KR101761459B1 - Energy harvesting device, electrocaloric cooling device, method of fabricating the devices and monolithic device having the devices - Google Patents

Abstract

The present invention relates to an element for energy conversion, and relates to an energy harvesting element, an electrothermal cooling element, a method of manufacturing the same, and a monolithic element including the same. According to one embodiment of the present invention, there is provided a pyroelectric layer comprising a compound of the formula Hf _1-x Zr _x O _2, wherein 0.7? X < 0.9.

Description

TECHNICAL FIELD [0001] The present invention relates to an energy harvesting device, an electrocaloric cooling device, and a monolithic device having the same,

The present invention relates to an energy conversion element, and more particularly, to an energy harvesting element, an electrothermal cooling element, a method of manufacturing the same, and a monolithic element including the same.

Modern society, in addition to environmental problems, faces the limitations of energy resources and the need for high efficiency in the use of energy resources. For example, cooling devices that utilize vapor compression techniques, such as refrigerators and air conditioners, require large amounts of electrical energy to regulate the temperature, but are less efficient. In addition, the cooling device requires many driving devices and large and complex components.

In addition to the above-mentioned large-scale cooling apparatuses, electric energy is also being abandoned as heat energy which can not be reused in electronic products. For example, in a central processing unit used in a computer, electric energy is partially used for calculation, and unused electric energy is converted into heat energy and becomes unusable.

To increase the efficiency of energy use, solid state thermoelectric device technology, which converts thermal energy into electrical energy, is also used. The thermoelectric element can generate electric energy using a temperature difference between both ends of a semiconductor element including a junction of p-type and n-type semiconductor materials connected in series. Although the thermoelectric technology does not require many driving devices and large and complex components required for vapor compression technology, it is less efficient than using vapor compression technology, and thus it is difficult to replace conventional cooling devices.

To solve this problem, a pyroelectric device using a pyroelectric material having a high energy efficiency has been proposed. The carnot efficiency of a conventional thermoelectric device is 1.7%, while that of a superconducting device is 50%. The pyroelectric device can be applied to a pyroelectric energy harvesting device and an electrocaloric cooling device.

As a typical pyroelectric material, an inorganic material containing a lead component and a polymer based on poly (vinylidene fluoride-trifluoroethylene) (P (VDF-TrFE)) are used. These materials have a high harvesting energy density, which can provide an energy harvesting and cooling device with high efficiency. However, these materials have limitations in that they are insufficient in temperature stability and electrical breakdown strength, have low energy harvesting capacity and cooling capacity, and are not easy to manufacture due to material complexity.

It is an object of the present invention to provide a superconducting layer having excellent temperature stability and voltage stability and having a high harvesting energy density and a cooling capacity.

Another object of the present invention is to provide an energy harvesting device having high energy harvesting efficiency and excellent operation stability by using a superconducting layer having the above advantages, .

It is another object of the present invention to provide an energy harvesting device and / or an electrothermal cooling device having the above-described advantages and having high energy harvesting efficiency and cooling efficiency, To provide this excellent monolithic device.

According to an aspect of the present invention, there is provided a pyroelectric layer comprising a compound represented by Formula 1 below.

[Chemical Formula 1]

Hf _1-x Zr _x O ₂ , and 0.7? X <0.9.

The compound may comprise a tetragonal-phase P42 / nmc space group, and the thickness of the superplastic layer may be in the range of 7.0 nm to 30.0 nm. Also, the operating temperature range of the superplasticization layer is in the range of 298 K to 448 K, and the magnitude of the operating voltage of the superplasticization layer may be in the range of 0.0 MV / cm to 4 MV / cm.

According to another aspect of the present invention, there is provided an energy harvesting device comprising: a pyroelectric layer including a compound represented by Formula 1 between a first electrode and a second electrode at least partially opposed to each other;

[Chemical Formula 1]

Hf _1-x Zr _x O ₂ , and 0.7? X <0.9.

A second heat source that is in heat exchange with the pyroelectric layer and has a first heat source having a first temperature and a second temperature higher than the first heat source; And a bias source for applying a voltage to the superlattice layer through the first electrode and the second electrode, wherein a voltage source, which is generated due to a temperature change of the superlattice layer, Can be produced.

The compound may comprise a tetragonal-phase P42 / nmc space group. Wherein the superconducting layer has a thickness in the range of 7.0 nm to 30.0 nm and the operating temperature range of the superconducting layer is in the range of 298 K to 448 K and the magnitude of the operating voltage of the superconducting layer is greater than 0.0 MV / It can be in range.

In one embodiment, the pyroelectric layer may further include a switch for regulating heat exchange alternately with the first heat source and the second heat source. The first heat source or the second heat source may be in contact with the first electrode or the second electrode to perform heat exchange with the superlattice layer, And a reservoir for storing electrical energy.

The pyroelectric layer includes a plurality of superconductive layers, and the plurality of superconductive layers may have different contents of Zr or electrodes may be inserted between the plurality of superconductive layers. The plurality of pyroelectric layers may be filled with any one or a combination of dielectric material and conductive material therebetween.

According to another aspect of the present invention, there is provided an electrothermal cooling element comprising: a pyroelectric layer including a compound represented by the following formula (1) between a first electrode and a second electrode at least partially opposed to each other;

[Chemical Formula 1]

Hf _1-x Zr _x O ₂ , and 0.7? X <0.9.

A second heat source that is in heat exchange with the pyroelectric layer and has a first heat source having a first temperature and a second temperature higher than the first heat source; And a bias source for applying a voltage to the superlattice layer through the first electrode and the second electrode. The temperature change may be caused by a change in the voltage of the superlattice layer.

Wherein the compound comprises a tetragonal-phase P4 ₂ / nmc space group, wherein the thickness of the superplastic layer is in the range of 7.0 nm to 30.0 nm and the operating temperature range of the superplasticizer is in the range of 298 K It can be within the 448 K range. The magnitude of the operating voltage of the superconducting layer may be in the range of 0.0 MV / cm to 4 MV / cm.

In one embodiment, the pyroelectric layer may further include a switch for regulating heat exchange alternately with the first heat source and the second heat source. The first heat source or the second heat source may be in contact with the first electrode or the second electrode to perform heat exchange with the pyroelectric layer. And a reservoir for storing electric energy generated from the superconducting layer through the first electrode and the second electrode.

The pyroelectric layer includes a plurality of superconductive layers, and the plurality of superconductive layers may have different contents of Zr or electrodes may be inserted between the plurality of superconductive layers. The plurality of pyroelectric layers may be filled with any one or a combination of dielectric material and conductive material therebetween.

According to another aspect of the present invention, there is provided a monolithic device including a plurality of circuits formed on a substrate, the plurality of circuits including a compound represented by the following formula (1) An energy harvesting element portion including a pyroelectric layer; An electrothermal charge cooling element including a pyroelectric layer including a compound represented by the following formula (1); A storage for storing energy generated from the energy harvesting element; A first electronic circuit operatively connected to the energy harvesting device; A second electronic circuit part connected to the electrothermal cooling element; And a control unit for controlling operations of the first electronic circuit, the second electronic circuit, the energy harvesting unit, the electrothermal cooling element, and the energy storage.

[Chemical Formula 1]

Hf _1-x Zr _x O ₂ , and 0.7? X <0.9.

The compound may comprise a tetragonal-phase P4 ₂ / nmc space group, wherein the first electronic circuit portion and the second electronic circuit portion may be identical to each other. The energy harvesting element portion and the electrothermal cooling element portion may have the same structure.

In one embodiment, the energy harvesting element part may be controlled through a sequence of controlling the electric field change or the temperature change of the control part, and the electric heat amount cooling element part may be controlled through a sequence of controlling the electric field change or the temperature change of the control part . The energy harvesting element part and the electrothermal cooling element part may be the same element.

According to one embodiment of the present invention, by using a compound containing zirconium (Zr) in hafnium oxide as a superconductive layer, a reversible phase change between antiferroelectricity and ferroelectricity can be easily ensured and the density of pyroelectric energy harvesting is high , An energy-harvesting element and an electrothermal cooling element can be provided with excellent electric-calorie effect, temperature stability and voltage stability. In addition, the above compound can provide an environmentally friendly, excellent stability, and an easy manufacturing method according to the embodiment of the present invention, excluding the use of harmful heavy metals such as lead (Pb).

According to an embodiment of the present invention, there is provided a monolithic device for forming an element having a high efficiency, easy manufacture, and various functions on one substrate by using the superconducting layer in the manufacture of an element .

Figure Ia is a graph showing thermodynamically reversible interactions between the thermal and electrical properties of the pyroelectric material.
FIG. 1B is an Olsen cycle showing the degree of polarization according to the electric field change of the superconducting material by temperature for energy harvesting and electrocaloric cooling.
Figure 1C is an Olsen cycle illustrating the change in temperature and entropy of the pyroelectric material for energy harvesting and electrocaloric cooling.
2 is a cross-sectional view of an energy conversion element according to an embodiment of the present invention.
3 is a flowchart showing a method of manufacturing the energy conversion element according to an embodiment of the present invention.
FIG. 4A is a graph of GIXRD (glancing incidence X-ray diffraction) according to the composition ratio of the pyroelectric layer of Experimental Examples 1-1 to 2-2.
FIG. 4B is a graph of harvesting energy density of the HZO thin film according to the temperature range (ΔT _HL ) of the pyroelectric layer of Experimental Examples 1-1 to 1-3.
4C is a hubbing energy density according to the magnitude of the electric field applied to the pyroelectric layer of Experimental Example 1-2.
FIG. 5A is a graph showing a temperature change (? T) according to the measurement temperatures of Experimental Examples 2-1 and 2-2.
5B is a graph showing an entropy change (? S) of the HZO thin film according to the measurement temperature.
5C is a graph showing the change in the cooling capacity according to the temperature range (DELTA T _HL ) indicating the difference between the low temperature (T _L ) and the high temperature (T _H ).
6 is a configuration diagram of a monolithic device in which an energy harvesting device 200a and an electrothermal cooling device 200b are formed on one substrate according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

In the following drawings, thickness and size of each layer are exaggerated for convenience and clarity of description, and the same reference numerals denote the same elements in the drawings. As used herein, the term "and / or" includes any and all combinations of any of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, &quot; comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers and / or portions, these members, components, regions, layers and / It is obvious that no. These terms are only used to distinguish one member, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section described below may refer to a second member, component, region, layer or section without departing from the teachings of the present invention.

Reference to a layer formed "on" another layer herein may refer to a layer formed directly on top of the other layer or may refer to a layer formed on intermediate or intermediate layers formed on the other layer . It will also be appreciated by those skilled in the art that structures or shapes that are "adjacent" to other features may have portions that overlap or are disposed below the adjacent features.

As used herein, the terms "below," "above," "upper," "lower," "horizontal," or " May be used to describe the relationship of one constituent member, layer or regions with other constituent members, layers or regions, as shown in the Figures. It is to be understood that these terms encompass not only the directions indicated in the Figures but also the other directions of the devices.

In the following, embodiments of the present invention will be described with reference to cross-sectional views schematically illustrating ideal embodiments and intermediate structures of the present invention. In these figures, for example, the size and shape of the members may be exaggerated for convenience and clarity of explanation, and in actual implementation, variations of the illustrated shape may be expected.

Accordingly, embodiments of the present invention should not be construed as limited to any particular shape of the regions shown herein. Also, like reference numerals in the drawings denote like elements throughout the drawings.

Figure Ia is a graph showing thermodynamically reversible interactions between the thermal and electrical properties of the pyroelectric material. FIG. 1B is an Olsen cycle showing the degree of polarization according to the electric field change of the superconducting material by temperature for energy harvesting and electrocaloric cooling. Figure 1C is an Olsen cycle illustrating the change in temperature and entropy of the pyroelectric material for energy harvesting and electrocaloric cooling.

The pyroelectric material broadly belongs to the polarizable materials class. When the pyroelectric material is heated or cooled, the position of the atoms in the crystal structure constituting the pyroelectric material changes, and a polarization phenomenon occurs in which the size of the electric dipole changes. As a result, a potential difference is generated in the pyroelectric material. When both ends of the pyroelectric material are connected by an external circuit, current flows in the load. Similarly, when the voltage applied to the pyroelectric material is changed, the temperature of the pyroelectric material can be changed while the size of the electric dipole in the pyroelectric material changes.

Referring to FIG. 1A, the electrocaloric effect may be a change in isothermal entropy and / or a change in adiabatic temperature due to the polarization and depolarization of the pyroelectric material that varies depending on an applied electric field. The pyroelectric effect utilizes the polarization phenomenon which varies with the temperature of the pyroelectric material as described above. This is a physically opposite effect to the caloric effect and can be used for energy harvesting or IR sensors. For example, the cooling element or the energy harvesting element using the pyroelectric material absorbs the heat radiated from the cup-shaped chip to cool the cup-shaped chip, and generates a voltage due to the pyroelectric effect .

Materials including polarizable ions such as the pyroelectric material can be used in energy storage devices in addition to the devices that utilize the energy harvesting and the electrothermal cooling because they have high dielectric constants. Therefore, when the device is manufactured using the above-described pyroelectric material, the device having one or more functions of the energy harvesting, the electrothermal cooling, the infrared sensing, and the energy storage may be provided on one substrate.

Referring to FIG. IB, in the Olsen cycle, the low temperature (T _L ) and the high temperature (T _L ) are the temperatures of the isothermal process in the equilibrium state of the forward and / or reverse Orson cycle, respectively. Curve 1 means that the pyroelectric material is polarized in an isothermal state when the electric field increases at a low temperature (T _L ). Graph ② explains that depolarization occurs partially while the temperature increases from a low temperature (T _L ) to a high temperature (T _H ). Graph ③ shows the depolarization in the isothermal state with decreasing electric field at high temperature (T _H ). In the graph ④, the temperature decreases from the high temperature (T _H ) to the low temperature (T _L ) And explains that polarization is partially performed.

The degree of polarization or depolarization of the pyroelectric material is directly related to a decrease or increase in the entropy (S) of the pyroelectric material, and the polarization or depolarization of the pyroelectric material results in the release and absorption of heat or entropy . For example, when the pyroelectric material is polarized, the temperature of the pyroelectric material is decreased or the entropy inside is reduced. Also, when the superconducting material is depolarized, the internal temperature of the superconducting material increases or the entropy increases.

Referring to FIG. 1C, the entropy increases at a high temperature (T _H ) without a temperature change, and entropy decreases without a temperature change at a low temperature (T _L ). That is, the entropy of the pyroelectric material is changed by the polarization phenomenon. If it is an isothermal reversible reaction, the magnitude of the amount of heat released and absorbed by the pyroelectric material can be calculated from the product of the temperature and the amount of change in entropy. Thus, in one Olsen cycle shown in FIG. 1C, the calorific value cal- culated as the product of the high temperature (T _H ) and the entropy change is the emission calculated from the product of the low temperature (T _L ) and the change in entropy Which is larger than the calories. Therefore, the Orson cycle of the pyroelectric material can be used for pyroelectric energy harvesting, since the calorific value emitted by the pyroelectric material is smaller than the caloric value absorbed.

The Orson cycle can be understood as a kind of Ericsson thermal engine using a pyroelectric material. Therefore, the reverse cycle of the Orson cycle, that is, the inverse Olsen cycle, can be utilized as a refrigeration cycle. In the reverse Orson cycle, the pyroelectric material absorbs heat at a low temperature (T _L ) and releases heat at a high temperature (TH). That is, the amount of heat released at a high temperature (T _H ) is larger than the amount of heat absorbed at a low temperature (TL). Therefore, the reverse olsen cycle using the pyroelectric material can be applied as an electrothermal cooling element because it can emit heat larger than the absorbed heat.

The Orson cycle or the reverse Orson cycle is illustrative, and the present invention is not limited thereto. For example, in order to obtain the energy harvesting effect and the caloric effect, a Carnot cycle, a synchronized electric charge extraction (SECE), a synchronized switch damping on an inductor inductor, resistive cycle, or a process in which the temperature is variable, other than the isothermal process, can be used.

Referring again to FIG. 1C and FIG. 1B, in order to improve the pyroelectric energy harvesting and the electric calorimetric effect in the isothermal process in the Orson cycle or the reverse Orson cycle, the pyroelectric coefficient of the pyroelectric material is large, It can be understood that stable polarization can be obtained at a large electric field strength or stable polarization and depolarization at a wide range of electric field strength are possible.

Accordingly, the inorganic material containing lead and the P (VDF-TrFE) -based polymer have a high density of the harvesting energy and a large cooling effect by the effect of the electric calorimetric effect. Therefore, the material suitable for the energy harvesting device and the electrothermal cooling device . However, since the lead-containing inorganic material and the P (VDF-TrFE) -based polymer cause environmental pollution and have a limited temperature stability, they are not easily applicable to the energy harvesting device and the electrothermal cooling device .

Further, in the application of a conventional energy harvesting device, since the temperature fluctuation frequency of the waste heat source in which the energy harvesting device is used is lower than 1 Hz in most cases, Producing a sufficient amount of electrical energy using a heat source is limited. Therefore, a thin-film-type superconductive material or a nanostructured superconductive material, which can generate energy efficiently in response to a small temperature fluctuation, can obtain high-efficiency energy conversion in a low-temperature temperature fluctuation environment This can be a simple and effective solution.

In an embodiment of the present invention, the pyroelectric material includes a compound represented by the following general formula (1). The Hf _1-x Zr _x O ₂ compound is a compound containing zirconium (Zr), which is a dopant, with a HfO ₂ material as a basic structure. By controlling the composition ratio x of hafnium (Hf) and zirconium (Zr) The characteristics of the Hf _1-x Zr _x O ₂ compound can be controlled.

[Chemical Formula 1]

Hf _1-x Zr _x O ₂ , (0.7? X <0.9)

When the Zr composition ratio x satisfies 0.7 < x &lt; 0.9, since the superconducting material has a high electric field yield strength, it is possible to apply an experimentally proved high voltage of about 3.26 MV / cm, energy density and electric calorie effect can be improved. The magnitude of the operating voltage of the pyroelectric material may be greater than 0 and within the range of 4 MV / cm depending on the application. Therefore, the Hf _1-x Zr _x O ₂ compound according to the embodiment of the present invention can obtain a higher energy density of the hubbing energy and an electric calorie effect than the P (VDF-TrFE) based polymer having a low electric field yield strength have.

Hereinafter, the Hf _1-x Zr _x O ₂ compound is used as a superconductive layer formed to have a thin film or a nanostructure, and has a high hubbing energy density, durability against temperature change, and high dielectric breakdown strength (electrical eco-friendly &lt; / RTI &gt; pyroelectric energy harvesting element and an electrothermal chill element having breakdown strength will be disclosed. Hereinafter, the pyroelectric energy harvesting element and the electrothermal cooling element are collectively referred to as energy conversion elements in consideration of reversible conversion of electric energy and thermal energy by the superconducting layer.

FIG. 2 is a cross-sectional view of an energy conversion device according to an embodiment of the present invention, and FIG. 3 is a flowchart illustrating a method of manufacturing the energy conversion device according to an embodiment of the present invention.

Referring to FIGS. 2 and 3, the energy conversion element 200 may be formed on the substrate 20. The energy conversion element 200 may include a superconductive layer 23 between the first electrode 21 and the second electrode 25 facing each other. The energy conversion element 200 may be exposed to the first heat source 26 and / or the second heat source 27 through the first electrode 21 and / or the second electrode 25, as shown in FIG. The pyroelectric layer 23 can perform heat exchange with the first heat source 26 and / or the second heat source 27.

In one embodiment, the substrate 20 may be a Group IV semiconductor such as Si or Ge, a mixed semiconductor such as SiGe, a III-V compound semiconductor such as GaAs and GaN, a CdS Lt; RTI ID = 0.0 &gt; II-VI &lt; / RTI &gt; semiconductor material. Alternatively, the substrate 20 for the manufacture of a single-chip system (SOC) or a three-dimensional semiconductor device may include a substrate 20 having an insulating layer such as silicon oxide or a passivation layer formed in a region where the energy conversion element 200 is to be formed Or may be an integrated circuit layer having a structure.

In one embodiment, before forming the energy conversion element 200 on the substrate 20, appropriate surface treatment may be performed to remove impurities on the surface of the substrate 20, or to improve the diffusion or adherence characteristics of the impurities have. For example, impurities can be removed from the surface of the substrate 20 through a plasma process, a hydrogen peroxide solution, a chemical solution such as ethanol and acetone, or a cleaning process using deionized water. An additional layer (not shown) such as a silicon oxide film, a metal oxide film, or a metal nitride film is formed on the substrate 20 in order to improve the diffusion and adherence characteristics of impurities generated between the substrate 20 and the energy conversion element 200. [ May be further performed.

The first electrode 21 may be formed on the substrate 20 (S10). The first electrode 21 may be formed of a conductive material on the substrate 20, and the upper pyroelectric layer 23 may be connected to the outside to receive an electric field. Further, an electrode extending to the first electrode 21 may be further formed (not shown) so as to be easily connected to the device or the power source from the outside.

The conductive material is a conductive material and is made of at least one of platinum (Pt), tungsten (W), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), tantalum (Al), copper (Cu), silver (Ag), nickel (Ni), manganese (Mn), tin (Sn), or a mixture of at least one element selected from the group consisting of Mo, Cr, V, Ti, Or alloys, nitrides or oxides thereof. However, the material of the first electrode 21 is not limited to the above-mentioned metal conductor. For example, one or more of silicon (Si), a silicon compound, activated carbon, graphite, a carbon nano tube, and fullerene.

The first electrode 21 may be formed by a chemical vapor deposition method such as a low pressure chemical vapor deposition (LPCVD) method or a plasma enhanced chemical vapor deposition method, a laser ablation method, or a physical vapor deposition method. However, this is merely exemplary and the present invention is not limited thereto. In addition, the first electrode 21 may be provided only on a part of the substrate 20 by performing a patterning process on the layer of the conductive material formed for the first electrode 21.

In some embodiments, the first electrode 21 may comprise a barrier metal 22 at the interface with the superpowder layer 23. The metal barrier layer 22 is formed between the first electrode 21 and the superconductive layer 23 to prevent contamination of each layer due to diffusion of constituent elements, The film may be formed of any one or two or more of tungsten nitride (WN), titanium nitride (TiN), chromium (Cr), tantalum (Ta), and tantalum nitride (TaN). Examples of the contamination phenomenon include oxidation of metal due to diffusion of impurities, change of the crystal structure of the superconducting material, movement of charge caused by a low energy barrier between the first electrode 21 and the superconducting layer 23, The contact failure between the first electrode 21 and the superconducting layer 23 may occur. The metal barrier layer 22 may be formed by a method of forming the first electrode 21 described above.

A superconducting layer 23 is formed on the first electrode 21 (S20). The pyroelectric layer 23 is formed at least partially on the first electrode 21, and stores electrical energy or stores thermal energy using the polarization characteristic. The pyroelectric layer (23) comprises a compound represented by the following formula (1)

[Chemical Formula 1]

Hf _1-x Zr _x O ₂ , (0.7? X <0.9)

X is stabilized in a tetragonal phase (t-phase) or an equiaxial phase by deviating from a stable monoclinic phase (or m-phase) of HfO ₂ and the Hf _1-x Zr _x O ₂ compound Respectively. In one embodiment, the Hf _1-x Zr _x O ₂ compound is stabilized in a tetragonal or isostatic phase in the range of x <0.7 <x <0.9. Therefore, by adjusting the composition ratio x of the Hf _1-x Zr _x O ₂ compound is a compound with a HfO ₂ thin film as the basic structure of zirconium (Zr) is contained, hafnium (Hf) and zirconium (Zr), Hf _1- The electrical and physical properties of _x Zr _x O ₂ can be controlled.

The superconducting layer 23 containing the compound may be formed by a vapor deposition method such as a low pressure chemical vapor deposition (LPCVD) method, a plasma enhanced chemical vapor deposition method, a laser ablation method or a sputtering method, Or the like. However, this is merely exemplary and the present invention is not limited thereto. For example, step S20 of forming the superparamagnetic layer 23 may be performed by an atomic layer deposition process. The atomic layer deposition process may control the composition ratio of the superconducting layer 23 by controlling the number of cycles of the hafnium (Hf) precursor and the zirconium (Zr) precursor or the thickness of the layer formed in each cycle. The atomic layer deposition process may be performed by alternating the hafnium oxide layer and the zirconium oxide layer, and the hafnium oxide layer may be formed first and the zirconium oxide layer may be formed, or vice versa.

The pyroelectric layer 23 may have a planar structure for forming a flat plate structure, a fin structure for increasing an electrode surface area, a cup structure, a pillar structure, a three-dimensional structure such as a cylinder structure , Or a combination thereof. The pyroelectric layer 23 may include a plurality of pyroelectric layers. In this case, each of the plurality of superposed layers may be a superposed layer having a different Zr content, or an electrode may be inserted between the plurality of superposed layers. Further, a dielectric material and / or a conductive material may be filled between the respective super pyroelectric layers 23.

A second electrode is formed on the pyroelectric layer 23 (S30). The second electrode 25 includes a conductive material formed on the superconducting layer 23 so that at least a part of the superconducting layer 23 overlaps with the superconducting layer 23 and the superconducting layer 23 of the underlayer is connected to an external circuit, . Further, an electrode, for example, leads (not shown) extending to the second electrode 25 may be further formed and configured to be easily connected to the device or the power source from the outside.

The conductive material is a conductive material and is made of at least one selected from the group consisting of platinum (Pt), tungsten (W), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), tantalum (Al), copper (Cu), silver (Ag), nickel (Ni), manganese (Mn), tin (Sn), or a mixture of at least one element selected from the group consisting of Mo, Cr, V, Ti, An alloy, a nitride, or an oxide thereof. However, the material of the second electrode 25 is not limited to the above-mentioned metal conductor. For example, the second electrode 25 may be formed of one or more of silicon (Si), a silicon compound, activated carbon, graphite, a carbon nano tube, and fullerene . Also, the second electrode 25 may be formed along the mopology of the lower superconducting layer 23.

Step S30 of forming the second electrode 25 may be performed by chemical vapor deposition such as LPCVD or plasma enhanced chemical vapor deposition or laser ablation or physical vapor deposition &Lt; / RTI &gt; However, this is merely exemplary and the present invention is not limited thereto. For example, only a part of the second electrode 25 may be provided on the superconducting layer 23 by the patterning process.

The second electrode 25 may further include a metal barrier layer 24 at an interface with the superparallel layer 23. The metal barrier layer 24 acts as a control layer of a barrier of a diffusion barrier, an adhesive layer or an energy band as described with respect to the metal barrier layer 22 described above, and is formed of tungsten nitride (WN), titanium nitride (TiN) Chromium (Cr), tantalum (Ta), and tantalum nitride (TaN). The phenomenon of contamination may include oxidation of metal due to diffusion of impurities, change of the crystal structure of the superconducting layer 23, movement of charges caused by a low energy barrier between the second electrode 25 and the superconducting layer 23, And a poor contact between the second electrode 25 and the superconducting layer 23, as shown in FIG. The metal barrier layer 24 may be formed by the above-described method of forming the second electrode 25.

After forming the second electrode 25, the energy conversion element 200 may be subjected to heat treatment (S40). Through the heat treatment, the compound of the superconducting layer 23 is crystallized, and the superconducting layer 23 can exhibit anti-ferroelectricity. The heat treatment may be performed within a temperature range of 400 ° C to 1,000 ° C. Also, the heat treatment may be a rapid thermal treatment performed within a range of 10 seconds to 30 seconds. When the heat treatment is performed at a temperature of less than 400 DEG C, the dielectric does not crystallize and thus does not exhibit anti-ferroelectricity. Further, at a temperature exceeding 1,000 占 폚, the device characteristic may deteriorate due to an increase in the leakage current of the capacitor. When the heat treatment is performed for less than 10 seconds, crystallization of the superconducting layer 23 is not sufficient and it is difficult to obtain antiferroelectricity. When the heat treatment is performed for 30 seconds or more, the device characteristics Can be deteriorated.

In some embodiments, the heat treatment may be performed in a reducing or inert atmosphere. The reducing atmosphere may be provided using nitrogen or hydrogen gas, and the inert atmosphere may be provided using argon, neon, or helium gas. The heat treatment may vary the heat treatment time, temperature, and / or atmosphere depending on the type of the metal or metalloid, and may be selected so that the dielectric has a crystalline phase belonging to the P4 ₂ / nmc space group of the t-phase. A suitable time, temperature and / or atmosphere may be selected.

In the energy conversion element 200 according to the embodiment of the present invention, the first electrode 21 and / or the second electrode 25 are connected to the superconducting layer 23, the first heat source 26 and the second heat source 27, The thermal energy is transferred between the first heat source 26 and the second heat source 27 and the superconducting layer 23 through the first electrode 21 and / or the second electrode 25 . When the first electrode 21 and / or the second electrode 25 are not formed in contact with the superconducting layer 23 and the first heat source 26 and the second heat source 27, the superconducting layer 23 May be in contact with the first heat source 26 and / or the second heat source 27 through a switch that controls mechanical operation, thereby enabling thermal energy exchange between the device and the heat source.

The switch may include a thermal switch, an optical switch, a vibration switch, a discharge switch, a current switch, a pressure switch, a capacitive switch, a wave switch, a contact switch, and an electronic operation switch or a combination thereof. In addition, the operating sequence of the switch may be adjusted to increase or decrease the energy harvesting capacity or the cooling capacity.

In one embodiment, the first heat source 26 and / or the energy conversion element 200 may include an exposed environment. For example, the first heat source 26 may be the temperature of the substrate 20 and the second heat source 27 may be the air to which the elements are exposed. However, the present invention is not limited thereto. The first heat source 26 and / or the second heat source 27 may be in a gas, liquid, or solid state and may be fixed at a specific temperature by a control device.

The energy conversion element 200 according to an embodiment of the present invention may be a fin structure, a cup structure, a pillar structure, a cylinder structure, a three-dimensional structure such as a porous structure, Structure. Further, the energy conversion element 200 can be formed in the substrate as described above, or can be integrated into fine patterns.

<Experimental Example>

Each of the following samples is an energy-changing element 200 having the structure shown in Fig. A lower electrode of a TiN thin film having a thickness of 50 nm was formed by DC sputtering on a Si substrate on which SiO ₂ was formed on the surface, and the pyroelectric layer was formed on the lower electrode through an atomic layer deposition process at 280 ° C. The pyroelectric layer is a Hf _1-x Zr _x O ₂ compound. Hereinafter, the term pyroelectric layer is collectively used in terms of energy harvesting and electrothermal cooling.

In the atomic layer deposition process for forming the pyroelectric _{layer, Hf [N (C 2 H} 5) CH 3] 4, Zr [N (C 2 H 5) CH 3] 4 , and ozone (O ₃₎ a was used as the precursor , And the ratio of the number of pulses of each precursor implantation was controlled to control the composition ratio of the superconducting layer. In one embodiment, by controlling the composition ratio of the superplastic layer, that is, the content of zirconium (Zr) in the hafnium oxide, the superconductive layer is stabilized in a tetragonal or isotropic crystal structure that is not a monoclinic crystal structure, which is a general dominant stable phase of the hafnium oxide And the like.

The upper electrode formed on the superlattice layer was formed by depositing a titanium nitride (TiN) thin film having a thickness of 5 nm and a platinum (Pt) thin film having a thickness of 30 nm by a DC sputtering process using a mask having a hole having a diameter of 300 [ Sequentially formed. After the formation of the upper electrode, rapid thermal annealing was performed in an N ₂ atmosphere in a reducing atmosphere at 500 ° C for 30 seconds in a range of 400 ° C to 1,000 ° C for crystallization of the Si pyroelectric layer.

Table 1 below shows the composition ratios of the Hf _1-x Zr _x O ₂ compounds prepared by an atomic layer deposition process, the temperature range and the voltage range for evaluation of the harvesting energy density and the electric calorie effect. Table 1 shows composition ratios and thin film thicknesses of the Hf _1-x Zr _x O ₂ compound in each of the experimental examples, and the thickness of the Hf _1-x Zr _x O ₂ compound is in the range of 7 nm to 30 nm Can be selected within the range. Further, in a voltage range of 0 MV / cm to about 3.26 MV / cm, which is within a temperature range of about 288 K to about 448 K and a range of 0 MV / cm to 4 MV / cm, Hf _1-x Zr _x The energy harvesting and the caloric effect of the O ₂ compounds were evaluated.

Referring to Table 1, Experimental Examples 1-1, 1-2 and 1-3 are experimental examples in which the harvesting energy density of the Hf _1-x Zr _x O ₂ compound thin film was evaluated. Experimental Examples 2-1 and 2-2 are experimental examples in which the electrocaloric effect of the Hf _1-x Zr _x O ₂ compound was evaluated.

Experimental Example Hf ratio
(1-x) Zr ratio
(x) Thin film thickness
(nm) Low temperature
T _L (K) High temperature
T _H (K) Field
(MV / cm) Experimental Example 1-1 0.1 0.9 9.2 298 448 0 - 3.26 Experimental Example 1-2 0.2 0.8 9.2 298 448 0 - 3.26 Experimental Example 1-3 0.3 0.7 9.2 298 448 0 - 3.26 Example 2-1 0.2 0.8 9.2 298 448 0 - 3.26 EXPERIMENTAL EXAMPLE 2-2 0.3 0.7 9.2 298 448 0 - 3.26

The Hf _1-x Zr _x O ₂ compound having the above composition ratios x = 0.7, 0.8 and 0.9 was confirmed to have a polarization-electric field (PE) double hysteresis loops characteristic through separate experiments. It is understood that the double hysteresis loop characteristic is caused by the possibility of field induction phase transition between the ferroelectric phase and the antiferroelectric phase and the electric field induced phase transition is 298 K to 448 K Lt; / RTI &gt; However, this is exemplary and the double hysteresis loop characteristic is observed in a temperature range of less than 298 K or 448 K or more. In addition, the Hf _1-x Zr _x O ₂ compound operates stably even at a high electric field of about 3.26 MV / cm. However, the present invention is not limited thereto, and the magnitude of the operating voltage may be in the range of 0 MV / cm to 4 MV / cm.

FIG. 4A is a graph of GIXRD (glancing incidence X-ray diffraction) according to the composition ratio of the Hf _{1 -x} Zr _x O ₂ compound of Experimental Examples 1-1 to 2-2, and FIG. and Hf _1-x Zr _x O ₂ compound in a temperature range of -3 harvesting energy density of the Hf _1-x Zr _x O ₂ compound according to _{(ΔT HL) (harvestable energy density} ) graph, Figure 4c experiment 1 -2 &gt; Hf _0.2 Zr _0.8 O ₂ compound.

Referring to FIG. 4A, the Hf _1-x Zr _x O ₂ compound according to an embodiment of the present invention has t (101), t (101), and the like, which are peaks in a tetragonal phase (space group: P4 ₂ / nmc) 110) and t (200). When the Hf _1-x Zr _x O ₂ compound has a t-phase, the electric field induced phase transition easily occurs between the t-phase and the O-phase (orthorhombic phase, space group: Pca _{2 1} ) Can have an antiferroelectric behavior with double hysteresis loops. In general, hafnium oxide and zirconium oxide have a phase dielectric behavior when they have a crystal structure of m-phase (monoclinic phase, space group: P2 ₁ / c), and it is difficult to have the above-mentioned double hysteresis loop characteristic. In addition, pure zirconium oxide is reported to have some t-phase when thinned, but in this case, the electric field strength for phase transition between the t-phase and the O-phase is too large to have a practical meaning.

In the Hf _1-x Zr _x O ₂ compound according to the embodiment of the present invention, when the content of zirconium (Zr) is 0.7 or more and less than 0.9, phase transition between the t-phase and the o- And the antiferroelectric behavior is strengthened according to the temperature change, so that the pyroelectric effect can be maximized. Therefore, according to the embodiment of the present invention, the energy harvesting efficiency of the energy harvesting device using the Hf _1-x Zr _x O ₂ compound and the cooling efficiency of the electrothermal cooling device can be improved.

Table 2 shows the harvesting energy densities of the lead component-containing inorganic material, the P (VDF-TrFE) -based polymer, and the (Ba, Sr) TiO ₃ -based ferroelectric oxide and the Hf _0.2 Zr _0.8 O ₂ compound according to the embodiment of the present invention HED), a difference in applied voltage (? E), and a difference in temperature (? T _HL ).

material shape HED
[J cm ^-3 cycle ^-1 ] ΔE
[kVcm ^-1 ] ΔT _HL
[K] 0.90 PbMg _1/3 Nb _2/3 O ₃ 0.10 PbTiO ₃ ceramic 0.186 35 50 0.68 PbMg _1/3 Nb _2/3 O ₃ 0.32 PbTiO ₃ Single crystal 0.100 7 90 (Pb, La) (Zr _0.65 Ti _0.35 ) O ₃ ceramic 1.014 68 170 (Bi _0.5 Na _0.5 ) _0.915-
(Bi _0.5 K _0.5 ) _0.05 Ba _0.02 Sr _0.015 TiO ₃ ceramic 1.523 39 140 P (VDF-TrFE) pellicle 0.521 300 85 P (VDF-TrFE) pellicle 0.155 150 85 Hf _0.2 Zr _0.8 O ₂ pellicle 11.549 3260 150

Referring to Table 2, with Figure 4b, the Olsen cycle (Olsen cycle) high temperature (T _H) and the Hf _1-x Zr _x O ₂ compound according to the temperature range (ΔT _HL) of the lower temperature (T _L) of The change in harvestable energy density (HED) can be seen. When the composition ratio of zirconium (Zr) is 0.9 (curve Ha), the density of the hubbing energy is almost zero, and no change occurs even when the temperature range is 150K. Compounds with a composition ratio of zirconium (Zr) of 0.9 have little change in polarization-field hysteresis characteristics with temperature change up to 448 K. Because of this property, it is assumed that the density of the harvesting energy is almost zero.

In contrast, when the composition ratio of zirconium (Zr) is 0.8 (curve Hb) and the composition ratio of zirconium (Zr) is 0.7 (curve Hc), the behavior of increasing the density of the hubbing energy linearly see. When the composition ratio of zirconium (Zr) is 0.8 (curve Hb), the maximum value of the harvesting energy density reaches 11.5 J / cm ³ per cycle when the temperature range (ΔT _HL ) is 150 K. Zirconium (Zr) harvesting the maximum value of the energy density of the boot from the composition ratio of 0.7 (curve Hc) in the range when the temperature (ΔT _HL) is 150 K, it is 5.7 J / cm ³ per cycle. The behavior of these Hf _0.2 Zr _0.8 O ₂ compounds and Hf _0.2 Zr _0.8 O ₂ compounds is consistent with the apparent shift of the antiferroelectric polarization-field history loops towards higher field regions as the temperature increases. The experimental temperature range is an experimental example, and the present invention is not limited to the above temperature range, and the temperature change characteristic may be implemented in a wider temperature range. This temperature change characteristic is useful for achieving a high harvesting energy density.

(Pb, La) (Zr _0.65 Ti _0.35 ) O ₃ ceramics having a maximum value through the ergodic relaxor-ferroelectric phase transition among the titanium oxides containing lead, 1.014 [J cm ³ cycles ^-1 ], the Hf _0.2 Zr _0.8 O ₂ compound has a higher energy density of 11.3 times and the Hf _0.3 Zr _0.7 O ₂ compound has a higher energy density of 5.6 times higher than the hubbing energy density of the Hf _0.2 Zr _0.8 O ₂ compound. In addition, the superconducting layer is 7.6 times and 3.7 times higher than that of the ferroelectric oxide (Bi _0.5 Na _0.5 ) _0.915 (Bi _0.5 K _0.5 ) _0.05 Ba _0.02 Sr _0.015 TiO ₃ , which has the highest harvesting energy density.

Referring to FIG. 4C and Table 2, the hubbing energy density of the Hf _0.2 Zr _0.8 O ₂ compound according to the embodiment of the present invention increases as the temperature range (ΔT _HL ) increases under the same electric field. In addition, the hubbing energy density of the Hf _0.2 Zr _0.8 O ₂ compound increases as the electric field applied increases in the same temperature range (ΔT _HL ).

The maximum hubbing energy density for each temperature range (? T _HL ) was about 2.3, about 4.4, about 6.7, and about 8.1, respectively, in the temperature range of 25 K, 50 K, 75 K, 100 K, 125 K, , About 10.1 and about 11.5 J cm ^-3 · cycle- ¹ . The Hf _0.2 Zr _0.8 O ₂ compound exhibits a wider temperature range (ΔT _HL ) than other pyroelectric materials. The temperature range of the Hf _0.2 Zr _0.8 O ₂ compound is as small as 20 K compared to (Pb, La) (Zr _0.65 Ti _0.35 ) O ₃ having the largest temperature range in Table 2, but exhibits a larger hubbing energy density .

The electric field difference E that can be applied to the Hf _0.2 Zr _0.8 O ₂ compound according to the embodiment of the present invention is 3.26 MV / cm, and the highest value of P (VDF -TrFE) is about 10.8 times higher than 0.3 MV / cm. Since the Hf _1-x Zr _x O ₂ compound has high electrical breakdown strength, an electric field of 3.26 MV / cm can be applied even at 150 ° C. As described above, since the Hf _1-x Zr _x O ₂ compound has a wide temperature range (ΔT _HL ) and a large electric field to be applied, it can have a larger hubbing energy density than other conventional pyroelectric materials . Accordingly, it is possible to provide an energy harvesting device having high efficiency, temperature stability, and voltage stability using the Hf _1-x Zr _x O ₂ compound.

In addition, the high energy hubbing density of the Hf _1-x Zr _x O ₂ compound is also due to the good quality of the thin film and the large energy bandgap provided through the atomic layer deposition process. Since the Hf _1-x Zr _x O ₂ compound may be by simple composition component formed by using the atomic layer deposition process, the atomic layer deposition process is the current process used in the semiconductor process, the Hf _1-x the Zr _x O ₂ compound can be easily applied at the time of device manufacture that component.

In one embodiment, the Hf _1-x Zr _x O ₂ compound is capable of determining suitability via an electrothermal coupling factor (k ² = p ² T / C ε _r ε ₀ ) in addition to the harvesting energy density have. The electrothermal coupling factor can be calculated by a pyroelectric coefficient p, an operating temperature T, a heat capacity C, a permittivity? _R and a vacuum permittivity? ₀ . The heat transfer coupling factor of the HF _0.2 Zr _0.8 O ₂ thin film according to the embodiment of the present invention is 24.4 × 10 ^-3 , and the conventional pyroelectric energy harvesting material LiNbO ₃ (k ² to 2.69 × 10 ^-3 ) and LiTaO ³ ₃ (k ² to 6.15 x 10 ^-3 ).

FIG. 5A is a graph showing a temperature change (.DELTA.T) according to the measurement temperatures of Experimental Examples 2-1 and 2-2, and FIG. 5B shows an entropy change (.DELTA.S) of the HZO thin film according to the measurement temperature. 5C is a graph showing the change in the cooling capacity according to the temperature range (DELTA T _HL ) indicating the difference between the low temperature (T _L ) and the high temperature (T _H ).

The temperature change (? T) and the entropy change (? S) of the Hf _1-x Zr _x O ₂ compound can be calculated through the following equations (1) and (2). According to Maxwell's law, (∂S / ∂E) _T = (∂P / ∂T) _E holds. Since the value of (∂S / ∂E) _T is hardly measurable experimentally, the entropy change (ΔS) according to the temperature change can be calculated from the measurable (∂P / ∂T) _E value. By using this, the Hf _1-x Zr _x O temperature change (ΔT) of the _second compound is to apply an electric field to E ₂ in the E ₁ to the Hf _1-x Zr _x O ₂ compound, the Hf _1-x Zr _x O &lt; ₂ &gt; compound and the change in polarization depending on the temperature. Further, the entropy change (ΔS), similarly to the change in temperature (ΔT), the Hf _1-x Zr _x O ₂ compound when an electric field is applied to E ₂ in E _1, according to the temperature Hf _1-x Zr _x O ₂ &lt; / _RTI &gt; compound.

(식 1)

(Equation 1)

(식 2)

(Equation 2)

In the above equations (1) and (2), rho is the density and C is the specific heat. The density was measured by using the X-ray reflectance of the Hf _1-x Zr _x O ₂ compound. The density of the Hf _0.2 Zr _0.8 O ₂ compound thus measured (ie, Experimental Example 2-1 in Table 1) was 5.71 gcm ^-1 , and the Hf _0.3 Zr _0.7 O ₂ compound (ie, Experimental Example 2-2 ) Is 6.01 gcm &lt; ^{-1 &} gt ;. In addition, the specific heat of the compounds of Experimental Examples 2-1 and 2-2 were 373 Jkg ^-1 K ^-1 and 429 Jkg ^-1 K ^-1 at 298 K and 448 K, respectively.

Referring to FIG. 5A, since the degree of polarization of the Hf _1-x Zr _x O ₂ compound changes with temperature, in the compound having a composition ratio of zirconium (Zr) of 0.8 (curve Ga, Experimental Example 2-1) (Curve Gb, Experimental Example 2-2) exhibited a maximum value of 9.8 K at a temperature of 448 K, while the temperature change (ΔT) at a temperature of 307 K showed a maximum value of 13.4 K. The compound having a composition ratio of zirconium (Zr) Respectively. Since the temperature change (? T) of the compound according to the above experimental examples has a larger value than the temperature change? T of Pb (Zr, Ti) O ₃ and P (VDF-TrFE) The present invention can provide an electrothermal cooling element having an advantage as an electrochemical calorie material not including lead and corresponding to a larger change.

Table 3 shows the operating temperature (T), the temperature (T) and the temperature (T) of the lead-containing inorganic material, P (VDF-TrFE) based polymer, tantalum oxide and Hf _1-x Zr _x O ₂ compound according to the embodiment of the present invention, (ΔT), an electric field change (ΔE), a temperature change per electric field change (ΔT / ΔE) and an entropy change (ΔS). Referring to FIG. 5A together with Table 3, the Hf _0.3 Zr _0.7 O ₂ compound was able to measure the temperature up to 448 K, which was exemplarily tested, but even at a larger temperature range, due to the higher Curie temperature (Tc) (? T) is expected to be large. The Hf _0.2 Zr _0.8 O ₂ compound has a larger temperature change (ΔT) in the more practical temperature change (ΔT) zero region compared to the Hf _0.3 Zr _0.7 O ₂ compound. The characteristics of this Hf _0.2 Zr _0.8 O ₂ compound enable wider applications as cooling elements for conventional electronic devices such as computers or consumer electronic devices.

Referring to FIG. 5B, the temperature-dependent entropy change? S can be considered to be converted into a refrigerant capacitor (RC), which is a quantitative evaluation criterion for application as a cooling element. The entropy change (? S) can be translated into a practical meaning as a refrigerant capacitor (RC) by the following equation (3).

In an actual cooling cycle, the high temperature (T _H ) and the low temperature (T _L ) may be determined by the performance or specification of a given application. In order to increase the magnitude of the electrical energy converted into heat emitted by the heat sink, the RC value must be maximized at a given high temperature (T _H ) and a low temperature (T _L ). Therefore, a material having a wider temperature range and a higher entropy? S value is more preferable than conventional materials having a higher entropy? S value only in a narrow temperature range near the Curie temperature Tc. Referring to Table 3, the Hf _1-x Zr _x O ₂ compound according to an embodiment of the present invention exhibits a broader temperature range near the Curie temperature (Tc), a wider temperature range Lt; RTI ID = 0.0 &gt; ΔS.

Referring to the curve Gc, the entropy change (ΔS) of Hf _0.2 Zr _0.8 O ₂ has a maximum of 96 mJcm ^-3 K ^-1 at 298 K and a minimum of 60 mJ cm ^-3 K ^-1 at 448 K, with reference to the curve Gd The entropy change (ΔS) of Hf _0.2 Zr _0.8 O ₂ has a minimum of 16 mJcm ^-3 K ^-1 at 298 K and a maximum of 49 mJ cm ^-3 K ^-1 at 448 K. The temperature range of 298 K to 448 K is selected as an experimental example by way of non-limiting example, and the present invention can be modified in temperature range depending on the application to which the cooling and / or hubbing element is applied.

material T
[K] ΔT
[K] ΔE
[kVcm ^-1 ] ΔT / ΔE
[KcmkV ^-1 ] ΔS
[mJK ^-1 cm ^-1 ] PbZr _0.95 Ti _0.05 O ₂ 495 12 481 0.025 66 Pb _0.8 Ba _0.2 ZrO ₃ 290 45.3 598 0.076 361 PbSc _0.5 Ta _0.5 O ₃ 341 6.2 774 0.008 55 (PbMg _1/3 Nb _2/3 O ₃ ) _0.9 (PbTiO ₃ ) _0.1 348 5 895 0.006 45 P (0.55VDF-0.45TrFE) 353 12.6 2090 0.006 106 SrBi _2.1 Ta ₂ O ₉ 500 4.9 600 0.008 - Hf _0.2 Zr _0.8 O ₂ 298 13.4 3260 0.004 96 Hf _0.3 Zr _0.7 O ₂ 448 8.9 3260 0.003 49

Referring to FIG. 5C together with Table 3, Hf _1-x Zr _x O ₂ compounds according to the embodiment of the present invention have a high RC value in various temperature ranges when the low temperature (T _L ) is fixed at 298 K . Therefore, it can be seen that the cooling device using the electrothermal effect of Hf _1-x Zr _x O ₂ compounds can reliably operate with a sufficiently high RC value even when the temperature of the cooling load has a deviation from the target temperature. In particular, from the results of FIG. 5C, it is expected that the cooling element using the electric heat quantity effect of the Hf _0.2 Zr _0.8 O ₂ compounds of Experimental Example 2-1 will have even better reliability.

Specifically, the Hf _0.2 Zr _0.8 O cooling capacity of the _second compound (curved Ge) has, in a temperature range (ΔT _HL), 25, 50, 100, or 150 K temperature range (ΔT _HL) of, respectively, 2.79, 5.41, 10.45 And 13.93 Jcm ^-3 cycle ^-1 . In particular, when the temperature range (DELTA T _HL ) is 50 K, the cooling capacity of the Hf _0.2 Zr _0.8 O ₂ compound is 5.41 Jcm ^-3 cycle ^-1 , and the gadolinium (Gd) Is much higher than the cooling capacity 3.1 Jcm ^-3 cycle ^-1 in an environment with a range (DELTA T _HL ) and a magnetic field change of 50 kOe. The cooling capacity (curve Gf) of the Hf _0.3 Zr _0.7 O ₂ compound is 0.91, 2.11, 4.44 and 6.87 Jcm ^-3 cycle ^-1 in the temperature range (ΔT _HL ) of 25, 50, 100 and 150 K, Is about 56% smaller than the cooling capacity of the Hf _0.2 Zr _0.8 O ₂ compound.

Referring to Table 3, the temperature change ΔT and the entropy change ΔS of the Hf _1-x Zr _x O ₂ compound according to the embodiment of the present invention are less than Pb (Zr, Ti) O ₃ , P (VDF-TrFE) Although it is generally larger, it can be confirmed that the value of DELTA E has been drastically improved. Compared to other materials of the Hf _1-x Zr _x O ₂ compounds according to embodiments of the present invention, a large ΔE value results from the large electrical bandgap and breakdown field of the material, which can be the basis for improving cooling capacity .

The above-mentioned experimental examples relate to compounds having Zr contents of 0.7, 0.8, and 0.9. However, since the compounds have solid-solubility characteristics, interpolations can be performed by interpolating 0.7? X &Lt; 0.9, a similar degree of energy harvesting effect and electric calorie effect can be obtained. Then, based on Vegard's law, we can predict from the values presented in the vicinity of the composition of each composition.

In one embodiment, the energy storage density of the Hf _1-x Zr _x O ₂ compound is four times greater than the energy density of a typical Pb (Zr, Ti) O ₃ -based material, 10 Jcm ^-3 to 15 Jcm ^-3 Or 3 times as large as 46 Jcm ^-3 , the Hf _1-x Zr _x O ₂ compound can be used as an energy storage element to replace a battery or an electrochemical supercapacitor. In addition, due to the high pyroelectric energy harvesting effect of the Hf _1-x Zr _x O ₂ compound, it can be applied to an infrared sensor. In order to understand the applicability of the Hf _1-x Zr _x O ₂ compound to the infrared sensor, the minimum sensitivity (figure of merit, Fv) of the pyroelectric material can be calculated.

The typical sensitivities of LiNbO ₃ and LiTaO ₃ applied to infrared sensors are 10.8 × 10 ^-2 m ² C ^-1 and 11.6 × 10 ^-2 m ² C ^-1 , respectively, and the Hf _0.2 Zr _0.8 O ₂ thin film is 32.0 × 10 ^-2 m ² C ^-1 , which is 2.8 times larger than that of LiTaO ₃ . In addition, since LiNbO ₃ and LiTaO ₃ can not produce a thin film having the same characteristics as a single crystal thin film on a silicon substrate, application of LiNbO ₃ and LiTaO ₃ to a device made of nanoelectronic technology or thin films may be limited . On the other hand, the polycrystalline Hf _0.2 Zr _0.8 O ₂ thin film has a minimum sensitivity (Fv) higher than that of monocrystalline LiNbO ₃ and LiTaO ₃ thin films, and can be compatible with silicon, which makes it possible to facilitate nanoelectronic technology and mass production .

6 is a configuration diagram of a monolithic device in which an energy harvesting device 200a and an electrothermal cooling device 200b are formed on one substrate according to another embodiment of the present invention.

Referring to FIG. 6, an energy harvesting device 200a and an electrothermal cooling device 200b may be formed on the same substrate to provide a single monolithic device 1000. The superconducting layer constituting the energy harvesting element 200a and the electrothermal cooling element 200b may include a compound of Hf _1-x Zr _x O ₃ (0.7 ≦ x <0.9) according to an embodiment of the present invention. Since the pyroelectric layer is a material compatible with silicon, the energy harvesting device 200a and the electrothermal heating chiller 200b having the superconductive layer containing the compound on the substrate through a conventional Si processing technique can be used as one It is easy to implement with the monolithic device 1000.

The operating cycles of the energy harvesting device 200a and the electrothermal cooling element 200b of the monolithic device 1000 are pyroelectric energy harvesting and electrocaloric effect as described above . Since the pyroelectric energy harvesting and the calorimetric effect are exactly opposite to each other, the energy harvesting element 200a is connected to the electrothermal cooling element 200b by a method of reversing the sequence of applied electric field and temperature change You can use it, or vice versa. Therefore, the energy harvesting element 200a and the electrothermal heating element 200b may have the same structure. In one embodiment, a single element may be implemented as an energy harvesting element and an electrothermal chill element at a time by reversing the sequence of applied field and temperature changes.

The monolithic device 1000 may further include an energy storage 300 for storing energy generated from the energy harvesting device 200a. The electronic circuit portion 400 may receive a voltage from the energy harvesting device 200a as a first heat source (see 26 in FIG. 2) or a second heat source (see 27 in FIG. 2) 300 may be used. The heat generated in the electronic circuit portion 400 as the first heat source (see FIG. 2) or the second heat source (see FIG. 2) is transmitted to the outside of the electronic circuit portion 400 through the electrothermal cooling element 200b So that the electronic circuit portion 400 can be cooled.

The monolithic device 1000 is connected to at least one of the energy harvesting device 200a, the electrothermal cooling device 200b, the energy storage 300, and the electronic circuit unit 400, As shown in FIG. In other embodiments, each device may include a separate power source (not shown), or it may be powered from the outside. In yet another embodiment, the monolithic device 1000 may further include a plurality of circuits coupled to the energy harvesting device 200a and the electrothermal cooling device 200b, respectively. For example, the monolithic device 1000 may further include any one or more of two or more of an energy storage capacitor, an IR sensor, and a high capacity capacitor. In addition, the energy storage capacitor, the infrared sensor, and the high capacity capacitor may be formed of the same electroconductive material as the energy harvesting device 200a and the electrothermal cooling device 200b, as described above. However, the present invention is not limited thereto.

The pyroelectric layer may be applied as an infrared sensor itself. In this case, the pyroelectric layer may be implemented as a single pixel, or the pyroelectric layer may be patterned, and an array structure electrode A thermal imaging system having a plurality of pixels may be implemented.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Will be clear to those who have knowledge of.

Claims (29)

A compound represented by the following formula (1)
The compound comprises a tetragonal-phase crystalline phase of the space group P4 ₂ / nmc and has an antiferroelectric property with a dual hysteresis loop characteristic due to the electric field induced phase transition between the tetragonal phase and the orthorhombic phase of the space group Pca2 ₁ A pyroelectric layer representing the behavior.
[Chemical Formula 1]
Hf _1-x Zr _x O ₂ ,
0.7? X < 0.9. delete The method according to claim 1,
Wherein the superconducting layer has a thickness in the range of 7.0 nm to 30.0 nm. The method according to claim 1,
Wherein the superconducting layer has an operating temperature ranging from 298K to 448K. The method according to claim 1,
Wherein the operating voltage of the superconducting layer is in the range of greater than 0.0 MV / cm to 4 MV / cm. Comprising a compound represented by the following formula (1) between a first electrode and a second electrode at least partially opposed to each other,
The compound comprises a tetragonal-phase crystalline phase of the space group P4 ₂ / nmc and has an antiferroelectric property with a dual hysteresis loop characteristic due to the electric field induced phase transition between the tetragonal phase and the orthorhombic phase of the space group Pca2 ₁ A pyroelectric layer representing the behavior;
[Chemical Formula 1]
Hf _1-x Zr _x O ₂ ,
0.7? X < 0.9.
A second heat source that is in heat exchange with the pyroelectric layer and has a first heat source having a first temperature and a second temperature higher than the first heat source; And
And a bias source for applying a voltage to the superlattice layer through the first electrode and the second electrode, wherein an electric energy generated due to a temperature change of the superlattice layer, Producing energy harvesting device. delete The method according to claim 6,
Wherein the thickness of the superconducting layer is in the range of 7.0 nm to 30.0 nm. The method according to claim 6,
Wherein the operating temperature range of the superconducting layer is in the range of 298K to 448K. The method according to claim 6,
Wherein the operating voltage of the superconducting layer is in the range of greater than 0.0 MV / cm to 4 MV / cm. The method according to claim 6,
Wherein the pyroelectric layer further comprises a switch for regulating heat exchange alternately with the first heat source and the second heat source. The method according to claim 6,
Wherein the first heat source or the second heat source is in contact with the first electrode or the second electrode to perform heat exchange with the pyroelectric layer. The method according to claim 6,
And a reservoir for storing electrical energy generated from the superlattice layer through the first electrode and the second electrode. The method according to claim 6,
Wherein the superconducting layer comprises a plurality of superconducting layers, each of the plurality of superconducting layers having different Zr contents or electrodes inserted between the plurality of superconducting layers. 15. The method of claim 14,
Wherein the plurality of pyroelectric layers are filled with a dielectric material and / or a conductive material therebetween. Comprising a compound represented by the following formula (1) between a first electrode and a second electrode at least partially opposed to each other,
The compound comprises a tetragonal-phase crystalline phase of the space group P4 ₂ / nmc and has an antiferroelectric property with a dual hysteresis loop characteristic due to the electric field induced phase transition between the tetragonal phase and the orthorhombic phase of the space group Pca2 ₁ A pyroelectric layer representing the behavior;
[Chemical Formula 1]
Hf _1-x Zr _x O ₂ ,
0.7? X < 0.9.
A second heat source that is in heat exchange with the pyroelectric layer and has a first heat source having a first temperature and a second temperature higher than the first heat source; And
And a bias source for applying a voltage to the superlattice layer through the first electrode and the second electrode, wherein the temperature change is caused by a voltage change of the superlattice layer. delete 17. The method of claim 16,
Wherein the superconducting layer has a thickness in the range of 7.0 nm to 30.0 nm. 17. The method of claim 16,
Wherein the operating temperature range of the superconducting layer is in the range of 298 K to 448 K. 17. The method of claim 16,
Wherein the operating voltage of the superconducting layer is in the range of more than 0.0 MV / cm to 4 MV / cm. 17. The method of claim 16,
Further comprising a switch for controlling the superconducting layer to heat exchange alternately with the first heat source and the second heat source. 17. The method of claim 16,
Wherein the first heat source or the second heat source is in contact with the first electrode or the second electrode to perform heat exchange with the super pyroelectric layer. 17. The method of claim 16,
Further comprising a reservoir for storing electrical energy generated from the superconducting layer through the first electrode and the second electrode. 17. The method of claim 16,
Wherein the superconducting layer includes a plurality of superconducting layers, and the plurality of superconducting layers have Zr contents different from each other, or electrodes are inserted between the plurality of superconducting layers. 25. The method of claim 24,
Wherein the plurality of pyroelectric layers are filled with a dielectric material and / or a conductive material therebetween. 1. A monolithic device comprising a plurality of circuits formed on a substrate,
Wherein the plurality of circuits comprises:
Wherein the first compound comprises a tetragonal-phase crystalline phase of the space group P4 ₂ / nmc, wherein the tetragonal-phase and the orthorhombic-phase of the space group Pca2 ₁ An energy hubbing element part including a pyroelectric layer exhibiting an antiferroelectric behavior with a double hysteresis loop characteristic due to an electric field induced phase transition between the energy hubbing element part and the pyroelectric layer;
Wherein the second compound comprises a tetragonal-phase crystal of the space group P4 ₂ / nmc, wherein the tetragonal-phase and the orthorhombic-phase of the space group Pca2 ₁ comprise a second compound represented by the following formula An electrothermal cooling element including a pyroelectric layer exhibiting an antiferroelectric behavior having a double hysteresis loop characteristic due to an electric field induced phase transition between the electrodes;
[Chemical Formula 1]
Hf _1-x Zr _x O ₂ ,
0.7? X < 0.9.
An energy storage for storing energy generated from the energy harvesting element;
A first electronic circuit part connected to the energy harvesting device part and operated;
A second electronic circuit part connected to the electrothermal cooling element; And
A monolithic element including the first electronic circuit portion, the second electronic circuit portion, the energy harvesting element portion, the electrothermal coolant element, and a control portion for controlling operation of the energy storage. delete 27. The method of claim 26,
Wherein the first electronic circuit portion and the second electronic circuit portion are implemented as a single common circuit. 27. The method of claim 26,
Wherein at least one of the energy harvesting element part and the electrothermal cooling element part is controlled through a sequence of controlling an electric field change or a temperature change of the control part.

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