bulk samples of LiGa5O8, respectively. For the bulk β-Ga2O3sample, an Fe-doped β-Ga2O3substrate with a (010) orientation was utilized. The valence band offset (AEv) between LiGa5O8and β-Ga2O3is calculated using Kraut’ s method [A33] with the equation:

[0183] In this formula, represents the binding energies of specific core levels in the bulk samples of β-Ga2O3or LiGa5O8refers to the binding energies of the same core levels measured in the LiGa5O8 / β-Ga2O3 interface sample denotes the position of the valence band maximum (VBM) in the bulk β-Ga2O3or LiGa5O8. The relative positions of these core levels are determined with respect to the Fermi level. A positive AEv value indicates that the VBM of LiGa5O8is positioned below that of β-Ga2O3. Equation (1) can be computed through XPS [A34-A37], The initial two terms of this equation are derived from XPS data obtained from the bulk samples of β-Ga2O3and LiGa5O8. For the third term, XPS analysis of the heterojunction formed between these two materials is employed. An important aspect of this analysis involves detecting photoelectrons originating from the β-Ga2O3layer at the base of the bi-layered heterostructure, essential for accurately measuring the core level of the entire structure. However, this process faces a challenge due to the limited escape depth of the photoelectrons. If the LiGa5O8layer on top is excessively thick, it may fully absorb the photoelectrons emerging from the bottom β-Ga2O3layer, impeding their detection. Therefore, it is important to maintain the top LiGa5O8layer at a minimal thickness to ensure that a sufficient number of photoelectrons can escape from the underlying 0-Ga2O3 layer for effective detection.

[0184] Figure 13A-Figure 13C displays XPS spectra near the Li Is and Ga 3s peaks, along with sections of the XPS spectra illustrating the valence band edges of the three samples. Voigt peak shapes and Shirley backgrounds were assumed during analysis, and the spectra were calibrated using the C Is peak position (284.5 eV) as the reference. No metallic contaminants, aside from common impurities such as O and C observed in the XPS survey spectra, were identified, affirming the high purity of the Ga2O3 and LiGa5O8materials. The 50 nm LiGa5O8layer in the bulk sample is sufficiently thick to absorb all XPS signals originating in the underlying Ga2O3substrate. Consequently, the Ga 3s peak in the spectra from this sample is assigned to the Ga atoms in the top alloy layer. The binding energies of the Li Is peaks are determined to be 54.90 ± 0.02 eV and 57.22 ± 0.02 eV, respectively, for the bulk LiGa5O8sample and the heterointerface sample. For the Ga 3s peaks, the binding energies are 161.17 ± 0.02 eV in the bulk 0- Ga2O3sample and 161.30 ± 0.02 eV in the interface sample. The valence band maxima positions in the bulk 0-Ga2O3 and LiGa5O8samples are found to be 3.35 ± 0.05 eV and 3.24 ± 0.03 eV, respectively. Extracting the valence band offset (VBO) between β-Ga2O3and LiGaxOx using the Li Is and Ga 3s core levels yields 1.86 ± 0.09 eV. The experimentally determined valence band alignment of LiGa5O8with 0-Ga2CL, along with the conduction band alignment considering the band gap of 5.4 eV for LiGa5O8grown on (010) 0-Ga2O3, is illustrated in Figure 14.

[0185] In conclusion, the M-CVD growth of p-type LiGa5O8thin films on (010) Fe doped 0- Ga2O3 substrate was demonstrated, showcasing its great potential to form pn junction for power electronic applications. The films exhibit p-type conductivity with a hole concentration of approximately 2.3 IxlO18cm'3and hole mobility around 2.07 cm2 / V s at room temperature. A smooth, uniform film growth was observed from both SEM and AFM imaging. The growth of spinel cubic crystal structure LiGa5O8along the

[0110] direction was confirmed by STEM imaging and XRD, showing high crystalline quality. By examining the onset of inelastic energy loss in core-level atomic spectra, the bandgap of the LiGa5O8film was determined to be 5.4 ± 0.12 eV, aligning well with previous experimental characterization based on optical transmission. Importantly, the valence band offset between LiGa5O8and 0-Ga2O3was experimentally determined to be 1.86 ± 0.09 eV, showing a type-II band alignment. Results from this work provide great promises in employing p-LiGa5O8in UWBG Ga2O3based power device design and fabrication of future power device technologies. Supplementary Material. Surface morphologies of typical LiGasO8films grown on (010) Ga2O3substrates were characterized via SEM and AMF imaging. XRD characterization of LiGa5O8film grown on (010) Fe doped P-GasO3substrate with relatively thick film thickness (~ 400nm) were performed with 20-(o scan and XRD rocking curve.

[0186] Surface morphology and roughness of the LiGa5O8sample grown on (010) Fe doped β-Ga2O3 substrate. Figure 15A-Figure 15B shows the surface morphology and roughness of the LiGa5O8sample grown on (010) Fe doped β-Ga2O3substrate characterized by plan view scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging. The sample was grown at 850 °C with a targeted thickness of - 50 nm.

[0187] XRD characterization of LiGa5Og film grown on (010) Fe doped p~Ga2O3 substrate with increased film thickness. Figure 16A shows the XRD 20-(o scan ofGasO8film grown on (010) Fe doped β-Ga2O3substrate with a film thickness of -400 nm, which was grown at the same growth condition as the -160 nm-thick LiGa5O8sample discussed before but longer growth period.

[0188] The peaks at approximately 15.11°, 30.85° and 61.44° are attributed to the (010) Ga2O3peaks arising from the substrate. The LiGa5O8(440) peak at around 64.22° shows much- increased intensity due to the increased film thickness. Furthermore, the lower order (110) and (330) peaks at around 15.22° and 47.01° become observable. Figure 16B shows the XRD rocking curve scan of the (440) peak from the same sample. A full-width-half-maximum (FWHM) of -0.32° was extracted.

[0189] References

[0190] [Al] M. Higashiwaki et al. “Gallium oxide (Ga2O3) metal -semi conductor field-effect transistors on single-crystal β-Ga2O3(010) substrates,” Applied Physics Letters 100(1), 013504 (2012).

[0191] [A2] M. Higashiwaki et al. “Depletion-mode Ga2O3metal-oxide-semiconductor fieldeffect transistors on β-Ga2O3(010) substrates and temperature dependence of their device characteristics,” Applied Physics Letters 103(12), 123511 (2013).

[0192] [A3] K. Sasaki et al. “Ga2O3Schottky Barrier Diodes Fabricated by Using Single-Crystal β-Ga2O3(010) Substrates,” IEEE Electron Device Letters 34(4), 493-495 (2013).

[0193] [A4] A.J. Green et al. “3.8-MV / cm Breakdown Strength of MOVPE-Grown Sn-Doped β- Ga2O3MOSFETs,” IEEE Electron Device Letters 37(7), 902-905 (2016).

[0194] [A5] T. Onuma et al. “Correlation between blue luminescence intensity and resistivity in β-Ga2O3single crystals,” Applied Physics Letters 103(4), 041910 (2013). [A6] A.F.M.A.U. Bhuiyan et al. “Tutorial: Metalorganic chemical vapor deposition of P- Ga2O3thin films, alloys, and heterostructures,” Journal of Applied Physics 133(21), 211103 (2023).

[0195] [A7] H.H. Tippins, “Optical Absorption and Photoconductivity in the Band Edge of P- Ga2O3,” Phys. Rev. 14O(1A), A316-A319 (1965).

[0196] [A8] M. Baldini et al “Semiconducting Sn-doped β-Ga2O3homoepitaxial layers grown by metal organic vapour-phase epitaxy,” J Mater Sci 51(7), 3650-3656 (2016).

[0197] [A9] K. Goto et al. “Halide vapor phase epitaxy of Si doped β-Ga2O3and its electrical properties,” Thin Solid Films 666, 182-184 (2018).

[0198] [A10] E. Ahmadi et al. “Ge doping of β-Ga2O3films grown by plasma-assisted molecular beam epitaxy,” Appl. Phys. Express 10(4), 041102 (2017).

[0199] [Al l] Y. Zhang et al. “MOCVD grown epitaxial β-Ga2O3thin film with an electron mobility of 176 cm2 / V s at room temperature,” APL Materials 7(2), 022506 (2019).

[0200] [A12] S. Rafique et al. “Towards High-Mobility Heteroepi taxi al β-Ga2O3on Sapphire - Dependence on The Substrate Off-Axis Angle,” Physica Status Solidi (a) 215(2), 1700467 (2018).

[0201] [A13] A. Kuramata et al. “High-quality β-Ga2O3single crystals grown by edge-defined film-fed growth,” Jpn. J. Appl. Phys. 55(12), 1202A2 (2016).

[0202] [A14] J.B. Varley et al. “Role of self-trapping in luminescence and p-type conductivity of wide-band-gap oxides,” Phys. Rev. B 85(8), 081109 (2012).

[0203] [Al 5] J.L. Lyons, “A survey of acceptor dopants for β-Ga2O3,” Semicond. Sci. Technol. 33(5), 05LT02 (2018).

[0204] [A16] S. Nakagomi et al. “Beta-Gallium Oxide / SiC Heterojunction Diodes with High Rectification Ratios,” ECS J. Solid State Sci. Technol. 6(2), Q3030 (2016).

[0205] [A17] Y. Zhang et al. “Investigation of β-Ga2O3films and β-Ga2O3 / GaN heterostructures grown by metal organic chemical vapor deposition,” Sci. China Phys. Meeh. Astron. 63(11), 117311 (2020).

[0206] [A18] Y. Wang et al. “2.41 kV Vertical P-NiO / n-Ga2O3Heterojunction Diodes With a Record Baliga’s Figure-of-Merit of 5.18 GW / cm2,” IEEE Trans. Power Electron. 37(4), 3743- 3746 (2022).

[0207] [A19] Y. Kokubun et al. “All-oxide p-n heterojunction diodes comprising p-type NiO and n-type P-Ga2O3,” Appl. Phys. Express 9(9), 091101 (2016).

[0208] [A20] X. Lu et al. “1-kV Sputtered p-NiO / n-Ga2O3Heterojunction Diodes With an UltraLow Leakage Current Below 1 uA / cm2,” IEEE Electron Device Lett. 41(3), 449-452 (2020). [A21] T. Watahiki et al. “Heterojunction p-Cu2O / n-Ga2O3diode with high breakdown voltage,” Applied Physics Letters 111(22), 222104 (2017).

[0209] [A22] M. Budde et al. “SnO / β-Ga2O3vertical pn heterojunction diodes,” Applied Physics Letters 117(25), 252106 (2020).

[0210] [A23] J.C. Gallagher et al. “Demonstration of Cui as a P-N heterojunction to β-Ga2O3,” Appl. Phys. Express 12(10), 104005 (2019).

[0211] [A24] B. Wang et al. “2.5 kV Vertical Ga2O3Schottky Rectifier With Graded Junction Termination Extension,” IEEE Electron Device Lett. 44(2), 221-224 (2023).

[0212] [A25] W. Hao et al. in 2022 IEEE 34th International Symposium on Power Semiconductor Devices and ICs (ISPSD) (2022), pp. 105-108.

[0213] [A26] X. Xia et al. “Annealing temperature dependence of band alignment of NiO / p- Ga2O3,” J. Phys. D: Appl. Phys. 55(38), 385105 (2022).

[0214] [A27] K. Zhang et al. “Discovery of a Robust P-Type Ultrawide Bandgap Oxide Semiconductor: LiGa5O8,” Advanced Electronic Materials n / a(n / a), 2300550 (n.d.).DOL 10.1002 / aelm.202300550

[0215] [A28] O.M. Sousa et al. “Theoretical study of the structural, energetic, electronic and magnetic properties of the host matrix LiGa5O8doped with Cr3+,” Journal of Solid State Chemistry 289, 121472 (2020).

[0216] [A29] O.M. De Sousa, “Study of the structural, electronic, and optical properties of the host matrices of LiALOs and LiGa5O8via DFT,” Computational and Theoretical Chemistry 1123, 96-101 (2018).

[0217] [A30] W.R.L. Lambrecht, “Spinel LiGa5O8prospects as ultra-wideband-gap semiconductor: band structure, optical properties and doping,” (2023). arXiv:2312.08486

[0218] [A31] Z. Feng et al. “MOCVD homoepitaxy of Si-doped (010) P-Ga2O3thin films with superior transport properties,” Applied Physics Letters 114(25), 250601 (2019).

[0219] [A32] M.T. Nichols et al. “Measurement of bandgap energies in low-k organosilicates,” Journal of Applied Physics 115(9), 094105 (2014).

[0220] [A33] E.A. Kraut et al. “Semiconductor core-level to valence-band maximum bindingenergy differences: Precise determination by x-ray photoelectron spectroscopy,” Phys. Rev. B 28(4), 1965-1977 (1983).

[0221] [A34] S.-K. Hong et al. “Band alignment at a ZnO / GaN (0001) heterointerface,” Applied Physics Letters 78(21), 3349-3351 (2001).

[0222] [A35] M.R. Karim et al. “Experimental determination of the valence band offsets of ZnGeN2and (ZnGe)o.94Gao.i2N2with GaN,” J. Phys. D: Appl. Phys. 54(24), 245102 (2021). [A36] A.F.M.A.U. Bhuiyan et al. “Band offsets of (100) P-(AlxGai~x)2O3 / p-Ga2O3 heterointerfaces grown via MOCVD,” Applied Physics Letters 117(25), 252105 (2020).

[0223] [A37] K. Zhang et al. “Pulsed-Mode MOCVD Growth of ZnSn(Ga)N2 and Determination of the Valence Band Offset with GaN,” Crystal Growth & Design 22(8), 5004- 5011 (2022).

[0224] EXEMPLARY ASPECTS

[0225] In view of the described compositions, devices, systems, and methods, herein below are described certain more particularly described aspects of the inventions. The particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.

[0226] Example 1 : A composition comprising ultrawide bandgap oxide semiconductor with p- type conductivity comprising:

[0227] LixGayOzwherein Li and Ga have an atomic ratio (e.g., x:y) of from 0.0001 to 1.0; Li and O have an atomic ratio (e g., x:z) of from 0.0001 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

[0228] Example 2: The composition of any examples herein, particularly example 1, wherein Li and Ga have an atomic ratio (e.g., x:y) of from 0.01 to 1.0; Li and O have an atomic ratio (e.g., x:z) of from 0.00625 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

[0229] Example 3 : A composition comprising ultrawide bandgap oxide semiconductor with p- type conductivity comprising:

[0230] LixGayOzwherein Li and Ga have an atomic ratio (e.g., x:y) of from 0.01 to 1.0; Li and O have an atomic ratio (e.g., x:z) of from 0.00625 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

[0231] Example 4: The composition of any examples herein, particularly examples 1-3, wherein Li, Ga, and O have an atomic ratio (e.g., x:y:z) of 1 :5:8.

[0232] Example 5: The composition of any examples herein, particularly examples 1-4, wherein the composition comprises P-LixGayOz.

[0233] Example 6: The composition of any examples herein, particularly examples 1-5, wherein the composition comprises LiGa5O8. Example 7: The composition of any examples herein, particularly examples 1-6, wherein the composition comprises Li rich LiGa5O8.

[0234] Example 8: The composition of any examples herein, particularly examples 1-6, wherein the composition comprises Li poor LiGa5O8.

[0235] Example 9: The composition of any examples herein, particularly examples 1-6, wherein the composition comprises O poor LiGa5O8.

[0236] Example 10: The composition of any examples herein, particularly examples 1-6, wherein the composition comprises O rich LiGa5O8.

[0237] Example 11 : The composition of any examples herein, particularly examples 1-10, wherein the composition further comprises a dopant, such as a p-type dopant.

[0238] Example 12: The composition of any examples herein, particularly examples 1-10, wherein the composition is substantially free of any dopants.

[0239] Example 13: The composition of any examples herein, particularly examples 1-12, wherein the composition has a carrier concentration (e g., a hole concentration) of from 1 x 1014per cubic centimeter to 1 x 1021cm'3.

[0240] Example 14: The composition of any examples herein, particularly examples 1-13, wherein the composition has a carrier concentration (e g., a hole concentration) of from 1 x 1014to 1 5 x 1019cm'3, such as from 1 x 1017to 5 x 1018cm'3.

[0241] Example 15: The composition of any examples herein, particularly examples 1-14, wherein the composition has a mobility, such as a hole mobility, of from 0.01 to 100 cm2 / Vs.

[0242] Example 16: The composition of any examples herein, particularly examples 1-15, wherein the composition has a mobility, such as a hole mobility, of from 0.1 to 10 cm2 / Vs, such as from 0.35 to 2 cm2 / Vs.

[0243] Example 17: The composition of any examples herein, particularly examples 1-16, wherein the composition exhibits high p-type conductivity.

[0244] Example 18: A device comprising the composition of any examples herein, particularly examples 1-17.

[0245] Example 19: The device of any examples herein, particularly example 18, wherein the device further comprises a substrate, wherein the composition is deposited on the substrate as a layer.

[0246] Example 20: The device of any examples herein, particularly example 19, wherein the substrate comprises LiGaxOx, free standing GaN, GaN on c-plane sapphire templates, on-axis c- sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), GaiCh, AIN, AlGaN, diamond, or a combination thereof. Example 21 : The device of any examples herein, particularly example 19 or example 20, wherein the substrate comprises LiGa5O8, GaN on c-plane sapphire templates, on-axis c- sapphire, off-axis c-sapphire (e g., 6°-offcut c-plane sapphire), GasCh, or a combination thereof

[0247] Example 22: The device of any examples herein, particularly examples 19-21, wherein the layer has a surface roughness with an RMS value of 20 nm or less.

[0248] Example 23: The device of any examples herein, particularly examples 19-22, wherein the layer has a surface roughness with an RMS value of 15 nm or less, 10 nm or less, 5 nm or less, 2.5 nm or less, 1.75 nm or less, or 1.5 nm or less.

[0249] Example 24: The device of any examples herein, particularly examples 19-23, wherein the layer has an average thickness of from 10 to 2000 nm.

[0250] Example 25: The device of any examples herein, particularly examples 19-24, wherein the layer has an average thickness of from 25 nm to 1000 nm, such as from 50 to 100 nm.

[0251] Example 26: The device of any examples herein, particularly examples 18-25, wherein the device comprises a vertical PN diode, a MOSFET device such as a power MOSFET or a trench MOSFET, a MESFET device, a MODFET device, a Current Aperture Vertical Electron Transistor (CAVET) device, or a combination thereof.

[0252] Example 27: The device of any examples herein, particularly examples 18-26, wherein the device comprises a vertical PN diode, a MOSFET device such as a power MOSFET or a trench MOSFET, a Current Aperture Vertical Electron Transistor (CAVET) device, or a combination thereof.

[0253] Example 28: The device of any examples herein, particularly examples 18-27, wherein the device comprises a vertical power device.

[0254] Example 29: The device of any examples herein, particularly examples 18-28, wherein the device comprises an optical device, an electronic device, an optoelectronic device, or a combination thereof.

[0255] Example 30: The device of any examples herein, particularly examples 18-29, wherein the device comprises a diode.

[0256] Example 31 : The device of any examples herein, particularly examples 18-30, wherein the device comprises a n-Ga2O3 / p-LixGayOz (e.g., a n-Ga2O3 / p-LiGa5Os) heterojunction.

[0257] Example 32: The device of any examples herein, particularly examples 18-31, wherein the device comprises n-GaN / p-LixGayOz, n-AlN / p-LixGayOz, n-diamond / p-LixGayOz, or a combination thereof.

[0258] Example 33: A method of use of the composition of any examples herein, particularly examples 1-17. Example 34: A method of making the composition of any examples herein, particularly examples 1-17, the method comprising contacting a gallium containing precursor and a lithium containing precursor at a temperature in the presence of oxygen or an oxygen containing precursor to thereby react the gallium containing precursor, the lithium containing precursor, and the oxygen or the oxygen containing precursor to form the composition.

[0259] Example 35: The method of any examples herein, particularly example 34, wherein the gallium containing precursor comprises a metalorganic Ga containing precursor.

[0260] Example 36: The method of any examples herein, particularly example 34 or example 35, wherein the gallium containing precursor comprises Ga(acac)3([CH3COCH=C(O- )CH3]3Ga).

[0261] Example 37: The method of any examples herein, particularly examples 34-36, wherein the lithium containing precursor comprises a metalorganic Li containing precursor.

[0262] Example 38: The method of any examples herein, particularly examples 34-37, wherein the lithium containing precursor comprises lithium acetoacetate (CLHsLiCh ).

[0263] Example 39: The method of any examples herein, particularly examples 34-38, wherein the gallium containing precursor and / or the lithium containing precursor independently comprise(s) a fluid.

[0264] Example 40: The method of any examples herein, particularly examples 34-39, wherein the gallium containing precursor and / or the lithium containing precursor are independently provided with a carrier gas.

[0265] Example 41 : The method of any examples herein, particularly example 40, wherein the carrier gas comprises argon, helium, N2, and the like, or combinations thereof.

[0266] Example 42: The method of any examples herein, particularly example 40 or example 41, wherein the carrier gas comprises argon.

[0267] Example 43: The method of any examples herein, particularly examples 34-42, wherein the temperature is from 300°C to 1200°C.

[0268] Example 44: The method of any examples herein, particularly examples 34-43, wherein the temperature is from 800°C to 1000°C, such as from 800°C to 950°C, or from 850°C to 950°C.

[0269] Example 45: The method of any examples herein, particularly examples 34-44, wherein the temperature is 900°C.

[0270] Example 46: The method of any examples herein, particularly examples 34-45, wherein the method comprises metal organic chemical vapor deposition (MOCVD), molecular-beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), pulsed laser deposition (PLD), low pressure chemical vapor deposition (LPCVD), mist-CVD, or a combination thereof.

[0271] Example 47: The method of any examples herein, particularly examples 34-46, wherein the method comprises mist-CVD.

[0272] Example 48: The method of any examples herein, particularly examples 34-47, wherein the method comprises depositing the composition on a substrate.

[0273] Example 49: The method of any examples herein, particularly example 48, wherein the substrate comprises LiGa5O8, free standing GaN, GaN on c-plane sapphire templates, on-axis c- sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga2O3, AIN, AlGaN, diamond, or a combination thereof.

[0274] Example 50: The method of any examples herein, particularly example 48 or example 49, wherein the substrate comprises LiGa5O8, GaN on c-plane sapphire templates, on-axis c- sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga2O3, or a combination thereof.

[0275] Other advantages which are obvious and which are inherent to the invention will be evident to one skilled in the art. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

[0276] The methods of the appended claims are not limited in scope by the specific methods described herein, which are intended as illustrations of a few aspects of the claims and any methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative method steps disclosed herein are specifically described, other combinations of the method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less, however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.

Claims

CLAIMSWhat is claimed is:

1. A composition comprising ultrawide bandgap oxide semiconductor with p-type conductivity comprising:LixGayOzwhereinLi and Ga have an atomic ratio (e.g., x:y) of from 0.0001 to 1.0;Li and O have an atomic ratio (e.g., x:z) of from 0.0001 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

2. The composition of claim 1, wherein Li and Ga have an atomic ratio (e.g., x:y) of from 0.01 to 1.0; Li and O have an atomic ratio (e.g., x:z) of from 0.00625 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

3. A composition comprising ultrawide bandgap oxide semiconductor with p-type conductivity comprising:LixGayOzwhereinLi and Ga have an atomic ratio (e g., x:y) of from 0.01 to 1.0;Li and O have an atomic ratio (e.g., x:z) of from 0.00625 to 0.5; and Ga and O have an atomic ratio (e.g., y:z) of from 0.5 to 1.0.

4. The composition of any one of claims 1-3, wherein Li, Ga, and O have an atomic ratio (e.g., x:y:z) of 1:5:8.

5. The composition of any one of claims 1-4, wherein the composition comprises 0-LixGayOz.

6. The composition of any one of claims 1-5, wherein the composition comprises LiGa5O8.

7. The composition of any one of claims 1-6, wherein the composition comprises Li rich LiGa5O8.

8. The composition of any one of claims 1-6, wherein the composition comprises Li poor LiGa5O89. The composition of any one of claims 1-6, wherein the composition comprises O poor LiGa5O8.

10. The composition of any one of claims 1-6, wherein the composition comprises O rich LiGa5O8.

11. The composition of any one of claims 1-10, wherein the composition further comprises a dopant, such as a p-type dopant.

12. The composition of any one of claims 1-10, wherein the composition is substantially free of any dopants.

13. The composition of any one of claims 1-12, wherein the composition has a carrier concentration (e.g., a hole concentration) of from 1 x 1014per cubic centimeter to 1x1021cm'3.

14. The composition of any one of claims 1-13, wherein the composition has a carrier concentration (e.g., a hole concentration) of from 1 x 1014to 1 5 x 1019cm'3, such as from 1 x 1017to 5 x 1018cm'3.

15. The composition of any one of claims 1-14, wherein the composition has a mobility, such as a hole mobility, of from 0.01 to 100 cm2 / Vs.

16. The composition of any one of claims 1-15, wherein the composition has a mobility, such as a hole mobility, of from 0.1 to 10 cm2 / Vs, such as from 0.35 to 2 cm2 / Vs.

17. The composition of any one of claims 1-16, wherein the composition exhibits high p-type conductivity.

18. A device comprising the composition of any one of claims 1-17.

19. The device of claim 18, wherein the device further comprises a substrate, wherein the composition is deposited on the substrate as a layer.

20. The device of claim 19, wherein the substrate comprises LiGa5O8, free standing GaN, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c- plane sapphire), Ga?O3, AIN, AlGaN, diamond, or a combination thereof.

21. The device of claim 19 or claim 20, wherein the substrate comprises LiGa5O8, GaN on c- plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga?O3, or a combination thereof.

22. The device of any one of claims 19-21, wherein the layer has a surface roughness with an RMS value of 20 nm or less.

23. The device of any one of claims 19-22, wherein the layer has a surface roughness with an RMS value of 15 nm or less, 10 nm or less, 5 nm or less, 2.5 nm or less, 1.75 nm or less, or 1.5 nm or less.

24. The device of any one of claims 19-23, wherein the layer has an average thickness of from 10 to 2000 nm.

25. The device of any one of claims 19-24, wherein the layer has an average thickness of from 25 nm to 1000 nm, such as from 50 to 100 nm.

26. The device of any one of claims 18-25, wherein the device comprises a vertical PN diode, a MOSFET device such as a power MOSFET or a trench MOSFET, a MESFET device, a MODFET device, a Current Aperture Vertical Electron Transistor (CAVET) device, or a combination thereof.

27. The device of any one of claims 18-26, wherein the device comprises a vertical PN diode, a MOSFET device such as a power MOSFET or a trench MOSFET, a Current Aperture Vertical Electron Transistor (CAVET) device, or a combination thereof.

28. The device of any one of claims 18-27, wherein the device comprises a vertical power device.

29. The device of any one of claims 18-28, wherein the device comprises an optical device, an electronic device, an optoelectronic device, or a combination thereof.

30. The device of any one of claims 18-29, wherein the device comprises a diode.

31. The device of any one of claims 18-30, wherein the device comprises a n-Ga2O3 / p-LixGayOz(e.g., a n-Ga2O3 / p-LiGa5O8) heterojunction.

32. The device of any one of claims 18-31, wherein the device comprises n-GaN / p-LixGayOz, n-AlN / p-LixGayOz, n-diamond / p-LixGayOz, or a combination thereof.

33. A method of use of the composition of any one of claims 1-17.

34. A method of making the composition of any one of claims 1-17, the method comprising contacting a gallium containing precursor and a lithium containing precursor at a temperature in the presence of oxygen or an oxygen containing precursor to thereby react the gallium containing precursor, the lithium containing precursor, and the oxygen or the oxygen containing precursor to form the composition.

35. The method of claim 34, wherein the gallium containing precursor comprises a metalorganic Ga containing precursor.

36. The method of claim 34 or claim 35, wherein the gallium containing precursor comprises Ga(acac)3 ([CH3COCH=C(O-)CH3]3Ga).

37. The method of any one of claims 34-36, wherein the lithium containing precursor comprises a metalorganic Li containing precursor.

38. The method of any one of claims 34-37, wherein the lithium containing precursor comprises lithium acetoacetate (C4H5LiO3).

39. The method of any one of claims 34-38, wherein the gallium containing precursor and / or the lithium containing precursor independently comprise(s) a fluid.

40. The method of any one of claims 34-39, wherein the gallium containing precursor and / or the lithium containing precursor are independently provided with a carrier gas.

41. The method of claim 40, wherein the carrier gas comprises argon, helium, N2, and the like, or combinations thereof.

42. The method of claim 40 or claim 41, wherein the carrier gas comprises argon.

43. The method of any one of claims 34-42, wherein the temperature is from 300°C to 1200°C.

44. The method of any one of claims 34-43, wherein the temperature is from 800°C to 1000°C, such as from 800°C to 950°C, or from 850°C to 950°C.

45. The method of any one of claims 34-44, wherein the temperature is 900°C.

46. The method of any one of claims 34-45, wherein the method comprises metal organic chemical vapor deposition (MOCVD), molecular-beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), pulsed laser deposition (PLD), low pressure chemical vapor deposition (LPCVD), mist-CVD, or a combination thereof.

47. The method of any one of claims 34-46, wherein the method comprises mist-CVD.

48. The method of any one of claims 34-47, wherein the method comprises depositing the composition on a substrate.

49. The method of claim 48, wherein the substrate comprises LiGa5O8, free standing GaN, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c- plane sapphire), Ga2O3, AIN, AlGaN, diamond, or a combination thereof.

50. The method of claim 48 or claim 49, wherein the substrate comprises LiGa5O8, GaN on c-plane sapphire templates, on-axis c-sapphire, off-axis c-sapphire (e.g., 6°-offcut c-plane sapphire), Ga2O3, or a combination thereof.

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