Ferroelectric nanoparticle capacitors for non-binary logic

Abstract

To provide a ferroelectric nanoparticle capacitor-device with a limited number of ferroelectric nanoparticles to provide discrete remanent ferroelectric polarization states.SOLUTION: A ferroelectric nanoparticle capacitor-device 100 comprises a pair of conductive elements 102, 112 electrically insulated from each other, and ferroelectric nanoparticles 104a, 104b arranged between the conductive elements of the pair. The ferroelectric nanoparticles are adapted to provide at least three polarization states 106 with different total ferroelectric polarizations. The ferroelectric nanoparticle capacitor-device may be adapted to receive a preselected voltage or a preselected charge at one of the conductive elements of the pair to selectively set the ferroelectric nanoparticles to any of the at least three polarization states, and in particular, the other conductive element of the pair is adapted to carry a constant electrical charge. In other words, the polarization states of the ferroelectric nanoparticles can be individually addressed and the ferroelectric nanoparticles are set to the respective polarization state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates in particular to ferroelectric nanoparticle capacitor devices having a limited number of ferroelectric nanoparticles to provide discrete remanent ferroelectric polarization states that can be individually addressed. In particular, each of the nanoparticles can be in a monodomain ferroelectric state. The present disclosure also relates to methods of setting the polarization states of the ferroelectric nanoparticles. [Background technology]

[0002] The computer industry strives for the continued miniaturization of devices to reduce the energy required to store or switch information such as logic bits. To this end, existing computing circuits use standard binary logic to store and process information. These circuits are reaching fundamental limits set by the fundamental Landauer principle of atomic size miniaturization and energy dissipation per bit processing. Summary of the Invention

[0003] In view of the above technical problems, there is a need for a multi-valued logic device.

[0004] In the context of this disclosure, the term multi-valued logic device may refer to a device that provides at least three states, such as at least three switchable and / or individually addressable logic states or at least three switchable and / or individually addressable polarization states. In other words, a multi-valued logic device may be considered a non-binary logic device. Thus, a multi-valued logic device is distinct from a binary logic device that provides two states (i.e., two switchable and / or individually addressable logic states or polarization states).

[0005] The use of multi-valued logic devices can reduce energy losses and enable unprecedentedly high information density in devices, thus overcoming the binary dominance of conventional devices. Exploring multi-valued logic is important for realizing non-von Neumann computation.

[0006] Despite the active search for systems capable of realizing switchable multi-valued logic, a practically viable physical implementation of multi-valued logic devices has thus far remained an unsolved and challenging task.

[0007] Existing implementations of pseudo multilevel logic units currently used in solid-state drives and flash memories actually involve a combination of individual binary (i.e., bit) logic devices, and therefore require analog methods of bit writing, which can result in erratic behavior of logic cells due to probabilistic loss of information.

[0008] In a first aspect of the present disclosure, a ferroelectric nanoparticle capacitor device comprises a pair of electrically insulated conductive elements and a ferroelectric nanoparticle disposed between the pair of conductive elements, the ferroelectric nanoparticle adapted to provide at least three polarization states having different total ferroelectric polarizations.

[0009] The ferroelectric nanoparticle capacitor device according to the first aspect therefore provides a multi-valued logic device, or an implementation of multi-valued logic, respectively.

[0010] The ferroelectric nanoparticle capacitor device may be adapted to selectively set the ferroelectric nanoparticles to one of at least three polarization states. For example, the ferroelectric nanoparticle capacitor device may be adapted to receive a preselected voltage or a preselected charge on one of the conductive elements of the pair to selectively set the ferroelectric nanoparticles to one of at least three polarization states, in particular, the other conductive element of the pair is adapted to carry a constant charge. In other words, the polarization states of the ferroelectric nanoparticles can be addressed individually. Addressing the polarization states can refer to setting the ferroelectric nanoparticles to their respective polarization states.

[0011] Thus, the ferroelectric nanoparticle capacitor device constitutes a multi-valued logic device, where each polarization state acts as a multi-valued logic state (e.g., a memory level), and switching by application of charge represents a transition between states or memory levels, respectively.

[0012] The ferroelectric nanoparticles may be adapted to provide up to 64 discrete polarization states with different total ferroelectric polarizations, in particular up to 32 discrete polarization states with different total ferroelectric polarizations, in particular up to 16 discrete polarization states with different total ferroelectric polarizations, in particular up to 8 discrete polarization states with different total ferroelectric polarizations, in particular up to 4 discrete polarization states with different total ferroelectric polarizations.

[0013] To address any of the polarization states individually, or to switch between any pair of polarization states, the ferroelectric nanoparticle capacitor device can provide respective pathways, which are well-defined and specific to each polarization state to be addressed, or pair of polarization states to be switched. In the context of the present disclosure, the term pathway can refer to charges applied to at least one of the conductive elements, or charges applied sequentially (i.e., differing by total value and / or sign, etc.) to at least one of the conductive elements.

[0014] The at least three polarization states may be at least three remanent polarization states, in other words, the ferroelectric nanoparticles may be adapted to maintain any of the at least three polarization states and / or to store a set one of the at least three polarization states, particularly when no charge or voltage is applied to the conductive element.

[0015] This allows for the realization of multi-valued logic memory levels.

[0016] The polarization state may refer to the overall polarization state of the ferroelectric nanoparticle, in other words, the polarization state of the entire ferroelectric nanoparticle, as opposed to the individual polarization states of, for example, individual ferroelectric nanoparticles of a ferroelectric nanoparticle.

[0017] The polarization state may refer to a ferroelectric polarization state.

[0018] The polarization states may be discrete polarization states, for example the at least three polarization states may be at least three discrete polarization states.

[0019] The ferroelectric nanoparticles may be adapted to provide respective individual polarization states, in particular respective discrete polarization states, such as respective individual polarization up states and respective individual polarization down states.

[0020] The individual polarization states may refer to individual ferroelectric polarization states.

[0021] The ferroelectric nanoparticle capacitor device may be adapted to switch the individual polarization states of the individual ferroelectric nanoparticles of the ferroelectric nanoparticles. The ferroelectric nanoparticle capacitor device may be adapted to switch the individual polarization states of the individual ferroelectric nanoparticles while maintaining the individual polarization states of the remaining ferroelectric nanoparticles.

[0022] The ferroelectric nanoparticles can have the same material composition.

[0023] This can facilitate economical manufacturing of the device.

[0024] A conductive element can refer to an electrically conductive element.

[0025] The conductive element may be a conductive layer and / or a conductive plate.

[0026] The (particularly each) ferroelectric nanoparticle of the ferroelectric nanoparticles may be disposed between the first sections of the conductive element. In other words, the first sections of the conductive element may correspond to a projection of the ferroelectric nanoparticles onto the conductive element. The ferroelectric nanoparticle (or each of the plurality of ferroelectric nanoparticles) and the (respective) first section of the conductive element may define a ferroelectric capacitor (or a plurality of ferroelectric capacitors, respectively).

[0027] Up to 10 ferroelectric nanoparticles may be disposed between the pairs of conductive elements, or up to 5 ferroelectric nanoparticles, or up to 3 ferroelectric nanoparticles, or exactly 3 ferroelectric nanoparticles, or exactly 2 ferroelectric nanoparticles.

[0028] A limited number of nanoparticles each can improve the reliability of switching between polarization states.

[0029] The sections of the conductive element that sandwich one of the ferroelectric nanoparticles can define a respective ferroelectric capacitor, in other words, the ferroelectric nanoparticle and the sections of the conductive element that sandwich the ferroelectric nanoparticle can define a ferroelectric capacitor.

[0030] The conductive elements of the pair can include respective surfaces that face each other, and the respective surface areas of the respective surfaces can each exceed the total projected surface area of ​​the ferroelectric nanoparticle.

[0031] In other words, the conductive elements may include excess portions of each that do not include ferroelectric nanoparticles therebetween.

[0032] In a corresponding embodiment, the surface area of ​​the conductive element over the total surface area projected area of ​​the ferroelectric nanoparticles (or the portions of the respective surfaces not containing ferroelectric nanoparticles therebetween, or the remaining portions of the conductive element, respectively) can define a dielectric capacitor or the capacitance of the dielectric capacitor. The dielectric capacitor can be adapted to provide a dielectric capacitance. The sections of the respective surfaces between which there are no ferroelectric nanoparticles can refer to sections of the respective surfaces where the ferroelectric nanoparticles fill less than 50%, in particular less than 40%, in particular less than 30%, in particular less than 20%, or in particular less than 10% of the distance between the respective surfaces.

[0033] The dielectric capacitor may be arranged electrically in parallel and / or in series with the ferroelectric capacitor, and the dielectric capacitor and the ferroelectric capacitor (or the capacitance of the dielectric capacitor and the capacitance of the ferroelectric capacitor, respectively) may be adapted to together define a path between at least three polarization states and / or to define a number of remnant polarization states.

[0034] The total surface projected area of ​​the ferroelectric nanoparticles can correspond to the projected area of ​​the ferroelectric nanoparticles onto one of the respective surfaces.

[0035] The surfaces of each of the conductive elements of the pair may be contiguous, for example having a circular or elliptical or rectangular or polygonal or rounded polygonal shape.

[0036] Ferroelectric nanoparticles can be disposed between the respective surfaces.

[0037] Each surface may include and / or define a lateral direction parallel to the respective surface, in other words, each surface may extend in a lateral direction.

[0038] Each of the respective surface areas can exceed the total projected surface area of ​​the ferroelectric nanoparticles by at least 5%, or at least 10%, or at least 30%, or at least 50%, or at least two times.

[0039] The ferroelectric nanoparticles may be spaced apart from one another and / or a dielectric separator material may be disposed between the ferroelectric nanoparticles.

[0040] Corresponding embodiments can ensure discrete polarization states and / or discrete individual polarization states.

[0041] In corresponding embodiments, the dielectric separator material may be included in and / or provide the dielectric of the dielectric capacitor.

[0042] At least a section of the dielectric separator material can be disposed between the second sections of the conductive element. In other words, the second sections of the conductive element can correspond to a projection of the at least a section of the dielectric separator material onto the conductive element. The at least a section of the dielectric separator material and the second sections of the conductive element can define a dielectric capacitor (i.e., according to the alternative definition).

[0043] The dielectric separator material may be adapted to separate the conductive elements and / or to electrically insulate the conductive elements from one another.

[0044] The dielectric separator material may surround at least one of the ferroelectric nanoparticles, or may specifically surround the ferroelectric nanoparticles laterally (ie along a lateral direction).

[0045] The conductive elements of the pair may comprise respective surfaces. The respective surfaces may be spaced apart by a distance. The ferroelectric nanoparticles may extend along at least 60% of the distance, or along at least 75% of the distance, or along at least 90% of the distance, or along the entire distance. Alternatively or additionally, the respective surfaces may be connected by a reference line, and the ferroelectric nanoparticles may extend along the reference line. The distance may correspond to the length of the reference line.

[0046] The ferroelectric nanoparticles can be spaced apart from one another laterally (ie, along a lateral direction).

[0047] A first ferroelectric nanoparticle of the ferroelectric nanoparticles can have a first size. A second ferroelectric nanoparticle of the ferroelectric nanoparticles can have a second size. The first size can be in particular at least 10% or at least 30% or at least 50% or at least twice as large as the second size.

[0048] The first size (or the second size, respectively) can refer to the maximum extension of the first ferroelectric nanoparticle (or the second ferroelectric nanoparticle, respectively). In other words, the first size (or the second size, respectively) can refer to the size of the first ferroelectric nanoparticle (or the second ferroelectric nanoparticle, respectively) along a direction in which it is maximum.

[0049] Alternatively, the first size (or the second size, respectively) can refer to the volume of the first ferroelectric nanoparticle (or the second ferroelectric nanoparticle, respectively).

[0050] The first (and / or second) ferroelectric nanoparticles may be disposed between the first (and / or second) first sections of the conductive element. In other words, the first (and / or second) first sections of the conductive element may correspond to a projection of the first (and / or second) ferroelectric nanoparticles onto the conductive element. The first (and / or second) ferroelectric nanoparticles and the first (and / or second) first sections of the conductive element may define a first (and / or second) ferroelectric capacitor. The first (and / or second) ferroelectric capacitor may be adapted to provide a respective capacitance.

[0051] According to an embodiment, the size of each of the ferroelectric nanoparticles along any direction does not exceed 100 nm, in particular does not exceed 50 nm, or does not exceed 30 nm, or does not exceed 20 nm, or does not exceed 10 nm, or does not exceed 5 nm. In the context of the present disclosure, ferroelectric nanoparticles having a size of up to 20 nm may also be referred to as ferroelectric nanodots.

[0052] The size of each of the ferroelectric nanoparticles can be beneficial to ensure the monodomain ferroelectric state of the ferroelectric nanoparticles. In particular, defining the size of the ferroelectric nanoparticles can result in a controlled coercivity of each nanoparticle, and thus controlling the size gives control over the pathways for addressing or switching between polarization states. This is an advantage of using ferroelectric nanoparticles over, for example, using ferroelectric films where the ferroelectric domains form randomly without good control over their size distribution. In the case of ferroelectric nanoparticles, narrow size tolerances or narrow size distributions can be achieved.

[0053] Each size can correspond to a size of the ferroelectric nanoparticle along a direction that is the greatest elongation or largest, as described above in the context of the first size and the second size.

[0054] The minimum size of each of the ferroelectric nanoparticles along any direction may be 4 nm or more, may be 3 nm or more, may be 2 nm or more, or may be 1 nm or more.

[0055] The ferroelectric nanoparticles can comprise respective monodomain ferroelectric states.

[0056] At least three polarization states can correspond to combinations of monodomain ferroelectric states for each of the ferroelectric nanoparticles.

[0057] Each monodomain ferroelectric state of a ferroelectric nanoparticle can be a remanent polarization state and / or a discrete polarization state.

[0058] The first conductive element of the pair may be adapted to carry a constant charge and / or may be electrically insulating and / or electrically floating.

[0059] The ferroelectric nanoparticle capacitor device may further comprise a charge control device adapted to control and / or vary the charge on the second conductive element of the pair.

[0060] The ferroelectric nanoparticle capacitor device may further comprise a transistor, the channel of the transistor forming the first conductive element or the second conductive element.

[0061] The charge control device may comprise an additional conductive element electrically isolated from the pair of conductive elements. The charge control device may be adapted to apply a voltage between the additional conductive element and the second conductive element.

[0062] The additional conductive element and the second conductive element may be disposed on either side of the first conductive element.

[0063] The additional conductive element may be separated from the first conductive element by a dielectric spacer.

[0064] The dielectric spacers may form the gate dielectric of the transistor.

[0065] The conductive element and / or the further conductive element may comprise or consist of a metallic material or a semiconducting material.

[0066] At least three polarization states may be associated with respective voltage levels.

[0067] The respective voltage levels may refer to the voltage levels of the first conductive element and / or the second conductive element, or the voltage difference between the first conductive element and the second conductive element.

[0068] The ferroelectric nanoparticle capacitor device may further comprise a voltage readout element adapted to determine the voltage of the first conductive element and / or the voltage of the second conductive element, or a voltage difference between the first conductive element and the second conductive element, such as to identify respective voltage levels associated with the at least three polarization states.

[0069] The ferroelectric nanoparticle capacitor device may further comprise a temperature control element adapted to control and / or vary the temperature of the ferroelectric nanoparticles.Alternatively or additionally, the ferroelectric nanoparticle capacitor device may comprise a force control element adapted to control and / or vary the mechanical force applied to the ferroelectric nanoparticles.

[0070] The temperature control element and / or the force control element can allow for post-adjustment of the pathway to address and / or switch polarization states. For example, the temperature control element and / or the force control element can allow for addressing polarization states, such as a polarization state with zero net polarization, which cannot be addressed by applying a charge or voltage to at least one of the conductive elements, for example, at ambient temperature or without a force applied by the force control element.

[0071] A second aspect relates to the use of the above-described ferroelectric nanoparticle capacitor device as a multi-logic level data storage device.

[0072] A third aspect relates to a method for operating a ferroelectric nanoparticle capacitor device, the ferroelectric nanoparticle capacitor device comprising a pair of electrically insulated conductive elements and a ferroelectric nanoparticle disposed between the conductive elements of the pair. The ferroelectric nanoparticle is adapted to provide at least three polarization states with different total ferroelectric polarizations, including a minimum ferroelectric polarization state, a maximum ferroelectric polarization state, and at least one intermediate ferroelectric polarization state. The method includes selecting an intermediate ferroelectric polarization state, selecting a first voltage or charge according to the selected intermediate ferroelectric polarization state, and applying the first voltage or charge to the conductive elements of the pair to set the ferroelectric nanoparticle to the selected intermediate ferroelectric polarization state.

[0073] The method may implement multi-valued logic.

[0074] The method may further include maintaining the other conductive element of the pair (ie, the first conductive element) at a constant charge.

[0075] Preferably, the first voltage or charge refers to a charge. In other words, the method can refer to selecting a first charge according to a selected intermediate ferroelectric polarization state and applying the first charge.

[0076] Selecting an intermediate ferroelectric polarization state can refer to selecting an intermediate ferroelectric polarization state of at least one intermediate ferroelectric polarization state.

[0077] The maximum ferroelectric polarization state may provide the maximum ferroelectric polarization of the at least three polarization states, in other words, none of the at least three polarization states may have a ferroelectric polarization greater than the maximum ferroelectric polarization state.

[0078] The minimum ferroelectric polarization state may provide the minimum ferroelectric polarization of the at least three polarization states, in other words, none of the at least three polarization states may have a ferroelectric polarization less than the maximum ferroelectric polarization state.

[0079] The ferroelectric polarization of the intermediate ferroelectric polarization state may be greater than the minimum ferroelectric polarization and less than the maximum ferroelectric polarization.

[0080] In the context of the present disclosure, the magnitude of the ferroelectric polarization may be determined by the component of the respective ferroelectric polarization along the reference axis. In other words, a negative (e.g., with respect to the reference axis) ferroelectric polarization may be considered to be less than a ferroelectric polarization of zero. The reference axis may intersect at least one of the conductive element and the ferroelectric nanoparticles.

[0081] The conductive element of the pair to which the first voltage or charge is applied can correspond to the second conductive element of the pair described above in the context of the ferroelectric nanoparticle capacitor device, and the other conductive element of the method can correspond to the first conductive element of the pair described above in the context of the ferroelectric nanoparticle capacitor device.

[0082] The ferroelectric nanoparticle capacitor device may further comprise an additional conductive element electrically isolated from the pair of conductive elements. Applying a first voltage or charge to the pair of conductive elements (i.e., the second conductive element) may include applying a voltage between the additional conductive element and the pair of conductive elements (i.e., the second conductive element). The additional conductive element may be included in a charge control device of the ferroelectric nanoparticle capacitor device.

[0083] The method may further include providing the ferroelectric nanoparticles in a first of the at least three polarization states before applying the first voltage or charge to set the ferroelectric nanoparticles to the selected intermediate ferroelectric polarization state, selecting a second voltage or charge according to the selected intermediate ferroelectric polarization state and / or the first polarization state, and applying a second voltage or charge to the pair of conductive elements to set the ferroelectric nanoparticles from the first to the second of the at least three polarization states. The first polarization state may be different from the selected intermediate ferroelectric polarization state. The second polarization state may be different from both the first and selected intermediate ferroelectric polarization states.

[0084] In terms of their respective absolute values, the second voltage or charge can exceed the first voltage or charge.

[0085] The sign of the second voltage or charge may be opposite to the sign of the first voltage or charge.

[0086] The method may further include providing the ferroelectric nanoparticles in a third polarization state of the at least three polarization states prior to applying the second voltage or charge to set the ferroelectric nanoparticles to the selected intermediate ferroelectric polarization state, selecting the third voltage or charge according to the selected intermediate ferroelectric polarization state and / or the first polarization state, and applying a third voltage or charge to the pair of conductive elements to set the ferroelectric nanoparticles from the first polarization state to a third polarization state of the at least three polarization states. The third polarization state may be different from the first polarization state, the second polarization state, and the selected intermediate ferroelectric polarization state.

[0087] The third voltage or charge can exceed the second voltage or charge in terms of their respective absolute values.

[0088] The sign of the third voltage or charge may be opposite to the sign of the second voltage or charge.

[0089] The selected intermediate ferroelectric polarization state may be a remanent state. Alternatively or additionally, the method may include reducing the voltage or charge applied to the conductive element, in particular reducing the voltage by at least 30%, by at least a factor of 2, by at least a factor of 3, by at least a factor of 5, by at least a factor of 10, or by at least a factor of 100, thereby maintaining the set intermediate ferroelectric polarization state.

[0090] The method may further include heating the ferroelectric nanoparticles and / or applying a mechanical force to the ferroelectric nanoparticles, e.g., to change their polarization state and / or to modify the relationship between the selected intermediate ferroelectric polarization state and the applied voltage or charge.

[0091] The method can include heating the ferroelectric nanoparticles to change their polarization state to a polarization state having a ferroelectric polarization of zero.

[0092] The method may further include detecting a current polarization state of the ferroelectric nanoparticles based on the voltage of at least one of the conductive elements.

[0093] The method can include detecting a current polarization state of the ferroelectric nanoparticles based on a change in the at least one voltage of the conductive element, such as by counting jumps in the at least one voltage of the conductive element.

[0094] The first polarization state and / or the second polarization state may be a remanent state. [Brief description of the drawings]

[0095] The techniques of the present disclosure and their associated advantages will become best apparent from a description of exemplary embodiments taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 illustrates a ferroelectric nanoparticle capacitor device according to a first embodiment. [Figure 2a]FIG. 1 illustrates the electrostatic energy of individual polarization states of ferroelectric nanoparticles between conductive elements and the switching between them. [Figure 2b] FIG. 2b shows charge-voltage hysteresis loops illustrating switching between the individual polarization states of the ferroelectric nanoparticles of FIG. 2a. [Diagram 3] FIG. 2 shows an equivalent electrical circuit for the ferroelectric nanoparticle capacitor device of FIG. 1 connected to a charge control device. [Figure 4a] 2 illustrates the electrostatic energy of the polarization states of a ferroelectric nanoparticle capacitor device according to an embodiment corresponding to FIG. 1, as well as pathways for managing and / or switching the polarization states. [Figure 4b] FIG. 4b illustrates charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to the embodiment of FIG. 4a, as well as pathways for addressing and / or switching the polarization states. [Figure 5a] 2 illustrates the electrostatic energy of the polarization states of a ferroelectric nanoparticle capacitor device according to another embodiment corresponding to FIG. 1, as well as pathways for managing and / or switching the polarization states. [Figure 5b] FIG. 5b illustrates charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to the embodiment of FIG. 5a, as well as pathways for addressing and / or switching the polarization states. [Figure 6a] 2 illustrates the electrostatic energy of the polarization states of a ferroelectric nanoparticle capacitor device according to another embodiment corresponding to FIG. 1, as well as pathways for managing and / or switching the polarization states. [Figure 6b] FIG. 6b illustrates charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to the embodiment of FIG. 6a, as well as pathways for addressing and / or switching the polarization states. [Figure 7a] FIG. 1 illustrates a ferroelectric nanoparticle capacitor device according to an embodiment having a temperature control element and a force control element. [Figure 7b] FIG. 7b shows an equivalent electrical circuit for the ferroelectric nanoparticle capacitor device of FIG. 7a. [Figure 8a] FIG. 1 illustrates a ferroelectric nanoparticle capacitor device according to an embodiment in which the channel of a transistor forms the conductive element of the ferroelectric nanoparticle capacitor device. [Figure 8b] FIG. 8b shows an equivalent electrical circuit for the ferroelectric nanoparticle capacitor device of FIG. 8a. [Figure 9a] FIG. 13 illustrates a ferroelectric nanoparticle capacitor device according to another embodiment, in which the ferroelectric nanoparticles provide four polarization states. [Figure 9b] FIG. 9b illustrates the four polarization states of the ferroelectric nanoparticles of FIG. 9a. [Figure 9c] FIG. 13 illustrates a ferroelectric nanoparticle capacitor device according to another embodiment, in which the ferroelectric nanoparticles provide four polarization states. [Figure 9d] FIG. 9c illustrates the four polarization states of the ferroelectric nanoparticles of FIG. [Figure 10a] FIG. 9C illustrates charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to embodiments corresponding to FIG. 9a or FIG. 9c, as well as pathways for addressing and / or switching the polarization states. [Figure 10b] FIG. 9C shows charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to another embodiment corresponding to FIG. 9a or FIG. 9c, as well as pathways for addressing and / or switching the respective polarization states. [Figure 10c] FIG. 9C shows charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to another embodiment corresponding to FIG. 9a or FIG. 9c, as well as pathways for addressing and / or switching the respective polarization states. [Figure 10d] FIG. 9C shows charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to another embodiment corresponding to FIG. 9a or FIG. 9c, as well as pathways for addressing and / or switching the respective polarization states. [Figure 10e]FIG. 9C shows charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to another embodiment corresponding to FIG. 9a or FIG. 9c, as well as pathways for addressing and / or switching the respective polarization states. [Figure 10f] FIG. 9C shows charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to another embodiment corresponding to FIG. 9a or FIG. 9c, as well as pathways for addressing and / or switching the respective polarization states. [Figure 10g] FIG. 9C shows charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to another embodiment corresponding to FIG. 9a or FIG. 9c, as well as pathways for addressing and / or switching the respective polarization states. [Figure 10h] FIG. 9C shows charge-voltage hysteresis loops associated with the polarization states of ferroelectric nanoparticles according to another embodiment corresponding to FIG. 9a or FIG. 9c, as well as pathways for addressing and / or switching the respective polarization states. [Figure 11] FIG. 2 illustrates a method according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0096] FIG. 1 is a schematic diagram of a ferroelectric nanoparticle capacitor device 100 according to a first embodiment.

[0097] The ferroelectric nanoparticle capacitor device 100 comprises two conductive elements 102, 112 in the form of conductive layers 102, 112 and ferroelectric nanoparticles 104a, 104b therebetween.

[0098] The conductive layers 102, 112 or their respective surfaces 108, 118 extend along horizontal and lateral directions x, y, respectively, and are therefore parallel to each other along those directions x, y.

[0099] Along a vertical longitudinal direction z, the conductive layers 102, 112 or their respective surfaces 108, 118 are spaced apart from each other by a distance d of 1 nm to 100 nm.

[0100] The conductive layer may include noble metals (such as Cu or Au) as well as tantalum and / or titanium or their respective nitrides, and / or other metallic or semiconductor materials.

[0101] The ferroelectric nanoparticles 104a, 104b are each made of a ferroelectric material. In the illustrated embodiment, the ferroelectric nanoparticles 104a, 104b are made of the same ferroelectric material.

[0102] Ferroelectric materials have a nonlinear dependence of their polarization on the electric field, P=±P s +ε0ε f E, where ±P s is the spontaneous polarization, oriented parallel or antiparallel to the electric field E, ε0 is the vacuum permittivity, and ε f is the dielectric constant of the ferroelectric material. The switching between different spontaneous polarization directions of a ferroelectric material is driven by the coercive field E c For simplicity, the coercive field is also called the coercive force.

[0103] The ferroelectric material of the ferroelectric nanoparticles includes Pb(Zr,Ti)O3, PbTiO3, or other ferroelectric oxides HfO2, in particular doped HfO2, for example with zirconium, BaTiO3, Ba(Sr,Ti)O3, or other ferroelectric oxides, P(VDF-TrFE). Alternatively or additionally, it includes the superferroelectric materials LiZnAs, LiBeSb, NaZnSb, LiBeBi. In the superferroelectric materials, the coercivity can achieve values ​​substantially greater than the depolarizing electric field, which makes it possible to easily select the desired relative strengths of Qc and Qs, for example by controlling temperature and strain to tune the system.

[0104] Each of the ferroelectric nanoparticles 104a, 104b is small enough to support a monodomain ferroelectric state. To this end, the ferroelectric nanoparticles 104a, 104b are formed with their maximum extension (i.e. bulk diagonal) of 100 nm, 50 nm, 30 nm, 20 nm or 10 nm or less, depending on the ferroelectric material of the ferroelectric nanoparticles 104a, 104b. Typical sizes of the ferroelectric nanoparticles 104a, 104b are 1 nm, 5 nm, 10 nm, 50 nm or 100 nm.

[0105] The illustrated ferroelectric nanoparticles 104a, 104b are in one of three possible ferroelectric polarization states 106, also referred to below as polarization states 106 for simplicity.

[0106] The polarization state 106 refers to the overall polarization state 106 of the ferroelectric nanoparticles 104a, 104b, ie, the combination of the individual (ie, ferroelectric) polarization states of the ferroelectric nanoparticles 104a, 104b.

[0107] More specifically, the polarization state 106 refers to the projection of the total (i.e., net, overall) polarization of the ferroelectric nanoparticles 104a, 104b on the axis z. In other words, the polarization state 106 refers to the z-component of the total polarization.

[0108] Correspondingly, the individual polarization states refer to the projection of the individual polarizations of the ferroelectric nanoparticles 104a, 104b onto the axis z.

[0109] The illustrated polarization state 106 is characterized by antiparallel individual polarization states of the ferroelectric nanoparticles 104a, 104b, with the individual polarization of the ferroelectric nanoparticles 104a being along the axis z (i.e. parallel) and the individual polarization of the ferroelectric nanoparticles 104b being antiparallel to the axis z. The same polarization state, i.e. having the same z component of the total polarization, is achieved when the individual polarization of the ferroelectric nanoparticles 104b is along the axis z and the individual polarization of the ferroelectric nanoparticles 104a is antiparallel to the axis z. In the illustrated embodiment, these two configurations are equivalent because the ferroelectric nanoparticles 104a are equivalent, i.e. have the same individual polarization. Thus, the two configurations establish a first of the polarization states 106.

[0110] A second polarization state 106 is achieved when the individual polarizations of the ferroelectric nanoparticles 104a, 104b are both aligned along the axis z.

[0111] A third polarization state 106 is achieved when the individual polarizations of the ferroelectric nanoparticles 104a, 104b are both anti-parallel to the axis z.

[0112] The ferroelectric nanoparticles 104a are sandwiched between the first sections 110a, 120a of the conductive layers 102, 112. Conversely, the first sections 110a, 120a of the conductive layers 102, 112 or of their corresponding surfaces correspond to the projection of the ferroelectric nanoparticles 104a onto the conductive layers 102, 108, respectively.

[0113] The first sections 110a, 120a of the conductive layers 102, 112 and the ferroelectric nanoparticles 104a form a first ferroelectric capacitor .

[0114] Correspondingly, the second first section 110b, 120b of the conductive layer 102, 112 is associated with the ferroelectric nanoparticle 104b. The second first section 110b, 120b of the conductive layer 102, 112 and the ferroelectric nanoparticle 104b form a second ferroelectric capacitor 126.

[0115] The first sections 110a, 110b of the first conductive layer 102 have a total area 110 that corresponds to the projections of the ferroelectric nanoparticles 104a, 104b, respectively, onto the first conductive layer 102 or onto its surface 118. In the context of the present disclosure, this area 110 is referred to as the total surface projected area of ​​the ferroelectric nanoparticles 104a, 104b.

[0116] Alternatively, the total surface projected area 110, 120 of the ferroelectric nanoparticles 104a, 104b is defined by the projection 120 of the ferroelectric nanoparticles 104a, 104b onto the second conductive layer 112. Alternatively, the surface projected area 110, 120 of the ferroelectric nanoparticles 104a, 104b is defined by the sum of the areas of the ferroelectric capacitors 124, 126 defined by the ferroelectric nanoparticles 104a, 104b.

[0117] The area of ​​each of the conductive layers 102, 122 exceeds the total surface projected area 110, 120 of the ferroelectric nanoparticles 104a, 104b. As a result, the excess portions 102', 112' of the conductive layers 102, 122 extend beyond the first sections 110a, 110b, 120a, 110b.

[0118] These excess portions 102', 112' form a dielectric capacitor 130, ie a capacitor with a linear charge-voltage characteristic or without (significant) hysteresis.

[0119] In the illustrated embodiment, the dielectric capacitor 130 includes a dielectric material 122 disposed between the second portions 102', 112' of the conductive layers 102, 112. In the illustrated embodiment, the dielectric material 122 fills the entire space between the excess portions 102', 112' of the conductive layers 102, 112 such that the second portions 102', 112' are identical to the excess portions 102', 112' of the conductive layers 102, 112.

[0120] The dielectric material 122 is subjected to an applied electric field, P=ε0ε d It is characterized by a linear dependence of its polarization on E, where ε dis the dielectric constant of the dielectric material 122. According to an embodiment, the dielectric material includes a high-κ dielectric such as Al2O3, Li2O, HfSiO4, Sc2O3, SrO, ZrO2, Y2O3, BaO, Ta2O5, BaO, WO3, MoO3, TiO2, SrTiO3, DyScO3. The dielectric material 122 may also include a low-κ dielectric such as SiO2 or an organic dielectric. In an alternative embodiment, the dielectric material 122 is implemented as an air gap that may be filled with a displacement gas or vacuum.

[0121] In the illustrated embodiment, the dielectric material 122 serves as a dielectric separator material 122 for isolating the ferroelectric nanoparticles 104a, 104b from one another. To this end, the dielectric material 122 is disposed between the ferroelectric nanoparticles 104a, 104b and surrounds the ferroelectric nanoparticles 104a, 104b individually in the horizontal / lateral planes x, y.

[0122] The ferroelectric nanoparticle capacitor device 100 is fabricated using existing nanofabrication procedures, particularly those developed in the context of the semiconductor industry. These procedures allow for the fabrication of complex designs with increasing precision and reliability. For example, advances in fabrication make it possible to create three-dimensional designs of the ferroelectric nanoparticle capacitor device 100 on a suitable substrate support. Exemplary single crystal semiconductor substrates of each selected type of doping or conductivity (e.g., n-conductivity) are commercially available from a variety of sources. The appropriate geometric design is achieved by suitable lithography and etching techniques, for example, electron beam lithography and ion etching. The conductive elements 102, 112 are produced by CVD and PVD methods and / or other suitable processes. After deposition of the first conductive elements 102, 112, a ferroelectric layer is placed thereon, for example using ALD methods and / or other suitable processes. The constituent ferroelectric nanoparticles 104a, 104b are structured from the ferroelectric layer individually or together, for example in a single structuring step. In the former case, the geometric configuration at each stage is designed using appropriate lithography techniques, such as, for example, extreme ultraviolet or electron beam lithography. A dielectric material 122 is grown on the first conductive elements 102, 112, for example, by ALD techniques. The second conductive elements 102, 112 are deposited. Optional interconnect structures are formed on or in the substrate, for example, by CVD and PVD techniques, to form gate, source and drain wiring connections. The patterning and architecture of the device 100 should be implemented, for example, by the Cadence Allegro software package and / or other suitable packages.

[0123] To explain the mechanism of action of the ferroelectric nanoparticle capacitor device 100, Figures 2a and 2b refer to the situation of a single ferroelectric nanoparticle 104a between the conductive elements 102, 112, with a charge control device 114 electrically connected 114a to one of the conductive elements 102, 112.

[0124] As shown in Fig. 2a, a ferroelectric nanoparticle 104a is uniformly polarized and confined between two conductive elements 102, 112 carrying an electric charge 132. It can remain in one of two individual (ferroelectric) polarization states 106a: a state (+1) with its polarization oriented "up" along the z-axis, and a state (-1) with its polarization oriented "down". Thus, a single ferroelectric nanoparticle 104a between the conductive elements 102, 112 implements two corresponding logic levels, |+1) and |-1).

[0125] As a result, the individual polarization states 106a can be controlled by the charge applied to the conductive elements 102, 112. Thus, a single ferroelectric nanoparticle 104a of FIG. 2a confined between the conductive elements 102, 112 implements a binary (i.e., two-level) logic device having logic levels |+1) and |-1).

[0126] Hereinafter, a charge control device 114 having an electrical connection 114a to at least one of the conductive elements 102, 112 is used to control the charge of each conductive element 102, 112 and thus the individual polarization states 106a of the ferroelectric nanoparticles 104a, or the polarization states 106 in FIG. 1. This approach differs from the conventional technique of controlling the voltage of the conductive elements. Advantageously, by the charge control and the charge control device 114, the nanoparticles 104a or nanoparticles 104a, 104b in FIG. 1 and their respective polarization states 106a, 106 are addressed much more reliably than the conventional techniques based on voltage control.

[0127] Importantly, the effective electric field E that drives the polarization of the ferroelectric nanoparticle 104a is not only the electric field induced by the charge 132 on the conductive plate, but also the bound charge Q that appears at the termination points of the polarizing magnetic field lines located at the interface between the ferroelectric nanoparticle 104a and the conductive elements 102, 112. s =SP s This also includes the depolarizing electric field induced by s refers to the spontaneous polarization of the ferroelectric nanoparticle associated with the polarization state 106a. The voltage-charge relationship of a single ferroelectric nanoparticle capacitor is Cf V=Q±Q s where V is the voltage and C f =ε0ε f S / d is the capacitance of the ferroelectric material, and the sign ± corresponds to the "up" (+1) or "down" (-1) orientation of the polarization 106a.

[0128] FIG. 2b shows the electrostatic energy W corresponding to the (+1) and (−1) polarization states 106a of FIG. 2a as a function of applied charge Q. ± =(Q±Q s ) 2 / 2C f These are ±Q s The minimum corresponds to the situation where the charge on the conductive elements 102, 112 exactly compensates for the bound charge, resulting in a zero internal electric field. 1,2 The critical charge N0 corresponding to the switching from (-1) to (+1) and from (+1) to (-1) corresponds to the situation where the polarization state 106a in one polarization direction becomes unstable with respect to switching the polarization state 106a to the opposite polarization direction. 1,2 =±(Q s -Q c ) respectively, where Q c =C f E c d. This energy profile results in a charge-voltage 2 branch with upper and lower branches corresponding to polarization states 106a, or logic levels |+1) and |-1), respectively.

number

[0129] Figure 3 shows the effective electrical circuit of the ferroelectric nanoparticle capacitor device 100 of Figure 1. The ferroelectric nanoparticle capacitor device 100 includes two ferroelectric capacitors 124, 126, each having a capacitance Cf. It further comprises a dielectric capacitor 130, connected in parallel to the ferroelectric capacitors 124, 126, having a capacitance Cd.

[0130] The effective electrical circuit further comprises a charge control element 114 in electrical contact 114a with at least one of the conductive elements 102, 112. The charge control element 114 is adapted to apply a charge Q to the conductive element 102, 112 to which it is connected.

[0131] Importantly, the charge Q applied to the conductive elements 102, 112 may be distributed non-uniformly across the conductive elements 102, 112, with the charge Q being distributed non-uniformly across the conductive elements 102, 112, such that the charge Q is distributed non-uniformly across the region of the first ferroelectric nanoparticle 104a (or on the first first sections 110a, 120a of the conductive elements 102, 112 that correspond to the first ferroelectric capacitors 124, respectively). a , forming a charge Q in the region of the second ferroelectric nanoparticle 104b (or on the sections 110b, 120b of the conductive elements 102, 112, respectively, corresponding to the second ferroelectric capacitor 126). b , and the area of ​​the dielectric material 130 (or on the second or excess portion 102′, 112′, respectively, of the conductive layers 102, 112 corresponding to the dielectric capacitor 130) d Form.

[0132] The charge on the corresponding capacitors 124, 126, 130, Q a , Q b , and Q d is determined by the equivalence of the potentials at the plates of the capacitor, Q a +Q b +Q d Taking into account the condition =Q,

number

number

[0133] FIG. 4a shows the emerging polarization states 106 and their total energy W.

[0134] In the following, the term "level" refers to a logical level, and the two terms are used equivalently.

[0135] A level is represented by the polarization state 106 of the ferroelectric nanoparticles 104a, 104b, and vice versa. In other words, the polarization state 106 provides a level. For this reason, the terms "level" and "polarization state" may be used interchangeably.

[0136] The polarization states 106 are preferentially discrete in the sense that, for example, switching between two different polarization states 106 is characterized by a subtle abrupt change in the ferroelectric polarization. In other words, the ferroelectric nanoparticles 104a, 104b are adapted not to assume any stable ferroelectric polarization between one of the discrete polarization states 106.

[0137] The polarization state 106 is a total energy that provides an energy corresponding to one of the three states 106, |-1), |0), and |+1), that define a logic level.

number

[0138] 4a, 5a, and 6a show the above-mentioned energy profiles W for the polarization states 106, |-1), |0), and |+1). +1 (Q), W0(Q), W -1 4b, 5b, and 6b respectively show the corresponding three-branch hysteresis loop and the paths for addressing or switching between the polarization states 106, |-1), |0), and |+1). The polarization states 106, |-1), |0), and |+1), are the three branches of the charge-voltage characteristic.

number

number

number

[0139] Figures 4a, 4b, 5a, 5b, 6a, and 6b represent the three existing different regimes of hysteresis loop topology, determined by the relative strengths of the effective charge parameters Qc and Qs.

[0140] The energy profiles and transition orders of the polarization states 106, |-1), |0), and |+1) are s >Q c >2Q s 4a, 4b for the case of N0. The end point N0 corresponds to a switching instability of one of the ferroelectric nanoparticles 104a, 104b towards the lowest energy state with opposite polarization 106. The corresponding hysteresis loop with sequential switching between logic levels |-1), |0), and |+1) at the critical charges Q1, Q2, Q3, and Q4 is shown in FIG. 4b.

[0141] Figures 5a and 5b show this condition Q c >3Q s The energy profile and charge-voltage characteristics realized under Q = 0 are shown. It has three logic levels |-1), |0), and |+1), which are realized at Q = 0, but the intermediate ferroelectric polarization state |0) is topologically unstable in the sense that once switching from this logic level to either |-1) or |+1) occurs, the system cannot be returned to the |0) logic level and a two-branch hysteresis loop with switching between the minimum ferroelectric polarization state |-1) and the maximum ferroelectric polarization state |+1) becomes the only valid regime. However, switching of the system to the "hidden" logic level |0) can be achieved by a change in an external parameter different from charging, for example by thermal cycling, which involves passing through a high-temperature paraelectric state.

[0142] Figures 6a and 6b show this condition Q c <2Q sThe energy profile and charge-voltage characteristic achieved are shown below. At zero charge there is only one logic level |0), but hysteretic switching occurs at finite charge, thus implementing a three-position relay element, also known as a Schmitt trigger.

[0143] Importantly, the hysteresis loops shown in Figure 4b (Figure 4a), Figure 5b (Figure 5a), and Figure 6b (Figure 6a) realize the set of all topologically possible switching in three-level logic [Baudry, L., Lukyanchuk, I. and Vinokur, V. Sci. Rep. 7, 42196 (2017)]. In our embodiment, it is the relationship of the material-dependent key parameters Qs and Qc that determines which type of logic is realized. Specific switching characteristics / protocols can be achieved by choosing the desired ratio between the parameters Qs and Qc or by appropriately selecting the size and material composition of the ferroelectric nanoparticles 104a, 104b, respectively.

[0144] FIG. 7a shows an embodiment of a ferroelectric nanoparticle capacitor device 100 similar to that of FIG. 1, which alternatively implements the hysteresis loops shown in FIG. 4b (FIG. 4a), FIG. 5b (FIG. 5a) and FIG. 6b (FIG. 6a).

[0145] 1, the ferroelectric nanoparticle capacitor device 100 of FIG. 7a is formed with various modifications and includes a charge control device 104 consisting of an additional conductive element 202 and a dielectric spacer 204. In addition, the ferroelectric nanoparticle capacitor device 100 of FIG. 7a includes a temperature control element 206. It also includes a force control element 210. According to various embodiments (not shown), the ferroelectric nanoparticle capacitor device 100 is formed with any, any combination, or all of the described modifications (charge control device 104 and / or temperature control element 206 and / or force control element 210).

[0146] The charge control device 104 includes an additional conductive element 202 disposed below the first conductive element 102, opposite the second conductive element 112 disposed above the first conductive element 102.

[0147] The charge control device 104 further comprises a dielectric spacer 204 formed as a layer 204 of dielectric material between the first conductive element 102 and the additional conductive element 202 to electrically insulate them from each other. The dielectric spacer 204 is made of any of the dielectric materials mentioned above, preferentially including SrTiO3, SiO2, Si3N4 or HfO2.

[0148] The charge control device 104 is operated by applying a voltage between the additional conductive element 202 and the second conductive element 112 while the first conductive element 102 is held at a fixed charge (e.g., electrically floating), thereby applying a charge to the second conductive element 112.

[0149] The temperature control element 206 is implemented as a heater 206, more specifically an ohmic heater 206. The heater 206 is disposed below the conductive elements 102, 112 and heats the respective conductive elements 102, 112 and thus the ferroelectric nanoparticles 104a, 104b. The temperature change of the ferroelectric nanoparticles 104a, 104b can be in the range of 10 to 300 Kelvin.

[0150] The ferroelectric nanoparticle capacitor device 100 of FIG. 7 a further comprises a substrate 208 for supporting the ferroelectric nanoparticle capacitor device 100 .

[0151] The substrate is disposed below the conductive elements 102, 112 and, if present, below the additional conductive element 202. The substrate is in thermal contact with one of the (first, second or additional) conductive elements 102, 112, 202 by direct physical contact or indirect contact, for example via a thermally conductive material such as a metal or a sufficiently thin (<100 nm or <20 nm) intermediate layer.

[0152] Heating the substrate 208 using a heater 223 results in mechanical deformation 212 in the form of expansion 212, which induces strain in the ferroelectric nanoparticles 104a, 104b. Alternatively, the strain can be induced by the piezoelectric effect that occurs when an electric field is applied to the substrate 208. For example, the strain induced can be in the range of 0.001-0.1% of the crystal lattice constant.

[0153] The temperature control element 206 and / or the force control element 210 allow for tuning the interrelationship between the parameters Qs and Qc by the external stimuli temperature and / or strain. They therefore allow for on-the-fly modification of the switching logic of the device 100. This tuning can be done by taking into account the different temperature and strain dependencies of these parameters. The so-called superelastic materials, e.g. LiZnAs, LiBeSb, NaZnSb, and LiBeBi, are particularly interesting for the implementation of ferroelectric nanoparticles 104a, 104b, because in these materials the coercive field can achieve values ​​substantially larger than the depolarizing electric field and the relative strengths of the parameters Qs and Qc can be varied over a fairly wide range.

[0154] FIG. 7b shows an equivalent electrical circuit of the ferroelectric nanoparticle capacitor device 100 of FIG. 7a. The additional conductive element 202 and the dielectric spacer 204 form an additional capacitor 214 having a capacitance Ci. The additional capacitor 214 shares the first conductive element 102 with the capacitors 124, 126, 130. Thus, the equivalent electrical circuit comprises the capacitors 124, 126, 130 (defined by the conductive elements 102, 112) and the additional capacitor 214 (defined by the conductive elements 102, 202) connected in series. The second conductive element 112 and the additional conductive element 202 receive an input voltage Vin between them. The charge on the conductive elements 102, 112 induced by the voltage Vin is given by the equation Vin=Q / Ci+V(Q), where V(Q) is a voltage determined by the charge-voltage characteristics as illustrated in FIG. 4b, FIG. 5b, FIG. 6b. This relationship becomes particularly simple and translates to Q≈CiVin when the effective capacitance of the parallel arrangement of capacitors 124, 126, 130 substantially exceeds the capacitance of the additional capacitor 214. The charge controlling the polarization state 106 of the ferroelectric nanoparticles 104a, 104b is directly regulated by the voltage Vin applied to the second conductive element 112 and the additional conductive element 202.

[0155] Figure 8a shows the integration of a ferroelectric nanoparticle capacitor device 100 into a field effect transistor 300, which alternatively implements the hysteresis loops shown in Figures 4b (Figure 4a), 5b (Figure 5a) and 6b (Figure 6a). Figure 8b shows the equivalent electrical circuit of the device 100 of Figure 8a.

[0156] The field effect transistor 300 comprises source / drain regions 304, 306, a channel 302 extending between the source / drain regions 304, 306, and a gate stack 308 disposed above the channel 302. The field effect transistor 300 further comprises a grounded body electrode 312.

[0157] The channel 302 functions as the additional conductive element 202 described in the context of FIG. 8a.

[0158] The gate dielectric 204 is a high-κ dielectric layer that prevents charge leakage between the first conductive element 102 and the channel 302 .

[0159] The gate stack comprises a gate dielectric 204 provided by a dielectric spacer 204 and at least one electrode. In the illustrated embodiment, at least one electrode of the gate stack 308 is provided by a ferroelectric nanoparticle capacitor device 100 similar to that of FIG. 1. More specifically, the second conductive element 112 of the ferroelectric nanoparticle capacitor device 100 serves as the gate electrode of the transistor 300 and is coupled to a driving voltage V in . Preferably, the driving voltage V in is applied between the second conductive element 112 and the additional conductive element (channel) 202, 302, implementing the charge control device 114 described above in the context of FIG. 7a.

[0160] As described above in the context of the previous embodiment, the first conductive element 102 is kept at a constant charge, e.g., electrically insulated and remains floating. This therefore serves to stabilize the polarization 106 of the ferroelectric nanoparticles 104a, 104b. Furthermore, the floating first conductive element 102 homogenizes the potential along the interface between the ferroelectric nanoparticles 104a, 104b and the first conductive element 102, thus maintaining a uniform electric field across the gate stack 308 and the substrate 304.

[0161] Drive voltage V in Under the appropriate protocol for the variation of the voltage V that operates the current in the channel 302, out The stepwise switching of realizes a multi-level logic switching sequence that corresponds to one of the topologically possible hysteresis loops (see Figs. 4a-6b). The switching sequence of the logic levels can be modified by an external stimulus, e.g., by temperature or strain, as described above in the context of Figs. 7a-7b, allowing on-the-fly modification of the switching logic of the ferroelectric nanoparticle capacitor device 100.

[0162] According to a different embodiment, the ferroelectric nanoparticle capacitor device 100 is formed with the temperature control element 206 and / or the force control element 210 as described above in the context of Figure 7a integrated in or below the substrate 312, for example instead of the substrate 312. In the latter embodiment, a substrate 312 with high thermal conductivity is applied.

[0163] Figures 9a, 9c show an embodiment of a ferroelectric nanoparticle capacitor device 100 for implementing a topologically configurable four-level logic unit, while Figures 9b, 9d show respective polarization states 106 representing the four logic levels.

[0164] 9a shows a ferroelectric nanoparticle capacitor device 100 having three identical, e.g., cylindrical, ferroelectric nanoparticles 104a, 104b, 104c between the conductive elements 102, 112. The ferroelectric nanoparticles 104a, 104b, 104c provide equal coercive fields and equal cross-sectional areas.

[0165] In the illustrated embodiment, a dielectric separator material 122 fills the remaining space between the conductive elements 102,114.

[0166] The system is driven and controlled by a charge Q placed on at least one of the conductive elements 102, 114 using a charge control element 114 as described above.

[0167] As shown in FIG. 9b, the ferroelectric nanoparticle capacitor device 100 of FIG. 9a provides polarization states ((+++), (++-) (or equivalently, (+-+) and (-++), (+--)), or equivalently (-+-) and (--+), and finally (---), where the downward arrow (or upward arrow) in FIG. 9b represents a negative "-" or positive "+" polarization relative to the z-axis.

[0168] As a result, the ferroelectric nanoparticle capacitor device 100 of FIG. 9a realizes four-level logic characterized by logic levels |+2), |+1), |-1), and |-2), respectively.

[0169] 9c shows another embodiment of a ferroelectric nanoparticle capacitor device 100 for implementing a four-level logic device, where two non-equivalent ferroelectric nanoparticles 104a, 104b are disposed between conductive elements 102, 112 and coated with a dielectric separator material 122. The ferroelectric nanoparticles 104a, 104b can be made of different ferroelectric materials and can have different sizes.

[0170] Figure 9d shows the polarization states 106 of the ferroelectric nanoparticles 104a, 104b of Figure 9c, which are similar to the polarization states 106 of Figure 4a associated with the ferroelectric nanoparticles 104a, 104b, 104c of Figure 1. However, in Figure 9d, the states (+-) and (-+) are not equivalent, so the four polarization states 106 implement the logic levels of a four-level logic unit, namely (--)⇔|-2), (-+)⇔|-1), (+-)⇔|+1), and (++)⇔|+2).

[0171] Except for the number or size / material composition of the ferroelectric nanoparticles 104a, 104b, 104c, the embodiment of Figures 9a, 9c is similar to the embodiment of Figure 1. In an alternative embodiment (not shown), the ferroelectric nanoparticles 104a, 104b, 104c (i.e. in their respective numbers or with their respective sizes / material compositions) described in the context of Figures 9a or 9c are applied to a ferroelectric nanoparticle capacitor device 100 similar to the embodiment of Figures 7a or 8a.

[0172] Figures 10a, 10b, 10c, 10d, 10e, 10f, 10g, and 10h show charge-voltage hysteresis loops associated with the polarization states 106 of a ferroelectric nanoparticle capacitor device 100 similar to those of Figure 9a or 9c.

[0173] Considerations similar to those described above for the three-level logic unit show that the hysteresis loop V(Q) of the four-level configuration of ferroelectric nanoparticles 104a, 104b has four branches corresponding to the logic levels 116, |+2), |+1), |-1), and |-2). Figures 10a, 10b, 10c, 10d, 10e, 10f, 10g, and 10h show all possible hysteresis loops with different switching sequences in four-level logic [Baudry, L., Lukyanchuk, I., and Vinokur, V. Sci. Rep. 7, 42196 (2017)].

[0174] FIG. 10a shows a charge-voltage hysteresis loop with sequential switching between logic levels / polarization states 106, |+2), |+1), |-1), and |-2), driven by varying the charge Q in the conductive elements 102, 112.

[0175] The charge-voltage hysteresis loops of Figures 10a, 10b, 10c, and 10d correspond to the design of a four-level logic memory or other processing protocols having different switching sequences between the available logic levels / polarization states 106, |+2), |+1), |-1), and |-2), or different topological ways of accessing the information stored in these logic levels / polarization states 106, |+2), |+1), |-1), and |-2).

[0176] The charge-voltage hysteresis loops of Fig. 10e and Fig. 10f include "hidden" logic levels |-1), |1). Such a protocol can be used when information stored in the "hidden levels" |-1), |1) needs to be protected from unwanted changes and other interferences. Any attempt to access these levels |-1), |1) will immediately switch the corresponding information units to another level |-2), |2) and cannot be restored. Said charge-voltage hysteresis loops thus provide security protection for the ferroelectric nanoparticle capacitor device 100, which is a particularly novel feature of our disclosure.

[0177] The charge-voltage hysteresis loops of Figures 10g and 10h implement a multi-level Schmitt trigger required for multiple applications in electronics.

[0178] The ferroelectric nanoparticle capacitor device 100 of FIG. 9a or 9c is enabled to implement any preselected charge-voltage hysteresis loop of those represented in FIG. 10a, FIG. 10b, FIG. 10c, FIG. 10d, FIG. 10e, FIG. 10f, FIG. 10g, and FIG. 10h by selection of appropriate size and material composition of the ferroelectric nanoparticles 104a, 104b, 104c.

[0179] External stimuli, e.g., temperature or strain as described above in the context of Figures 7a, 8b, the charge-voltage hysteresis loop, and control of the switching sequence between logic levels / polarization states 106, |+2), |+1), |-1), and |-2), can be selected and modified on the fly, i.e. after fabrication of the ferroelectric nanoparticle capacitor device 100 with a given size and material composition of the ferroelectric nanoparticles 104a, 104b, 104c.

[0180] Similarly, the charge-voltage hysteresis loop can be controlled for ferroelectric nanoparticle capacitor devices 100 that include more than three, for example, four, five, or any larger number of ferroelectric nanoparticles 104a, 104b, 104c. The charge-voltage hysteresis loop can be controlled initially by the selection of an appropriate number of suitable ferroelectric nanoparticles 104a, 104b, 104c and their size and material composition. Subsequent on-the-fly control is achieved by incorporating temperature control elements 206 or force control elements as described above. A smaller number of ferroelectric nanoparticles 104a, 104b, 104c, such as up to 10, 5, 4, or 3 ferroelectric nanoparticles 104a, 104b, 104c, is preferred to ensure sufficient spacing between the polarization states 106 in terms of total energy W, voltage V, and / or charge Q. In other words, the number of polarization states 106 must be limited, for example, to a maximum of 64, 32, 16, 8, or 5 polarization states 106. The smaller the number of ferroelectric nanoparticles 104a, 104b, 104c and / or the number of polarization states 106, the more reliable the switching and reading of the polarization states 106.

[0181] Embodiments having more than three ferroelectric nanoparticles 104a, 104b, 104c use the (ferroelectric and / or dielectric) materials and temperature and / or strain ranges described above. The remaining device parameters are similar to those described above. Devices including any other number of nanoparticles and their configurations realize multi-level logic units with more complex paths for the charge-voltage hysteresis loops, thus enabling even higher levels of neuromorphic computing.

[0182] FIG. 11 illustrates a method 400 for operating the ferroelectric nanoparticle capacitor device 100.

[0183] The ferroelectric nanoparticle capacitor device 100 is similar to one of the ferroelectric nanoparticle capacitor devices 100 described above in the context of Figure 1, Figure 7a, Figure 8a, Figure 9a, or Figure 9c. Any of these ferroelectric nanoparticle capacitor devices 100 provide a maximum ferroelectric polarization state (and a minimum ferroelectric polarization state) having a maximum (and minimum) ferroelectric polarization, such that none of the at least three polarization states has a ferroelectric polarization greater (or less, respectively) than the maximum ferroelectric polarization state (or the minimum ferroelectric polarization state). Additionally, any of these ferroelectric nanoparticle capacitor devices 100 provide an intermediate ferroelectric polarization state having a polarization between the minimum ferroelectric polarization and the maximum ferroelectric polarization.

[0184] In step 402, the method 400 includes selecting an intermediate ferroelectric polarization state.

[0185] In step 404, the method 400 includes selecting a first voltage or charge according to the selected intermediate ferroelectric polarization state.

[0186] In step 406, the method 400 includes applying a first voltage or charge to the pair of conductive elements 102, 112 to set the ferroelectric nanoparticles 104a, 104b, 104c to a selected intermediate ferroelectric polarization state.

[0187] Preferentially, the current polarization state 106 of the ferroelectric nanoparticles 104a, 104b, 104c is detected based on the voltage of at least one of the conductive elements 102, 112. For this purpose, the voltage between the conductive elements 102, 112 is measured, which corresponds to a voltage in the charge-voltage hysteresis loop described above. Thus, for a given device, the measured voltage is directly related to the polarization state 106.

[0188] Alternatively, the current polarization state 106 of the ferroelectric nanoparticles 104a, 104b, 104c is detected based on a change in the voltage of at least one of the conductive elements 102, 112, such as by counting jumps in the voltage of at least one of the conductive elements 102, 112. To this end, voltage measurements are performed continuously to identify changes in the voltage.

[0189] Of the two options for selecting the first voltage or charge, it is preferred to select the first charge, and correspondingly, it is preferred to apply the first charge.

[0190] The other conductive element 102, 112 of the pair is held at a constant charge.

[0191] Preferably, a first voltage or charge is applied between one of the conductive elements (i.e. the second conductive element 112 described above) and the additional conductive element 202, 302, preferably using the charge control device 114 described above.

[0192] When applied to a ferroelectric nanoparticle capacitor device 100 having a charge-voltage hysteresis loop as shown in Figure 10a, the voltage or charge applied to the conductive elements 102, 112 increases continuously until a first voltage or charge is reached. A greater or lesser voltage or charge is applied to the conductive elements 102, 112 to reach a polarization state 106 having a greater or lesser (i.e., more negative) polarization.

[0193] The voltage or charge applied to the conductive elements 102, 112 may then be reduced to zero, at which point the polarization state 106 remains maintained. The ferroelectric nanoparticle capacitor device 100 thus implements a non-volatile memory that can be used to store information without the support of external power, voltage, or charge.

[0194] When applied to a ferroelectric nanoparticle capacitor device 100 having a charge-voltage hysteresis loop as shown in Figure 10b, to reach the intermediate ferroelectric polarization state |+1), the voltage or charge applied to the conductive elements 102, 112 must first be increased to a value positive enough to reach state |+2). The applied voltage is then lowered until a negative first voltage or charge is reached, setting the polarization to state |+1). A reverse voltage or charge sequence is applied to the conductive elements 102, 112 to reach the intermediate ferroelectric polarization state |-1).

[0195] When applied to a ferroelectric nanoparticle capacitor device 100 having a charge-voltage hysteresis loop as shown in FIG. 10c, to reach the intermediate ferroelectric polarization state |+1), the voltage or charge applied to the conductive elements 102, 112 must first be increased to a value positive enough to reach state |+2). The applied voltage is then lowered until the ferroelectric nanoparticles 104a, 104b, 104c switch to state |-1). The applied voltage is then increased until a positive first voltage or charge is reached, setting the polarization 106 to state |+1). A reverse voltage or charge sequence is applied to the conductive elements 102, 112 to reach the intermediate ferroelectric polarization state |-1).

[0196] In a ferroelectric nanoparticle capacitor device 100 having a "hidden state" as shown in the context of Figures 5b, 10e, and 10f, the polarization state 106 of the ferroelectric nanoparticles 104a, 104b, 104c can be set to the hidden state using heating the ferroelectric nanoparticles 104a, 104b, 104c and / or applying a mechanical force to the ferroelectric nanoparticles 104a, 104b, 104c.

[0197] Alternatively, heating the ferroelectric nanoparticles 104a, 104b, 104c and / or applying a mechanical force to the ferroelectric nanoparticles 104a, 104b, 104c can be used to modify the charge-voltage hysteresis loop of the ferroelectric nanoparticle capacitor device 100.

[0198] The description of the embodiments and drawings merely serves to illustrate the technology of the present disclosure and its associated beneficial effects, and does not imply any limitations. The scope of the present disclosure should be determined from the appended claims. [Explanation of symbols]

[0199] 100 Ferroelectric Nanoparticle Capacitor Devices 102, 112 (pair) of conductive elements 104a, 104b Ferroelectric nanoparticles 106 Polarization state 108, 118 Opposing surfaces of conductive elements 110a, 120a: First section of the conductive element associated with the ferroelectric nanoparticle 104a (first section) 110b, 120b: first section portion (second first section) of the conductive element associated with the ferroelectric nanoparticle 104b 110, 120 Total surface area of ​​ferroelectric nanoparticles 114 Charge Control Device 114a Electrical connection 122 Dielectric separator material 124, 126, 128 First, second, and third ferroelectric capacitors 130 Dielectric Capacitor 132 Charge Cf is the capacitance of the (first) ferroelectric capacitor Cd Capacitance of the dielectric capacitor 102', 112' Sections of conductive element above and below dielectric separator material 202 Additional conductive elements 204 Dielectric Spacer 206 Heaters, temperature control elements 208 Substrate 210 Force control element 212 Mechanical Deformation 214 Charge Control Devices, Series Capacitors 300 Transistors 302 Channel 304 Semiconductor Substrate 306 Source / Drain Region 308 Gate Stack 310 Gate electrode 312 Bottom electrode

Claims

1. A ferroelectric nanoparticle capacitor device (100), comprising: A pair of electrically insulated conductive elements (102, 112); ferroelectric nanoparticles (104a, 104b) disposed between the pair of conductive elements (102, 112); the ferroelectric nanoparticles (104a, 104b) are adapted to provide at least three polarization states (106) having different total ferroelectric polarizations; the size of said ferroelectric nanoparticles (104a, 104b) along any direction does not exceed 100 nm; the ferroelectric nanoparticles (104a, 104b) comprise respective monodomain ferroelectric states; Ferroelectric nanoparticle capacitor devices.

2. at most 10 ferroelectric nanoparticles (104a, 104b), in particular at most 5 ferroelectric nanoparticles (104a, 104b), or at most 3 ferroelectric nanoparticles (104a, 104b), or exactly 3 ferroelectric nanoparticles (104a, 104b), or exactly 2 ferroelectric nanoparticles (104a, 104b), are arranged between the conductive elements of the pair, The ferroelectric nanoparticle capacitor device (100) of claim 1.

3. the conductive elements of the pair (102, 112) include respective surfaces (108, 118) that face each other; the surface area of ​​each of said surfaces (108, 118) exceeds the total projected surface area (110, 120) of said ferroelectric nanoparticles (104a, 104b), respectively; The ferroelectric nanoparticle capacitor device (100) of claim 1 or 2.

4. the ferroelectric nanoparticles (104a, 104b) are spaced apart from one another and / or a dielectric separator material (122) is disposed between the ferroelectric nanoparticles (104a, 104b); The ferroelectric nanoparticle capacitor device (100) of claim 1 or 2.

5. a first ferroelectric nanoparticle (104a) of the ferroelectric nanoparticles (104a, 104b) has a first size; a second ferroelectric nanoparticle (104b) of the ferroelectric nanoparticles (104a, 104b) has a second size; The first size is in particular at least 10%, or at least 30%, or at least 50%, or at least twice as large as the second size; The ferroelectric nanoparticle capacitor device (100) of claim 1 or 2.

6. the size of each of said ferroelectric nanoparticles along any direction is not greater than 50 nm, or not greater than 30 nm, or not greater than 20 nm, or not greater than 10 nm; The ferroelectric nanoparticle capacitor device (100) of claim 1 or 2.

7. The method of claim 1, wherein the at least three polarization states correspond to combinations of respective monodomain ferroelectric states of the ferroelectric nanoparticles. The ferroelectric nanoparticle capacitor device (100) of claim 1 or 2.

8. the first conductive element (102) of said pair (102, 112) is adapted to carry a constant charge and / or is electrically isolated and / or is electrically floating; The ferroelectric nanoparticle capacitor device (100) of claim 1 or 2.

9. a charge control device (114) adapted to control and / or vary the charge on the second conductive element (112) of the pair; The ferroelectric nanoparticle capacitor device (100) of claim 1 or 2.

10. the charge control device comprises an additional conductive element (202) electrically isolated from the pair of conductive elements (102, 112), and the charge control device (114) is adapted to apply a voltage between the additional conductive element (202) and the second conductive element (112); The ferroelectric nanoparticle capacitor device (100) of claim 9.

11. a temperature control element (206) adapted to control and / or vary the temperature of said ferroelectric nanoparticles (104a, 104b), and / or a force control element (210) adapted to control and / or vary the mechanical force applied to the ferroelectric nanoparticles (104a, 104b), The ferroelectric nanoparticle capacitor device (100) of claim 1 or 2.

12. As a multi-logic level data storage device, Use of a ferroelectric nanoparticle capacitor device (100) according to claim 1 or 2.

13. A method (400) for operating a ferroelectric nanoparticle capacitor device (100), comprising: The ferroelectric nanoparticle capacitor device (100) A pair of electrically insulated conductive elements (102a, 112); and ferroelectric nanoparticles (104a, 104b) disposed between the conductive elements (104a, 104b) of the pair. the ferroelectric nanoparticles (104a, 104b) are adapted to provide at least three polarization states (106) having different total ferroelectric polarizations, including a minimum ferroelectric polarization state, a maximum ferroelectric polarization state, and at least one intermediate ferroelectric polarization state; the size of said ferroelectric nanoparticles (104a, 104b) along any direction does not exceed 100 nm; the ferroelectric nanoparticles (104a, 104b) comprise respective monodomain ferroelectric states; The method (400), Selecting an intermediate ferroelectric polarization state (402); selecting (404) a first voltage or charge according to the selected intermediate ferroelectric polarization state; and applying (406) the first voltage or charge to the pair of conductive elements (102, 112) to set the ferroelectric nanoparticles (104a, 104b) to the selected intermediate ferroelectric polarization state. method.

14. prior to applying the first voltage or charge to set the ferroelectric nanoparticles to the selected intermediate ferroelectric polarization state; providing the ferroelectric nanoparticles (104a, 104b) in a first of the at least three polarization states (106), the first polarization state being different from the selected intermediate ferroelectric polarization state; selecting a second voltage or charge according to the selected intermediate ferroelectric polarization state and / or the first polarization state; applying the second voltage or charge to the conductive elements (102, 112) of the pair to set the ferroelectric nanoparticles (104a, 104b) from the first polarization state to a second polarization state of the at least three polarization states (106), wherein the second voltage or charge is applied such that the second polarization state is different from the first polarization state and the selected intermediate ferroelectric polarization state.

14. The method (400) of claim 13.

15. the selected intermediate ferroelectric polarization state is a remanent state; and / or the method further comprising reducing the voltage or charge applied to the conductive element (102, 112), in particular reducing the voltage by at least 30%, at least by a factor of 2, at least by a factor of 3, at least by a factor of 5, at least by a factor of 10, or at least by a factor of 100, thereby maintaining the set intermediate ferroelectric polarization state.

15. The method (400) of claim 13 or 14.

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