Group III nitride high electron mobility heterostructures with double continuous gradient back barrier

Abstract

A high electron mobility heterostructure and a method for manufacturing said heterostructure, wherein the high electron mobility heterostructure comprises a substrate, a buffer on the substrate, a doped charge compensation layer on the buffer, a double continuous gradient barrier having increasing polarization charge and decreasing polarization charge located on the doped charge compensation layer, a channel on the double continuous gradient barrier, and a charge generation layer on the channel. The method comprises the steps of forming a substrate, forming a buffer on the substrate, forming a doped charge compensation layer on the buffer, forming a double continuous gradient barrier on the doped charge compensation layer, forming a channel on the double continuous gradient barrier, and forming a charge generation layer on the channel.

Description

Background Technology

[0001] Next-generation high-charge, high-electron-mobility devices (e.g., high electron mobility transistors (HEMTs) and diodes) currently face the problem of increased leakage current due to insufficient electron confinement. Current scandium aluminum nitride (ScAlN)-based HEMTs exhibit high buffer leakage due to their high charge density. High buffer leakage can occur because the back-sealing of the two-dimensional electron gas (2DEG) is inadequate. Buffer leakage can be two to three times greater than that of aluminum gallium nitride (AlGaN)-based gallium nitride (GaN) HEMTs. Higher buffer leakage leads to reduced radio frequency (RF) efficiency and increased power loss.

[0002] FIG. 1 is an example of an exemplary prior art HEMT heterostructure (100) having a single back barrier layer. FIG. 2 is an example of an exemplary prior art HEMT heterostructure (200) having a single back barrier layer and a transition layer. FIG. 3 is a chart showing energy and free carrier density versus position for the prior art HEMT heterostructures of FIG. 1 and 2, which exhibit parasitic 2DEG. Parasitic 2DEG increases leakage current and reduces the maximum power of the HEMT device. Current back barrier HEMT heterostructures cannot completely eliminate parasitic 2DEG without requiring narrow tolerances for the dimensions of the heterostructure or reducing the back barrier slope.

[0003] FIG. 4 is a drawing of an exemplary prior art HEMT heterostructure (400) having two back barriers. Each back barrier contains AlGaN and has a single fixed percentage of aluminum (Al) concentration, and the first back barrier has a lower Al concentration than the second back barrier. FIG. 5 is a chart of the exemplary HEMT heterostructure of FIG. 4, wherein the first back barrier has a 2% concentration of Al and the second back barrier has a fixed 5% concentration of Al.

[0004] In heterojunctions involving epitaxial growth, achieving precise in-plane lattice matching is difficult, and as a result, it is common for a certain degree of in-plane mismatch to exist between different layers. When an epitaxial layer is grown on a crystalline substrate or on one or more epitaxial layers having defined crystallinity, the in-plane lattice of the epitaxial layer will initially be adjusted to match the in-plane lattice constants of the underlying material. However, as the epitaxial layer undergoes tensile or compressive in-plane strain while attempting to match the underlying in-plane lattice, the strain energy of the epitaxial layer increases until misfit dislocations become large enough to nucleate. The formation of misfit crystal dislocations reduces the strain of the epitaxial layer and causes the in-plane lattice parameters to relax toward the bulk lattice structure above the interface. The thickness at which mismatch potentials nucleate to alleviate strain in an epitaxial layer is known as the critical thickness of the layer. The greater the in-plane lattice mismatch, the thinner the critical thickness of the epitaxial layer becomes. If the thickness of the epitaxial layer is thinner than the critical thickness, the epitaxial layer is said to be pseudomorphic. For Group III nitride-based transistors, nearly matching in-plane lattices between the various layers are required to minimize mismatch potentials and defect formation.

[0005] According to the concepts described in this specification, exemplary heterostructures and methods are, Without forming parasitic 2DEGs It improves electron sealing by providing a pair of continuously gradient back barrier layers of similar shape that enable a much steeper conduction band slope below the channel.

[0006] According to the concept described herein, an exemplary heterostructure and method provide a pair of similarly shaped back barrier layers, wherein one of the pair of back barrier layers is continuously sloped from a buffer material toward a group III nitride (III-N) alloy, and the other of the pair of back barrier layers is continuously sloped from the III-N alloy toward a channel material. Brief explanation of the drawing

[0007] The manner and method of making and using the disclosed embodiments can be understood by referring to the drawings in the accompanying drawings. It should be understood that the components and structures shown in the drawings do not necessarily correspond to actual dimensions and are intended to illustrate the principles of the concepts described herein. The same reference numerals indicate corresponding parts throughout the different drawings. Furthermore, the embodiments are described in the drawings by way of example and are not limiting. FIG. 1 is a drawing of an exemplary HEMT heterostructure of the prior art having a single rear barrier. FIG. 2 is a drawing of an exemplary HEMT heterostructure of the prior art having a single rear barrier and a transition layer. Figure 3 is a chart showing energy and free carrier density versus position for the HEMT heterostructure of the exemplary prior art of Figures 1 and 2. FIG. 4 is a drawing of an exemplary HEMT heterostructure of the prior art having two rear barriers with a fixed percentage of Al concentration in each rear barrier. Figure 5 is a chart of the fixed Al concentration percentages of each of the two rear barriers of the HEMT heterostructure of the prior art of Figure 4. FIG. 6a is a drawing of an exemplary high electron mobility heterostructure of the present disclosure. FIG. 6b is a diagram of an exemplary high electron mobility device of FIG. 6a composed of HEMT. FIG. 6c is a diagram of an exemplary high electron mobility device of FIG. 6a composed of diodes. Figure 7a is a chart of the consecutive percentages of Al concentration in each of the two back barriers of the exemplary high electron mobility heterostructure of Figure 6a. Figure 7b is a chart of the successive polarization gradients at each of the two back barriers of another exemplary high electron mobility heterostructure of Figure 6a. FIG. 8 is a chart showing energy and free carrier density versus position for an exemplary high electron mobility heterostructure of the present disclosure. FIG. 9 is a drawing of a first alternative exemplary high electron mobility heterostructure of the present disclosure. FIG. 10 is a drawing of a second alternative exemplary high electron mobility heterostructure of the present disclosure. FIG. 11 is a drawing of a third alternative exemplary high electron mobility heterostructure of the present disclosure. FIG. 12 is an exemplary method for manufacturing a high electron mobility heterostructure of the present disclosure. Specific details for implementing the invention

[0008] The present disclosure provides a pair of similar-shaped back barrier layers, wherein one of the pair of back barrier layers is continuously gradient from the buffer material toward a group III nitride (III-N) alloy, and the other of the pair of back barrier layers is continuously gradient from the III-N alloy toward the channel material. The gradient of the material generates a quasi-field that affects the shape of the electron energy barrier. To compensate for the quasi-field generated by the varying polarization of the pair of back barrier layers, a certain amount of doping is added to the buffer layer immediately below the pair of similar-shaped back barrier layers. The two consecutive gradients of the pair of back barrier layers and the compensating doping of the buffer material form a barrier in an advantageous manner by increasing the 2DEG confinement through a higher back barrier conduction band gradient. Polarization of the semiconductor arises from the asymmetry of the electron cloud within the crystal lattice. The polarization charge is the sum of the spontaneous polarization charge and the piezoelectric polarization charge. Piezoelectric polarization charges are induced by deformation applied to a material through the piezoelectric effect. Crystals can be subjected to tensile or compressive deformation by growing them into similar shapes using materials with larger or narrower lattice constants. The amount of piezoelectric polarization charge depends on the lattice constant of the material, the lattice constant of the surrounding material, and the extent to which this difference deforms the crystal. Spontaneous polarization charge is a dipole charge induced by the intrinsic asymmetry of the crystal lattice. This appears in crystals with a würzite structure because it exhibits asymmetry in the c-direction of the crystal, and its value varies depending on the constituent atoms and their compositional ratios. A continuous polarization gradient of a material refers to a situation where the material composition of the crystal is gradually adjusted as it grows, causing the polarization charge within the gradient to also gradually change from one material composition to the next. An exemplary continuous polarization gradient can be formed by changing the percentage of Al in an AlGaN layer as it grows.

[0009] FIG. 6a is a drawing of an exemplary high electron mobility heterostructure (600) of the present disclosure. In an exemplary embodiment, the high electron mobility heterostructure (600) comprises a substrate (601), a buffer (603) on the substrate (601), a double continuous gradient back barrier (605) on the buffer (603), a channel (607) on the double continuous gradient back barrier (605), and a charge generating layer (609) on the channel (607).

[0010] The buffer (603) can be doped near the boundary between the buffer (603) and the double continuous gradient back barrier (605). Doping in the buffer (603) near the double continuous gradient back barrier enables band banding there, thereby setting the depletion depth in the buffer (603).

[0011] The dual continuous gradient back barrier (605) comprises a pair of continuously gradient similar-shaped back barrier layers, enabling a significantly steep conduction band gradient below the channel (607) without parasitic 2DEG compared to the HEMT heterostructure of the prior art, and the steep conduction band gradient improves 2DEG confinement. The dual continuous gradient back barrier (605) has a compositional profile that increases the conduction band gradient of the channel (607) and has a higher tolerance for heterostructure dimensions that enables the tunability of the high electron mobility heterostructure (600). For example, the high electron mobility heterostructure (600) can have an increased back barrier gradient, a thicker barrier, or a narrower channel while preventing parasitic 2DEG. There is a directional change in the gradient between the pair of back barrier layers (e.g., the direction of change of Al percentage, or the direction of change of polarization charge). However, each of the pair of back barrier layers is continuous independently of the other. The dual continuous gradient back barrier is gradient according to two directions of change of polarization charge. For example, the lower of a pair of back barrier layers is continuously gradiented so that the polarization charge becomes more positive or increases in the growth direction, whereas the upper of a pair of back barriers is continuously gradiented so that the polarization charge becomes more negative or decreases in the growth direction, as shown in FIG. 9 (e.g., as shown in FIG. 7b).

[0012] The dual polarization gradients in the present disclosure may, for example, be two adjacent, independent, consecutive polarization gradients. The first polarization gradient (e.g., the lower rear barrier (907) shown in FIG. 9) may have a polarization charge that changes monotonically over the first polarization gradient, for example. The second polarization gradient (e.g., the upper rear barrier (907) shown in FIG. 9) may have a polarization charge that changes monotonically over the second polarization gradient that changes in the opposite direction to the first polarization gradient, for example. The polarization gradients may change monotonically (e.g., not inverted, but changed so that increasingly higher or lower values ​​are continuously generated).

[0013] FIG. 6b is a diagram of the exemplary high electron mobility device of FIG. 6a composed of a HEMT. In the exemplary HEMT (600), contacts (611, 613, and 615) are provided for the source, gate, and drain of the HEMT (600), respectively.

[0014] FIG. 6c is a drawing of an exemplary high electron mobility device of FIG. 6a composed of diodes. In the exemplary diode (600), contacts (617 and 619) are provided at the anode and cathode of the diode (600), respectively.

[0015] FIG. 7a is a chart of the continuous percentage of Al concentration in the exemplary double continuous gradient back barrier (605) of FIG. 6a. The double continuous gradient back barrier (605) comprises a pair of back barriers, each of which has a continuous gradient of Al percentage, and the direction of the gradient of polarization charge in each of the two back barriers is opposite to each other. For example, FIG. 7a shows that the lower back barrier of the double continuous gradient back barrier (605) within the AlGaN back barrier is gradiented from 0% Al to a positive rational percentage of Al, which is described in more detail below with reference to FIG. 9, 10, and 11. The upper back barrier of the double continuous gradient back barrier (605) within the AlGaN back barrier is gradiented from a positive rational percentage of Al to 0% Al, which is also described in more detail below with reference to FIG. 9, 10, and 11.

[0016] FIG. 7b is a chart of the continuous change of polarization charge in another exemplary double continuous gradient back barrier (605) of FIG. 6a. The double continuous gradient back barrier (605) comprises a pair of back barriers, each of the pair of back barriers having a continuous gradient of polarization charge, and the direction of the polarization charge gradient in each of the two back barriers is opposite to each other. For example, FIG. 7b shows that the lower back barrier of the double continuous gradient back barrier (605) increases the polarization charge, which is described in more detail below with reference to FIG. 9, 10 and 11. The upper back barrier of the double continuous gradient back barrier (605) decreases the polarization charge, which is also described in more detail below with reference to FIG. 9, 10 and 11.

[0017] FIG. 8 is a chart showing energy and free carrier density versus position for the exemplary high electron mobility heterostructure of FIG. 6a. This chart is for an exemplary embodiment of a GaN / AlGaN double continuous gradient back barrier / GaN heterostructure having a linear 0-10%-0% AlGaN gradient. That is, this exemplary embodiment has a lower back barrier of a double continuous gradient back barrier in which an exemplary Al percentage is linearly gradient from 0% to 10%, and an upper back barrier of a double continuous gradient back barrier in which an exemplary Al percentage is linearly gradient from 10% to 0%.

[0018] FIG. 9 is a drawing of a first alternative exemplary high electron mobility heterostructure (900) of the present disclosure. An exemplary high electron mobility heterostructure (900) comprises a substrate (901), a buffer (903) on the substrate (901), a doped charge compensation layer (905) on the buffer (903), a lower continuous gradient back barrier (907) having a continuously increasing (e.g., monotonically increasing) polarization charge on the doped charge compensation layer (905), an upper continuous gradient back barrier (909) having a continuously decreasing (e.g., monotonically decreasing) polarization charge on the lower continuous gradient back barrier (907), an unintentionally doped (UID) channel (911) on the upper continuous gradient back barrier (909), and a charge generation layer (913) on the unintentionally doped (UID) channel (911). Optionally, there may be at least one nucleation layer (915) between the substrate (901) and the buffer (903), at least one intermediate layer (917) between the unintentionally doped (UID) channel (911) and the charge generation layer (913), and a capping layer (919) on the charge generation layer (913). The lower continuous gradient back barrier (907), the upper continuous gradient back barrier (909), the intermediate layer (917), the charge generation layer (913), and the capping layer (919) comprise a pseudomorphically strained layer.

[0019] The substrate (901) may be silicon (Si), silicon carbide (SiC), sapphire, GaN, AlN, diamond, boron nitride (BN), or other suitable substrate (e.g., SiC). The buffer (903) may be GaN or AlN or any other suitable material (e.g., GaN).

[0021] The lower continuous gradient back barrier (907) may have a thickness greater than 3 nm. In an exemplary embodiment in which the lower continuous gradient back barrier (907) (e.g., AlGaN) contains Al, the percentage of Al in the lower continuous gradient back barrier (907) may be continuously gradiented in the Al range of 0 to 5% and may increase (e.g., monotonically increase) to the Al range of 2 to 30%. In an exemplary embodiment in which the lower continuous gradient back barrier (907) (e.g., InGaN back barrier) contains indium (In) but does not contain Al, the percentage of In in the lower continuous gradient back barrier (907) may be continuously gradiented in the In range of 5 to 100% and may decrease (e.g., monotonically decrease) to the In range of 0 to 95%. The upper continuous gradient back barrier (909) may have a thickness greater than 3 nm. In an exemplary embodiment in which Al is included in the upper continuous gradient rear barrier (909), the percentage of Al present in the upper continuous gradient rear barrier (909) is continuously gradiented in the Al range of 2 to 30% and decreases (e.g., monotonically decreases) to the Al range of 0 to 5%. In an exemplary embodiment in which Indium (In) is included in the upper continuous gradient rear barrier (909) (e.g., InGaN rear barrier) but not Al is included, the percentage of In in the upper continuous gradient rear barrier (909) can be continuously gradiented in the In (e.g., GaN) range of 0 to 95% and can increase (e.g., monotonically increase) to the In (e.g., InGaN) range of 5 to 100%. That is, the lower continuous gradient rear barrier (907) and the upper continuous gradient rear barrier (909) are gradiented in opposite directions.The lower continuous gradient rear barrier (907) and the upper continuous gradient rear barrier (909) may each be gradiented with the same percentage of material (e.g., 0% to 100% Al or In) but in opposite directions (e.g., 0% to 100% Al or In versus 100% to 0% Al or In), or gradiented with different percentages of material (e.g., 0% to 100% Al or In versus 95% to 5% Al or In) but in opposite directions (e.g., 0% to 100% to 95% to 5%). The total thickness of the lower continuous gradient rear barrier (907) and the upper continuous gradient rear barrier (909) may be the same or different, and they are thinner than the critical thickness for relaxation. In the growth of a layer deformed into a similar shape, the critical thickness is the thickness until relaxation does not occur, and if this is exceeded, it is the thickness at which relaxation occurs due to the formation of a mismatched dislocation.

[0022] The UID channel (911) may be GaN, AlGaN, or InGaN, and its thickness is within the range of 5 nm to 200 nm. 2DEG may be induced in the UID channel (911) by a charge generation layer (913). The charge generation layer (913) may be AlGaN, ScAlN, InAlN, InGaAlN, or AlN. At least one intermediate layer (917) may be AlN or GaN. The capping layer (919) may be GaN, AlN, or SiN x It can be, where x is a positive rational number.

[0023] FIG. 10 is a drawing of a second alternative exemplary high electron mobility heterostructure of the present disclosure. The exemplary high electron mobility heterostructure (1000) comprises a substrate (1001), a doped buffer (1003) on the substrate (1001), a doped charge compensation layer (1005) on the doped buffer (1003), a lower continuous increasing (e.g., monotonically increasing) polarization charge gradient back barrier (1007) on the doped charge compensation layer (1005), an upper continuous decreasing (e.g., monotonically decreasing) polarization charge gradient back barrier (1009) on the lower continuous increasing back barrier (1007), an unintentionally doped (UID) channel (1011) on the upper continuous increasing back barrier (1009), and a charge generating layer (1013) on the UID channel (1011). Optionally, there may be at least one nucleation layer (1015) between the substrate (1001) and the doped buffer (1003), at least one intermediate layer (1017) between the UID channel (1011) and the charge generation layer (1013), and a capping layer (1019) on the charge generation layer (1013). The lower continuous gradient back barrier (1007), the upper continuous gradient back barrier (1009), at least one intermediate layer (1017), the charge generation layer (1013), and the capping layer (1019) comprise layers with similar shape deformation.

[0024] The substrate (1001) may be silicon (Si), silicon carbide (SiC), sapphire, GaN, AlN, diamond, boron nitride (BN), or other suitable substrates (e.g., SiC). The doped buffer (1003) may be GaN or AlN, or other suitable materials (e.g., GaN). The doped charge compensation layer (1005) may be GaN.

[0025] The lower continuous gradient back barrier (1007) may be AlGaN with a thickness greater than 3 nm, wherein the Al percentage of the lower continuous gradient back barrier (1007) is continuously gradiented in the Al range of 0 to 5% and increases in the Al range of 2 to 30% (e.g., monotonically increasing). The upper continuous gradient back barrier (1009) may be AlGaN with a thickness greater than 3 nm, wherein the Al percentage of the upper continuous gradient back barrier (1009) is continuously gradiented in the Al range of 2 to 30% and decreases in the Al range of 0 to 5% (e.g., monotonically decreasing). That is, the lower continuous gradient back barrier (1007) and the upper continuous gradient back barrier (1009) are gradiented in opposite directions. The lower continuous gradient rear barrier (1007) and the upper continuous gradient rear barrier (1009) may be gradiented with the same but opposite percentages of Al, or gradiented with different but opposite percentages of Al. The total thickness of the lower continuous gradient rear barrier (1007) and the upper continuous gradient rear barrier (1009) may be the same or different, and they are thinner than the critical thickness for relaxation. In the growth of a layer deformed in a similar shape, the critical thickness is the thickness until relaxation does not occur, and exceeding this is the thickness at which relaxation occurs due to the formation of mismatched dislocations.

[0026] The UID channel (1011) may be GaN, AlGaN, or InGaN (e.g., GaN), and its thickness may be in the range of 5 nm to 200 nm. 2DEG may be induced in the UID channel (1011) by a charge generation layer (1013). The charge generation layer (1013) may be AlGaN, ScAlN, InAlN, InGaAlN, or AlN. At least one intermediate layer (1017) may be AlN or GaN. The capping layer (1019) may be GaN, AlN, or SiN x It can be, where x is a positive rational number.

[0027] FIG. 11 is a drawing of a third alternative exemplary high electron mobility heterostructure of the present disclosure. An exemplary high electron mobility heterostructure (1100) comprises a substrate (1101), a nucleation layer (1103) on the substrate (1101), a doped buffer (1105) on the nucleation layer (1103), a doped charge compensation layer (1107) on the doped buffer (1105), a lower continuous increasing (e.g., monotonically increasing) polarization charge gradient back barrier (1109) on the doped charge compensation layer (1107), an upper continuous decreasing (e.g., monotonically decreasing) polarization charge gradient back barrier (1111) on the lower continuous gradient back barrier (1109), a UID channel (1113) on the upper continuous gradient back barrier (1111), at least one intermediate layer (1115) on the UID channel (1113), a charge generation layer (1117) on at least one intermediate layer (1115), and on the charge generation layer (1117). It includes a cap layer (1119). The lower continuous gradient rear barrier (1109), the upper continuous gradient rear barrier (1111), at least one intermediate layer (1115), the charge generating layer (1117), and the cap layer (1119) include a similar shape deformation layer.

[0028] The substrate (1101) may be Si, SiC, sapphire, GaN, AlN, diamond, BN, or other suitable substrates. The doped buffer (1105) may be GaN or AlN or other suitable materials (e.g., GaN). The doped charge compensation layer (1107) may be beryllium (Be)-doped GaN with a thickness of 15 nm. More generally, the doped charge compensation layer (1107) may be doped with Be, magnesium (Mg), iron (Fe), carbon (C), manganese (Mn), or other dopants to allow band bending to match the quasi-magnetic field generated near the lower back barrier interface, thereby allowing the buffer to remain in a semi-insulating state.

[0029] The lower continuous gradient back barrier (1109) may be AlGaN with a thickness greater than 3 nm (e.g., 15 nm), wherein the Al percentage of the lower continuous gradient back barrier (1109) is continuously gradiented in the Al range of 0 to 5% (e.g., 0%) and increases (e.g., monotonically increases) to the Al range of 2 to 30% (e.g., 10%). The upper continuous gradient back barrier (1111) may be AlGaN with a thickness greater than 3 nm (e.g., 15 nm), wherein the Al percentage of the upper continuous gradient back barrier (1111) is continuously gradiented in the Al range of 2 to 30% (e.g., 10%) and decreases (e.g., monotonically decreases) to the Al range of 0 to 5% (e.g., 0%). That is, the lower continuous gradient rear barrier (1109) and the upper continuous gradient rear barrier (1111) are gradients in opposite directions. The lower continuous gradient rear barrier (1109) and the upper continuous gradient rear barrier (1111) may be gradients with the same percentage of Al but in opposite directions, or gradients with different percentages of Al but in opposite directions. The total thickness of the lower continuous gradient rear barrier (1109) and the upper continuous gradient rear barrier (1111) may be the same or different, and they are thinner than the critical thickness for relaxation. In the growth of a layer deformed in a similar shape, the critical thickness is the thickness until relaxation does not occur, and exceeding this is the thickness at which relaxation occurs due to the formation of mismatched dislocations.

[0030] The UID channel (1113) may be GaN, AlGaN, or InGaN, and its thickness is in the range of 5 nm to 200 nm (e.g., 70 nm GaN). An optional intermediate layer (1115) (e.g., an AlN intermediate layer) may separate the UID channel (1113) from the charge generation layer (1117). A 2DEG may be induced in the UID channel (1113) by the charge generation layer (1117). The barrier (1117) may be AlGaN, ScAlN, InAlN, InGaAlN, or AlN (e.g., ScAlN). The cap layer (1119) may be GaN, AlN, or SiN x It can be (e.g., GaN), where x is a positive rational number.

[0031] FIG. 12 is an exemplary method for manufacturing a high electron mobility heterostructure (e.g., HEMT or high electron mobility diode) of the present disclosure. The exemplary method (1200) comprises forming a substrate in step (1201). Step (1203) of the method (1200) comprises forming a buffer on the substrate. Step (1205) comprises forming a doped charge compensation layer on the buffer. Step (1207) comprises forming a double continuous gradient barrier on the doped charge compensation layer. Step (1209) comprises forming a channel on the double continuous gradient barrier. Step (1211) comprises forming a charge generation layer on the channel.

[0032] Since exemplary embodiments of the present disclosure have been described, those skilled in the art will understand that other embodiments incorporating the concept may also be used. The embodiments included in this specification are not to be limited to the disclosed embodiments, but rather should be limited only by the spirit and scope of the appended claims. All publications mentioned in this specification are incorporated herein by reference in their entirety.

[0033] The elements of the various embodiments described herein may be combined to form other embodiments not specifically stated above. The various elements described in the context of a single embodiment may also be provided individually or in any suitable sub-combination. Other embodiments not specifically described herein are also within the scope of the following claims.

[0034] Various aspects of the concepts, systems, devices, structures, and technologies to be protected are described herein with reference to the relevant drawings. Alternative aspects may be devised without departing from the scope of the concepts, systems, devices, structures, and technologies described herein.

[0035] Note that various connections and positional relationships (e.g., above, below, adjacent, etc.) are established between the elements in the description and drawings above. Unless otherwise specified, these connections and / or positional relationships may be direct or indirect, and the described concepts, systems, devices, structures, and technologies are not intended to be limiting in this regard. Accordingly, the combination of entities may imply a direct or indirect combination, and the positional relationships between entities may be direct or indirect positional relationships.

[0036] As an example of an indirect positional relationship, references in this description to forming layer "A" on layer "B" include a situation in which one or more intermediate layers (e.g., layer "C") are located between layer "A" and layer "B," provided that the relevant characteristics and functions of layer "A" and layer "B" are not substantially altered by the intermediate layer(s). The following definitions and abbreviations are used to interpret the claims and the specification. Any term used herein, such as "comprises," "comprising," "includes," "including," "has," "having," "contains," or "containing," or any other variation thereof, is intended to encompass non-exclusive inclusions. For example, a composition, mixture, process, method, article, or device comprising a list of elements is not necessarily limited to such elements and may include other elements not explicitly listed or inherent in such composition, mixture, process, method, article, or device.

[0037] Additionally, the term “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described as “exemplary” herein must not be interpreted as being preferred or advantageous over other embodiments or designs. The terms “one or more” and “at least one” are understood to include integers greater than or equal to 1, i.e., 1, 2, 3, 4, etc. The term “plural” is understood to include integers greater than or equal to 2, i.e., 2, 3, 4, 5, etc. The term “connection” may include indirect “connection” and direct “connection.”

[0038] References to "one embodiment," "one embodiment," "exemplary embodiment," etc., in the specification indicate that while the described embodiments may include specific features, structures, or characteristics, all embodiments may include specific features, structures, or characteristics. Furthermore, such wording does not necessarily refer to the same embodiment. Additionally, when specific features, structures, or characteristics are described in relation to an embodiment, it indicates that the influence of such features, structures, or characteristics in relation to other embodiments is within the scope of knowledge of a person skilled in the art, regardless of whether it is explicitly described.

[0039] For the purposes of explanation in this specification, terms such as “top,” “bottom,” “right,” “left,” “vertical,” “horizontal,” “top,” and “bottom,” and their derivatives, shall relate to structures and methods described as oriented in the drawings. The terms “on top,” “on the top,” “on the top,” “located on top,” or “located on the top” mean that a first element, such as a first structure, exists on a second element, such as a second structure, wherein an intermediate element, such as an interface structure, may exist between the first element and the second element. The term “direct contact” means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediate element. These terms are sometimes also referred to as directional terms or positional terms.

[0040] The use of ordinal terms such as "first," "second," "third," etc., in a claim to modify the elements of the claim does not, in itself, imply any priority, order, or sequence of one claim element over another, nor does it imply a chronological order in which the operation of the method is performed; instead, it is used as a marker to distinguish claim elements by separating one claim element with a specific name from another element having the same name (in the case of using ordinal terms).

[0041] The terms "approximately" and "about" may be used to mean within ±20% of the target value in some embodiments, within ±10% of the target value in some embodiments, within ±5% of the target value in some embodiments, and within ±2% of the target value in some embodiments. The terms "approximately" and "about" may include the target value. The term "virtually identical" may be used to refer to values ​​within ±20% of each other in some embodiments, within ±10% of each other in some embodiments, within ±5% of each other in some embodiments, and within ±2% of each other in some embodiments.

[0042] The term “effectively” may be used to refer to values ​​within ±20% of the comparative measurement in some modalities, within ±10% in some modalities, within ±5% in some modalities, and within ±2% in some modalities. For example, a first direction that is “effectively” perpendicular to the second direction may refer to a first direction that is within ±20% of the angle of 90° with the second direction in some modalities, within ±10% of the angle of 90° with the second direction in some modalities, within ±5% of the angle of 90° with the second direction in some modalities, and within ±2% of the angle of 90° with the second direction in some modalities.

[0043] It should be understood that the disclosed subject matter is not limited to the configuration details and arrangement of components specified in the following description or illustrated in the drawings. Other embodiments of the disclosed subject matter are possible and may be practiced or performed in various ways.

[0044] Furthermore, it should be understood that the phrases and terms applied herein are for illustrative purposes only and should not be construed as limitations. Accordingly, those skilled in the art will understand that the concepts forming the basis of this disclosure can be readily utilized as a basis for designing other structures, methods, and systems to achieve various purposes of the disclosed subject matter. Accordingly, the claims should be deemed to include such equivalent configurations without departing from the spirit and scope of the disclosed subject matter.

[0045] Although the disclosed subject matter has been described and explained in the exemplary embodiments mentioned above, it should be understood that the present disclosure is made merely by way of example and that numerous changes to the details of the implementation of the disclosed subject matter may be made without departing from the spirit and scope of the disclosed subject matter.

Claims

Claim 1 A high electron mobility heterostructure comprising: a substrate; a buffer on the substrate; a doped charge compensation layer on the buffer; a double continuous grade barrier having increasing polarization charge and decreasing polarization charge located on the doped charge compensation layer; a channel on the double continuous grade barrier; and a charge generation layer on the channel. Claim 2 A high electron mobility heterostructure according to claim 1, wherein the substrate is one of silicon (Si), silicon carbide (SiC), sapphire, gallium nitride (GaN), aluminum nitride (AlN), boron nitride (BN), and diamond. Claim 3 A high electron mobility heterostructure according to claim 1, wherein the buffer is one of gallium nitride (GaN) and aluminum nitride (AlN). Claim 4 A high electron mobility heterostructure according to claim 1, wherein the doped charge compensation layer is gallium nitride (GaN) doped with at least one of beryllium, magnesium, iron, carbon, and manganese. Claim 5 In claim 1, the double continuous gradient barrier comprises a high electron mobility heterostructure comprising: a first aluminum gallium nitride (AlGaN) barrier layer having a monotonically increasing polarization charge and an aluminum (Al) content gradient from a first range of 0% to 5% to a second range of 2% to 30%; and a second aluminum gallium nitride (AlGaN) barrier layer on the first aluminum gallium nitride (AlGaN) barrier layer having a monotonically decreasing polarization charge and an aluminum (Al) content gradient from a first range of 2% to 30% to a second range of 0% to 5%. Claim 6 A high electron mobility heterostructure according to claim 5, wherein the first range of the first aluminum gallium nitride (AlGaN) barrier layer comprises one of the same as the second range of the second aluminum gallium nitride (AlGaN) barrier layer or different from the second range of the second aluminum gallium nitride (AlGaN) barrier layer, and the second range of the first aluminum gallium nitride (AlGaN) barrier layer comprises one of the same as the first range of the second aluminum gallium nitride (AlGaN) barrier layer or different from the first range of the second aluminum gallium nitride (AlGaN) barrier layer. Claim 7 A high electron mobility heterostructure according to claim 5, wherein the first aluminum gallium nitride (AlGaN) barrier layer has a thickness greater than 3 nm, the second aluminum gallium nitride (AlGaN) barrier layer has a thickness greater than 3 nm, the thickness of the first aluminum gallium nitride (AlGaN) barrier layer is one of being equal to or different from the thickness of the second aluminum gallium nitride (AlGaN) barrier layer, and the thickness of the combination of the first aluminum gallium nitride (AlGaN) barrier layer and the second aluminum gallium nitride (AlGaN) barrier layer is thinner than the critical thickness for relaxation. Claim 8 A high electron mobility heterostructure according to claim 1, wherein the channel is an unintentionally doped channel that is one of gallium nitride (GaN) and indium gallium nitride (InGaN). Claim 9 A high electron mobility heterostructure according to claim 1, wherein the charge generating layer is one of aluminum gallium nitride (AlGaN), scandium aluminum nitride (ScAlN), indium aluminum nitride (InAlN), indium aluminum gallium nitride (InAlGaN), and aluminum nitride (AlN). Claim 10 In claim 1, further comprising: a nucleation layer between the substrate and the buffer; at least one intermediate layer between the channel and the charge generation layer; and a capping layer on the charge generation layer; wherein the at least one intermediate layer is one of aluminum nitride (AlN) and gallium nitride (GaN), and the capping layer is GaN, AlN, and silicon nitride (SiN x A high electron mobility heterostructure that is one of ) where x is a positive rational number. Claim 11 A method for manufacturing a high electron mobility heterostructure, wherein the method comprises the steps of: forming a substrate; forming a buffer on the substrate; forming a doped charge compensation layer on the buffer; forming a double continuous gradient barrier having an increasing polarization charge and a decreasing polarization charge on the doped charge compensation layer; forming a channel on the double continuous gradient barrier; and forming a charge generation layer on the channel. Claim 12 A method for manufacturing a high electron mobility heterostructure according to claim 11, wherein the substrate is one of silicon (Si), silicon carbide (SiC), sapphire, gallium nitride (GaN), aluminum nitride (AlN), boron nitride (BN), and diamond. Claim 13 A method for manufacturing a high electron mobility heterostructure, wherein, in claim 11, the buffer is one of gallium nitride (GaN) and aluminum nitride (AlN). Claim 14 A method for manufacturing a high electron mobility heterostructure, wherein, in claim 11, the doped charge compensation layer is gallium nitride (GaN) doped with at least one of beryllium, magnesium, iron, carbon, and manganese. Claim 15 A method for manufacturing a high electron mobility heterostructure according to claim 11, wherein the double continuous gradient barrier comprises: a first aluminum gallium nitride (AlGaN) barrier layer having an aluminum (Al) content gradient from a first range of 0% to 5% to a second range of 2% to 30%, having a monotonically increasing polarization charge; and a second aluminum gallium nitride (AlGaN) barrier layer on the first aluminum gallium nitride (AlGaN) barrier layer having an aluminum (Al) content gradient from a first range of 2% to 30% to a second range of 0% to 5%, having a monotonically decreasing polarization charge. Claim 16 A method for manufacturing a high electron mobility heterostructure according to claim 15, wherein the first range of the first aluminum gallium nitride (AlGaN) barrier layer comprises one of the same as the second range of the second aluminum gallium nitride (AlGaN) barrier layer or different from the second range of the second aluminum gallium nitride (AlGaN) barrier layer, and the second range of the first aluminum gallium nitride (AlGaN) barrier layer comprises one of the same as the first range of the second aluminum gallium nitride (AlGaN) barrier layer or different from the first range of the second aluminum gallium nitride (AlGaN) barrier layer. Claim 17 A method for manufacturing a high electron mobility heterostructure according to claim 15, wherein the first aluminum gallium nitride (AlGaN) barrier layer has a thickness greater than 3 nm, the second aluminum gallium nitride (AlGaN) barrier layer has a thickness greater than 3 nm, the thickness of the first aluminum gallium nitride (AlGaN) barrier layer is one of being equal to or different from the thickness of the second aluminum gallium nitride (AlGaN) barrier layer, and the thickness of the combination of the first aluminum gallium nitride (AlGaN) barrier layer and the second aluminum gallium nitride (AlGaN) barrier layer is thinner than the critical thickness for relaxation. Claim 18 A method for manufacturing a high electron mobility heterostructure, wherein, in claim 11, the channel is an unintentionally doped channel that is one of gallium nitride (GaN) and indium gallium nitride (InGaN). Claim 19 A method for manufacturing a high electron mobility heterostructure, wherein, in claim 11, the charge generating layer is one of aluminum gallium nitride (AlGaN), scandium aluminum nitride (ScAlN), indium aluminum nitride (InAlN), indium aluminum gallium nitride (InAlGaN), and aluminum nitride (AlN). Claim 20 In claim 11, the method further comprises the steps of: forming a nucleation layer between the substrate and the buffer; forming at least one intermediate layer between the channel and the charge generation layer; and forming a capping layer on the charge generation layer, wherein the at least one intermediate layer is one of aluminum nitride (AlN) and gallium nitride (GaN), and the capping layer is GaN, AlN, and silicon nitride (SiN x A method for manufacturing a high electron mobility heterostructure, wherein it is one of ) where x is a positive rational number.

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