Aluminum nitride based high power device and its manufacturing method

Abstract

Exemplary embodiments of the present disclosure provide devices, substrates, and doped materials. The doped materials include a group III metal nitride and one of a p-type dopant or an n-type dopant. The doped materials are disposed on the substrate at a temperature less than 1000° C. and have an increased dopant concentration. Additionally, a method of producing a doped group III metal nitride product is disclosed. The method includes flowing a nitrogen-containing plasma into a growth chamber from a remote plasma chamber, introducing a group III metal and at least one of a p-type dopant or an n-type dopant into the growth chamber, and disposing a conductive group III metal nitride product having an increased electrical carrier concentration on the substrate at a temperature less than about 1000° C.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 298,387, filed January 11, 2022, and U.S. Provisional Application No. 63 / 298,424, filed January 11, 2022, which are incorporated by reference in their entireties as if fully set forth below.

[0002] (Declaration of Federally Funded Research) This invention was made with Government support under Grant / Award No. N00014-18-1-2429 awarded by the Office of Naval Research and No. FA9550-21-1-0318 awarded by the Air Force Office of Scientific Research. The Government has certain rights in this invention.

[0003] (Technical field) Various embodiments of the present disclosure relate generally to methods of doping Group III metal nitrides and systems having conductive p-type and / or n-type doped Group III metal nitrides, and more particularly to methods of growing aluminum nitride with dopants at low temperatures using periodic pulsing of both Group III metals and p-type or n-type dopants, and diodes constructed from combinations of regions of p-type doping and regions of n-type doping with optional internal regions. [Background technology]

[0004] Nitride-based semiconductor materials made from group III metals and nitrogen have a wide energy band gap and are therefore widely used in diodes, light-emitting diodes (LEDs), solar cells, photodetectors, high electron mobility transistors (HEMTs), and laser diodes. The energy band gap ranges from about 0.65 eV to about 6.1 eV for group III metals, which spans the photon absorption range from about 2 μm (infrared) to about 200 nm (ultraviolet). Semiconductor materials are doped with group III elements such that the sum of the group III elements is equal to the sum of nitrogen (e.g., Al x Iny Ga 1-x-y The relative composition of Group III elements can be varied to tune important electrical properties such as the energy band gap, and hence the emission energy and wavelength, as well as the voltage at which the material decomposes to conduct electricity. Semiconductor materials can be doped with trace amounts of electron-donating (n-type) or electron-accepting (p-type) dopant atoms to improve the electrical, optical and structural properties of the resulting devices.

[0005] Although various dopants have been theorized, no dopants useful for achieving substantial electrical conductivity, i.e., electrical conductivity useful for electronic and optoelectronic devices without excessive resistive losses, have been experimentally achieved in extremely wide bandgap semiconductors, including AlN.

[0006] Silicon and germanium have been theorized to be suitable n-type dopants for wide bandgap materials. For ultra-wide bandgap (UWBG) semiconductors, whose bandgaps are typically greater than about 4.5 eV, doping can be extremely challenging and can even exhibit high resistivity or insulating behavior. Ultra-wide bandgap semiconductors such as AlN and AlN-based semiconductors and alloys with bandgaps close to AlN are well-known insulators, and converting such materials into doped semiconductors has been difficult due to limitations of typical doping methods.

[0007] Beryllium (Be) is an element found in wide bandgap nitride-based semiconductor materials (e.g., gallium nitride, aluminum nitride, indium nitride, and Al x In y Ga 1-x-yBe is one of the dopants theorized to be one of the best p-type dopants for alloys such as N, where x≦1, y≦, and x+y≦1, constructed with binary nitride substitutions. However, despite several theoretical studies supporting the use of Be as a receptive dopant, substantial p-type conduction with Be has not been realized in any nitride semiconductor.

[0008] Metal-organic chemical vapor deposition (MOCVD) is a method used to deposit single- or polycrystalline thin films, which requires high temperatures and moderate pressures to form alloys. Molecular beam epitaxy (MBE) grows crystals by physical vaporization or sublimation, but requires high vacuum and high temperature environments to grow single-crystal thin films. Both MBE and MOCVD operate at high substrate temperatures that are well above the desorption temperature of wide-bandgap semiconductors such as group III metal nitrides. This excessive heat load leads to increased impurity outgassing in the epitaxy chamber, resulting in an exponentially higher concentration of vacancies in the growing crystal that could compensate for doping. Substantial doping of bulk aluminum nitride (AlN) and AlN-based semiconductors with extremely large bandgaps with p- or n-type dopants has not been successful due to the high temperatures of MBE and MOCVD methods. The high temperatures in these methods result in excess vacancies where the dopants form defects in the crystal structure and prevent electrical conduction instead of behaving as dopants.

[0009] Therefore, there is a need for a method to sufficiently dope group III metal nitrides, such as AlN and AlN-based band gap semiconductors, to open up possibilities for deep ultraviolet emission and photodetection applications, or for high temperature, high voltage, high power electronics. Summary of the Invention

[0010] The present disclosure relates to methods of doping group III metal nitrides and systems having conductive p-type and / or n-type doped group III metal nitrides. An exemplary embodiment of the present disclosure provides a device comprising a substrate and a doped material. The doped material may include a group III metal nitride and one of a p-type dopant or an n-type dopant. The doped material may be disposed on the substrate at a temperature less than 1000° C. and may have an increased dopant concentration.

[0011] In any of the embodiments disclosed herein, the doped material contains about 1×10 of either the p-type dopant or the n-type dopant. 11 cm -3 ~Approx. 3×10 20 cm -3 The concentration may range from 0.1 to 100%.

[0012] In any of the embodiments disclosed herein, the doped material has a hole carrier concentration of about 1×10 11 ~1×10 19 cm -3 The range may be:

[0013] In any of the embodiments disclosed herein, the doped material has an electron carrier concentration of at least 6×10 15 cm -3 (For example, about 6 × 10 15 cm -3 ~Approx. 3×10 20 cm -3 ).

[0014] In any of the embodiments disclosed herein, the doped material may be configured to have a dopant concentration increased by at least 100,000 as compared to a second Group III metal nitride grown at a temperature greater than 1000° C.

[0015] In any of the embodiments disclosed herein, the doped material can have a band gap energy greater than 4.5 electron volts (eV).

[0016] In any of the embodiments disclosed herein, the doped material may have a band gap energy of approximately 6.1 eV.

[0017] In any of the embodiments disclosed herein, the doped material can be configured to emit one or more photons having a wavelength between about 200 nm and about 350 nm.

[0018] In any of the embodiments disclosed herein, the Group III metal nitride comprises a material selected from aluminum nitride (AlN), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium aluminum nitride (InAlN), aluminum scandium nitride (AlScN), indium gallium aluminum scandium nitride (InGaAlScN), or a combination thereof.

[0019] In any of the embodiments disclosed herein, the p-type dopant can include beryllium.

[0020] In any of the embodiments disclosed herein, the n-type dopant may include silicon.

[0021] In any of the embodiments disclosed herein, the device may further comprise a semiconductor disposed on the doped material.

[0022] In any of the embodiments disclosed herein, the doped material may be disposed on a semiconductor to form a homojunction.

[0023] In any of the embodiments disclosed herein, the doped material may be disposed on a semiconductor to form a heterojunction.

[0024] In any of the embodiments disclosed herein, the device may be configured to disrupt the replication of viruses and bacteria.

[0025] In any of the embodiments disclosed herein, the device may be configured to facilitate curing of a polymer.

[0026] In any of the embodiments disclosed herein, the substrate may comprise sapphire, crystalline silicon, gallium nitride, gallium oxide, aluminum nitride, aluminum gallium nitride, zinc oxide, lithium gallate, lithium aluminate, single crystal diamond, heteroepitaxial single crystal diamond, silicon carbide, or a combination thereof.

[0027] An exemplary embodiment of the present disclosure provides a method for growing an electrically conductive group III metal nitride product, which may include flowing a nitrogen-containing plasma into a growth chamber from a remote plasma chamber, introducing a group III metal and at least one of a p-type dopant or an n-type dopant into the growth chamber, and disposing an electrically conductive group III metal nitride product having an increased electrical carrier concentration on a substrate at a temperature less than about 1000° C.

[0028] In any of the embodiments disclosed herein, the method further comprises the step of: forming a conductive group III metal nitride product having a hole carrier concentration of at least 1×10 11 cm -3 (For example, about 1×10 11 cm -3 ~Approx. 1×10 19 cm -3 ).

[0029] In any of the embodiments disclosed herein, the method further comprises the step of: forming a conductive Group III metal nitride product having an electron carrier concentration of at least 6×10 15 cm -3 (For example, about 6 × 10 15 cm -3 ~Approx. 3×10 20 cm -3 ).

[0030] In any of the embodiments disclosed herein, the method further comprises the step of: the conductive group III metal nitride product having at least a 100,000-fold increase in electrical carrier concentration compared to a second group III metal nitride product grown at a temperature greater than 1000° C.

[0031] In any of the embodiments disclosed herein, the conductive group III metal nitride product may contain a material selected from aluminum nitride (AlN), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium aluminum nitride (InAlN), aluminum scandium nitride (AlScN), indium gallium aluminum scandium nitride (InGaAlScN), or a combination thereof.

[0032] In any of the embodiments disclosed herein, introducing the p-type dopant or the n-type dopant into the growth chamber may further comprise pulsing the flux of one or more of the dopants.

[0033] In any of the embodiments disclosed herein, the step of introducing the p-type dopant or the n-type dopant into the growth chamber may further comprise pulsing one or more fluxes of a group III metal with a constant nitrogen supply.

[0034] In any of the embodiments disclosed herein, pulsing each dopant may further comprise delivering for a delivery period ranging from about 0.1 seconds to about 30 seconds.

[0035] In any of the embodiments disclosed herein, pulsing each dopant may further comprise pausing for a pause period ranging from about 1 second to about 30 seconds.

[0036] In any of the embodiments disclosed herein, pulsing the dopants may further include delivering for a delivery period ranging from about 1 second to about 25 seconds and pausing for a rest period ranging from about 2 seconds to about 15 seconds.

[0037] In any of the embodiments disclosed herein, the temperature may range from about 600°C to about 900°C.

[0038] In any of the embodiments disclosed herein, in the above method of growing a group III metal nitride product, the III / V flux ratio may be about 1 or greater.

[0039] In any of the embodiments disclosed herein, the III / V ratio may be in the range of about 1.1 to 1.5.

[0040] In any of the embodiments disclosed herein, the temperature can range from about 500° C. to about 850° C. when the p-type dopant is introduced into the growth chamber.

[0041] In any of the embodiments disclosed herein, the temperature may range from about 600°C to about 700°C.

[0042] In any of the embodiments disclosed herein, in the above method of growing a group III metal nitride product, the III / V ratio may be about 1.5 or greater.

[0043] In any of the embodiments disclosed herein, the III / V ratio may be in the range of about 1.6 to 2.0.

[0044] In any of the embodiments disclosed herein, the temperature may range from about 500° C. to about 1000° C. when the n-type dopant is introduced into the growth chamber.

[0045] In any of the embodiments disclosed herein, the temperature may range from about 600°C to about 800°C.

[0046] In any of the embodiments disclosed herein, the method may further comprise constructing a diode containing the conductive group III metal nitride product.

[0047] In any of the embodiments disclosed herein, the method may further comprise constructing a transistor containing the conductive group III metal nitride product.

[0048] In any of the embodiments disclosed herein, the method may further comprise emitting one or more photons having a wavelength between about 200 nm and about 350 nm.

[0049] In any of the embodiments disclosed herein, the method may further comprise the step of disinfecting the surface from viruses or bacteria.

[0050] An exemplary embodiment of the present disclosure provides a diode comprising a substrate, a first doped group III metal nitride disposed on the substrate, and a second doped group III metal nitride disposed on at least a portion of the first doped group III metal nitride. The first doped group III metal nitride may have a higher electrical carrier concentration than the second doped group III metal nitride. The first doped group III metal nitride and the second doped group III metal nitride may be grown at a temperature less than 1000° C.

[0051] Any of the embodiments disclosed herein may further include a Schottky barrier electrode disposed on at least a portion of the second doped Group III nitride.

[0052] In any of the embodiments disclosed herein, the diode may further comprise an ohmic electrode disposed on at least a portion of the first doped III-nitride.

[0053] In any of the embodiments disclosed herein, the first doped Group III metal nitride has a first electron carrier concentration of about 5×10 17 cm -3 ~Approx. 3×10 20 cm -3 The range may be:

[0054] In any of the embodiments disclosed herein, in the diode, the second p-doped group III metal nitride has a second electron carrier concentration of about 1×10 15 cm -3 ~3.1×10 18 cm -3 The range is.

[0055] In any of the embodiments disclosed herein, in the diode, the second p-doped group III metal nitride has a second electron carrier concentration of about 1×10 15 cm -3 ~5×10 19 cm -3 The range is.

[0056] An exemplary embodiment of the present disclosure provides a diode comprising a substrate, a first n-doped group III metal nitride disposed on the substrate at a temperature of less than or equal to 800° C., and a p-doped group III metal nitride disposed on the n-doped group III metal nitride at a temperature of less than or equal to 700° C. The diode may be configured to have a turn-on voltage of approximately 6 volts (V).

[0057] In any of the embodiments disclosed herein, the first n-doped group III metal nitride has an electron carrier concentration of at least 1×10 17 cm -3 (For example, about 1×10 17 cm -3 ~Approx. 3×10 20 cm -3 ).

[0058] In any of the embodiments disclosed herein, the p-doped group III metal nitride has a hole carrier concentration of at least 1×10 17 cm -3 (For example, about 1×10 17 cm -3 ~Approx. 3×10 20 cm -3 ).

[0059] In any of the embodiments disclosed herein, the diode may further comprise a second n-doped group III metal nitride grown between the first n-doped group III metal nitride and the p-doped group III metal nitride.

[0060] In any of the embodiments disclosed herein, the second n-doped group III metal nitride may have a lower electron carrier concentration than the first n-doped group III metal nitride.

[0061] In any of the embodiments disclosed herein, the second n-doped Group III metal nitride may be configured to function as an unintentionally doped layer.

[0062] In any of the embodiments disclosed herein, the second n-doped group III metal nitride may be configured such that its energy bandgap is smaller than the energy bandgap of the first n-doped layer or the p-doped layer.

[0063] In any of the embodiments disclosed herein, the second n-doped group III metal nitride may include alternating wells, the energy band gap of which may be smaller than the energy band gap of the first n-doped layer or the p-doped layer.

[0064] In any of the embodiments disclosed herein, the second n-doped group III metal nitride may further include alternating barriers that may be interposed between the wells, and the energy band gap of the barriers may be greater than the energy band gap of the wells.

[0065] In any of the embodiments disclosed herein, the barrier can have an energy bandgap equal to or less than the energy bandgap of the first n-doped layer or the p-doped layer.

[0066] In any of the embodiments disclosed herein, the diode can be configured to emit one or more photons having a wavelength between about 200 nm and about 350 nm.

[0067] In any of the embodiments disclosed herein, the diode may further comprise an optically reflective surface configured to internally reflect one or more photons.

[0068] In any of the embodiments disclosed herein, the diode may further comprise a roughened surface configured to reduce internal reflection.

[0069] The following detailed description of certain embodiments of the present disclosure will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the present disclosure, certain embodiments are shown in the drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities of the embodiments shown in the drawings. [Brief description of the drawings]

[0070] [Figure 1] FIG. 1 is a prophetic schematic of a material or device having an additional metal layer on the crystal surface to facilitate growth and increased charge carrier concentration at temperatures below 1000° C., according to an exemplary embodiment of the present invention.

[0071] [Figure 2A]FIG. 2A is a schematic representation of a predicted vertical group III metal nitride Schottky diode according to an exemplary embodiment of the present invention.

[0072] [Figure 2B] FIG. 2B is a schematic representation of a predicted quasi-vertical III-nitride Schottky diode according to an exemplary embodiment of the present invention.

[0073] [Figure 2C] FIG. 2C is a schematic prophetic diagram of a p-type Group III metal nitride according to an exemplary embodiment of the present invention.

[0074] [Figure 3A] FIG. 3A is a schematic diagram of a Group III metal nitride crystal structure showing the incorporation of Be (atomic radius .about.112 pm) as a p-type substitutional impurity substituting Al (atomic radius .about.118 pm) in accordance with an exemplary embodiment of the present invention.

[0075] [Figure 3B] FIG. 3B is a schematic diagram of a Group III metal nitride crystal structure showing the incorporation of Si (atomic radius ∼111 pm) as an n-type substitutional impurity substituting Al (atomic radius ∼118 pm) in accordance with an exemplary embodiment of the present invention.

[0076] [Figure 4A] FIG. 4A shows current-voltage characteristic profiles of Pt(10 nm) / Pd(10 nm) / Au(100 nm) contacts in an exemplary group III metal nitride device with dopants according to an exemplary embodiment of the present invention.

[0077] [Figure 4B] FIG. 4B shows current-voltage characteristic profiles of Pt(10 nm) / Pd(10 nm) / Au(100 nm) contacts in an exemplary group III metal nitride device without dopants, according to an exemplary embodiment of the present invention.

[0078] [Diagram 5] FIG. 5 illustrates p-contact transmission line measurement (PTLM) aspects of an exemplary III-metal nitride device with dopants, according to an exemplary embodiment of the present invention.

[0079] [Figure 6A] FIG. 6A illustrates an n-contact transmission line measurement (NTLM) profile for an exemplary III-metal nitride device with dopants according to an exemplary embodiment of the present invention.

[0080] [Figure 6B] FIG. 6B illustrates a p-contact transmission line measurement (PTLM) profile for an exemplary III-metal nitride device with dopants, according to an exemplary embodiment of the present invention.

[0081] [Figure 7A] FIG. 7A shows current density-voltage JV characteristic profiles of an exemplary group III metal nitride device with dopants according to an exemplary embodiment of the present invention.

[0082] [Figure 7B] FIG. 7B illustrates a semi-log current density-voltage JV characteristic profile for an exemplary group III metal nitride device with dopants, according to an exemplary embodiment of the present invention.

[0083] [Figure 8A] FIG. 8A shows dopant SIMS concentration profiles for an exemplary III-metal nitride device grown at varying temperatures according to an exemplary embodiment of the present invention.

[0084] [Figure 8B] FIG. 8B illustrates an Arrhenius plot of dopant SIMS concentration showing the exponential dependence of doping in an exemplary III-metal nitride device on dopant effusion cell temperature, according to an exemplary embodiment of the present invention.

[0085] [Figure 9] FIG. 9 is a schematic diagram of an exemplary III-metal nitride device showing the open / close "O / C" times of a shutter sequence of a growing film and the corresponding RHEED patterns showing a relatively smooth surface morphology of the film according to an exemplary embodiment of the present invention.

[0086] [Figure 10] FIG. 10 shows the profile of hole concentration at an average dopant activation efficiency of 5% plotted against SIMS concentration in an exemplary group III metal nitride device at a substrate temperature of 600° C. according to an exemplary embodiment of the present invention.

[0087] [Figure 11] FIG. 11 illustrates the profile of dopant activation energy in an exemplary group III metal nitride device, according to an exemplary embodiment of the present invention.

[0088] [Figure 12A] FIG. 12A shows cross-sectional transmission electron microscope (TEM) images of an exemplary III-metal nitride device before and after Al flushing, according to an exemplary embodiment of the present invention. [Figure 12B] FIG. 12B shows cross-sectional transmission electron microscope (TEM) images of an exemplary III-metal nitride device before and after Al flushing, according to an exemplary embodiment of the present invention. [Figure 12C] FIG. 12C shows cross-sectional transmission electron microscope (TEM) images of an exemplary III-metal nitride device before and after Al flushing, according to an exemplary embodiment of the present invention. [Figure 12D] FIG. 12D shows cross-sectional transmission electron microscope (TEM) images of an exemplary III-metal nitride device before and after Al flushing, according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0089] In order to facilitate the understanding of the principles and features of the present disclosure, various exemplary embodiments are described below. The components, steps, and materials described below as constituting various elements of the embodiments disclosed herein are intended to be illustrative and not limiting. Many suitable components, steps, and materials that will perform the same or similar functions as the components, steps, and materials described herein are intended to be encompassed within the scope of the present disclosure. Such other components, steps, and materials not described herein include, but are not limited to, similar components or steps developed after the development of the embodiments disclosed herein.

[0090] As used herein, the term "about" or "approximately" in relation to any numerical value or range indicates an appropriate dimensional tolerance that enables a portion or collection of components to function for the intended purpose described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±20% of the stated value, for example, "about 90%" may refer to a range of values ​​of 71% to 110%.

[0091] Also, please note that as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0092] Ranges can be expressed herein as from "about" or "approximately" one particular value and / or to "about" or "approximately" another particular value. When a range is expressed in this manner, another embodiment includes from the one particular value and / or to the other particular value.

[0093] "Comprising," "containing," or "including" means that at least the specified compound, element, particle, or method step is present in a composition, article, or method, but does not exclude the presence of other compounds, substances, particles, or method steps if such other compounds, substances, particles, or method steps have the same function as the one specified.

[0094] It should also be understood that the recitation of one or more method steps does not preclude the presence of additional method steps or intervening method steps between the explicitly identified steps. Similarly, it should also be understood that the recitation of one or more components in a device or system does not preclude the presence of additional components or intervening components between the explicitly identified components.

[0095] As mentioned above, both MOCVD and MBE have been successful in obtaining moderately doped p-GaN using magnesium (Mg) dopant. However, while bulk doping with Be has yielded semi-insulating GaN suitable for high power devices, high p-type GaN has not been obtained due to the high experimental activation energy of Be in GaN (~700 meV). The high activation energy of Be in GaN is due to the strain caused by the large mismatch in atomic radii between Be (~112 pm) and Ga (~136 pm), which results in undesirable interstitial Be sites in the crystal lattice instead of Ga substitutional sites.

[0096] Compared to GaN, AlN is very difficult to dope, especially p-type doping. This is due to the high activation energy of Mg in AlN (~510 meV), which is probably due to the larger atomic radius of Mg (~145 pm) compared to the atomic radius of Al (~118 pm). Since the atomic radius of Be (~112 pm) is close to that of Al (~118 pm), it seems that Be may be suitable for p-type doping of AlN. Also, AlN:Be theoretically exhibits a much lower activation energy (330 meV) compared to AlN:Mg. Unfortunately, Be is not commonly used in MOCVD due to significant safety concerns. In comparison, using Be in MBE is generally a safe and conventional method.

[0097] FIG. 1 illustrates an exemplary device 100 having a substrate 102 and a doped material 104 disposed on the substrate 102. The doped material 104 includes at least a layer of a group III metal nitride, such as aluminum nitride (AlN), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium aluminum nitride (InAlN), aluminum scandium nitride (AlScN), or indium gallium aluminum scandium nitride (InGaAlScN). The group III metal nitride includes a group III metal-rich surface 105 that lowers the energy barrier for surface diffusion compared to N-rich surfaces commonly used in MOCVD, allowing for substantially higher surface diffusion at lower temperatures. This periodically accumulated and then depleted metal-rich surface 105 adlayer is generated by periodically supplying a regulated excess of metal to the semiconductor surface relative to a constant supply of nitrogen 107. During the portion of the cycle in which the metal source is disposed on the semiconductor surface, the accumulated excess metal density (metal not yet bonded to nitrogen atoms) increases. The metal coverage eventually and short-term decreases to zero coverage during the portion of the cycle where the metal source is not placed on the semiconductor surface. Due to the accumulated metal excess, crystal synthesis continues at all times, even when the metal source is not placed on the semiconductor surface, except for the short period when no group III metal is present on the surface. Unlike MOCVD and MBE, the applied substrate temperature is lower than the metal desorption temperature, so all the metal applied to the surface is consumed without desorption. In this way, very high growth rates and therefore very low background impurity concentrations are obtained, since the impurity concentration is inversely proportional to the crystal growth rate. Similarly, the presence of the accumulated excess group III surface metal promotes lateral surface diffusion of nitrogen-107, since atomic hopping of nitrogen-107 only needs to break weak metallic bonds and not strong semiconductor bonds. Nitrogen-107 can also diffuse vertically up to the semiconductor-metal interface where a new epitaxial monolayer is formed, extending the crystal upwards (away from the substrate). This enhanced lateral diffusion achieved by using the metal-rich surface 105 results in improved crystal quality at lower temperatures than other methods, with less thermal load and therefore less contamination of the growth system.This repeated cycle of first placing a group III metal on the surface and then no metal on the surface is repeated with a constant nitrogen 107 supply, so that some of this accumulated metal is converted into a group III metal nitride semiconductor. The group III metal nitride is doped with at least one of a p-type dopant 106a or an n-type dopant 106b. The doped material 104 is grown at temperatures below 1000° C. for AlN, or even lower for group III alloys of AlN, so that the p-type dopant 106a or the n-type dopant 106b can diffuse through the metal-rich surface 105 of the group III metal nitride and increase the dopant concentration inside the film, which is first incorporated at the metal-semiconductor interface and then eventually filled by the growing semiconductor adlayer. The doped material 104 with increased dopant concentration can be grown by metal modulation epitaxy (MME). Examples of systems and methods for Group III metal nitride growth by MME are disclosed in US Pat. Nos. 10,526,723 and 11,319,644, which are incorporated by reference in their entireties as if fully set forth below.

[0098] Although not shown, dopants (elements such as Be, Si, etc.) can be added to the group III metal nitride crystals at any temperature, but doing so results in dopants that act as insulators rather than active charge carriers. The systems and methods described herein result in electrically active dopants throughout the doped material 104. In other words, doped material 104 grown at temperatures below 1000° C. results in active dopants 106 that can either (i) donate to provide free electrons, or (ii) capture to provide free holes.

[0099] Unlike conventional molecular beam epitaxy (MBE), the method described here, metal modulation epitaxy (MME), has three growth parameters: substrate temperature, III / V ratio, and excess metal amount per shutter cycle, allowing for much more growth control.

[0100] The substrate temperature is set to a temperature below about 1000°C (e.g., below about 950°C, below about 900°C, below about 850°C, below about 800°C, below about 750°C, below about 700°C, below about 650°C, below about 600°C, below about 550°C, below about 500°C, and any value therebetween, e.g., below about 834°C). A low substrate temperature helps to control the interface chemistry and reaction mechanisms to reduce contamination by gaseous outgassing and promote proper incorporation of active dopants in the group III metal nitride material. In some embodiments, for the growth of p-type semiconductors with increased active charge carrier concentration, the substrate temperature is set to a temperature range of about 500°C to about 900°C, preferably about 600°C to about 700°C. For the growth of n-type semiconductors with increased active charge carrier concentration, the substrate temperature is set to a temperature range of between about 500°C to about 1000°C, preferably between about 600°C to about 800°C.

[0101] The substrate 102 may comprise any suitable semiconductor substrate material including, for example, sapphire, crystalline silicon, gallium nitride, gallium oxide, aluminum nitride, aluminum gallium nitride, zinc oxide, lithium gallate, lithium aluminate, single crystal diamond, heteroepitaxial single crystal diamond, silicon carbide, or combinations thereof.

[0102] The III / V ratio refers to the concentration ratio of a group III metal to a group V element such as nitrogen, and the III / V ratio is preferably greater than 1 and less than 2. For p-type AlN-containing semiconductors, a III / V ratio close to 1 (e.g., about 1.5, about 1.4, about 1.3, about 1.2, about 1.1, or about 1.01) is ideal, and for n-type AlN-containing semiconductors, a III / V ratio close to 2 (e.g., about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, or about 2.0) is preferred.

[0103] Excess metal per shutter cycle refers to a higher concentration of metal (relative to nitrogen) that is allowed to accumulate on the substrate surface for a longer period based on the shutter open / close cycle time. In some embodiments, metal modulation epitaxy varies the metal flux while keeping the nitrogen flux constant during growth. Growth occurs during the metal shutter open cycle (when multiple metals are used, such as AlN-based alloys, both metal shutters can be open simultaneously) and after the shutter is closed for a portion of the cycle during which the accumulated metal is consumed. However, growth then temporarily stops before the start of the next cycle. In the methods described herein, both the Group III metal and the dopant may be introduced over a delivery period of from about 0.1 seconds to about 30 seconds (e.g., from about 0.5 seconds to about 28 seconds, from about 1.0 seconds to about 26 seconds, from about 1.5 seconds to about 24 seconds, from about 2.0 seconds to about 22 seconds, from about 2.5 seconds to about 20 seconds, from about 3.0 seconds to 18 seconds, from about 3.5 seconds to about 16 seconds, from about 4.0 seconds to 15 seconds, from about 4.5 seconds to about 14 seconds, from about 5.0 seconds to 12 seconds, and any time interval therebetween, e.g., from about 8.24 seconds to about 29.98 seconds). Furthermore, the shutter may be closed to pause the introduction of the Group III metal and dopant for a pause period in the range of about 1 second to about 30 seconds (e.g., about 1.5 seconds to about 28 seconds, about 2.0 seconds to about 26 seconds, about 2.5 seconds to about 24 seconds, about 3.0 seconds to about 22 seconds, about 3.5 seconds to about 20 seconds, about 4.0 seconds to about 18 seconds, about 4.5 seconds to about 16 seconds, about 5.0 seconds to about 15 seconds, about 5.5 seconds to about 14 seconds, about 6.0 seconds to about 12 seconds, and any time interval therebetween, e.g., about 4.17 seconds to about 27.34 seconds).

[0104] As will be appreciated by those skilled in the art, by adjusting any one of three parameters of the MME of the AlN doped material, the amount of charge carrier concentration that produces the AlN semiconductor can be adjusted due to the interaction of defects that have traditionally prevented substantial electrical conductivity in AlN and AlN-based semiconductor alloys by compensating for the charge carriers. Similarly, the charge carrier concentration can be increased or decreased by increasing or decreasing the flux of dopants to the surface. Various such examples are described in more detail with respect to the "Examples" section of this specification.

[0105] 2A is a schematic representation of a proposed example vertical III-metal nitride Schottky diode. As shown, a first semiconductor 202 has a wide, ultra-wide, or extremely large energy bandgap and contains either a p-type or n-type dopant. The first semiconductor 200 has a dopant concentration of about 1×10 15 ~5×10 20 cm -3 or about 5 x 10 17 ~7×10 19 cm -3 The first semiconductor 202 may be grown by methods and processes described in more detail below. Although not shown, the device 200A may be comprised of one or more layers of n-type or p-type doped first semiconductor 202 resulting in a material with a wide, ultrawide, or extremely large energy bandgap of conductivity.

[0106] Alternatively or additionally, the devices 200A, 200B can be layered into a structure with a second semiconductor 204. The second semiconductor 204 can be the same semiconductor material as the first semiconductor 202. For example, if the first semiconductor contains aluminum nitride (AlN), the second semiconductor can be the same or similar AlN. In such a case, if the first and second semiconductors 202, 204 are similar semiconductor materials, a homojunction can be formed at the interface between the layers. In particular, the homojunction can have equal bandgaps but different doping levels. As described herein and shown in Figures 2A and 2B, the first semiconductor 202 can have a higher concentration of p-type dopants ("p+" in Figures 2A and 2B and shown in more detail in Figure 3A), while the second semiconductor 204 can have a lower concentration of p-type dopants ("p-" in Figures 2A and 2B). A lightly p-type doped semiconductor can be grown on top of a heavily p-type doped semiconductor to provide a better cathode (or anode for n-type) contact with improved electrical breakdown performance. By lowering the dopant concentration or increasing the thickness of layer 204, the breakdown voltage of the Schottky diode can be increased.

[0107] In some embodiments, device 200A can be layered into a fully vertical Schottky diode with an anode metal or alloy 212A contacting the first semiconductor 202 and a cathode metal or alloy 214 contacting the second semiconductor 204, with the anode 212A and cathode 214 contacts on opposite or opposing sides of device 210A. In some embodiments, device 200B can be layered into a quasi-vertical AlN Schottky diode with the anode 214B and cathode 214 contacts on the same side of device 200B, as shown in FIG.

[0108] The anode metal or alloy 212A, 212B of the devices 200A, 200B can be a high work function metal, alloy, or multi-metal stack for p-type embodiments or a low work function metal or multi-metal stack for n-type embodiments, such as comprised of Ni, Pt, Pd, Ti, Al, Sc, Y, Nb, Au, or combinations thereof. The anode 212A, 212B can be annealed to the first semiconductor 202 to better form an ohmic contact.

[0109] The cathode metal or alloy 214 of devices 200A, 200B, 200C may be selected to have a high barrier height relative to the second semiconductor 204. The cathode 214 may be a low or lower work function metal, alloy, or multi-metal stack, such as, for example, Al, Mg, Ti, an alkali metal, or combinations thereof.

[0110] 2A and 2B show one configuration for a p-type diode, it is understood that in some embodiments, n-type material can be used instead of p-type material, in which the anode and cathode electrodes are reversed, as is the selection of metals based on high and low work functions.

[0111] Additionally, a semiconductor material may be stacked with another semiconductor material to enhance certain properties of the combined materials, thereby forming a junction where a first semiconductor material meets a second semiconductor material. A typical diode device relies on a junction with adjacent semiconductor materials, such as a pn junction, an np junction, or a pin junction. One advantage of a diode with a junction is that it facilitates the flow of charge in one direction while blocking the flow of current in the opposite direction, making it useful for generating direct current. In general, electrons tend to flow through the junction from the n layer to the p layer, and holes tend to flow through the junction from the p layer to the n layer. A wider bandgap provides a higher electrical breakdown voltage, i.e., a higher dielectric breakdown field, for a given thickness, and thus allows the fabrication of rectifiers with a higher blocking voltage. Without being bound by scientific theory, AlN has the highest bandgap of any semiconductor that has ever been substantially doped, and was substantially undoped until the development of the methods described herein, which is a substantial improvement in the present invention. Additionally, various intervening layers may replace the i layer of the pin junction to form optical and electronic devices well known in the art. For example, the i-layer can be replaced with one or more regions of a low-energy band-gap material suitable for trapping electrons and holes, resulting in increased light emission and efficiency. If multiple light generating layers are inserted, they can be separated by wider band-gap layers, each of which may have various levels of doping. Similarly, one or more layers can be introduced that have an optical index suitable for guiding light as well as emitting light from one or more of the light generating layers, allowing stimulated emission, i.e., lasing. Yet another option is to provide a p-n junction where an electric field modulates the carrier concentration of the semiconductor region, as in a transistor. Those skilled in the art will recognize that by allowing such p-type and n-type conduction, a wide variety of functional devices can be realized.

[0112] In some embodiments, devices with p-type conductivity grown by MME from Be-doped AlN can be used to fabricate high temperature, high voltage transistors and DUV photodetectors and light sources. The effectiveness of UV for disrupting viral and bacterial DNA peaks around 270 nm and 200 nm, with protein absorption being low at 270 nm and increasing towards 200 nm. Since AlN has a band gap energy of about 6.1 eV, devices with doped AlN can emit light around 203 nm.

[0113] Although not shown, the doped material 104 with increased active dopant concentration distributed throughout the group III metal nitride can be used to form common semiconductor diode devices (e.g., PIN diodes, Schottky diodes, transient voltage suppression diodes, tunnel diodes, Zener diodes, Gunn diodes, laser diodes, LEDs, photovoltaic cells, phototransistors, solar cells, IMPATT diodes, etc.) and transistor devices (e.g., field effect transistors, metal insulator semiconductor field effect transistors (MISFETs), high electron mobility transistors (HEMTs), etc.). For example, the group III metal nitride layer with increased active charge carriers can form a PIN diode having a homojunction with a layer acting as an insulator or an unintentionally doped layer, the layer grown by the MME method described herein. As used herein, an unintentionally doped layer means that the grown layer behaves as if it were undoped. In some examples, the unintentionally doped GaN layer has an electron concentration of 10 15 ~10 17 cm -3 It is inherently n-type due to residual defects in the GaN-GaN layer. Although the predominant donor has not been clearly identified, native defects such as residual oxygen and nitrogen vacancies are generally believed to be responsible for the n-type conductivity.

[0114] In some embodiments, the device can be layered in a structure with a first semiconductor of a different semiconductor material than the second semiconductor. For example, if the first semiconductor contains aluminum nitride (AlN), the second semiconductor can be GaN. In such a case, when the first and second semiconductors are different semiconductor materials, a heterojunction can be formed at the interface between the layers. In particular, the heterojunction can have unequal bandgaps, but different or equal doping types and concentrations. As will be appreciated by those skilled in the art, the properties of the semiconductor material can be altered to produce devices for deep ultraviolet light emission and photodetection applications, or high temperature, high voltage, and high power electronics, by varying the semiconductor material, doping type, group III composition, and dopant concentration. For example, a typical LED can be p-AlN / I or n-AlGaN / n-AlN, or can use multilayers of AlGaN with alternating bandgaps between p-type AlN and n-type AlN regions. A p-type region adjacent to an n-type region can be combined with any intervening layers to form a rectifying diode. Figure 2C shows an example device 200C that includes a layer of n-type GaN doped with Ge and grown by the MME method described herein, and a layer of p-type GaN doped with Be grown on the first layer providing the "i" layer. Figure 2C also provides an example of an additional layer of p-type combination adjacent to the n-type region (e.g., n-type GaN doped with Ge, followed by p-type GaN doped with Be, followed by p-type AlN doped with Be).

[0115] The doping of the semiconductor can be varied to control the forward conduction and reverse breakdown voltage of Schottky, PN, or PIN diodes, allowing their use in a variety of high power diode applications. Additionally, the forward conduction and reverse breakdown voltage of the diode can be further controlled by the choice of anode and cathode metals.

[0116] In some embodiments, devices having n-type and / or p-type doped nitride-based semiconductors may be produced by a method comprising the steps of: introducing a gas containing N atoms or a plasma-excited gas into a melt of a metal alloy deposited on a surface of a crystal substrate; epitaxially growing a nitride-based crystal on the seed crystal substrate at a temperature range of less than about 1000° C.; introducing one or more fluxes of metal and dopant in a pulsed periodic manner; and incorporating the dopant into the nitride-based crystal.

[0117] A nitrogen atom-containing gas or plasma-excited gas can be flowed into the growth chamber to react the nitrogen with the metal alloy melt. The metal alloy melt can include a group III element located in the first row of the P-block elements of the periodic table, including boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), or combinations thereof. Other metal alloy elements can include scandium (Sc), yttrium (Y), etc.

[0118] Epitaxial growth of nitride-based crystals may involve continuous or near-continuous growth of semiconductors in thin atomic layers. Metals and dopants may be cycled together or independently. Metals and dopants are pulsed into the chamber when shutters are open to allow one or more fluxes of metals and dopants to be incorporated into the growing crystal or semiconductor. When the metal and dopant shutters are open, excess metals and dopants may accumulate on the surface of the growing crystal or semiconductor. Metal-rich surfaces are formed during epitaxial growth at temperatures below 1000° C. When the metal and dopant shutters are closed, the excess metals and dopants are consumed or adsorbed into the crystal or semiconductor layer and growth of the crystal or semiconductor layer continues. In some embodiments, a short pause in growth may be performed after closing the metal and dopant shutters to allow the semiconductor to be annealed under nitrogen plasma.

[0119] The growth temperature of the doped crystal or semiconductor is substantially lower than conventional crystal or semiconductor growth methods. In some embodiments, epitaxial growth of the nitride-based crystal or semiconductor on the seed crystal substrate can be performed at a growth temperature of less than about 1000°C. The method described herein can produce a conductive doped nitride-based semiconductor by growing at a temperature in the range of about 600°C to about 1000°C (e.g., about 650°C to about 950°C, about 700°C to about 900°C, about 750°C to about 850°C, or any range therebetween, e.g., about 738°C to about 860°C).

[0120] In some embodiments, the nitride-based semiconductor may contain only Group III elements and nitrogen (e.g., AlN, GaN, InN, ScN, AlGaN, InAlN, ScInGaAlN, etc.). In some embodiments, non-Group III metal nitride alloys may be used to make conductive semiconductor alloys, such as, for example, antimony (III) nitride, barium nitride, bismuth nitride, cadmium nitride, cesium nitride, calcium nitride, cerium nitride, chromium nitride, cobalt (III) nitride, copper (I) nitride, gold (III) nitride trihydrate, lead nitride, lithium nitride, magnesium nitride, mercury nitride, plutonium nitride, potassium nitride, rhenium nitride tetrafluoride, rubidium nitride, silver nitride, sodium nitride, thallium (I) nitride, uranium (III) nitride, zirconium nitride, or combinations thereof.

[0121] The ratio of metal to dopant can vary from about 99.9999% metal and about 0.0001% dopant (e.g., about 99% metal and about 1% dopant, about 99.9% metal and about 0.1% dopant, about 99.99% metal and about 0.01% dopant, and any composition therebetween, e.g., about 99.63% metal and about 0.37% dopant).

[0122] As disclosed herein, approximately 6000 times higher bulk AlN electron concentration and approximately 300,000,000 times higher AlN hole concentration are obtained at room temperature compared to the prior art {Taniyasu, Y., Kasu, M. & Makimoto, T. An aluminum nitride light-emitting diode with wavelength of 210 nanometers. Nature 441, 325-328 (2006). https: / / doi.org / 10.1038 / nature04760}. Successful experiments with both n-type AlN:Si and p-type AlN:Be films demonstrate the first substantially doped AlN homojunction PIN diode. Six orders of magnitude rectification with a reasonable turn-on voltage of approximately 6V (higher than 20V in the prior art) for the 6.1 eV AlN semiconductor is demonstrated, providing ultimate confidence that the pioneering doping results shown are real. AlN is no longer just an insulator, and the era of the new semiconductor AlN has arrived. By simply changing the inner layer (a layer can have many sublayers), i.e., the layer or layers between the n-type and p-type regions, this embodiment shows exciting near-future promise for AlN-based deep ultraviolet (DUV) light emitters and detectors, high power / voltage / temperature and high frequency switching devices capable of operating in extreme radiation and thermal environments.

[0123] The following examples further illustrate aspects of the present disclosure, but do not limit in any way the teachings or disclosure set forth herein. EXAMPLES

[0124] Example 1 - p-type and n-type conductivity of AlN

[0125] One of the major limitations in realizing AlN-based electronic devices is the inability to dope them, nullifying their theoretical potential as power switches, and as a result GaN, β-Ga2O3, and SiC have been used instead for power devices. The p-type conductivity of AlN has been a major challenge, with the report of surface conductivity by carbon doping {K. Kishimoto, M. Funato, Y. Kawakami, Applied Physics Express 2020, 13, 015512}, but no substantial bulk conductivity has been experimentally demonstrated in the prior art. The best work has been done on Mg-doped AlN grown by high-temperature MOCVD, with a technologically irrelevant ∼10 10 cm -3 Taniyasu et al. achieved a room temperature hole concentration of 10 ... 15 cm -3 Previous studies have shown that the range of the lattice constant is limited by {in particular, Taniyasu et al; ML Nakarmi, et al, Applied Physics Letters 2004, 85, 3769; T. Ive, et al, Applied Physics Letters 2005, 86, 024106}. [Table 1]

[0126] Using the methods disclosed herein, improved growth kinetics of metal modulation epitaxy (MME) demonstrates high quality films at unprecedented low substrate temperatures, up to 3.1×10 18 cm -3p-type Be-doped AlN films have been achieved with hole concentrations of 1000 nm. MME utilizes low substrate temperatures during growth to reduce contamination typically caused by gaseous outgassing, and uses multiple parameters to control the interface chemistry and reaction mechanism to promote proper incorporation of dopants into cationic sites. MME also demonstrated the highest known hole concentration in p-type GaN using Mg as the dopant. MME p-type films of AlN:Be have been successfully applied in p-AlN / i-AlN / n-AlN diodes, p-AlN / i-GaN / n-GaN heterojunction Schottky, junction barrier Schottky (JBS), and pin diodes. As described herein, ultra-high vacuum purity proved to be key. Low background pressure during growth resulted in high hole concentrations and reduced compensation.

[0127] Si is a substitutional impurity in AlN, resulting in a theoretical relaxation of 6% of the nearest N-bonds. Although n-doping of the near-surface region (non-bulk growth) of AlN by ion implantation has shown promising results in the prior art, n-doping of bulk AlN films has only been achieved with a low doping rate of 10 15 cm -3 No bulk electron concentration above 100 has been demonstrated. Thus, the discrepancy in results, where doping is possible with one technique and not with the other, suggests that Si itself is not the problem, but that other defect / impurity related species are the bottleneck, and other doping techniques may be more suitable. Si is a shallow donor in GaN with an activation energy of about 17 meV, but the activation energy in AlGaN increases with Al content, and 0.85 Ga 0.15 24 meV in N to Al 0.96 Ga 0.04The problem of doping Si into AlN can be understood by considering the atomic positions where Si is located in the crystal lattice. The solubility limit of the dopant depends on the formation energy of the dopant. The formation energy further depends on the match of atomic radii, the bond strength between the host and dopant atoms, and the preferred geometric arrangement of the dopant in the lattice. The traditionally measured activation energy of Si in AlN is greater than 200 meV, which is due to the formation of Al vacancies, the trapping of electrons by high-threading dislocations, and the formation of DX centers. DX centers are formed when Si captures a secondary electron due to a geometric rearrangement involving a 2% contraction of the Si-N bonds at the three basile positions and the breaking of the c-axis Si-N bond, as shown in Figure 3B, causing a shallow-to-deep state transition. In the DX configuration shown in Figure 3B, the Si atom remains close to the substitutional Al site, but shifts downwards when the c-axis bond is broken as a result of the contraction of the nearest N-bond. Complicating the issue is that Al vacancies form complexes with Si, resulting in self-compensation of the doping at higher Si doping levels. Similarly, oxygen is a donor in AlN at low concentrations, resulting in a theoretical 4% elongation of the nearest-neighbor N-bond. However, as shown in Figure 3A and Figure 3B, at higher doping concentrations, oxygen also forms DX centers, shifting the 0.19 nm basile AlN bond to an asymmetric length of 0.182 nm, 0.182 nm, and 0.175 nm, resulting in an oblique displacement of O toward the open space in the crystal. This reconstruction of the DX center forms deep states that compensate n-type AlN at higher O concentrations. Furthermore, this self-compensation is found to increase in magnitude with increasing threading dislocations. Thus, by growing AlN films under high crystallinity conditions (reduced threading dislocation density), the compensation of Si doping in AlN can be reduced. Vacancies, especially Al vacancies, facilitate rearrangements by larger vacancies in an otherwise dense crystal structure and also enhance the possibility of DX centre formation by forming complexes with Si and O vacancies that also act as deep centres.

[0128] Example 2 - Metal Modulation Epitaxy

[0129] The method described herein, metal modulation epitaxy (MME), is a derivative of cyclic molecular beam epitaxy (MBE) that operates in an ultra-high vacuum, ultra-high purity, low impurity outgassing environment, and achieves background carbon and oxygen values ​​typically below 10 15 ~10 17 cm -3 Since MBE or metal-organic chemical vapor deposition (MOCVD) of III-nitrides operates well above the desorption temperature, impurity outgassing from the epitaxy chamber increases, resulting in exponentially higher concentrations of vacancies N, as governed by the vacancy generation equation: Vacancies is naturally generated.

number

[0130] In the formula, N Atomic is the atomic concentration of the missing element, C is the equivalent number of vacancies, and E formation is the energy required for vacancy formation, including the net energy required for atomic bond breaking and reformation. In contrast, MME operates well below the desorption temperature and at metal-rich surface conditions, minimizing vacancy generation, especially Al vacancies. MME compensates for the lower growth temperature by a highly metal-rich interface chemistry that nearly eliminates deleterious Al vacancies and facilitates surface bond breaking, thereby enabling long surface adatom diffusion lengths. For example, consider the following surface diffusion equation:

[0131]

number

[0132] where a is the hopping distance, φ is the energy barrier for hopping, and ω is the frequency. Considering that the metal-N barrier for hopping is 15 times larger than that for metal-metal surfaces, this barrier height mismatch makes the diffusion length for metal-rich surfaces 50-60 times longer than for surfaces rich in semiconductor bonds such as ammonia-based MBE and MOCVD. Even with a 500 degree temperature difference between MOCVD and MME, the surface diffusion for MME is longer than for N-rich MOCVD because the hopping barrier height is much lower at 0.1-0.2 eV. This is because the barrier for N-rich is about 10-15 times higher. This difference in surface diffusion length is evident in the comparison of the surface morphology of MME (and most MBE) to that of MOCVD. MME and metal-rich MBE tend to exhibit surfaces where spiral hillocks form around dislocations because step-flow growth is interrupted by surface voids found at dislocations. Conversely, MOCVD morphology is dominated by gas-phase diffusion rather than adatom diffusion, and even in the presence of dislocations that disrupt the step-flow growth of atoms on the surface, the atoms conformally cover the region of dislocations to form a flat surface. Combined with the metal-rich surface of the MME, which increases the adatom diffusion length for higher crystal quality obtained by the long surface diffusion length, the MME can reduce the Al vacancy concentration, which is known to combine with silicon and oxygen to form deep centers that steal electrons from AlN via DX center formation.

[0133] Furthermore, the formation of DX centers requires a geometric rearrangement of the dopants, as the lattice expands at very high temperatures (1100-2200 °C for most growth methods compared to 600-700 °C as disclosed herein), resulting in a 5.27 × 10 -6The thermal expansion coefficient of , predicts an increase in the c-axis elongation differential of about 2-6%, increasing the possibility of atomic rearrangements specifically due to c-axis bond breaking, which is a requirement for DX center formation. In summary, low temperature growth of AlN and AlN-based semiconductors is counterintuitive for most nitride semiconductor growth, but a deep analysis of the mechanisms that control dopant placement and activation reveals that MME provides a high purity, low outgassing environment free of Al vacancies with long dopant diffusion lengths, providing high density crystals that are less susceptible to crystal rearrangements.

[0134] The match between the atomic radii of Si and Al in AlN and the optimal MME growth reaction mechanism form a strong case to investigate n-type Si-doped AlN films, which, in combination with previously obtained p-type AlN:Be MME films, complete the essential building blocks for demonstrating AlN diodes and a wide variety of electrical and optical devices constructed from these p- and n-type building blocks.

[0135] Example 3 - Methods for producing AlN:Si and AlN:Be films

[0136] AlN:Si films and AlN homojunction diodes were grown by MME on HVPE-processed AlN-on-sapphire templates (MSE Supplies) using a Riber32 plasma-assisted molecular beam epitaxy (PAMBE) system. Two-inch diameter AlN-on-sapphire wafers (MSES) were first cleaned in piranha solution (H2SO4:H2O2 3:1 by volume) at 150 °C for 1 min, followed by a mixture of deionized water and hydrofluoric acid (DI H2O:HF 5:1 by volume) for 30 s. The cleaned wafers were back-metallized with 2 μm of tantalum for uniform heating during growth. The back-metallized wafers were then diced into 1 cm × 1 cm templates. The metallized and diced AlN templates were then solvent cleaned (acetone clean at 45 °C for 20 min, methanol clean for 3 min, DI water rinse, and nitrogen blow dry) followed by cleaning with piranha solution (H2SO4:H2O2 in a volume ratio of 3:1) at 150 °C for 10 min to remove the organic solvents. The templates were then chemically cleaned ex situ with DI H2O:HF in a volume ratio of 10:1 for 25 s to partially remove the surface oxide, followed by rinsing with DI water and drying with nitrogen.

[0137] The AlN template was heated at a base pressure of about 10 -9 It was immediately placed in a Torr loading chamber and thermally outgassed for 20 min at 200 °C. The template was then transferred to the growth chamber via the analysis chamber and outgassed at 850 °C for 30 min.

[0138] Al, Be, and Si fluxes were delivered from standard effusion cells. A Veeco UNI-Bulb radio frequency (RF) nitrogen plasma source was used to deliver nitrogen plasma during the growth with an RF plasma power of 350 W and a flow rate of 2.5 sccm. The RF plasma power and flow rate were kept constant throughout the growth. The base pressure of the MBE growth chamber was approximately 5 × 10 -11 At Torr, the beam equivalent pressure (BEP) of the nitrogen plasma is approximately 1.2×10 -5The pressure was 1000 MPa (5000 m / s) at 1000 sq. m and 1000 sq. m at 1000 sq. m. The growth rates were 700 nm / hr for the AlN:Be films and 1.40 μm / hr for the AlN:Si films. However, higher growth rates of about 10 μm / hr can be obtained with the MME. The MME open / close shutter cycle schemes for the AlN:Be and AlN:Si samples are shown in Table 2, although there are periods in each cycle when all the metal is consumed and therefore no growth occurs during these periods. [Table 2]

[0139] A STAIB Instruments RH20S 20 kV reflection high-energy electron diffraction (RHEED) gun was used in combination with a k-Space Associates kSA400 analytical RHEED system to monitor the in situ surface morphology and calculate the run-time growth rate of the films. AlN:Be films were grown with a III / V ratio of 1.3 and a substrate temperature of 700 °C with precise control of excess metal coverage (by shutter timing) to compensate for loss of adatom mobility at low temperatures. Al, N, and Be atoms hopping at the metal-terminated surface only need to break weak metal bonds that are substantially smaller than the strong AlN semiconductor bonds of a stoichiometric AlN surface. The non-growth time, or dead time, was kept at 8.5 s to consume excess metal and dopants in each cycle and to prevent vertical diffusion of dopants during growth. The metal-rich conditions result in a smooth surface morphology of the film, while the low substrate temperature helps to limit Be diffusion in the growth direction, allowing precise placement of the dopant at the desired location inside the device and preventing desorption of Be, which would cause a reactor memory effect in which subsequently grown films are unintentionally doped with Be. The AlN:Si films were grown under highly crystalline MME growth conditions (high III / V ratio and metal content - see Table 2 and previous discussion) that are not suitable for proper p-type doping, with a substrate temperature of 800 °C and a III / V ratio of 1.3.

[0140] Example 4 - Charge carrier concentration measurements in AlN:Si and AlN:Be films

[0141] Pt / Pd / Au (10 nm / 10 nm / 100 nm) contact stacks were deposited in a Denton Explorer e-beam evaporation chamber for both n-type and p-type AlN films for Hall measurements (van der Pauw configuration) and device characterization. The contacts were then annealed in a MILA-3000 rapid thermal annealing (RTA) furnace under pure nitrogen at 800 °C for 1 min for p-type AlN films and 875 °C for 1 min for n-type AlN:Si films. Secondary ion mass spectrometry (SIMS) of Si-doped calibration samples was performed at Evans Analytical Group (EAG). Lake Shore Cryotronics' state-of-the-art Hall measurement tool M91 FastHall controller was used for the four-point resistivity and Hall effect measurements. The 1T magnet resistance measurement range of the FastHall station is 1 mΩ to 1 GΩ, and the mobility measurement range is 10 -2 ~10 6 cm 2 / Vs.

[0142] The Si incorporation into AlN was calibrated by SIMS. The MME growth process was performed at 800 °C, with a III / V ratio of 1.3 and an MME O / C shutter cycle open time of 21 s and close time of 11 s, resulting in 150 nm thick AlN:Si layers with various Si dopings. The SIMS results were used as a guide for doping thicker films for hole analysis. Specifically, the MME growth process was performed on a HVPE processed AlN-on-sapphire template (MSES) at a substrate temperature of 800 °C, with a III / V ratio of 1.3 and an MME O / C shutter cycle open time of 21 s and close time of 11 s, and the Si concentration determined by SIMS was 5 × 10 17 ~7×10 19 cm -3 A 500 nm AlN:Si film was obtained in the range.

[0143] A metal stack of 10 nm Pt / 10 nm Pd / 100 nm Au was chosen as the contact for the AlN:Si film for hole and resistivity measurements. The contact has a very large 1 × 1 cm 2The sample corners were deposited by lithography and lift-off. First, the samples were washed with acetone, isopropanol (IPA), and DI water, dried with nitrogen, and then dehydration baked at 100 °C for 5 min. Then, NR9-1500PY negative photoresist (PR) was spin-coated at 3000 rpm with a dwell time of 40 s and acceleration / deceleration rate of 5 s, followed by a pre-exposure bake at 150 °C for 60 s. The PR spin-coated and baked samples were then exposed to 365 nm UV light at 350 mJ / cm. 2 The PR spin-coated and exposed samples were then developed in RD6 for 10 seconds and cleaned in a 1:1 buffered oxide etch (BOE):DI water solution for 30 seconds. Pt / Pd / Au contacts of 10 nm / 10 nm / 100 nm were deposited in a Denton Explorer electron beam evaporator at a deposition rate of 0.1 nm / s, approximately 1×10 -6 The deposition was performed at a background pressure of 1000 Å and 1000 Å, followed by lift-off in acetone for 20 min. The samples were finally rinsed with IPA and DI water and dried with nitrogen. The lithography and lift-off process resulted in a van der Pauw configuration for contact current-voltage linearity checks and Hall measurements.

[0144] After contact deposition, the samples were annealed in a MILA-3000 rapid thermal annealing (RTA) furnace for 1 min at 875 °C in a nitrogen environment with 60 s ramp-up and ramp-down times.

[0145] 7×10 grown at a substrate temperature of 700°C with an MME open / close cycle of 5 s / 10 s 18 cm -3 Another p-type sample, N4492, with 100000 Be doping was used for circular transmission line measurements (CTLM) to compare the contact resistance of the individual films with the device contacts.

[0146] Specific n-type AlN sample films and / or devices and some important parameters are listed in Table 3. In the example of the PIN diode N4633, growth was first performed on an AlN-on-sapphire template (MSES) that had been HVPE-processed to a thickness of about 4 μm, with a substrate temperature of 800° C., MME open / close cycles of 21 sec / 11 sec, and a III / V ratio of about 1.8, resulting in 8×10 18 cm -3 A 1 μm n-type AlN:Si film was obtained with a Si doping of 5 × 10, which corresponds to an unmeasurably low doping, as shown in Table 3. 17 cm -3 A 200 nm AlN:Si film with an "i-layer" doped with 7 × 10 was then grown at a substrate temperature of 700 °C, with an MME open / close cycle of 5 s open and 10 s closed, and a III / V ratio of about 1.3. 18 cm -3 A 200 nm thick p-type AlN:Be film was obtained with 1000 nm of Be doping. [Table 3]

[0147] After growth, 100 μm diameter quasi-vertical devices were fabricated on the samples using ICP plasma etching. The same metal stacks were used for the p-type and n-type contacts as for the layers above, except they were annealed at 950 °C for 1 min under nitrogen. Higher annealing temperatures were determined by annealing at lower temperatures, measuring the current, and then annealing at higher temperatures until performance degraded. The higher rapid thermal annealing temperatures for these devices appear to be related to the different metal coverage of the device mask compared to the contact study mask, and are likely a result of the transparency of AlN in the light-heated annealing setup.

[0148] The size (strain) dictates that Si is the optimal dopant atom to replace Al atoms in AlN. The atomic radius of Si (111 pm) closely matches that of Al (118 pm). The match between the atomic radius of Si and Al in AlN, combined with the ability of MME to exceed the solubility limit of dopants in III-nitride materials by improving the growth reaction mechanism (non-equilibrium growth with rapid synthesis), was utilized to investigate Si-doped AlN films. First, secondary ion mass spectrometry (SIMS) was used to calibrate the incorporation of Si into AlN. The MME growth process was performed to obtain multiple 150 nm thick AlN:Si layers with various Si dopings. The SIMS results were used as a guide for doping thicker films for hole analysis. Specifically, the MME growth process was performed and the Si concentration determined by SIMS was 5×10 17 ~7×10 19 cm -3 A 500 nm AlN:Si film was obtained in the range.

[0149] The Pt / Pd / Au metal stack was assembled into a very large 1 x 1 cm 3D array in a van der Pauw configuration for contact current-voltage linearity checks and Hall measurements. 2 The contacts were deposited lithographically on the corners of the AlN:Si samples. Using large samples ensures that the measured properties are global properties and not just local anomalies. After deposition of the contacts, the samples were annealed in a rapid thermal annealing (RTA) furnace. The effect of this annealing treatment on the electrical contact properties of the samples was investigated by studying the I-V characteristics with four-point probe measurements. The I-V characteristics of Pt / Pd / Au contacts of representative MME-grown films are shown in Figures 4A and 4B. The annealed AlN:Si film, N4595 in Figure 4A, critically crosses zero current at zero voltage, indicating the absence of any thermal voltage or piezoelectric offset. The annealed AlN:Si contacts are also highly linear. The annealed AlN:Si film (N4595) shown in Figure 4A exhibits approximately five orders of magnitude higher current than the control undoped AlN film (N4436) shown in Figure 4B, proving that the increase in conductivity is a result of Si doping.

[0150] The electrical conductivity of the AlN:Si samples was investigated by Hall measurements. The contact resistance of the AlN:Si films was in the kΩ range, which was within the measurement capabilities of the Lake Shore Hall measurement tool. However, Hall measurements could not be performed on the least doped AlN film, N4591, because the National Institute of Standards and Technology (NIST) "F-factor" symmetry factor was less than 95% for the various contact resistance measurements. 5×10 17 ~7×10 19 cm -3 Hall measurements of AlN:Si films in the Si doping range of 9×10 17 ~6×10 18 cm -3 The results show that F>99% is reliable for electron concentrations in the range of 6×10 18 cm -3 The electron bulk concentration is approximately 6000 times higher than previously reported in the prior art.

[0151] Given that the contact resistance is still high compared to the film resistance, the contact voltage drop adds to the bulk resistivity voltage drop in van der Pauw measurements, leading to uncertainty in the measured resistivity (and corresponding mobility). Thus, the electron mobility provides only an estimate. Since the carrier concentration measurements in Hall measurements are measured from a different contact than the current and voltage, the effect of this contact voltage drop does not degrade the carrier concentration measurements, and the uncertainties in all reported carrier concentrations are less than 0.5%.

[0152] Example 5 - Transmission Line Measurements of AlN:Si and AlN:Be Films

[0153] Transmission line measurements are a technique used to determine the contact resistance between metals and semiconductors, but also to determine the linearity of the contacts (relative ohmic vs. Schottky rectifying). In this technique, a series of metal-semiconductor contacts are separated by various distances, or gaps. The resistance between a pair of contacts is measured by applying a voltage across the contacts and measuring the resulting current. Current flows from the first probe to the metal contact, across the metal-semiconductor junction, through the semiconductor sheet, across the metal-semiconductor junction again (but this time in the opposite direction), to the second contact, from there to the second probe, into an external circuit where it is measured by an ammeter. The measured resistance is a linear combination (sum) of the contact resistance of the first contact, the contact resistance of the second contact, and the sheet resistance of the semiconductor between the contacts.

[0154] Figure 5 shows p-contact transmission line measurements (PTLM) of N4492, a planar p-type membrane with a constant outer radius of 200 μm and gaps of 25, 35, 45, 55, 65, and 75 μm. In N4492, the gap is much smaller than that used for Hall measurements of p-type AlN:Be membranes (about 1 cm), and therefore the current levels of the method and device are significantly higher. The contacts of the p-type membrane N4492 have high linearity, passing a significant current of about 0.4 mA.

[0155] Specific p-type AlN sample films and / or devices and some important parameters are shown in Table 4. To verify the p-type nature of the AlN:Be film and the n-type nature of the AlN:Si film, an AlN homojunction diode is desired that exhibits a turn-on voltage comparable to the semiconductor band gap. In this regard, an AlN PIN diode (N4633) was grown. Those skilled in the art will appreciate that, given that the n-type and p-type layers were an obstacle prior to this invention, the i-layer could be replaced with a quantum well, or various other modifications could be made to achieve a diode suitable for transistor-like spontaneous or stimulated light emission, light detection, electrical rectification, and carrier modulation. [Table 4]

[0156] Figures 6A and 6B show circular transmission line measurements (CTLM) of the n-type and p-type contact layers of the PIN diode structure. Both the n-type and p-type contacts show a linear trend. However, the current levels of both the n-type and p-type contacts of the N4633 AlN diode were repeatedly lower than the n-type N4595 and p-type N4492 films (non-devices) when multiple devices were fabricated, likely due to anomalies due to the plasma tool and annealing during the fabrication process. Specifically, an unexplained dark tint formed on the wafers when the PIN diodes were etched, suggesting that the plasma etching of the Be and Si doped AlN requires further optimization. This discoloration (presumed to be contamination) cannot be removed and can increase the contact resistance of the homojunction AlN diode by 3-4 orders of magnitude for the two contacts combined. The current of the N4633 (etched) n-type layer was 2-3 orders of magnitude lower than the N4595 (unetched) n-type film for the same contact pattern. Additionally, the current through the p-type layer in device N4633 (processed, unetched) is approximately one order of magnitude smaller compared to the p-type film N4492 (unprocessed). This reduction in current through the p-type contact in device N4633 is due to the higher than optimal annealing temperature of the p-type contact layer required to optimize the poorly conductive n-type contact. Future work will involve separate anneals of the n-type contact followed by the p-type contact, but this was not pursued in this initial study due to the complexities of optimal temperatures based on mask metal coverage (see Methods section).

[0157] Nevertheless, the forward diode response was nearly ideal, except for the high series resistance due to the aforementioned contact issues in the fabricated devices. Figures 7A and 7B show the linear and semi-log current density-voltage (JV) characteristics of the N4633 AlN PIN diode. The turn-on voltage in the linear and semi-log plots is about 6 V, which is consistent with the expected value for an AlN semiconductor of 6.1 eV. While six orders of magnitude of rectification are clearly shown, the low breakdown voltage and very high series resistance are also evident by the high current density tail in the semi-log plot and the smooth turn-on in the linear plot. The current density of this sample can be improved by another 3-4 orders of magnitude by optimizing the device fabrication process and matching it to previously fabricated films. Nevertheless, the small reverse current to large forward current sweep shows six orders of magnitude of rectification in this first-ever AlN homojunction diode, and may be further improved by optimizing the growth and fabrication conditions to realize even higher performance high power and high energy devices.

[0158] Example 6 - Comparison of AlN:Be film depth and SIMS concentration

[0159] Figure 8A plots the SIMS concentration of Be versus sample depth. An irregular Be profile was observed in the AlN film. Be is a small atom known to diffuse from where it was placed during epitaxial growth, often smearing the doping profile. However, as disclosed herein, the low substrate temperature of the present invention allows for precise and permanent placement of the Be dopant, making device Be dopant profiling of III-nitride semiconductors practical for the first time. Figure 8B shows a linear Be doping profile on a logarithmic scale showing the exponential dependence of Be doping on cell temperature, indicating that the effusion cell is still in the Knudsen limit, i.e., there is a linear relationship between evaporated Be flux and incorporated Be dopant.

[0160] Example 7 - Example of a device with highly doped AlN:Be and AlN:Si layers

[0161] In some instances, AlN films with different dopants can be grown in layers using the methods disclosed herein. Figure 9 shows the layer schematics of these films and the corresponding representative RHEED patterns, confirming crystalline material even at such excessively low growth temperatures. After cleaning and outgassing of the HVPE processed AlN template (MSES), a growth process was first performed on top of the HVPE processed AlN template at a substrate temperature of 800°C to bury surface contaminants such as oxygen, which is a strong compensation defect of Be, to obtain an undoped 300 nm AlN buffer layer. Al is well known to incorporate oxygen, and it is estimated that there is oxygen diffusion up to several hundred nanometers in the regrown AlN film. The buffer layer is intended to limit the high concentration of oxygen that would otherwise compensate the AlN:Be film. The growth process was performed under p-type MME growth conditions typically optimized for GaN to obtain the top 100 nm of AlN:Be. The low substrate and long shutter closure time limited the vertical surface diffusion of Be in the growth direction, while the metal-rich III / V ratio of 1.3 allowed for a smooth surface morphology with slightly speckled RHEED targeting a slightly faceted surface. The top layer was doped with Be. Time-dependent evolution of RHEED images and post-growth atomic force microscopy (AFM) suggested that as the film thickness increased, MME-grown AlN exhibited the slightly rougher morphology common to all p-type III-nitrides by all growth methods (films with 2-3 nm root-mean-square (RMS) roughness vs. 1.9 nm RMS roughness for templates) and surface pitting common to MBE grown in the interphase region. Additionally, the most highly doped films exhibit additional surface features that may be segregated Be, as the concentration is substantially higher than the solubility limit. Interestingly, the pit density was significantly higher in the undoped films and decreased with increasing Be concentration, suggesting that Be may have some favorable interfacial activity effect. Contacts were then deposited on these films by electron beam evaporation.Those skilled in the art will appreciate that devices containing a variety of discrete and continuously variable doping concentrations are possible, useful for controlling electrical and optical properties.

[0162] Hall measurements on the AlN:Be samples were performed with a Lake Shore Cryotronics M91 FastHall controller. This system is capable of measuring sample resistances up to 1 GΩ. The contact resistance of the AlN:Be films was in the megaohm range, which was within the measurement capabilities of the Lake Shore Hall measurement tool. However, Hall measurements on the undoped AlN film, N4436, could not be performed due to the very high contact resistance. Hall measurements on AlN:Be films grown at substrate temperatures of 600 °C and 700 °C are shown in Table 4. These measurements were in the reliable range for all measurements, with symmetry factors of 96-99.9% and signal-to-noise ratios of the Hall voltages of 100-900. The conductivity type was also confirmed by hot-wire probe measurements. Hot-wire probe measurements on the unintentionally doped sample, N4436, were not measurable (the voltage drifted as if the voltage probe was floating on an insulator). The 5 × 10 16 ~7×10 18 cm -3 AlN:Be films grown at 600 °C in the Be doping range of 15 ~7.6×10 17 cm -3 These results are plotted in Fig. 10. The activation efficiency of Be extracted from this figure was ≈5% for the AlN:Be film grown by MME at 600 °C.

[0163] Example 8 - Activation energy measurements of highly doped AlN:Be and AlN:Si devices

[0164] Independent confirmation of the conductivity type and experimental activation energy measurements of the N4472 AlN:Be sample was performed at Lake Shore Cryotronics. This sample was chosen because it had a lower hole concentration, suggesting significant compensation, compared to the more lightly doped sample, N4434. High temperature DC and FastHall measurements were performed on this sample in the temperature range 325-475 K and are shown in Figure 11. All measurements showed p-type conductivity, with p=1×1017 e -(0.037 / kT) The results fit the curve of the SIMS concentration of this sample, 2×10 18 cm -3 Since the compensation ratio is ≈95%, this gives us an insight into the possible source of run-to-run variability, as shown in Fig. 10, where several different hole concentrations were measured with almost the same doping. Self-compensation of Be located on interstitial sites, as well as defect trapping due to the low growth temperature applied and compensation by impurities such as oxygen, may play an important role in the obtained hole concentration.

[0165] Example 9 - Growth reaction mechanism of AlN:Be films

[0166] As shown in Table 5, the growth reaction mechanism of the AlN:Be film is as follows: 17 (N4434), 7×10 18 (N4435), and 1×10 20 cm -3 Films were grown and measured in the range of 0.1 V to 1.5 V (N4433). Films were grown on HVPE processed AlN templates (MSES). Pt / Pd / Au (10 nm / 10 nm / 100 nm) van der Pauw contacts were deposited by e-beam evaporation. Before annealing, all samples showed non-ohmic behavior with currents of + / - 10 volts at the noise floor of the Lake Shore M91 FastHall system, the most advanced Hall Effect Measurement (HEM) instrument on the market. The samples were then annealed at 700°C for 10 minutes in a nitrogen atmosphere with a flow rate of 400 sccm. After annealing, N4433 and N4436 still showed non-ohmic behavior and weak currents. However, N4434 and N4435 showed very ohmic behavior with currents 40-50 higher than before annealing. [Table 5]

[0167] Hot wire probe measurements of the samples with a Keithley 6517A high impedance electrometer showed that N4433 and N4436 behaved as n-type, and N4434 and N4435 as p-type. Four-point resistivity and Hall measurements on N4433 and N4436 could not be performed due to poor contacts. Resistivity and Hall measurements on both N4434 and N4435 were repeated 100 times to increase the reliability and statistical validation of the results. Longer measurement times of several hours were used to accommodate the RC time constants of the contacts.

[0168] To verify the p-type conductivity results by hot-wire probe, hole measurements were performed with a hole concentration of 4.65 × 10 16 and 1.4 × 10 17 cm -3 Both N4434 and N4435 showed p-type conduction in all 100 repeated measurements. Because the current during the Hall measurements was passed through different contacts than the Hall voltage measurements, and because the contacts had no rectification and were symmetrical across the repeated runs with polarity inverted according to NIST standards, the Hall measurements were + / - 2×10 14 and 4 × 10 14 cm -3 Note that the accuracy is based on the 4-point resistivity of N4434 and N4435. The 4-point resistivity of N4434 and N4435 showed resistance values ​​of 12.2mΩ-cm and 6.5mΩ-cm, respectively, which may be an underestimation of the actual values, since N4434 and N4435 showed linear but very high contact resistances of about 15MΩ and 6MΩ, respectively. When we checked the measured Hall voltage levels with Lake Shore staff, we found that the measured Hall voltage levels were far above the noise level, with S / N levels of 203 and 316, respectively.

[0169] Symmetric and asymmetric X-ray diffraction rocking curves of the peripheral region (full width at fractional peak height to distinguish thin films from bulk materials) showed that the regrown films closely matched the crystalline quality of the underlying template. Furthermore, the (002) symmetry of AlN was found to slightly decrease with Be concentration, while the (105) and (102) asymmetries slightly improved with Be concentration, suggesting a gradual change in the defect structure that has yet to be elucidated.

[0170] Example 10 - Metal cleaning to reduce defect density

[0171] Figures 12A-12F are transmission electron microscope cross-sectional images showing the extra defects (beyond those already present in the substrate) that form when the substrate does not undergo a procedure called "Al flushing." Al flushing allows the substrate crystal to be replicated without adding defects by flooding the surface with Al metal, removing stubborn surface oxides. As shown here, stacking faults and edge dislocations are substantially reduced or eliminated with Al flushing. There is also no increase in screw dislocations. Figures 12A and 12C highlight all defects (edge, screw, and stacking faults) in MME-grown AlN, while Figures 12B and 12D show the metallic aluminum wash, which dramatically reduces the defect density.

[0172] It is to be understood that the embodiments and claims disclosed herein are not limited in their application to the details of construction and arrangement of the components described herein and illustrated in the drawings. Rather, the specification and drawings provide examples of possible embodiments. The embodiments and claims disclosed herein are capable of further embodiments and can be implemented and carried out in various ways. It is also to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be construed as limiting the scope of the claims.

[0173] As such, those skilled in the art will appreciate that the conception underlying the present application and claims may be readily utilized as a basis for the designing of other structures, methods and systems for carrying out the purposes of the embodiments and claims presented herein, and it is important that the claims be regarded as including such equivalent constructions.

[0174] Furthermore, the purpose of the Abstract is to enable the U.S. Patent and Trademark Office and the general public, including those not familiar with patent and legal terminology and language, to quickly grasp the content and gist of the technical disclosure of the application upon a single reading. The Abstract does not define the scope of the claims of the application, nor does it limit the scope of the claims in any way.

Claims

1. A substrate; 1. A device comprising: a Group III metal nitride; and a doped material containing one of a p-type dopant or an n-type dopant, the doped material is disposed on the substrate at a temperature less than 1000°C; The doped material has a band gap energy greater than 4.5 electron volts (eV).

2. The dopant is about 1×10 １１ cm －３ ~Approx. 3×10 ２０ cm －３ The device of claim 1 , wherein the concentration ranges from

3. The doped material has a hole carrier concentration of about 1×10 １１ ~Approx. 1×10 １９ cm －３ 10. The device of claim 1, wherein the range is:

4. The doped material has an electron carrier concentration of about 6×10 １５ cm －３ ~Approx. 3×10 ２０ cm －３ 2. The device of claim 1, wherein:

5. 10. The device of claim 1, wherein the doped material is configured to provide at least a 100,000-fold increase in electron carrier concentration compared to a second Group III metal nitride grown at a temperature greater than 1000°C.

6. The device of claim 1 , wherein the doped material has a band gap energy of approximately 6.1 eV.

7. The device of claim 1 , wherein the doped material is configured to emit one or more photons having a wavelength between about 200 nm and about 350 nm.

8. 10. The device of claim 1, wherein the Group III metal nitride comprises a material selected from aluminum nitride (AlN), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium aluminum nitride (InAlN), aluminum scandium nitride (AlScN), indium gallium aluminum scandium nitride (InGaAlScN), or combinations thereof.

9. The device of claim 1 , wherein the p-type dopant comprises beryllium.

10. The device of claim 1 , wherein the n-type dopant comprises silicon.

11. The p-type dopant contains beryllium, the n-type dopant contains silicon; The device of any one of claims 1 to 8, wherein the doped material is disposed on the substrate at a temperature in the range of about 600°C to about 800°C.

12. The device of claim 1 further comprising a semiconductor disposed on the doped material.

13. The device of claim 12 , wherein the semiconductor disposed on the doped material forms a homojunction or a heterojunction.

14. configured to disrupt viral and bacterial replication, configured to promote curing of the polymer; 14. A device according to any one of claims 1 to 8 and claims 12 to 13, wherein:

15. 10. The device of claim 1, wherein the substrate comprises sapphire, crystalline silicon, gallium nitride, gallium oxide, aluminum nitride, aluminum gallium nitride, zinc oxide, lithium gallate, lithium aluminate, single crystal diamond, heteroepitaxial single crystal diamond, silicon carbide, or a combination thereof.

16. 1. A method for growing an electrically conductive Group III metal nitride product, comprising: flowing a nitrogen-containing plasma into a growth chamber from a remote plasma chamber; introducing a Group III metal and at least one of a beryllium-containing p-type dopant or a silicon-containing n-type dopant into the growth chamber; pulsing a flux of one or more of the p-type dopant or the n-type dopant and the Group III metal with a constant nitrogen supply; and disposing an electrically conductive Group III metal nitride product having a bandgap energy greater than 4.5 electron volts (eV) and an increased electrical carrier concentration on the substrate at a temperature in the range of about 600°C to about 800°C.

17. The conductive Group III metal nitride product has a hole carrier concentration of at least 1×10 １１ cm －３ 17. The method of claim 16, wherein:

18. The conductive Group III metal nitride product has an electron carrier concentration of at least 6×10 １５ cm －３ 17. The method of claim 16, wherein:

19. 17. The method of claim 16, wherein the conductive Group III metal nitride product has at least a 100,000-fold increase in electrical carrier concentration compared to a second Group III metal nitride product grown at a temperature greater than 1000°C.

20. 17. The method of claim 16, wherein the conductive Group III metal nitride product comprises a material selected from aluminum nitride (AlN), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium aluminum nitride (InAlN), aluminum scandium nitride (AlScN), indium gallium aluminum scandium nitride (InGaAlScN), or combinations thereof.

21. 17. The method of claim 16, wherein each pulse of the pulsing step occurs over a delivery period ranging from about 0.1 seconds to about 30 seconds.

22. 22. The method of claim 21, wherein each pulse of the pulsing step is separated by a rest period ranging from about 1 second to about 30 seconds.

23. Each pulse of the pulsing step comprises: occurs over a delivery period ranging from about 1 second to about 25 seconds; 17. The method of claim 16, wherein the plurality of pulses are separated by rest periods ranging from about 2 seconds to about 15 seconds.

24. The method described in claim 16, wherein the III / V flux ratio is greater than about 1.

25. 25. The method of claim 24, wherein the III / V flux ratio is in the range of about 1.1 to 1.

5.

26. 17. The method of claim 16, wherein the temperature of the growth chamber ranges from about 500° C. to about 850° C. when the p-type dopant is introduced into the growth chamber.

27. The method of claim 16, wherein when the p-type dopant is introduced into the growth chamber, the temperature of the growth chamber is in the range of about 600°C to about 700°C.

28. The method described in claim 16, wherein the III / V flux ratio is about 1.5 or more.

29. 29. The method of claim 28, wherein the III / V flux ratio is in the range of about 1.6 to 2.

0.

30. 17. The method of claim 16, wherein the temperature of the growth chamber ranges from about 500° C. to about 1000° C. when the n-type dopant is introduced into the growth chamber.

31. The method of claim 16, wherein when the n-type dopant is introduced into the growth chamber, the temperature of the growth chamber is in the range of about 600°C to about 800°C.

32. 32. The method of any one of claims 16 to 31, wherein the conductive Group III metal nitride product is selected from a diode and a transistor.

33. A method described in any one of claims 16 to 31, wherein the conductive Group III metal nitride product is a diode configured to have a turn-on voltage of approximately 6 volts (V).

34. A method according to any one of claims 16 to 31, wherein the conductive Group III metal nitride product is a heteroepitaxial diode exhibiting Schottky, PIN, and junction barrier Schottky (JBS) electrical behavior.

35. The method of claim 35, further comprising: a second doped Group III metal nitride disposed on at least a portion of the first doped Group III metal nitride; the device is a diode; the first doped group III metal nitride has a higher electrical carrier concentration than the second doped group III metal nitride; The device of claim 1 , wherein the first and second doped Group III metal nitrides are grown at a temperature less than 1000° C.

36. 36. The device of claim 35, further comprising a Schottky barrier electrode disposed over at least a portion of the second doped Group III metal nitride.

37. 37. The device of claim 35 or claim 36, further comprising an ohmic electrode disposed on at least a portion of the first doped Group III metal nitride.

38. The first doped Group III metal nitride has a first electrical carrier concentration of about 5×10 １７ cm －３ ~Approx. 3×10 ２０ cm －３ is in the range of 36. The device of claim 35, wherein the second p-doped Group III metal nitride has a second electrical carrier concentration in the range of about 1x10 15 cm -3 to about 5x10 19 cm -3 .

39. A method of growing a first doped Group III metal nitride at a temperature less than 1000°C; growing a second doped Group III metal nitride at a temperature less than 1000°C; disposing the first doped Group III metal nitride product on a substrate; and disposing said second doped Group III metal nitride over at least a portion of said first doped Group III metal nitride.

40. The first doped group III metal nitride is a first n-doped group III metal nitride; the second doped Group III metal nitride is a p-doped Group III metal nitride; 40. The method of claim 39, wherein the device is a diode.

41. The method of claim 39, further comprising growing a second n-doped Group III metal nitride between the first n-doped Group III metal nitride and the p-doped Group III metal nitride.

42. Disposing a Schottky barrier electrode on at least a portion of the second doped Group III metal nitride. disposing an ohmic electrode on at least a portion of the first doped Group III metal nitride; 40. The method of claim 39, further comprising at least one of:

43. The doped Group III metal nitride is grown by metal modulation epitaxy (MME); the first doped group III metal nitride is a first n-doped group III metal nitride; 40. The method of claim 39, wherein the second doped Group III metal nitride is a p-doped Group III metal nitride doped with beryllium.

44. The first doped Group III metal nitride comprises one or more n-doped Group III metal nitrides; the second doped Group III metal nitride comprises one or more p-doped Group III metal nitrides; the doped group III metal nitride is grown by MME; At least one of the n-doped group III metal nitrides is n-type GaN doped with germanium (Ge); At least one of the p-doped group III metal nitrides is p-type GaN doped with Be; At least one of the p-doped group III metal nitrides is p-type AlN doped with Be.

40. The method of claim 39, wherein the method comprises at least one of:

45. The first n-doped Group III metal nitride has an electron carrier concentration of about 1×10 17 cm −3 to about 3×10 20 cm −3 . the p-doped Group III metal nitride has a hole carrier concentration of about 1×10 17 cm −3 to about 3×10 20 cm −3 ; 41. The method of claim 40, wherein the method is at least one of:

46. ​​The second n-doped group III metal nitride has a lower electron carrier concentration than the first n-doped group III metal nitride. the second n-doped Group III metal nitride is configured to function as an unintentionally doped layer; the second n-doped Group III metal nitride is configured to have an energy bandgap smaller than the energy bandgaps of the first n-doped layer and the p-doped layer. the second n-doped Group III metal nitride comprises alternating wells; the second n-doped Group III metal nitride includes alternating wells, each of which has an energy bandgap smaller than each of the first n-doped layer and the p-doped layer; the second n-doped group III metal nitride includes alternating wells and alternating barriers, the barriers being interposed between the wells, and the energy band gap of the barriers being greater than the energy band gap of the wells; the second n-doped Group III metal nitride includes alternating wells and alternating barriers, the barriers being interposed between the wells, and the energy bandgaps of the barriers being greater than the energy bandgaps of the wells and less than or equal to the energy bandgaps of the first n-doped layer and the p-doped layer; the device is a diode configured to emit one or more photons having a wavelength between about 200 nm and about 350 nm; 46. ​​The method of claim 45, wherein the method comprises at least one of:

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