Electronic device, digital port, analog component, and method for generating a voltage

Abstract

The present invention relates to an electronic device (10) comprising an input (12) and an output (14), the device (10) generating an output voltage upon providing an input to the device (10), the device (10) comprising: - a conversion unit (16) that converts a spin current into a charging current having an amplitude and a sign; - a spin current application unit (20) that applies a spin current to the conversion unit (16); - a ferroelectric layer (22) that has a ferroelectric polarization and is arranged such that the ferroelectric polarization controls at least one of the amplitude and the sign of the charging current; and - an electric field application unit (24) that applies an electric field to the ferroelectric layer (22) to control the ferroelectric polarization.

Description

[0001] The present invention relates to an electronic device. The present invention also relates to a digital port or an analog component including such a device and a method for generating a voltage.

[0002] A microprocessor, like many electronic devices, is composed of transistors using CMOS technology. The acronym CMOS comes from the term complementary metal oxide semiconductor and represents the technology used to manufacture electronic devices.

[0003] During operation, the current passing through the transistor is modulated based on the voltage applied to an electrode commonly called the gate. More specifically, according to this voltage, charges accumulate or deplete in the channel, and the conductivity of this channel is thus modulated. In practice, this operation involves several sources of energy loss that are superimposed: the unwanted current in the channel in the off state, the losses caused by the establishment of stray current between the channel and the gate, or the losses on the gate.

[0004] Now, in the field of microelectronics, it has been observed that, according to Moore's law, the number of transistors per unit surface in an integrated circuit continues to increase exponentially.

[0005] This leads to an increase in the dissipated power per unit surface, which in turn increases the electrical consumption of the integrated circuit.

[0006] In addition, in a microprocessor, the storage unit and the computing unit are spatially separated, and the energy cost associated with the movement of information between the two units is much greater than the cost associated with the computing itself.

[0007] Therefore, the microprocessor consumes a large amount of electrical energy. This high electrical consumption limits the performance of the microprocessor.

[0008] There is a need for an electronic device, in particular a transistor, that can generate an output voltage with reduced consumption.

[0009] To this end, an electronic device including an input and an output is proposed. The device generates an output voltage when providing an input to the device. The device includes a conversion unit that converts a spin current into a charging current, and the charging current has an amplitude and a sign. The device further includes: a spin current application unit that applies the spin current to the conversion unit; a layer made of a ferroelectric material having a ferroelectric polarization, called a ferroelectric layer, and the ferroelectric layer is arranged such that the ferroelectric polarization controls at least one of the amplitude and the sign of the charging current converted by the conversion unit. The device further includes an electric field application unit that applies an electric field to the ferroelectric layer to control the ferroelectric polarization of the ferroelectric layer.

[0010] Such a device operates by controlling the polarization of the ferroelectric layer. Controlling this polarization makes it possible to control the charging current induced by the conversion unit.

[0011] This operation is different from the operations existing in the prior art. In the prior art, the current is controlled by controlling the magnetization of the ferromagnetic layer (more specifically, by controlling the magnetization intensity). In this case, a ferroelectric layer can be used to generate a piezoelectric effect, and thus can act on the magnetization of the ferromagnetic layer. This operation does not use the polarization of the ferroelectric layer at all.

[0012] In addition, reversing the magnetization by applying a magnetic field or a strong current consumes a very large amount of energy. Therefore, for an equal volume, the energy required to reverse the polarization of the ferroelectric layer is typically 1000 times lower than the energy required to reverse the magnetization; the device enables logical operations to be performed with very low energy consumption. In other words, different from the prior art, this operation enables an output voltage to be generated while reducing the energy consumption of the device.

[0013] According to a specific embodiment, the electronic device includes one or more of the following features considered separately or according to any technically possible combination:

[0014] - The conversion unit includes a ferroelectric layer and a layer with strong spin - orbit coupling. When the spin - orbit coupling is greater than or equal to 1 meV, the spin - orbit coupling is strong, and the ferroelectric layer is in contact with the layer with strong spin - orbit coupling.

[0015] - The layer with strong spin - orbit coupling is a layer made of a heavy material, and the heavy material is a material with an atomic number greater than or equal to 15.

[0016] - The layer with strong spin - orbit coupling is a layer made of a heavy metal, and the heavy metal is a metal with an atomic number greater than or equal to 15.

[0017] - The spin - current application unit includes a first terminal, the electric - field application unit includes a second terminal, and the first terminal and the second terminal are combined together.

[0018] - The device includes a dielectric layer that is located on a part of the input, the conversion unit is located on a part of the output, and the ferroelectric layer is arranged to establish contact between the dielectric layer and the conversion unit.

[0019] - The top of the conversion unit and the ferroelectric layer is a ferromagnetic layer.

[0020] - The conversion unit is used to convert a spin current into a charging current according to a physical phenomenon, and the physical phenomenon is the inverse Rashba - Edelstein effect or the inverse spin - Hall effect.

[0021] - The device is a transistor.

[0022] Furthermore, this specification also relates to a digital port, particularly a digital port belonging to a storage unit, which digital port includes at least one device as previously described.

[0023] This specification also presents an analog component, particularly an analog component belonging to a neural network, which analog component includes at least one device as described above.

[0024] This specification also describes a method for generating an output voltage by means of an electronic device (specifically a transistor), the device including an input and an output, the device generating an output voltage when providing an input to the device, the device including: a conversion unit; a spin current application unit; a layer made of a ferroelectric material having a ferroelectric polarization, called a ferroelectric layer, the ferroelectric layer being arranged such that the ferroelectric polarization controls at least one of the amplitude and sign of the charging current, and an electric field application unit. The method includes the step of applying a spin current to the conversion unit, the step of applying the spin current being performed by the spin current application unit. The method further includes: a step of conversion to a charging current by the spin current conversion unit, the charging current having an amplitude and a sign; and a step of applying an electric field to the ferroelectric layer, the step of applying the electric field being performed by the electric field application unit.

[0025] Other features and advantages of the present invention will become apparent upon reading the following description of embodiments of the present invention provided by way of example only and with reference to the accompanying drawings, which are:

[0026] Figure 1 is a schematic perspective view of an example electronic device;

[0027] Figure 2 is a schematic perspective view of another example electronic device;

[0028] Figure 3 is a schematic perspective view of yet another example electronic device; and

[0029] Figure 4 is a schematic perspective view of an example logic gate.

[0030] Figure 1 The electronic device 10 is schematically shown in.

[0031] The device 10 includes an input 12 and an output 14.

[0032] The input 12 and the output 14 are shown in Figure 1 in the form of conductive track portions.

[0033] When the device 10 is powered at the input 12, the device 10 is configured to generate a voltage at the output 14.

[0034] According to the proposed example, device 10 is a transistor, i.e., a device for amplifying an electrical signal in a controlled manner.

[0035] Device 10 includes a conversion unit 16, a spin current application unit 20, a layer 22 made of a ferroelectric material (referred to as ferroelectric layer 22), an electric field application unit 24, and a ferromagnetic layer 26.

[0036] The conversion unit 16 is configured to convert a spin current into a charge current.

[0037] The charge current thus converted has an amplitude and a sign.

[0038] As will be explained later, Figure 1 the conversion unit 16 is configured to convert a spin current into a charge current according to the inverse Rashba-Edelstein effect.

[0039] The conversion unit 16 includes the ferroelectric layer 22 and a layer 28 having strong spin-orbit coupling.

[0040] The layer having strong spin-orbit coupling is hereinafter referred to as SOC layer 28, and the abbreviation SOC refers to the term "spin-orbit coupling".

[0041] When the spin-orbit coupling is greater than or equal to 1 meV, the spin-orbit coupling is strong.

[0042] According to the shown example, the SOC layer 28 is a layer made of a heavy material.

[0043] A heavy material is a material having an atomic number greater than or equal to 15.

[0044] In one variant, the SOC layer 28 is made of an alloy or a compound including a heavy metal.

[0045] A heavy material is a metal having an atomic number greater than or equal to 15, such as Au, Pt, W, or Ir.

[0046] The ferroelectric layer 22 and the SOC layer 28 are in contact to form a stack in the stacking direction Z.

[0047] Hereinafter, a first lateral direction X and a second lateral direction Y are also defined, each lateral direction being perpendicular to the stacking direction Z and perpendicular to each other.

[0048] The spin current application unit 20 is configured to apply a spin current to the conversion unit 16.

[0049] In the proposed example, the spin current application unit 20 includes a spin current generator 30 and two terminals 32 and 34.

[0050] The spin current generator 30 is used to establish a spin current between two terminals 32 and 34.

[0051] The first terminal 32 is a contact formed in the ferromagnetic layer 26.

[0052] The second terminal 34 is a contact formed in the third track portion 36.

[0053] For each track portion, a main extension direction is defined.

[0054] The main extension direction corresponding to the first track portion 12 of the input is the same as the main extension direction corresponding to the second track portion 14 of the output. In Figure 1 this case, the main extension direction is the first lateral direction X.

[0055] The third track portion 36 is oriented along the main extension direction, which is perpendicular to the main extension directions of the input 12 and the output 14, that is, oriented along the second lateral direction Y.

[0056] The third track portion 36 is in contact with the SOC layer 28.

[0057] The ferroelectric layer 22 has a ferroelectric polarization.

[0058] For example, the ferroelectric layer 22 is made of BaTiO3, PbZrO3, PbTiO3, BiFeO3, HfO2, ZrO2, or polyvinylidene fluoride (PVDF).

[0059] The ferroelectric polarization is an order parameter of the ferroelectric material that makes up the ferroelectric layer 22.

[0060] The ferroelectric layer 22 is arranged such that the ferroelectric polarization controls at least one of the amplitude and sign of the charging current converted by the conversion unit 16.

[0061] In this case, the ferroelectric layer 22 is stacked on the SOC layer 28.

[0062] The electric field application unit 24 is used to apply an electric field to the ferroelectric layer 22.

[0063] The applied electric field makes it possible to control the ferroelectric polarization of the ferroelectric layer 22.

[0064] According to Figure 1 an example, the electric field application unit 24 includes an electric field generator 38 and terminals combined with the terminals 32 and 34 of the spin current application unit 20.

[0065] The ferromagnetic layer 26 is on top of the conversion unit 16 and more specifically above the ferroelectric layer 22.

[0066] According to the first example, the material for the ferromagnetic layer 26 is a metal such as Co, Fe, or Ni.

[0067] In a second example, the material of the ferromagnetic layer 26 is an alloy of Co, Fe, or Ni. In particular, the materials NiFe or CoFe are used.

[0068] In a variant, other alloys are considered to form the ferromagnetic layer 26, such as CoFeB or NiMnSb.

[0069] The operation of the device 10 will now be described with reference to an exemplary embodiment of the method for generating an output voltage by the device 10.

[0070] The generation method includes several steps briefly described below.

[0071] The magnetization of the ferromagnetic layer 26 is held fixed along a direction called the magnetization direction.

[0072] During the application step, the spin current application unit 20 applies a spin-polarized current between the ferromagnetic layer 26 and the third orbital section 36. The spin direction is parallel to the magnetization direction.

[0073] Then, the spin current propagates along the stacking direction Z toward the SOC layer 28.

[0074] During the conversion step, the spin current that has propagated to the SOC layer 28 reaches the interface between the SOC layer 28 and the ferroelectric layer 22.

[0075] As described above, through the inverse Rashba-Edelstein effect, the spin current is converted into a current.

[0076] The inverse Rashba-Edelstein effect is composed of the combination of two coexisting phenomena, which are the inverse Edelstein effect and the Rashba effect.

[0077] The inverse Edelstein effect allows the spin current to be converted into a charge current on the surface of a topological insulator or at an interface with the Rashba effect.

[0078] The Rashba effect appears on the surface of a material where the inversion symmetry is broken or at the interface between two materials, which results in the emergence of an electric field perpendicular to the surface or interface.

[0079] In Figure 1 the case of the device 10, the conversion unit 16 having the interface between the SOC layer 28 and the ferroelectric layer 22 constitutes a system with the Rashba effect.

[0080] In the presence of the Rashba effect, the spin couples with the wave vector of the electron; the spin degeneracy is lifted, and in the simplest case, the electronic structure of the surface or interface consists of two concentric Fermi contours with opposite spin chiralities.

[0081] When a spin current is injected into the conversion unit 16, the inverse Edelstein effect causes opposite but non-equivalent shifts of the Fermi contours to occur, which generates a charge current.

[0082] According to one variant, the spin / charge conversion can also be accomplished by using the inverse spin Hall effect.

[0083] Simultaneously with this step of converting to a charge current, the electric field application unit 24 applies an electric field to the ferroelectric layer 22. The applied electric field enables the ferroelectric polarization to be changed.

[0084] Along the polarization direction, the Rashba states at the interface between the SOC layer 28 and the ferroelectric layer 22 are modified, and the charge current generated by the conversion unit 16 via the inverse Edelstein effect is modulated in amplitude and / or sign.

[0085] Therefore, the polarization state of the ferroelectric layer 22 enables the output voltage of the device 10 to be controlled.

[0086] In this sense, the device 10 enables information to be stored, which is encoded by the ferroelectric polarization state.

[0087] The device 10 is reconfigurable because the configuration is controlled by the electric field application unit 24.

[0088] Compared with other spintronic devices, the reversal of magnetization by applying a magnetic field or a strong current is avoided, which is very energy-consuming, and it is beneficial to control the mutual conversion of spin current to charge current by controlling the reversal of ferroelectric polarization by applying an electric field. In addition, ferroelectric materials can accommodate and generate strong electric fields at the interfaces of the materials.

[0089] Therefore, in other words, spin current can also be generated, manipulated, and converted in a non-volatile manner by voltage without the use of the very energy-consuming magnetization reversal of ferromagnetic materials.

[0090] In addition, controlling the ferroelectric polarization yields better results than controlling the magnetization of materials, especially in terms of reversibility, reproducibility, or durability (up to 10 15 cycles compared to about 10 cycles).

[0091] Taken together, the device 10 is thus a bipolar transistor that is non-volatile and consumes little energy.

[0092] In Figure 2 Another exemplary device 10 is shown.

[0093] Regarding Figure 2 the device and Figure 1 the differences of the device of Figure 2 the device is described.

[0094] In particular, the description of the device of Figure 2 which is effective for the device of Figure 1 is not repeated. Additionally, in order to simplify Figure 2 , the application units 20 and 24 are not shown.

[0095] In the case of Figure 2 , the positions of the SOC layer 28 and the ferroelectric layer 22 are reversed.

[0096] Therefore, the SOC layer 28 is interposed between the ferromagnetic layer 26 and the ferroelectric layer 22.

[0097] The operations and advantages obtained by the device 10 according to Figure 2 are the same as those of the device 10 of Figure 1 .

[0098] In Figure 3 another exemplary device 10 is shown.

[0099] Regarding Figure 3 the device and Figure 1 the differences of the device of Figure 3 the device 10 is described. Therefore, the description effective for the devices of Figure 1 and Figure 2 is not repeated hereinafter.

[0100] According to the example of Figure 3 , the device 10 further includes a dielectric layer 40.

[0101] The dielectric layer 40 is located on a part of the input 12, and the SOC layer 28 is located on a part of the output 14.

[0102] The ferroelectric layer 22 is arranged to establish contact between the dielectric layer 40 and the conversion unit 16.

[0103] More specifically, the ferroelectric layer 22 is located above the dielectric layer 40 and the SOC layer 28, in contact with both layers 28 and 40.

[0104] Therefore, the device 10 includes two arms 42 and 44 connected to each other. The first arm 42 is formed by the dielectric layer 40 and the ferroelectric layer 22, and the second arm 44 is formed by the conversion unit 16 (the SOC layer 28 and the ferroelectric layer 22).

[0105] The two arms 42 and 44 are aligned along the second transverse direction Y such that the main extension directions of the input 12 and the output 14 are not likeFigure 1 and Figure 2 is not aligned as in the device 10 of Figure 1 , but is offset along the second transverse direction Y.

[0106] The ferromagnetic layer 26 is in contact with the ferroelectric layer 22.

[0107] As Figure 3 shown, the ferromagnetic layer 26 is grounded.

[0108] Therefore, using Figure 3 the element with the reference numeral 36 in Figure 3 , a spin current is generated in the stack in the second arm 44.

[0109] During operation, a current is applied to the input 12 to charge the first arm 42 that functions as a capacitive element.

[0110] Therefore, when the threshold voltage of the capacitive element is reached, the polarization of a part of the ferroelectric layer is reversed.

[0111] The reversal of the polarization moves into the ferroelectric layer 22 through domain wall displacement.

[0112] Therefore, the polarization reversal enables control of the amplitude or direction of the charging current converted by the conversion unit 16 from the spin current applied to the conversion unit 16.

[0113] In the case of this device 10, due to the strong resistance of the left arm (dielectric layer and ferroelectric layer assembly), the reversal of the ferroelectric polarization is performed at a very low energy cost.

[0114] Figure 3 The device 10 shown also has the advantage of being connectable, that is, the output voltage of a given device 10 can be used as the input voltage of a subsequent device 10.

[0115] Such a device 10 can be used in many applications.

[0116] For example, as Figure 4 shown, the device 10 is part of a digital port 42, and this digital port is in turn part of a storage unit.

[0117] In this case, the input 12 includes two insertion terminals 44 and 46, such that the digital port 42 performs a logic operation according to the values inserted on the two insertion terminals 44 and 46.

[0118] According to the way the input current injected onto the two insertion terminals 44 and 46 acts on the ferroelectric polarization and the correspondence between the polarization direction and the sign of the current generated at the output, the obtained logic operation can be performed.

[0119] The digital port 42 is reconfigurable and enables logic operations of the "OR" or "AND" type to be performed with low power consumption.

[0120] According to another example, device 10 includes analog components. The analog components are part of a neural network.

[0121] Here, again, using device 10 enables power consumption to be reduced.

Claims

1. An electronic device (10) includes an input (12) and an output (14). When providing the input of the electronic device (10), the electronic device (10) generates an output voltage. The electronic device (10) includes: - A conversion unit (16) for converting a spin current into a charge current, the charge current having an amplitude and a sign; - A spin current application unit (20) for applying a spin current to the conversion unit (16); - A layer made of a ferroelectric material (22) having a ferroelectric polarization, referred to as the ferroelectric layer (22), the ferroelectric layer (22) being arranged such that the ferroelectric polarization controls at least one of the amplitude and the sign of the charge current converted by the conversion unit (16); And - An electric field application unit (24) for applying an electric field to the ferroelectric layer (22) to control the ferroelectric polarization of the ferroelectric layer (22).

2. The apparatus according to claim 1, wherein, The conversion unit (16) includes the ferroelectric layer (22) and a layer (28) having strong spin-orbit coupling. When the spin-orbit coupling is greater than or equal to 1 meV, the spin-orbit coupling is strong, and the ferroelectric layer (22) and the layer (28) having strong spin-orbit coupling are in contact.

3. The device according to claim 2, wherein The layer (28) having strong spin-orbit coupling is a layer made of a heavy material, and the heavy material is a material with an atomic number greater than or equal to 15.

4. The device according to claim 1, wherein, The spin current application unit (20) includes first terminals (32, 34), and the electric field application unit (24) includes second terminals (32, 34), and the first terminals (32, 34) and the second terminals (32, 34) are combined together.

5. The device according to claim 1, wherein, The electronic device (10) includes a dielectric layer (40) that is located on a part of the input (12), the conversion unit (16) is located on a part of the output (14), and the ferroelectric layer (22) is arranged to establish contact between the dielectric layer (40) and the conversion unit (16).

6. The device according to claim 1, wherein, On top of the conversion unit (16) and the ferroelectric layer (22) is a ferromagnetic layer (26).

7. The device according to claim 1, wherein The conversion unit (12) is for converting a spin current into a charge current according to a physical phenomenon, and the physical phenomenon is the inverse Rashba-Edelstein effect or the inverse spin Hall effect.

8. The device according to any one of claims 1 to 7, wherein The device (10) is a transistor.

9. A digital port (42) includes at least one device (10) according to claim 1.

10. The digital port according to claim 9, wherein, The digital port (42) is part of a storage unit.

11. An analog component includes at least one device (10) according to claim 1.

12. The analog component according to claim 11, wherein, The analog component is part of a neural network.

13. A method for generating an output voltage by an electronic device (10), the electronic device (10) includes an input (12) and an output (14). When providing the input of the electronic device (10), the electronic device (10) generates an output voltage. The electronic device includes: - A conversion unit (16); - A spin current application unit (20), - A layer made of a ferroelectric material (22) having a ferroelectric polarization, referred to as a ferroelectric layer (22), the ferroelectric layer (22) being arranged such that the ferroelectric polarization controls at least one of the amplitude and the sign of the charging current; And - An electric field application unit (24), The method includes at least one of the following steps: - A step of applying a spin current to the conversion unit, the step of applying the spin current being performed by the spin current application unit (20), - A step of conversion to a charging current by a spin current conversion unit (16), the charging current having an amplitude and a sign; And - A step of applying an electric field to the ferroelectric layer (22), the step of applying the electric field being performed by the electric field application unit (24).

14. The method according to claim 13, wherein, The device (10) is a transistor.

Images