Electronic component, control method for electronic component, and manufacturing method for electronic component

Abstract

The electronic component comprises a first layer and a second layer, a major surface of the first layer disposed opposite a major surface of the second layer, the first layer comprising a polarized first material, the polarization of the first material being oriented in a first direction, the second layer comprising a polarized second material having at least one polarization state, the direction of polarization of the second material in at least one polarization state of the second material being at least partially opposite to the first direction, such that charge zones are formed along the major surfaces of the first layer and / or the second layer, the charge zones being conductive when at least the second material is in one polarization state.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the invention relate to electronic components, e.g. semiconductor structures. Some embodiments relate to semiconductor heterostructures. Further embodiments relate to methods of manufacturing electronic components, e.g. semiconductor structures. Further embodiments relate to methods of controlling electronic components.

[0002] Some embodiments relate to semiconductor devices with improved electrical conductivity. Some embodiments relate to High Electron Mobility Transistors (HEMTs), for use in, for example, converters or power amplifiers. [Background technology]

[0003] Increased efficiency and power density are one of the essential drivers for the development of converters for DC / DC, DC / AC and AC / DC applications. Specifically, in the server farm sector, the required cooling capacity depends directly on the conversion losses of the supply voltage at the PCB level. In the automotive sector, the motor integration of power electronic components increases the power density with an increased demand for heat dissipation and long-term reliability. Therefore, in recent years, components based on wide bandgap semiconductors, e.g. silicon carbide (SiC) or III-N, such as GaN, AlN and InN, as well as their tertiary compounds, are becoming more widespread. These semiconductor components, by exploiting the unipolar conductivity of electrons, significantly reduce switching losses compared to bipolar components, allowing them to decay to the background rather than on-state losses. The roadmap of future components is therefore, at present, substantially determined by the minimum available area resistivity of the component. In the blocking voltage region around 600V, at present, it is possible to achieve a resistance of 1 mOhm*cm based on GaN HEMT transistors. 2 An area specific forward resistance of less than 1000 nm is achieved.

[0004] Ultra-high charge carrier densities in wide bandgap semiconductor components are achieved by forming a two-dimensional electron gas (2DEG) at the interface of polar III-nitrides [1]. The cause of the formation of the 2DEG is the discontinuity of the polarization of the two materials. The polarization then results from the crystal structure of the materials used and includes spontaneous and piezoelectric polarization. There are studies [3]-[6] on the magnitude and sign of some materials, for example those with a wurtzite structure. The charge density of the 2DEG produced by conventional approaches is about 6×10 13 / cm 2 Up to 10μC / cm, which corresponds to an electron density of 2 achieve values ​​of about the same order of magnitude [2]. Summary of the Invention

[0005] With the first stated objective in mind, it would be desirable for electronic components to have high electrical conductivity. The inventors have found that when the first and second layers of a heterolayer structure are formed such that the polarization of the first material of the first layer is at least partially opposite to the polarization of the second material of the second layer, charge zones having particularly high electrical conductivity can be formed along the interface of the heterolayer structure in the heterolayer structure of an electronic component.

[0006] An embodiment of the present invention provides an electronic component having, for example, a semiconductor heterostructure, for example, a heterolayer structure. The electronic component comprises a first layer and a second layer. A main surface, for example, a main surface region, of the first layer is arranged opposite a main surface, for example, a main surface region, of the second layer. The first layer comprises a polarized first material, and the second layer comprises a polarized second material, the second material being distinguishable from the first material, for example having a band gap different from the band gap of the first material. Polarized material is understood to mean, for example, an electrically polarized material, for example a material having a polar crystal structure. Examples of polarized materials include pyroelectric materials, including ferroelectric materials. The polarization of the first material points in a first direction. The second material has at least one polarization state, i.e. a polarized state, i.e. the second material can be at least one polarized state characterized, for example, by the direction of polarization of the second material. A polarization state may be a single state (e.g., a permanent state of the second material) or may be one of a plurality of polarization states of the second material. For example, in one second polarization state direction of the at least second material, corresponding to a first polarization state of the plurality of possible polarization states, the direction of polarization of the second material is at least partially opposite to the first direction or at least partially antiparallel to the first direction. The second layer is configured such that, at least in a polarization state, a charge zone is formed along a major surface of the first layer and / or the second layer, which is conductive when at least the second material is in the polarization state. The charge zone is, for example, a two-dimensional depletion region, such as a 2DEG, which may be located, for example, in the first layer, in the second layer, or between the first layer and the second layer.

[0007] Since both the first and second materials are polarized, charge zones can be formed along the main surfaces of the first and / or second layers, which are confined in the direction perpendicular to the main surfaces to a few nanometers in the embodiment. In such one-dimensionally confined charge zones, also called 2DEG, the mobility of the charge carriers can also be very high, so that high electrical conductivity is achieved. Due to the small dimensions of the charge zones in the direction perpendicular to the main surfaces of the first or second layers, the charge carrier density in the charge zones can be influenced very efficiently, for example, by an electric field. This offers the possibility to implement transistors, for example for converters, that can switch very high currents with relatively small electric fields.

[0008] To create the 2DEG, conventional layers are deposited such that the polarization of both layers points in the same direction. In theoretical calculations, it was possible to assume that this is the optimal configuration for these structures and, moreover, that it is easier to manufacture than structures with opposite polarizations [1]. However, the inventors have found that a higher charge carrier density can be achieved if the polarization of the two materials in the two layers is opposite. In embodiments of the present invention, a charge carrier density that is increased by a factor of 25 compared to the prior art can be created in the charge zone. As a result, for example, the power losses of HEMTs based on such heterostructures can be significantly reduced.

[0009] The inventors have found that this can be achieved in the case of multiple polarized materials, the magnitude of the effect depending on the magnitude of the polarization of the materials used. In other words, the effect of increasing the charge carrier density can be expected for all heterostructures of two layers containing polar materials, for example materials with a wurtzite structure, as long as a state of two structures is created in which the polarization of the two layers is oriented in opposite directions. This state can be achieved in an embodiment by a suitable deposition process. In a further embodiment, this state can be achieved because the polarization of one of the two layers is reversed or at least changed so that the polarization of that layer is at least partially opposite to the other of these layers by the application of an electric field.

[0010] In an embodiment, the first material has a wurtzite crystal structure and the second material has a wurtzite crystal structure. Materials with a wurtzite crystal structure are polar and are particularly suitable for creating a polarization discontinuity between the first and second layers, so that the creation of a two-dimensional electron gas with a high charge carrier density can be achieved. Furthermore, these materials tend to have a high band gap, so that they are particularly suitable for power electronic components. Because both the first and second materials have a wurtzite crystal structure, the layer structure including the first and second layers can be manufactured in a way that is particularly low in defects, which has a positive effect on the electrical conductivity.

[0011] In an embodiment, the charge carrier density in the charge zone is greater than 10 when the first material is in one polarization state. 12 cm -2 More than or 10 13 cm -2 Over or 6x10 13 cm -2 It is.

[0012] Further embodiments of the present invention provide, for example, an electronic component having a semiconductor heterostructure, for example a heterolayer structure. The electronic component comprises a first layer and a second layer. A major surface, for example a major surface region, of the first layer is arranged opposite a major surface, for example a major surface region, of the second layer. The first layer comprises a first material having a wurtzite crystal structure. The polarization of the first material points in a first direction. For example, the first direction is perpendicular to the major surface of the first and / or second layer. The second layer comprises a second material having a wurtzite crystal structure. For example, the second material is different from the first material, for example, the second material has a band gap different from the band gap of the first material. The second material is ferroelectric. The direction of polarization of the second material is at least partially opposite to the first direction in at least one polarization state, for example a first polarization state of a plurality of possible polarization states, such as a predetermined polarization state. In an embodiment, the second material is polarized or can be set to a polarized state, for example, by an electric field. The second material includes a transition metal. For example, the second material is a compound of materials, at least one of which is a transition metal. An embodiment of the electronic component has the functions and advantages described in connection with the above embodiments.

[0013] Although the material with the wurtzite crystal structure is polar, charge zones can be formed along the main faces of the first and / or second layers. The polarization of the first material, which is at least partially opposite to the second material, allows a particularly strong manifestation of the polarization discontinuity between the first and second layers, so that a particularly high charge carrier density can be generated in this charge zone. Ferroelectric materials have the property that the orientation of the polarization can be changed by applying an electric field, which orientation is maintained even when the electric field is no longer applied. The change in the orientation of the polarization of the second material affects the manifestation of the polarization discontinuity between the first and second layers. Thus, in this way, the charge carrier density in the charge zone can be set. The use of ferroelectric materials can therefore make it possible to control the conductivity of the charge zone by setting the polarization state. Additionally, the ability to change the polarization direction of the second material allows for a simple manufacturing process of electronic components, where the polarization directions of the first and second layers are at least partially opposite to each other. For example, the first and second layers can be manufactured in a way that matches the polarization of the first and second layers, thus making it possible to achieve high conductivity in the charge zone by retroactively changing the polarization direction of the second layer, for example by an electric field.

[0014] The electric field strength of a ferroelectric material required to change the polarization direction is also referred to as the coercivity. The inventors have found that materials containing transition metals tend to have lower coercivity than corresponding materials that do not contain transition metals. Specifically, the coercivity of materials containing transition metals may be less than the breakdown electric field strength, thereby allowing these materials to be ferroelectric. For example, III-nitride compounds containing transition metals may be ferroelectric as opposed to corresponding pure III-nitride compounds.

[0015] Advantageous examples of the above-mentioned embodiments are described below. In an embodiment, when the first material is in one polarization state, the charge carrier density in the charge zone along the first layer and / or the second layer, such as the charge zone in the above embodiment, is greater than 10 12 cm -2 More than or equal to 1013 cm -2 Over 6 x 10 13 cm -2 The charge carrier density is over 10 12 cm -2 A charged zone is conductive if the charge carrier density is greater than 6×10 13 cm -2 .sup.1 has a particularly high electrical conductivity, for example higher than that in the solutions known from the prior art.

[0016] In an embodiment, the first material is a nitride compound containing at least one group III element. Alternatively or additionally, in this embodiment, the second material is a nitride compound containing at least one group III element. Group III nitride compounds tend to have high bandgaps. Thus, semiconductor components, such as HEMTs, can be constructed with particularly low losses through the use of Group III nitride compounds.

[0017] In an embodiment, the second material is a nitride compound containing one or more group III elements and further containing a transition metal. The inventors have found that some materials of group III nitride compounds further containing a transition metal are ferroelectric. Thus, the advantage of using ferroelectric materials can be combined with the advantage of a large band gap.

[0018] In an embodiment, the stoichiometric proportion of the transition metal in the nitrogen compound is between 10% and 50% of the total stoichiometric proportion of the one or more group III elements in the nitrogen compound of the second material. The inventors have found that such a proportion of the transition metal can ensure a particularly high polarization of the second material. Thus, a high charge carrier density can be achieved along the main faces of the first layer and / or the second layer in the charge zone. A proportion of more than 10% can ensure that the second material is ferroelectric.

[0019] In an embodiment, the first material is one of GaN, GaScN, AlScN, AlN, InGaN, InGaScN, AlGaN, AlGaScN. Alternatively or additionally, in an embodiment, the second material is one of AlscN, AlGaScN, GaScN, AlN, AlGaN, AlMgNbN, AlGaN, AlGaScN. These materials offer a particularly good combination of high bandgap and large polarization.

[0020] In an embodiment, the combination of the second material and the first material (second material / first material) is one of AlScN / GaN, AlScN / GaScN, AlGaScN / GaN, GaScN / AlScN, GaScN / AlN, AlScN / InGaN, AlScN / InGaScN, AlMgNbN / GaN. These combinations are particularly suitable due to the ratio of the band gaps of the first and second materials and the polarization of the first and second materials (which may depend on the combination) to form a high charge carrier density in the charge zone. Furthermore, these material combinations can be reliably manufactured by established manufacturing methods such that at least the polarization directions of the first and second materials are identical. Optionally, the first and second materials can be selected to have similar lattice constants. Thus, the manufacturing process of the electronic component can be particularly simple and a main surface of the first and second materials that is almost free of defects can be achieved, which may have a positive effect on the electrical conductivity in the charge zone.

[0021] In an embodiment, the second material is ferroelectric so that the direction of polarization of the second material can be changed. One polarization state, i.e. the polarization state mentioned above, in which the direction of polarization of the second material is at least partially opposite to the first direction, is the first polarization state. In the second polarization state of the second material, the direction of polarization of the second material is at least partially aligned with the first direction, e.g. at least partially parallel to the first direction. "At least partially aligned" is understood to mean that the polarization includes a directional component pointing in the first direction. By changing between the first and second polarization states, the electrical conductivity of the charge zone can be changed between a high value and a low value, since the charge carrier density in the charge zone along the major surface of the first layer and / or the second layer is higher when the polarizations of the first and second layers are at least partially opposite than when the polarizations of the first and second layers are at least partially aligned. This allows the implementation of switchable electronic components. Because the direction of polarization of the second material can be changed, electronic components can be implemented such that the polarization of the second material is oriented in a first direction in a first region and in a second direction in a second region, thereby implementing regions of different electrical conductivity, thereby defining, for example, conductive channels. Additionally, this embodiment has the advantages discussed above with respect to a ferroelectric second material.

[0022] In embodiments, the charge carrier density in the charge zone along a major surface of the first layer and / or the second layer is higher when the second material is in the first polarization state than when the second material is in the second polarization state, i.e., the second material and / or the first material are configured to produce this effect. This can be achieved, for example, using the materials described above.

[0023] In an embodiment, the electronic component further comprises a third layer disposed between the first layer and the second layer and having a wurtzite crystal structure. The third layer can change the location of the charge zone such that the third layer is spaced from the second layer, for example, at the first layer or at a major surface of the first layer (the charge zone can also extend into the third layer). The first layer, in an embodiment, can be epitaxially grown and therefore can have few defects. In some embodiments, the third layer between the first layer and the second layer can reduce the number of surface defects at the major surface of the first layer and / or the second layer compared to an arrangement in which the first layer and the second layer are directly adjacent. Thereby, a higher electrical conductivity is achieved. Furthermore, the second layer can compensate for the difference in lattice constants of the first layer and the second layer. In an embodiment, the polarization of the first layer and / or the second layer can be increased.

[0024] In an embodiment, the second layer has a thickness of less than 50 nm, or less than 30 nm, or less than 10 nm. A layer thickness of less than 50 nm allows a change between the first and second polarization states to be achieved using an electric field of moderate strength. Furthermore, a layer thickness of less than 50 nm allows the charge zone to be contacted using contacts, e.g. source and drain, arranged on a further major surface of the second layer opposite to the main surface of the second layer. As a result, easy contacting can be performed. A layer thickness of less than 50 nm also allows the charge carrier density in the charge zone to be controlled with a relatively low gate voltage of a gate electrode opposite to the further major surface of the second layer.

[0025] In an embodiment, the electronic component further comprises a source contact and a drain contact, and the charge zone is arranged in series between the source contact and the drain contact, i.e. for example electrically in series, which allows the charge zone to be used as a conduction channel.

[0026] In an embodiment, the electronic component further comprises a gate electrode, the gate electrode being arranged such that the second layer is arranged between the first layer and the gate electrode, by applying a voltage to the gate electrode it is possible to control the charge carrier density of the charge zone and therefore its electrical conductivity.

[0027] In an embodiment, the gate electrode is arranged opposite the second layer only in a region, for example in a region related to the lateral extent of the gate electrode. In this case, the lateral direction can be understood to mean a direction along, for example parallel to, the second layer. This makes it possible to achieve regional or locally different charge carrier densities in the charge zones.

[0028] In an embodiment, the electronic component further comprises an electrically insulating layer arranged between the gate electrode and the second layer, so that the ingress of charge carriers from the gate electrode to the second layer can be prevented, and thus leakage currents between the gate electrode and the charge zone can be prevented. Additionally or alternatively, oxidation of the second layer can be prevented by said layer.

[0029] In an embodiment, the second material is ferroelectric, whereby the direction of polarization of the second material can be changed, one polarization state of the second material being a first polarization state. In the second polarization state of the second material, the direction of polarization of the second material is at least partially aligned with the first direction. The gate electrode is configured to set the second material in a first polarization state by applying a first voltage of a first polarity to the gate electrode, at least in a region of the second layer opposite the gate electrode. Furthermore, the gate electrode is configured to set the second material in a second polarization state by applying a second voltage of a second polarity to the gate electrode, at least in a region of the second layer opposite the gate electrode. "Setting" can be understood to mean, for example, that after setting of the polarization state, the set polarization state, for example the first or second polarization state, is maintained when no voltage is applied to the gate electrode any more. The application of a voltage to the gate electrode can be done, for example, by applying a voltage between the gate electrode and the first layer or between the gate electrode and the charge zone, for example via a source or drain contact. The gate electrode can thus change the polarization state of the second material and thus set the charge carrier density in the region of the charge zone opposite the gate electrode. For example, the conductivity of the conduction channel between the source and drain contacts can be set by the gate electrode.

[0030] In an embodiment, the second material is configured to maintain, i.e., at least substantially maintain, the most recently set polarization state, e.g., the first polarization state or the second polarization state, in a state of the electronic component where no voltage is applied to the gate electrode. "Maintaining the polarization state" means, for example, that a polarization direction that is at least partially opposite to the first direction remains at least partially opposite to the first direction, and a polarization direction that is at least partially aligned to the first direction remains at least partially aligned. This can also be achieved by using a second material that is ferroelectric. Maintaining the polarization state without the application of a gate voltage allows for energy-efficient operation, e.g., leakage currents are prevented.

[0031] In an embodiment, the direction of polarization of the first material is oriented such that the second polarity of the second voltage is negative, and thus application of a voltage of the second polarity can result in a field effect that leads to a reduction in electron density in the charge zone.

[0032] A further embodiment of the present invention provides a method for controlling an electronic component, comprising setting the second material (121) in one polarization state in at least one region of the second layer (120), so that high conductivity in the charge zone can be achieved as described above for the electronic component. In particular, this provides the advantage that after manufacturing, the polarizations of the first and second materials are matched.

[0033] A further embodiment of the present invention provides a method for manufacturing an electronic component, e.g. a component according to any one of the preceding embodiments. The method comprises arranging a first layer and a second layer such that a major surface of the second layer is arranged opposite a major surface of the first layer. The first layer comprises a first material and the second layer comprises a second material. The second material has at least one polarization state. The arranging is performed such that the polarization of the first material is oriented in a first direction. The arranging is further performed such that a direction of the polarization of the second material in at least one polarization state, e.g. a given polarization state of the second material, is at least partially opposite to the first direction and charge zones are formed along the major surfaces of the first layer and / or the second layer, the charge zones being conductive when at least the second material is in a polarization state.

[0034] In an embodiment, the disposition of the first layer and the second layer is performed such that the second material is in one polarization state after disposition of the first layer and the second layer.

[0035] In an embodiment, the second material is ferroelectric, whereby the direction of polarization of the second material can be changed, one polarization state of the second material being a first polarization state. In the second polarization state of the second material, the direction of polarization of the second material is at least partially aligned with the first direction. Furthermore, the method includes applying an electric field to the second material in a direction that is at least partially perpendicular to a major surface of the first or second layer to set the second material in the first polarization state, at least in the region. This embodiment provides the advantage that known methods can be used to arrange the first and second layers, which methods are easy to perform, and by which the first and second layers can be arranged such that the major surfaces of the first and second layers have a small number of surface defects.

[0036] In an embodiment, the method further comprises disposing a gate electrode such that, in at least a region, the second layer is disposed between the first layer and the gate electrode. Further, applying an electric field to the second material is performed by applying a voltage to the gate electrode.

[0037] In an embodiment, the method further comprises at least partially removing the gate electrode after the second material has been set to the first polarization state at least in the region. By at least partially removing the gate electrode, the gate electrode can be used to apply a voltage to set the polarization state of the second material in the region opposite the remaining part of the gate electrode, while the region of the second material opposite the removed part of the gate electrode remains in the first polarization state. Thus, the charge carrier density in the charge zone can be set in the region. Furthermore, it can be ensured that the gate electrode is arranged so as to be electrically insulated from the source and drain contacts. Similarly, a low capacitance of the gate electrode can be achieved.

[0038] In an embodiment, the gate electrode is only partially removed and the voltage setting the first polarization state is a first voltage. The method further comprises applying a second voltage to the gate electrode after the partial removal of the gate electrode to set the second material to a second polarization state at least in an area, e.g., in an area opposite the part of the gate electrode that remains after the partial removal of the gate electrode. Thus, locally different charge carrier densities can be generated in the charge zones.

[0039] Embodiments of the present disclosure are described below with reference to the accompanying drawings. [Brief description of the drawings]

[0040] [Figure 1] FIG. 1 is a schematic diagram of an electronic component according to one embodiment. [Diagram 2] 1 is a schematic diagram of an electronic component according to a further embodiment; [Diagram 3] FIG. 1 is a schematic diagram of one embodiment of an electronic component that is a transistor. [Figure 4] FIG. 1 is a schematic diagram of one embodiment of an electronic component that is a transistor. [Diagram 5] 1 is a schematic diagram of a HEMT according to one embodiment. [Figure 6] FIG. 1 is a flow diagram of a method for manufacturing an electronic component according to one embodiment. [Figure 7] FIG. 10 is a flow diagram of a method for manufacturing an electronic component according to a further embodiment. [Figure 8] FIG. 2 is a flow diagram of a method for controlling an electronic component according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the following description, some details are described to provide a more complete description of the embodiments of the present disclosure. However, it is obvious to those skilled in the art that the embodiments can be practiced without these specific details. The features of the various embodiments described can be combined with each other, unless the features of the corresponding combinations are mutually exclusive or such combinations are expressly excluded.

[0042] It should be noted that identical or similar elements, or elements having the same function, may be given the same or similar reference numbers or may have the same names, and repeated descriptions of elements given the same or similar reference numbers or having the same names are typically omitted. Descriptions of elements having the same or similar reference numbers or having the same names are mutually interchangeable.

[0043] FIG. 1 is a schematic diagram of an electronic component 100 according to an embodiment. The electronic component 100 comprises a first layer 110 having a major surface 112. Furthermore, the electronic component 100 includes a second layer 120 having a major surface 122. The major surface 120 of the second layer 120 is disposed opposite the major surface 112 of the first layer 110. In an embodiment, the major surface 122 is disposed adjacent to the major surface 112, as shown by way of example in FIG. 1. In another embodiment, the major surface 122 is spaced apart from the major surface 112. The first layer 110 includes a polarized first material 111. The polarization 115 of the first material 111, indicated by an arrow 115 in FIG. 1, faces a first direction. In FIG. 1, the first direction is selected, for example, such that the polarization faces the second layer 120. In other embodiments, the polarization 115 of the first material 111 points in another direction, for example opposite to that shown in FIG. 1. The second layer includes a polarized second material 121. The second material 121 has at least one polarization state. An example of one polarization state is shown in FIG. 1. In at least one polarization state of the second material 121, the direction of the polarization 125 of the second material 121, also referred to as the polarization direction 125, is at least partially opposite to the polarization 115 of the first material 121. The first layer 110 and the second layer 120 are configured such that charge zones 180 are formed along the major surface 112 and / or the major surface 122. The charge zones 180 are conductive when at least the second material 121 is in one polarization state.

[0044] In an embodiment, the second material 121 has only one polarization state, and the second material 121 is in this state. In another embodiment, for example, if the second material is ferroelectric, the second material 121 has at least one first polarization state and one second polarization state, and the one polarization state shown in FIG. 1 may correspond to the first polarization state.

[0045] As shown in the embodiment of FIG. 1, the polarization 115 and the polarization 125 are perpendicular to the first main surface 112 and / or the second main surface 122. In other embodiments, the polarization 115 and / or the polarization 125 are not perpendicular to the first main surface 112 and / or the second main surface 122. The direction of the polarization 115 can, for example, correspond to the polarity direction of the first material 111 and, correspondingly, the direction of the polarization 125 can correspond to the polarity direction of the second material 121. Advantageously, the first material 111 is arranged such that the direction of the polarization 115, also referred to below as the polarization direction 115, has at least one non-zero component perpendicular to the main surface 112. Similarly, the material 121 is advantageously arranged such that the polarization direction 125 has at least one non-zero component perpendicular to the main surface 122.

[0046] In an embodiment, the first layer 110 and the second layer 120 are part of a layer structure. Each of the layers of the layer structure may comprise a main surface and a further main surface opposite the main surface. The main surfaces of the layers may be arranged parallel along a main direction of the layer structure. Figure 1 shows a Cartesian coordinate system chosen as an example, according to which the first layer 110 and the second layer 120 are arranged along the z direction. The first layer 110 and the second layer 120 may also be arranged parallel to the xy plane.

[0047] Charge zone 180 may be, for example, in first layer 110, as shown in Figure 1. In other embodiments, charge zone 180 may be formed in second layer 120 along major surface 122. In further embodiments where major surface 112 is spaced from major surface 142, charge zone 180 may be disposed between first layer 110 and second layer 120. The extent of charge zone 180 in the z-direction may be very small in embodiments, for example, less than 10 nm or less than a few nanometers.

[0048] In an embodiment, the first material 111 has a wurtzite crystal structure and the second material 121 also has a wurtzite crystal structure. The wurtzite crystal structure may be polar. In an embodiment, the polar axis of the first material 111 may be oriented parallel to the polar axis of the second material 121.

[0049] 2 is a schematic diagram of an electronic component 200 according to a further embodiment. The electronic component 200 comprises a first layer 110 having a main surface 112 (also referred to as the first main surface 112) and further comprises a second layer 120 having a main surface 122 (also referred to as the second main surface 122). The main surface 122 is disposed opposite the main surface 112. The first layer 110 comprises a first material 111 having a wurtzite crystal structure. The polarization 115 of the first material 111 points in a first direction - the polarization direction 115 of the first material 111. The second layer 120 comprises a second material 121 having a wurtzite crystal structure. The second material 121 is ferroelectric and has at least one polarization state as shown in FIG. 2. In an embodiment, the second material 121 has at least two polarization states. 2, the direction of polarization 125 of the second material 121—the polarization direction 125 of the second material 121—is at least partially opposite to the polarization direction 115 of the first material 111. In the electronic component 200, the second material 121 contains a transition metal.

[0050] In an embodiment, in at least one polarization state, a charge zone, such as charge zone 180 in FIG. 1, is formed along first major surface 112 and / or second major surface 122 .

[0051] The description of electronic component 100 and the arrangement of first layer 110, second layer 120, polarization direction 115, polarization direction 125, x, y, z directions, first material 111, second material 121, and major surfaces 112, 122 relative to electronic component 100 may be equally applicable to electronic component 200. In other words, features described below with reference to features of electronic component 100 of FIG. 1 may, optionally, relate to both electronic component 100 of FIG. 1 and electronic component 200 of FIG.

[0052] Due to the polarization of first material 111 and second material 121, the potential at first major surface 112 may deviate from the potential within first layer 110 and / or the potential at second major surface 122 may deviate from the potential within second layer 120. As a result, for example, charge zones 180 may form that constitute a 2DEG. In other embodiments, charge zones 180 may constitute a two-dimensional hole gas.

[0053] For example, this results in a charge carrier density σ of the 2DEG, or generally charge zone 180, formed at an interface between first layer 110 and second layer 120, e.g., at major surface 112 or major surface 122, in one polarization state in which first polarization direction 115 is at least partially opposite to second polarization direction 125 based on the sum of the polarizations of first material 111 and second material 121. In this case, the polarization of one of the materials can include spontaneous polarization and / or piezoelectric polarization and / or formal polarization.

[0054] Due to the charge carrier density in the charge zone, e.g., 2DEG, which is increased many times due to the partially opposite polarization direction, a smaller component surface, or optionally a smaller power loss, can be realized in the electronic components 100, 200 by a factor of 10. Furthermore, due to the smaller component surface and the larger gradient, smaller component capacitance and higher cutoff frequency are possible. As a result, the electronic components 100, 200 are particularly well suited for transistors such as 6G+ applications, e.g., HEMTs, and compact converters for SMPS and IT (communications, computing, storage), military (base stations, RF energy), consumer goods, EV / HEV.

[0055] For example, when the first material is in a polarized state, the charge carrier density in the charge zone 180 is 10 12 cm -2 More than or 10 13 cm -2 Over or 6 x 10 13 cm -2Additionally, in an embodiment, when the first material is in a polarized state, the charge carrier density in the charge zone 180 is greater than 800×10 12 cm -2 Less than or 400 x 10 13 cm -2 In an embodiment, the charge carrier density is less than 134×10 13 cm -2 It is.

[0056] In an embodiment, when the first material is in a polarized state, the charge carrier density in the charge zone 180 is 10 13 cm -2 ~800×10 13 cm -2 , or 6 × 10 13 cm -2 ~800×10 13 cm -2 , or 10 x 10 13 cm -2 ~800×10 13 cm -2 , or 50 x 10 13 cm -2 ~400×10 13 cm -2 It is.

[0057] A high charge carrier density can result in high conductivity of the charge zone 180. In an embodiment including GaN as the first material 121, the theoretical limit for the conductivity of the 2DEG in GaN is 0.1 mOhm*cm 2 Less than or equal to 600V, 0.03mOhm*cm 2 It may be less than.

[0058] In an embodiment, the first material 111 is a nitride compound containing at least one group III element. This type of nitride compound is hereinafter referred to as a group III nitride compound. Alternatively or additionally, the second material 121 is a group III nitride compound.

[0059] In an embodiment, the second material 121 is a nitride compound that includes one or more group III elements and further includes a transition metal.

[0060] In an embodiment, the stoichiometric ratio of the transition metal in the nitride compound of the second material 121 is between 10% and 50% of the total stoichiometric ratio of the one or more group III elements and the transition metal in the nitride compound. (1-x) T x N, where A represents a Group III element or a plurality of different Group III elements, T represents a transition metal, N is nitrogen, and x is 0.1 to 0.5.

[0061] For example, the second material 121 is one of AlscN, AlGaScN, GaScN, AlN, AlGaN, AlMgNbN, AlGaN, and AlGaScN. Additionally or alternatively, in embodiments, the first material 111 is one of GaN, GaScN, AlScN, AlN, InGaN, InGaScN, AlGaN, and AlGaScN.

[0062] In an embodiment, the combination of the second material 121 and the first material 111 is one of AlScN / GaN, AlScN / GaScN, AlGaScN / GaN, GaScN / AlScN, GaScN / AlN, AlScN / InGaN, AlScN / InGaScN, AlMgNbN / GaN.

[0063] In an embodiment, the first material 111 is GaN and the second material 121 is AlScN. Aluminum scandium nitride and gallium nitride exhibit high spontaneous polarization. Furthermore, since the lattice constant of AlScN can be similar to that of GaN or GaScN, the piezoelectric polarization can be neglected in an embodiment and does not reduce the overall polarization of AlScN, at least when it is placed adjacent to GaN (or separated by a third layer). Thus, this material combination provides a high charge carrier density and a low defect density.

[0064] In an embodiment, the first material 111 is GaN and the second material 121 is Al. (1-x) Sc xN where x=0.18. For this scandium portion, the lattice constant of the second material 121 is at least approximately the same as the lattice constant of the first material 111. The high spontaneous polarization of AlScN and GaN results in a high charge carrier density for the 2DEG in the charge zone 180.

[0065] In other words, from the spontaneous polarization alone, it is usually not possible to conclude the charge density of the 2DEG formed at the interface of two different layers with wurtzite structure, without knowing the piezoelectric polarization. However, the inventors have found that the combination of a layer of the material AlScN and 18% ScN on a GaN layer constitutes an exception. Since the lattice constants of the two materials are identical [7], no piezoelectric polarization occurs at the interface of the two layers. Moreover, the spontaneous polarization of the two materials is approximately known either from experimental data or from exact theoretical calculations [3], [4]. Thus, for the charge carrier density σ of the 2DEG formed at the interface between a layer of 18% AlScN on a GaN layer, when both layers have positive polarization, i.e., are deposited on a substrate according to a conventional configuration with, for example, matched polarization directions, it can be said that approximately the following applies: TIFF0007648784000001.tif13100 formula 1

[0066] The order of magnitude of the charge carrier density thus achieved corresponds to the prior art. In contrast, for example, in the case of the orientation according to the invention of a first polarization direction 115 and a second polarization direction 125 in one polarization state, as shown in FIG. TIFF0007648784000002.tif13103 formula 2 The charge carrier density of the 2DEG thus produced is therefore increased by a factor of 25 compared to the prior art.

[0067] Such considerations do not only apply to 18% AlScN on GaN. In other embodiments, the material combination of the first layer 110 and the second layer 120 is one of several other possible material combinations, such as one of those described above. In this case, the charge carrier density may be greater or less than that calculated in Equation 2. For example, the polarization in compounds such as GaScN and AlScN is smaller with increasing Sc content, and therefore the sum of Equation 2 is smaller, but when the polarization is fully reversed, it is greater than the polarization of the first layer, e.g., GaN. In an embodiment, the polarization reversal can be reduced to approximately 10 μC / cm 2 compared to the prior art, for example, by using pure AlN, which has a polarization greater than 18% AlScN. 2 Any charge carrier density from up to the above value given by Equation 2 can be achieved. In an embodiment, going beyond 18% AlScN, the invariance of III-N material properties [4], [8] can be utilized to select further material combinations for the first material 111 and / or the second material 121.

[0068] In the embodiment of the component 100 of FIG. 1, the second material 121 is ferroelectric such that the direction of the polarization 125 of the second material 121 can be changed, as in the component of FIG. 2. In one polarization state, the polarization of the second material 121 has, for example, the polarization direction 125 shown in FIG. 1, and in these embodiments of the first and second polarization states of the second material 121, the direction of the polarization of the second material 121 is at least partially aligned with the first direction. In some embodiments, the polarization of the second material 121 in the second polarization state can be parallel to the first polarization direction 125.

[0069] As the inventors have recently discovered, materials with a wurtzite structure can also be ferroelectric. Ferroelectric materials can have multiple polarization states in which the polarization of the material points in different directions. Ferroelectric materials can be set, for example, in one of the polarization states in that the material is exposed to an electric field that is at least partially oriented in the direction of the polarization to be set. In this case, changes in the crystal lattice can occur. For example, a material of a III-nitride compound can have a metal-polar orientation with one polarization direction in one polarization state and a nitrogen-polar orientation with another, for example, opposite, polarization direction in a further polarization state.

[0070] The effects described herein with respect to ferroelectric materials can also be realized, in embodiments, by heterostructures formed with other materials having structures different from the wurtzite structure, typically by polar or poled materials.

[0071] In an embodiment, the charge carrier density in the charge zone 180 along a major surface of the first layer and / or the second layer is higher when the second material 121 is in the first polarization state than when the second material 121 is in the second polarization state.

[0072] In embodiments, the second layer has a thickness of less than 50 nm, or less than 30 nm, or less than 10 nm.

[0073] 3 is a schematic diagram of an electronic component 300 according to a further embodiment. The electronic component 300 is based on one of the electronic components 100, 200. For example, the electronic component 300 can correspond to one of the electronic components 100, 200.

[0074] For example, electronic component 300 includes third layer 330. Third layer 330 is disposed between first layer 110 and second layer 120. For example, third layer 330 can be disposed adjacent to major surface 112 of first layer 110 and adjacent to major surface 122 of second layer 120.

[0075] In an embodiment, the lattice constant of the material of the third layer 330 can be similar to the lattice constant of the first material 110, so that few surface defects are formed at the major surface 112 of the first layer 110. FIG. 3 shows, by way of example, the arrangement of the charge zones 180 along the major surface 112 in the first layer 110. The arrangement of the third layer 330 separates the charge zones 180 from the second layer 120. Thus, due to the third layer 330, an arrangement of the charge zones 180 on an interface with few defects can be achieved even when the lattice constants of the first material 111 and the second material 121 are different. As a result, a high conductivity in the charge zones 180 can be achieved.

[0076] In an embodiment, electronic component 300 further comprises a source contact 372 and a drain contact 374. Charge zone 180 is disposed in series between source contact 172 and drain contact 374.

[0077] Thus, the charge zone 180 may provide an electrical connection between the source contact 372 and the drain contact 374 in a conductive state of the charge zone 180, e.g., in one or a first polarization state of the second material 121. The electronic component 100, 200 may, for example, be formed of a transistor or part of a transistor, e.g., a HEMT. In an embodiment, the source contact 372 may be provided by a source region of the electronic component. In an embodiment, the drain contact 372 may be provided by a drain region of the electronic component.

[0078] For example, the source contact 372 and the drain contact 174 can be arranged adjacent to a major surface of the second layer 120 opposite the major surface 142 of the second layer 120, as shown in FIG. 3. In other words, the source contact 372 and the drain contact 374 can be arranged above the second layer 120 in the z-direction. Such an arrangement of the source contact 372 and the drain contact 374 can be particularly advantageous in combination with a second layer 120 having a thickness of less than 50 nm or 30 nm or 10 nm. The arrangement of the source contact 372 and the drain contact 374 above the second layer 120 allows for simple implementation. Nevertheless, the thin thickness allows for ensuring electrical contact of the source contact 372 or the drain contact 374 with the charge zone 180. However, for example, the second layer 120 can also be intentionally formed to be thin in the regions adjacent to the source contact 372 and / or the drain contact 374 (thinner than in the region between the source contact and the drain contact) in order to allow good electrical contact with the charge zone 180. In an embodiment, the third layer may be completely removed in the areas adjacent the source contact 372 and / or the drain contact 374 .

[0079] In an embodiment, the electronic component 300 further comprises a gate electrode 370 such that the second layer 120 is disposed between the first layer 120 and the gate electrode 370. For example, the gate electrode 370 is implemented by a conductive layer in electrical contact therewith.

[0080] An electric field can be applied to the second layer 120 by applying a voltage between the gate electrode 370 and the first layer 110. For example, a voltage can be applied between the gate electrode 370 and a contact on the first layer 120. Alternatively, a voltage can be applied between the gate electrode 370 and the source contact 372 or the drain contact 374, such that an electric field is formed between the gate electrode and the charge zone 180. In this case, the direction of the electric field can depend on the polarity of the applied voltage. The polarity of the material 121 of the second layer 120 can align itself according to the applied electric field, especially if it is ferroelectric. Thus, the gate electrode 370 makes it possible to set the material 121 in a first polarization state by applying a first voltage with a first polarity and to set the material 121 in a second polarization state by applying a second voltage with a second polarity. FIG. 3 shows an example of a polarization direction 125 of one or a first polarization state of the second material 121. Further, an example is shown of a direction of polarization 125′, also referred to below as polarization direction 125′, in a second polarization state of the second material 121. According to the coordinate system shown by way of example in FIG. 3, the z-component of the polarization direction may be opposite to the z-component of the polarization direction of the second polarization state 125′.

[0081] The gate electrode 370 can be disposed opposite the region 324 of the first layer 121 such that the region 324 and the gate electrode 370 have the same lateral extent, eg, are coincident.

[0082] The gate electrode 370 can be spaced apart from both the source contact 372 and the drain contact 374. That is, the gate electrode can be positioned to extend across a portion of the area disposed between the source contact 372 and the drain contact 374.

[0083] A field effect can further be created in the charge zone 180 by applying a voltage between the gate electrode 370 and the charge zone 180, which can be contacted by, for example, a source contact 372 or a drain contact 374. In this case, the voltage between the gate electrode 370 and the charge zone 180 at which the field effect causes the charge zone to change between a conducting state and an insulating state can be referred to as a threshold voltage.

[0084] In embodiments, the second material 121 is ferroelectric, such that the direction of polarization of the second material 121 can be changed. In these embodiments, one polarization state, e.g., a polarization state having a polarization direction 125, is a first polarization state of the second material 121. In the second polarization state of the second material 121, the direction of polarization of the second material 121 is at least partially aligned with a first direction, i.e., the polarization direction 115 of the first material 111. The gate electrode 370 can be configured to set the second material 121 to a first polarization state by applying a first voltage having a first polarity to the gate electrode 370, at least in a region 324 of the second layer opposite the gate electrode 370. Further, the gate electrode 370 is configured to set the second material 121 to a second polarization state by applying a second voltage having a second polarity to the gate electrode 370, at least in a region 324 of the second layer opposite the gate electrode.

[0085] In an embodiment, the first and second voltages (taking into account the sign, i.e. polarity) required to set the second material to the first and second polarization states, respectively, are greater than the threshold voltage, making it possible to ensure that the polarization states of the second material can be set to the first and second polarization states without compromising the charge zones by field effects, making it difficult to apply an electric field to the second material.

[0086] Setting the polarization state makes it possible to modify the conductivity of the charge zone 180 in a region 384 of the charge zone 180 facing the region 324 of the second layer. In an embodiment in which the region 324 covers part of the lateral area between the source contact 372 and the drain contact 374, the conductivity of the charge zone 180 can be modified laterally, i.e. locally. Thus, by selecting the size of the region 324 covered by the gate electrode 370, it is possible to set how much the conductivity changes between the source contact 372 and the drain contact 374 across the charge zone 180 when changing between a first polarization state and a second polarization state.

[0087] Thus, in an embodiment, the gate electrode 370 is arranged opposite the second layer 120 only in an area, for example in an area with respect to a lateral extent.

[0088] For example, the second material 121 may have a first polarization state or a second polarization state in a region 326 of the second layer 120 located outside the region 324. In an embodiment, the second material 121 may have a first polarization state or a second polarization state in the region 326, and in a further embodiment, a second polarization state. When the second material 121 is in the first polarization state in the region 326, the electrical conductivity of a region 386 of the charge zone 180 facing the further region 326 of the second layer 120 may be higher than when the second material 121 is in the second polarization state in the further region 326.

[0089] In other words, a conductive layer, e.g., gate electrode 370, can also be configured to cover only a portion of the surface of the semiconductor structure rather than the entire surface, and thus the charge carrier density can be determined locally at large intervals and can be different from the charge carrier density in other regions.

[0090] 3, from source contact 372 to drain contact 374, and gate electrode 370 is electrically isolated from source contact 372 and drain contact 374. In an embodiment, at least 80% of the lateral area between source contact 372 and drain contact 374 is covered by gate electrode 370.

[0091] If the second material 121 is ferroelectric, the second material 121 can remain in the set polarization state even when a voltage is no longer applied to the gate electrode 370. In other words, the setting of the polarization direction 125, 125' can be done by temporarily applying a voltage that can be turned off once the polarization state is set.

[0092] Thus, the second material 121 can be configured to maintain the most recently set polarization state, e.g., the first or second polarization state, in the state of the electronic component when no voltage is applied to the gate electrode 370.

[0093] When no voltage is applied to the gate electrode 370, the charge zone 180 can have a higher conductivity when the second material 121 is in the first polarization state than when the second material 121 is in the second polarization state.

[0094] The polarization direction 115 of the first material 111 in Figures 1-3 should be understood as an example. In other embodiments, the z-component of the polarization direction 115 points in the opposite direction to that shown in the figures. Thus, in these other embodiments, the z-component of the polarization directions 125, 125' also points in the opposite direction to that shown in the figures.

[0095] In an embodiment, the first material 111 and the second material 121 are selected such that the conductivity of the charge zone 180 is ensured by electrons. In another embodiment, the first material 111 and the second material 121 are selected such that the conductivity of the charge zone 180 is ensured by holes. Applying a voltage between the gate electrode 370 and the first layer 110 or between the gate electrode 370 and the charge zone 180 makes it possible to create a field effect that can increase or decrease the charge carrier density in the charge zone 180 depending on the polarity of the voltage and the type of charge carriers in the charge zone.

[0096] In some embodiments, the direction of polarization of the first material is oriented such that the second polarity of the second voltage that can set the second material 121 to the second polarization state is negative. This is advantageous when the majority of charge carriers in the charge zone 180 are electrons. Thus, application of the second voltage has the effect of contributing to a decrease in the electron density and therefore the electrical conductivity of the charge zone. In some of these embodiments, the threshold voltage can be negative at least when the second material is in the first polarization state. In other of these embodiments, the threshold voltage is negative when the second material is in the first or second polarization state.

[0097] Although the features of the gate electrode 370, the source contact 372 and the drain contact 374, and the third layer 330 of Fig. 3 have been described in combination according to one embodiment, these features may also be realized independently of one another. In particular, the third layer 330 may be implemented, for example, in the electronic component 100, 200, without the gate electrode 370, the source contact 372 and the drain contact 374. An alternative embodiment of the source contact 372 and the drain contact 374 that may be combined with the embodiment shown in Fig. 3 is shown in Fig. 4.

[0098] 4 is a schematic diagram of an alternative embodiment of an electronic component 300. In this example, source contact 372 and drain contact 374 are arranged adjacent to main surface 112 of first layer 110. This can have the advantage that in the example as shown in FIG. 4, charge zone 180 is arranged on first layer 110 and source contact 372 and drain contact 374 are particularly close to charge zone 180, thus ensuring good electrical contact.

[0099] In an embodiment, electronic component 300 further comprises an insulating layer 478 disposed between gate electrode 370 and second layer 120. Insulating layer 478 electrically insulates gate electrode 370 from second layer 120, thereby preventing leakage current between gate electrode 370 and charge zone 180. Insulating layer 478 can also be implemented similarly to the embodiment of electronic component 300 shown in FIG.

[0100] In other words, in the case of the design of the electronic component 300 as a transistor, source and drain electrodes can be applied to either the first layer (FIG. 4) or the second layer (FIG. 3) so as to contact the 2DEG directly or through one of the layers. These electrodes can be made of conductors such as Pt, Mo, Al, Ti, TiN, NbN, W, Ni, Au, or doped Si. To shift the 2DEG away from the interface between the two layers 110, 120 of the heterostructure, which is typically subject to defects, a further thin crystalline layer, for example a third layer 330, can be inserted between the two layers 110, 120 of the heterostructure, the third layer also having a wurtzite structure.

[0101] 5 is a schematic diagram of a HEMT 500 according to a further embodiment. An example of the HEMT 500 can correspond to one of the electronic components 100, 200, 300 described above. The HEMT 500 comprises a substrate 590 arranged opposite the first layer 110 and the second layer 120, such that the first layer 110 is arranged between the substrate 590 and the second layer 120. Furthermore, the HEMT 500 comprises one or more adjustment layers 592 arranged between the first layer 110 and the substrate 590. The adjustment layer 590 can provide an adjustment of the lattice constant of the substrate 590 and the first layer 110, such that defects and / or stresses in a further main surface of the first layer 110 opposite the main surface 112 of the first layer 110 can be reduced or prevented. The HEMT 500 comprises a third layer 330 arranged between the first layer 110 and the second layer 120. A termination layer 578, which may be electrically insulating, is disposed between the gate electrode 370 and the second layer 120. A source contact 372 and a drain contact 374 are disposed adjacent the major surface 112 of the first layer 110. In the illustrated embodiment, the source contact 372 and the drain contact 374 are electrically connected through the charge zone 180 located along the major surface 112 of the first layer 110 when the charge zone 180 is in a conductive state.

[0102] Figure 8 is a flow diagram of a method 80 for controlling the electronic component 100, 200, 300, 500 according to Figures 1 to 5. The method 80 comprises a step 81 of setting the second material 121 in at least one region of the second layer 120 to a polarization state.

[0103] In an embodiment, step 81 may include or be performed by means of step 82. Step 82 includes applying a first voltage having a first polarity to the gate electrode 370 to set the second material 121 to a first polarization state, at least in a region 324 of the second layer 120 opposite the gate electrode 370.

[0104] In an embodiment, the method 80 further includes applying a second voltage having a second polarity to the gate electrode 370 to set the second material 121 to a second polarization state, at least in a region 324 of the second layer 120 opposite the gate electrode.

[0105] In an embodiment, the electronic component 100, 200, 300, 500 according to FIGS. 1 to 5 comprises a control unit capable of performing the method 80 by controlling the voltage applied to the gate electrode 370.

[0106] 6 is a flow diagram of a method 60 for manufacturing an electronic component, e.g., electronic components 100, 200, 300, 500. Method 60 includes the step 61 of disposing a first layer and a second layer. Disposing 61 is performed such that a major surface 122 of second layer 120 is disposed opposite major surface 112 of first layer 110. Further, disposing 61 is performed such that first layer 110 includes a first material 111 and second layer 120 includes a second material 121. Second material 121 has at least one polarization state. The arrangement 61 is such that the polarization of the first material 111 is oriented in a first direction, the direction of polarization of the second material 121 is at least partially opposite to the first direction in at least one polarization state of the second material 121, and charge zones 180 are formed along the major surfaces 112, 122 of the first layer 110 and / or the second layer 120, which charge zones are conductive when at least the second material 121 is in one polarization state.

[0107] In an embodiment, the arrangement 61 of the first layer 110 and the second layer 120 includes depositing the first layer and the second layer. In an embodiment, the first layer 110 is deposited first, the second layer 120 is deposited on the first layer 110, and one or more additional layers, e.g., the third layer 330, can be deposited on the first layer 110 before depositing the second layer 120. In another embodiment, the second layer 120 is deposited first, the first layer 110 is deposited on the second layer 120, and one or more additional layers, e.g., the third layer 330, can be deposited on the first layer 110 before depositing the first layer 110.

[0108] In an embodiment, the deposition may be performed such that after deposition of the first and second layers, the second material 121 is in one polarization state.

[0109] In these embodiments, it is possible to achieve by the deposition process that the polarization direction 125 of the second material 121 is at least partially opposite to the polarization direction 115 of the first material.

[0110] In other words, the reversal of the polarization direction can occur due to the creation of defects (e.g., by briefly providing oxygen, magnesium silicon, or germanium) at the boundary of two layers with wurtzite structure in the context of the deposition process.

[0111] FIG. 7 is a flow diagram of a method 70 according to one embodiment. Method 70 may be an example of method 60. In these examples, the second material 121 is ferroelectric, thereby allowing a direction of polarization of the second material to be changed. In these examples, at least one polarization state of the second material is a first polarization state. In the second polarization state of the second material 121, the direction of polarization of the second material 121 is at least partially aligned with the first direction. In these examples, the arrangement 61 further includes a step 73 of applying an electric field to the second material 121 in a direction at least partially perpendicular to the major surface 112 of the first layer 110 or the second layer 120 to set the second material 121 to the first polarization state, at least in a region.

[0112] For example, arrangement 61 includes depositing a first layer 110 and a second layer 120, the deposition being performed such that the polarization direction 115 of the first material 111 and the polarization direction 125, 125' of the second material are at least partially aligned, i.e., the second material is in a second polarization state, as described with reference to Figure 6. Step 73 may be performed, for example, with a gate electrode, which may be positioned after deposition of the first and second layers.

[0113] Thus, in an embodiment, disposing 61 of method 70 may further include step 72 of disposing, in at least a region, gate electrode 370. Step 72 is performed such that second layer 120 is disposed between first layer 110 and gate electrode 370. Conveniently, step 72 may be performed before step 73.

[0114] If the method includes step 74, step 72 of disposing the gate electrode can be performed such that the gate electrode extends across the region from the source contact to the drain contact. Thus, step 73 can ensure that the second material is set to a first polarization state, thereby achieving high conductivity across the entire region from the source contact to the drain contact. If charge zones are used to apply an electric field in step 73, the gate electrode 370 can be disposed in step 72 such that it is electrically isolated from the source and drain contacts.

[0115] Optionally, step 61 of method 70 further includes step 74 of at least partially removing the gate electrode deposited in step 72. For example, removal can be performed such that the gate electrode is electrically isolated from the source and drain contacts.

[0116] 3, the second material 121 can be made to assume a first polarization state in a region 326 outside the region 324 facing the gate electrode 370. The second material 121 in the region 324 can be set to a first or second polarization state, so that the conductivity of the charge zone 180 can be increased or decreased by applying an electric field to the remaining part of the gate electrode, shown as gate electrode 370 in FIG. 3 after step 74. By partially removing the gate electrode, it is possible to ensure that the gate electrode is electrically isolated from the source and drain contacts. Furthermore, the capacitance of the gate electrode can be reduced as a result.

[0117] In embodiments, step 74 is performed such that the gate electrode is only partially removed, e.g., such that after step 74, a remaining portion of the gate electrode, e.g., gate electrode 370, is disposed opposite second layer 120. In these embodiments, step 61 can further include step 75, after partial removal of the gate electrode, of applying a second voltage to gate electrode 370 to set second material 121 to a second polarization state at least in a region, e.g., region 324 opposite the remaining portion of gate electrode 73.

[0118] Thus, the second material can assume a second polarization state in a region 324 of the second layer 120 and a first polarization state in a further region 326 of the second layer.

[0119] Method 60 of Figure 6 and method 70 of Figure 7 may be suitable for manufacturing electronic components 100, 200, 300, 500. That is, methods 60, 70 may be configured such that the features and advantages described with reference to Figures 1-5 are achieved, for example, with respect to state and configuration.

[0120] In other words, the ferroelectric effect makes it possible to bring about a reversal of the relative polarization direction of the first and second layers. This kind of ferroelectric effect has been observed in AlScN and can also be predicted in other mixed crystals such as GaScN and AlMgNbN [9],

[10] . This effect makes it possible, for example, to deposit a heterostructure of two layers with a wurtzite structure with a metal-polar (or nitrogen-polar) orientation. The polarization of the upper layer (or the lower layer) can be reversed by the ferroelectric effect. According to equation 2, the heterostructure thus produced has a significantly increased electrical conductivity. The application of a voltage can be achieved, for example, in that a conductive layer, for example Pt, Mo, Al, Ti, TiN, NbN, Ni, Au, or Si (or a conductive substrate, for example doped Si or GaN), is brought into contact with the surface of the ferroelectric layer facing away from the 2DEG. A voltage can then be applied to the other side of the ferroelectric layer via this conductive layer and the 2DEG. This voltage reverses the polarization due to the ferroelectric effect, increasing the charge carrier density in the 2DEG. Subsequently, the conductive layer can be removed again or made smaller, for example to define a gate electrode for controlling the 2DEG.

[0121] Further embodiments are described below. One embodiment forms a structure consisting of a substrate, a crystalline layer having a wurtzite structure applied to the substrate, and a further crystalline layer having a wurtzite structure applied to the first layer, the further crystalline layer having a wurtzite structure and whose polarization is oriented opposite to the polarization of the first layer.

[0122] In this embodiment of the structure, the electrical conductivity along the interface between the two layers is higher than in a structure in which the polarization of both layers is oriented in the same direction. In the embodiment, the charge carrier density is 6×10 13 cm -2 ~164×10 13 cm -2 has a value of

[0123] In an embodiment, at least one of the two layers is ferroelectric. In an embodiment, at least one of the two layers is a III-nitride. In an embodiment, at least one of the two layers further comprises a transition metal.

[0124] In an embodiment, the second layer is thinner than 50 nm. In an embodiment, a further layer having a wurtzite structure is disposed between the first layer and the second layer. In an embodiment, the gate, source and drain electrodes are applied to the second layer.

[0125] In an embodiment, the source and drain electrodes are applied to a first layer and the gate electrode is applied to a second layer. In an embodiment, a further insulating layer is located between the gate and the second layer. In an embodiment, the transition metal portion is between 10 and 50% of the Group III elements.

[0126] One embodiment provides a method in which a second crystalline layer having a wurtzite structure is applied to a first crystalline layer having a wurtzite structure, the polarizations of the two layers point in the same direction, and at least one of the two layers is ferroelectric, and further, in which the electrical conductivity of the interface between the two layers is increased by applying a voltage to one of the ferroelectric layers, reversing the polarization.

[0127] One embodiment provides a method in which a second crystalline layer having a wurtzite structure is applied to a first crystalline layer having a wurtzite structure, the polarizations of the two layers point in the same direction, the second layer being ferroelectric, a conductive layer is applied to the ferroelectric layer covering at least 80% of the distance between the locations of the source and drain electrodes (which are then applied), the conductivity of the interface between the layers is increased by applying a voltage to the conductive layer and reversing the polarization, and the conductive layer is then at least partially removed.

[0128] An embodiment provides a method, in which a second crystalline layer having a wurtzite structure is applied to a first crystalline layer having a wurtzite structure, the polarizations of the two layers point in the same direction, the second layer being ferroelectric, the polarization of the ferroelectric layer according to any of claims 2 and 3 being reversed, the polarization of the ferroelectric layer being reversed again by a gate electrode to achieve a low conductivity, and a voltage being applied to the gate electrode to further deplete the 2DEG.

[0129] Although some aspects of the present disclosure are described as device-related features, it will be apparent that such description can also be considered as a description of the corresponding method features. Although some aspects of the disclosure are described as method-related features, it will be apparent that such description can also be considered as a description of the corresponding features of a device or device functionality.

[0130] In the foregoing detailed description, different features may be grouped together in an embodiment to provide a reasonable explanation of the disclosure. This type of disclosure should not be interpreted as intending that the claimed embodiments include more features than are expressly specified in each claim. Rather, as the following claims indicate, subject matter may be found in fewer than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description, with each claim also being considered as a separate embodiment. Although each claim may stand as a separate embodiment in itself, it should be noted that although a dependent claim in the claims may refer to a specific combination with one or more other claims, other embodiments may also include a combination of the dependent claim with the subject matter of all other dependent claims, or a combination of all features with other dependent or independent claims. Such combinations are included unless it is stated that a specific combination is not intended. Furthermore, it is intended that a combination of a feature of one claim with any other independent claim should be included even if the claim is not directly dependent on the independent claim.

[0131] The above-described embodiments are merely illustrative of the principles of the present disclosure. Naturally, modifications and variations of the arrangements and details described herein will be obvious to others skilled in the art. Therefore, it is intended that the present disclosure should be limited only by the scope of protection of the following claims, rather than by the specific details presented herein based on the description and explanation of the embodiments.

[0132] References [1] O. Ambacher et al., “Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N-and Ga-face AlGaN / GaN heterostructures”, J. Appl. Phys., vol. 85, no. 6, pp. 3222-3233, 1999, doi:10.1063 / 1.369664

[0133] [2] K.Frei et al., “Investigation of growth parameters for ScAlN-barrier HEMT structure by plasma-assisted MBE”, Jpn.J.Appl.Phys., vol.58, p.SC1045, 2019, doi:10.7567 / 1347-4065 / ab124f

[0134] [3] S. Fichtner, N. Wolff, F. Lofink, L. Kienle, and B. Wagner, “AlScN:A III-V Semiconductor Based Ferroelectric”, https: / / arxiv.org / abs / 1810.07968

[0135] [4] C.E. Dreyer, A. Janotti, C.G. Van de Walle, and D. Vanderbilt, "Correct implementation of polarization constants in wurtzite materials and impact on III-nitrides", Phys. Rev. X, vol. 6, no. 2, p. 021038, 2016, doi:10.1103 / PhysRevX.6.021038

[0136] [5] M. Caro et al., "Piezoelectric coefficients and spontaneous polarization of ScAlN", J. Phys. Condens. Matter, vol. 27, no. 24, p. 245901, 2015, doi:10.1088 / 0953-8984 / 27 / 24 / 245901

[0137] [6] F. Bernardini, V. Fiorentini, and D. Vanderbilt, "Spontaneous polarization and piezoelectric constants of III-V nitrides", Phys. Rev. B, vol. 56, no. 16, p. R10 024, 1997, doi:10.1103 / PhysRevB.56.R10024

[0138] [7] I. Edward A. Beam, and J. Xie, "High Electron Mobility Transistor (HEMT) device", US10636881B2, 2016

[0139] [8]L.Vegard,「Die Konstitution der Mischkristalle und die Raumfullung der Atome」,[The makeup of mixed crystals and the space filling of the atoms]Zeitschrift fur Phys.[Physics journal],vol.5,p.17,1921,doi:10.1007 / BF00549722

[0140] [9]M.Uehara,T.Mizuno,Y.Aida,H.Yamada,K.Umeda, and M.Akiyama,「Increase in the piezoelectric response of scandium-doped gallium nitride thin films sputtered using a metal interlayer for piezo MEMS」,Appl.Phys.Lett.,vol.114,no.012902,2019,doi:10.1063 / 1.5066613

[0141]

[10] M.Uehara et al.,「Giant increase in piezoelectric coefficient of AlN by Mg-Nb simultaneous addition and multiple chemical states of Nb」,Appl.Phys.Lett.,vol.111,no.11,p.112901,2017.

Claims

1. An electronic component (100, 300, 500) comprising a first layer (110) and a second layer (120), wherein a major surface (112) of the first layer (110) is disposed opposite a major surface (122) of the second layer (120); the first layer (110) comprises a polarized first material (111), the polarization (115) of the first material being oriented in a first direction; An electronic component (100, 300, 500), wherein the second layer (120) comprises a polarized second material (121), and in one polarization state in which the direction of the polarization (125) of the second material (121) is at least partially opposite to the first direction, charge zones (180) are formed along the main surfaces (112, 122) of the first layer and / or the second layer, and the charge zones are conductive.

2. 2. The electronic component (100, 300, 500) of claim 1, wherein the first material (111) has a wurtzite crystal structure and the second material (121) has a wurtzite crystal structure.

3. An electronic component (200, 300, 500) comprising a first layer (110) and a second layer (120), wherein a major surface (112) of the first layer (110) is disposed opposite a major surface (122) of the second layer (120); the first layer (110) comprises a first material (111) having a wurtzite crystal structure, the polarization (115) of the first material being oriented in a first direction; the second layer (120) comprises a second material (121) having a wurtzite crystal structure, the second material (121) comprises a transition metal, the second material (121) is ferroelectric and has at least one polarization state, a direction of polarization (125) of the second material (121) is at least partially opposite to the first direction at least in the one polarization state of the second material (121), charge zones (180) are formed along the main surfaces (112, 122) of the first layer and / or the second layer, the charge zones being conductive when at least the second material (121) is in the one polarization state, the one polarization state of the second material (121) is a first polarization state, and the direction of the polarization of the second material (121) in the second polarization state of the second material (121) is at least partially aligned with the first direction; The electronic component (200, 300, 500), wherein the electronic component is configured to set the second material (121) of the second layer to the first polarization state, at least in regions.

4. a charge carrier density in a charge zone (180) along the major surface (112, 122) of the first layer (110) and / or the second layer (120) is 10 １２ cm －２ More than or 10 １３ cm －２ Super or 6x10 １３ cm －２ Super or 10 １３ cm －２ ~800 x 10 １３ cm －２ or 6 x 10 １３ cm －２ ~800 x 10 １３ cm －２ or 10 x 10 １３ cm －２ ~800 x 10 １３ cm －２ is in the range The electronic component (100, 200, 300, 500) according to any one of claims 1 to 3, wherein said second material (121) is in said one polarization state.

5. The electronic component (100, 200, 300, 500) according to any one of claims 1 to 4, wherein the first material (111) is a nitride compound containing at least one group III element and / or the second material (121) is a nitride compound containing at least one group III element.

6. The electronic component (100, 200, 300, 500) according to any one of the preceding claims, wherein the second material (121) is a nitride compound comprising one or more group III elements and further comprising a transition metal.

7. The electronic component (100, 200, 300, 500) of claim 6, wherein the stoichiometric ratio of the transition metal in the nitride compound of the second material (121) is between 10% and 50% of the total stoichiometric ratio of the one or more group III elements and the transition metal in the nitride compound.

8. the first material (111) is one of GaN, GaScN, AlScN, AlN, InGaN, InGaScN, AlGaN, AlGaScN; and / or the second material (121) is one of AlScN, AlGaScN, GaScN, AlN, AlGaN, AlMgNbN, AlGaN, AlGaScN; An electronic component (100, 200, 300, 500) according to any one of claims 1 to 7.

9. The electronic component (100, 200, 300, 500) according to any one of the preceding claims, wherein the second material (121) / first material (111) combination is one of the following: AlScN / GaN, AlScN / GaScN, AlGaScN / GaN, GaScN / AlScN, GaScN / AlN, AlScN / InGaN, AlScN / InGaScN, AlMgNbN / GaN.

10. The electronic component (100, 200, 300, 500) according to any one of claims 1 to 9, wherein the second material (121) is ferroelectric such that the direction of the polarization (125) of the second material (121) can be changed, the one polarization state of the second material (121) being a first polarization state, and the direction of the polarization of the second material (121) in the second polarization state of the second material (121) being at least partially aligned with the first direction.

11. 11. The electronic component (100, 200, 300, 500) of claim 10, wherein a charge carrier density in a charge zone (180) along the major surface (112, 122) of the first layer (110) and / or the second layer (120) is higher when the second material (121) is in the first polarization state than when the second material (121) is in the second polarization state.

12. The electronic component (100, 200, 300, 500) according to any one of claims 2 to 11, further comprising a third layer (330) disposed between the first layer (110) and the second layer (120), the third layer having a wurtzite crystal structure.

13. The electronic component (100, 200, 300, 500) according to any one of the preceding claims, wherein the second layer (120) has a thickness of less than 50 nm.

14. The electronic component (100, 200, 300, 500) of any one of claims 1 to 13, further comprising a source contact (372) and a drain contact (374), the charge zone (180) being arranged in series between the source contact (372) and the drain contact (374).

15. The electronic component (100, 200, 300, 500) according to any one of claims 1 to 14, further comprising a gate electrode (370), the second layer (120) being disposed between the first layer (110) and the gate electrode (370).

16. 16. The electronic component (100, 200, 300, 500) of claim 15, wherein the gate electrode (370) is disposed opposite the second layer (120) only in a region.

17. 17. The electronic component (100, 200, 300, 500) of claim 15 or 16, further comprising an electrically insulating layer (478) disposed between the gate electrode (370) and the second layer (120).

18. the second material (121) is ferroelectric, the one polarization state of the second material (121) is a first polarization state, and the direction of the polarization of the second material (121) in the second polarization state of the second material (121) is at least partially aligned with the first direction, such that the direction of the polarization of the second material (121) can be changed; The electronic component (100, 200, 300, 500) according to any one of claims 15 to 17, wherein the gate electrode (370) is configured to set the second material (121) to the first polarization state by applying a first voltage having a first polarity to the gate electrode, at least in a region (324) of the second layer (120) facing the gate electrode (370), and to set the second material (121) to the second polarization state by applying a second voltage having a second polarity to the gate electrode (370), at least in the region (324) of the second layer (120) facing the gate electrode.

19. 20. The electronic component (100, 200, 300, 500) of claim 18, wherein the second material (121) is configured to maintain a most recently set polarization state in a state of the electronic component where no voltage is applied to the gate electrode (370).

20. 20. The electronic component (100, 200, 300, 500) of claim 18 or 19, wherein the direction of polarization of the first material is oriented such that the second polarity is negative.

21. A method for controlling an electronic component according to any one of claims 1 to 20, comprising: setting said second material (121) to said one polarization state in at least one region of said second layer (120).

22. the second material (121) is ferroelectric such that the direction of the polarization of the second material (121) can be changed, the one polarization state of the second material (121) being a first polarization state, the direction of the polarization of the second material (121) in the second polarization state of the second material (121) being at least partially aligned with the first direction, the electronic component further comprising a gate electrode (370), the second layer (120) being disposed between the first layer (110) and the gate electrode (370); said step of setting said second material to said first polarization state further comprising:

22. The method of claim 21, comprising applying a first voltage having a first polarity to the gate electrode to set the second material (121) to the first polarization state at least in a region (324) of the second layer (120) facing the gate electrode (370).

23. A method (60, 70) for manufacturing an electronic component, comprising: The method includes the step (61) of disposing a first layer (110) and a second layer (120); a major surface (122) of the second layer (120) is disposed opposite to a major surface (112) of the first layer (110); the first layer (110) comprises a first material (111), the second layer (120) comprises a second material (121), the second material (121) having at least one polarization state; the polarization of the first material (111) is oriented in a first direction; A method (60, 70) wherein the direction of the polarization of at least the second material (121) in the one polarization state of the second material (121) is at least partially opposite to the first direction such that a charge zone (180) is formed along the major surfaces (112, 122) of the first layer (110) and / or the second layer (120), and the charge zone (180) is conductive when at least the second material (121) is in the one polarization state.

24. 24. The method (60) of claim 23, wherein the step (61) of disposing the first layer (110) and the second layer (120) comprises depositing the first layer and the second layer, the depositing being performed such that after depositing the first layer and the second layer, the second material (121) is in the one polarization state.

25. the second material (121) is ferroelectric such that the direction of polarization of the second material (121) can be changed, the one polarization state of the second material (121) is a first polarization state, the direction of the polarization of the second material (121) in the second polarization state of the second material (121) is at least partially aligned with the first direction, and the method comprises:

24. The method (70) of claim 23, further comprising the step (73) of applying an electric field to the second material (121) in a direction at least partially perpendicular to the major surface (112, 122) of the first layer or the second layer to set the second material (121) in the first polarization state, at least in a region.

26. further comprising the step of disposing (72) a gate electrode, wherein at least in an area, the second layer (120) is disposed between the first layer and the gate electrode; 26. The method (70) of claim 25, wherein the step (73) of applying the electric field to the second material (121) is performed by applying a voltage to the gate electrode.

27. and at least partially removing (74) the gate electrode after the second material has been set to the first polarization state at least in regions.

27. The method (70) of claim 26.

28. The step of removing the gate electrode (74) is only partially performed, the voltage is a first voltage, and the method further comprises:

28. The method (70) of claim 27, further comprising applying (75) a second voltage to the gate electrode after the partial removal of the gate electrode to set the second material (121) to the second polarization state, at least in regions.

Images