Pyroelectric laminated film capacitor and preparation method and application thereof

Abstract

The invention provides a pyroelectric laminated film capacitor and a preparation method and application thereof, the pyroelectric laminated film capacitor comprises a substrate, a first electrode layer, n composite layers and a second electrode layer which are sequentially laminated, and n is greater than or equal to 3; the composite layer is of a superlattice structure and comprises a ferroelectric layer and a paraelectric layer which are arranged in a stacked mode, and the ferroelectric layer is close to the substrate; the unit cell number of the ferroelectric layer is x, the unit cell number of the paraelectric layer is y, and y = (0.5-1) * x. According to the pyroelectric laminated film capacitor, through simple physical lamination, a superlattice structure is constructed, so that the ferroelectric layer has ferroelectricity and has a wave-shaped polarization structure without forming a vortex domain, and therefore, the film capacitor can realize electro-thermal conversion and has excellent pyroelectric performance.

Description

Technical Field

[0001] This invention belongs to the field of thin film capacitor technology, and relates to a pyroelectric multilayer thin film capacitor, its preparation method and application. Background Technology

[0002] The pyroelectric effect refers to the phenomenon of charge release caused by changes in polarization intensity with temperature. Macroscopically, it manifests as a voltage or current across a material due to temperature changes. For crystals with spontaneous polarization, the change in temperature (ΔT) after heating or cooling leads to a change in spontaneous polarization intensity (ΔPs), resulting in surface polarization charges in a specific direction. This phenomenon is called the pyroelectric effect. In recent years, the pyroelectric effect has been widely used in pyroelectric infrared detectors, including radiation and non-contact temperature measurement, infrared spectroscopy, laser parameter measurement, industrial automation, space technology, and infrared imaging.

[0003] Materials exhibiting pyroelectric properties are called pyroelectric materials. Compared to pyroelectric single crystals, pyroelectric ceramics are easier to prepare and have lower costs. Currently, pyroelectric materials often rely on a large dielectric constant change near the Curie temperature. However, polarization is often low near the Curie temperature, and the key parameter dP / dT, which determines pyroelectricity, is not large in this case, limiting the improvement of the overall performance of pyroelectric materials.

[0004] Based on the above research, there is a need to provide a pyroelectric multilayer film capacitor, which has excellent pyroelectric performance. Summary of the Invention

[0005] The purpose of this invention is to provide a pyroelectric multilayer thin film capacitor, its preparation method and application. The pyroelectric multilayer thin film capacitor constructs a superlattice structure through simple physical stacking, so that the ferroelectric layer has ferroelectricity and has a wave-shaped polarization structure without forming vortex domains, thereby enabling the thin film capacitor to achieve electrothermal conversion and have excellent pyroelectric performance.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a pyroelectric multilayer thin film capacitor, the pyroelectric multilayer thin film capacitor comprising a substrate, a first electrode layer, an n-layer composite layer and a second electrode layer stacked sequentially, wherein n≥3;

[0008] The composite layer has a superlattice structure and includes a ferroelectric layer and a paraelectric layer stacked together, wherein the ferroelectric layer is close to the substrate;

[0009] The number of unit cells in the ferroelectric layer is x, and the number of unit cells in the paraelectric layer is y, where y = (0.5~1) × x.

[0010] Preferably, 10 < x < 20.

[0011] Preferably, the ferroelectric layer comprises KNbO3 and Pb(Ti) 0.8 Zr 0.2 Any one or at least a combination of O3 or BiFeO3.

[0012] Preferably, the paraelectric layer comprises KTaO3 and / or SrTiO3.

[0013] Preferably, the substrate comprises SrTiO3 and / or DyScO3.

[0014] Preferably, the first electrode layer comprises Nb-doped SrTiO3 and / or Nb-doped SrRuO3.

[0015] Preferably, the second electrode layer comprises Pt and / or Au.

[0016] Preferably, the thickness of the first electrode layer is 5-25 nm.

[0017] Preferably, the thickness of the second electrode layer is 5-25 nm.

[0018] In a second aspect, the present invention provides a method for preparing a pyroelectric multilayer thin-film capacitor as described in the first aspect, the method comprising the following steps:

[0019] A first electrode layer and an n-layer composite layer are sequentially grown on the substrate surface, and finally a second electrode layer is formed to obtain the pyroelectric multilayer thin film capacitor.

[0020] Preferably, the method for growing the first electrode layer includes pulsed laser deposition.

[0021] Preferably, the method for growing the n-layer composite layer includes pulsed laser deposition.

[0022] Preferably, the method for forming the second electrode layer includes vapor deposition.

[0023] Thirdly, the present invention provides an application of the pyroelectric multilayer thin-film capacitor as described in the first aspect, the application including electrothermal conversion.

[0024] Preferably, the method of using a pyroelectric multilayer thin-film capacitor for the electrothermal conversion includes the following steps:

[0025] An electric field is applied to the pyroelectric multilayer thin film capacitor described in the first aspect, and then the temperature is increased. After the temperature increase is completed, the electric field is removed and the temperature is reduced to achieve electrothermal conversion.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This invention employs a physical layering method, constructing a superlattice structure through stacked ferroelectric and paraelectric layers. By limiting y=(0.5~1)×x and n≥3, the ferroelectric layer acquires ferroelectricity and simultaneously possesses a wave-shaped polarization structure without forming vortex domains. This enables the thin-film capacitor to achieve electrothermal conversion and possesses excellent pyroelectric performance. Attached Figure Description

[0028] Figure 1 This is the hysteresis loop diagram of the pyroelectric multilayer thin film capacitor described in Embodiment 1 of the present invention;

[0029] Figure 2 This is a schematic diagram of the pyroelectric cycle of the pyroelectric multilayer thin film capacitor described in Embodiment 1 of the present invention. Detailed Implementation

[0030] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the specific embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0031] In one specific embodiment, a pyroelectric multilayer thin film capacitor is provided, the pyroelectric multilayer thin film capacitor comprising a substrate, a first electrode layer, an n-layer composite layer and a second electrode layer stacked sequentially, wherein n≥3;

[0032] The composite layer has a superlattice structure and includes a ferroelectric layer and a paraelectric layer stacked together, wherein the ferroelectric layer is close to the substrate;

[0033] The number of unit cells (unit cells, one unit cell is about 0.4 nm) of the ferroelectric layer is x, and the number of unit cells (unit cells, one unit cell is about 0.4 nm) of the paraelectric layer is y, where y = (0.5~1) × x.

[0034] This invention constructs a superlattice structure by stacking ferroelectric and paraelectric layers. The superlattice structure satisfies y = (0.5~1) × x, n ≥ 3, to maintain a certain ferroelectricity in the ferroelectric layer, giving it a wavy polarization structure without forming vortex domains, thus enabling the pyroelectric multilayer thin film capacitor to possess excellent pyroelectric performance. If n < 3, the paraelectric layer is easily induced to exhibit ferroelectricity by the ferroelectric layer, and the wavy polarization structure completely disappears. Furthermore, in this invention, x and y satisfy a specific relationship. If x and y do not satisfy y = (0.5~1) × x, and y is too small, it is easily induced to exhibit ferroelectricity by the ferroelectric layer, and the wavy polarization structure completely disappears; if y is too large, the overall ferroelectricity weakens, and the net polarization is too small.

[0035] The n≥3 can be, for example, 3, 4, 5, 6, 7, 8, 9 or 10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] For example, when the number of layers in the composite layer of the present invention is 3, the pyroelectric multilayer film capacitor includes a substrate, a first electrode layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, and a second electrode layer stacked sequentially; when the number of layers in the composite layer of the present invention is 5, the pyroelectric multilayer film capacitor includes a substrate, a first electrode layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, and a second electrode layer stacked sequentially.

[0037] In this invention, x can indicate the thickness of the ferroelectric layer, and y can indicate the thickness of the paraelectric layer. The value of y is (0.5~1)×x, where 0.5~1 can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, 10 < x < 20 can be, for example, 11, 12, 13, 14, 15, 16, 17, 18 or 19, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Within a specific range, the number of ferroelectric cells x in the ferroelectric layer described in this invention can fully form a wavy domain structure. If x is too large, vortex domains are easily formed, reducing performance. If x is too small, uniform ferroelectric domains will be formed instead of a wavy domain structure, causing the advantages of the superlattice structure to completely disappear.

[0040] Preferably, the ferroelectric layer comprises KNbO3 and Pb(Ti) 0.8 Zr 0.2 Any one or at least a combination of O3 or BiFeO3.

[0041] Preferably, the paraelectric layer comprises KTaO3 and / or SrTiO3.

[0042] Preferably, the substrate comprises SrTiO3 and / or DyScO3.

[0043] Preferably, the first electrode layer comprises Nb-doped SrTiO3 and / or Nb-doped SrRuO3.

[0044] Preferably, the second electrode layer comprises Pt and / or Au.

[0045] Preferably, the thickness of the first electrode layer is 5-25nm, for example, it can be 5nm, 7nm, 9nm, 11nm, 13nm, 15nm, 17nm, 19nm, 21nm, 23nm or 25nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] Preferably, the thickness of the second electrode layer is 5-25nm, for example, it can be 5nm, 7nm, 9nm, 11nm, 13nm, 15nm, 17nm, 19nm, 21nm, 23nm or 25nm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0047] In one specific embodiment, a method for preparing the pyroelectric multilayer thin-film capacitor is provided, the method comprising the following steps:

[0048] A first electrode layer and an n-layer composite layer are sequentially grown on the substrate surface, and finally a second electrode layer is formed to obtain the pyroelectric multilayer thin film capacitor.

[0049] The present invention prepares the pyroelectric multilayer thin film capacitor by sequentially growing a stacked structure.

[0050] Preferably, the method for growing the first electrode layer includes pulsed laser deposition.

[0051] Preferably, the method for growing the n-layer composite layer includes pulsed laser deposition.

[0052] Preferably, the method for forming the second electrode layer includes vapor deposition.

[0053] In one specific embodiment, an application of the pyroelectric multilayer thin-film capacitor is provided, the application including electrothermal conversion.

[0054] Preferably, the method of using a pyroelectric multilayer thin-film capacitor for the electrothermal conversion includes the following steps:

[0055] An electric field is applied to the pyroelectric multilayer thin film capacitor, and then the temperature is increased. After the temperature increase is completed, the electric field is removed and the temperature is reduced to achieve electrothermal conversion.

[0056] The pyroelectric multilayer thin-film capacitor of this invention achieves electrothermal conversion (electric-thermal-thermal-electric cyclic conversion) through a cycle. The specific operation steps are as follows: First, an electric current of 1 MV·cm is applied at temperature T1. -1 up to 2MV·cm -1An electric field is applied (this process consumes very little electrical energy because the material is insulating, there is almost no current (current <0.01mA), and the voltage is approximately 10~20V, for example, 10V, 15V or 20V), and then the temperature is raised to T2. After the electric field is removed, the temperature is lowered. This process will release pyroelectric current and voltage, and the energy density and relative conversion efficiency (compared to the ideal Carnot cycle between T1 and T2) can be calculated by the area of ​​the hysteresis loop.

[0057] Wherein, T1 is 20-35℃, for example, it can be 20℃, 25℃, 30℃ or 35℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, and room temperature of 25℃ is preferred; T2 is T1+45~55℃, for example, it can be T1+45℃, T1+50℃ or T1+55℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, and T1+50℃ is preferred.

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0059] Example 1

[0060] This embodiment provides a pyroelectric multilayer film capacitor, which includes a substrate, a first electrode layer, a composite layer, and a second electrode layer stacked sequentially. The composite layer includes a ferroelectric layer and a paraelectric layer stacked sequentially. That is, the pyroelectric multilayer film capacitor includes a substrate, a first electrode layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, and a second electrode layer stacked sequentially.

[0061] The composite layer has a superlattice structure, the number of unit cells of the ferroelectric layer is x, x=12, and the number of unit cells of the paraelectric layer is y, y=0.67×x=8;

[0062] The ferroelectric layer is made of KNbO3, the paraelectric layer is made of KTaO3, the substrate is made of SrTiO3, the first electrode layer is made of Nb-doped SrTiO3 with a thickness of 15 nm, the second electrode layer is made of Pt with a thickness of 15 nm.

[0063] The method for preparing the pyroelectric multilayer thin film capacitor includes the following steps:

[0064] The first electrode layer and five composite layers are sequentially grown on the substrate surface using pulsed laser deposition, and finally the second electrode layer is deposited by vapor deposition to obtain the pyroelectric multilayer thin film capacitor.

[0065] Example 2

[0066] This embodiment provides a pyroelectric multilayer film capacitor, which includes a substrate, a first electrode layer, a composite layer, and a second electrode layer stacked sequentially. The composite layer includes a ferroelectric layer and a paraelectric layer stacked sequentially. That is, the pyroelectric multilayer film capacitor includes a substrate, a first electrode layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, and a second electrode layer stacked sequentially.

[0067] The composite layer has a superlattice structure, the number of unit cells of the ferroelectric layer is x, x=12, and the number of unit cells of the paraelectric layer is y, y=0.83×x=10;

[0068] The ferroelectric layer is made of KNbO3, the paraelectric layer is made of KTaO3, the substrate is made of SrTiO3, the first electrode layer is made of Nb-doped SrTiO3 with a thickness of 15 nm, the second electrode layer is made of Au with a thickness of 15 nm.

[0069] The method for preparing the pyroelectric multilayer thin film capacitor includes the following steps:

[0070] The first electrode layer and five composite layers are sequentially grown on the substrate surface using pulsed laser deposition, and finally the second electrode layer is deposited by vapor deposition to obtain the pyroelectric multilayer thin film capacitor.

[0071] Example 3

[0072] This embodiment provides a pyroelectric multilayer film capacitor, which includes a substrate, a first electrode layer, three composite layers and a second electrode layer stacked sequentially. The composite layer includes a ferroelectric layer and a paraelectric layer stacked sequentially. That is, the pyroelectric multilayer film capacitor includes a substrate, a first electrode layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer and a second electrode layer stacked sequentially.

[0073] The composite layer has a superlattice structure, the number of unit cells of the ferroelectric layer is x, x=12, and the number of unit cells of the paraelectric layer is y, y=0.5×x=6;

[0074] The ferroelectric layer is made of KNbO3, the paraelectric layer is made of KTaO3, the substrate is made of SrTiO3, the first electrode layer is made of Nb-doped SrTiO3 with a thickness of 15 nm, the second electrode layer is made of Pt with a thickness of 15 nm.

[0075] The method for preparing the pyroelectric multilayer thin film capacitor includes the following steps:

[0076] The first electrode layer and three composite layers are grown sequentially on the substrate surface using pulsed laser deposition, and finally the second electrode layer is deposited by vapor deposition to obtain the pyroelectric multilayer thin film capacitor.

[0077] Example 4

[0078] This embodiment provides a pyroelectric multilayer film capacitor, which includes a substrate, a first electrode layer, a composite layer, and a second electrode layer stacked sequentially. The composite layer includes a ferroelectric layer and a paraelectric layer stacked sequentially. That is, the pyroelectric multilayer film capacitor includes a substrate, a first electrode layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, and a second electrode layer stacked sequentially.

[0079] The composite layer has a superlattice structure, the number of unit cells of the ferroelectric layer is x, x=12, and the number of unit cells of the paraelectric layer is y, y=0.5×x=6;

[0080] The ferroelectric layer is made of Pb(Ti) 0.8 Zr 0.2 The material of the paraelectric layer is SrTiO3, the material of the substrate is DyScO3, the material of the first electrode layer is Nb-doped SrRuO3, the thickness of the first electrode layer is 5nm, the material of the second electrode layer is Au, and the thickness of the second electrode layer is 5nm.

[0081] The method for preparing the pyroelectric multilayer thin film capacitor includes the following steps:

[0082] The first electrode layer and five composite layers are sequentially grown on the substrate surface using pulsed laser deposition, and finally the second electrode layer is deposited by vapor deposition to obtain the pyroelectric multilayer thin film capacitor.

[0083] Example 5

[0084] This embodiment provides a pyroelectric multilayer film capacitor, which includes a substrate, a first electrode layer, a composite layer, and a second electrode layer stacked sequentially. The composite layer includes a ferroelectric layer and a paraelectric layer stacked sequentially. That is, the pyroelectric multilayer film capacitor includes a substrate, a first electrode layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, a ferroelectric layer, a paraelectric layer, and a second electrode layer stacked sequentially.

[0085] The composite layer has a superlattice structure, the number of unit cells of the ferroelectric layer is x, x=15, and the number of unit cells of the paraelectric layer is y, y=x=15;

[0086] The ferroelectric layer is made of BiFeO3, the paraelectric layer is made of SrTiO3, the substrate is made of SrTiO3, the first electrode layer is made of Nb-doped SrTiO3 with a thickness of 25 nm, the second electrode layer is made of Pt with a thickness of 25 nm.

[0087] The method for preparing the pyroelectric multilayer thin film capacitor includes the following steps:

[0088] The first electrode layer and five composite layers are sequentially grown on the substrate surface using pulsed laser deposition, and finally the second electrode layer is deposited by vapor deposition to obtain the pyroelectric multilayer thin film capacitor.

[0089] Example 6

[0090] This embodiment provides a pyroelectric multilayer film capacitor, which is the same as that in Embodiment 1 except that x is 18 and y = 0.83 × x = 14.94.

[0091] Example 7

[0092] This embodiment provides a pyroelectric multilayer film capacitor, which is the same as that in Embodiment 1 except that x is 20 and y = 0.83 × x = 16.6.

[0093] Example 8

[0094] This embodiment provides a pyroelectric multilayer film capacitor, which is the same as that in Embodiment 1 except that x is 10 and y = 0.83 × x = 8.3.

[0095] Example 9

[0096] This embodiment provides a pyroelectric multilayer film capacitor, which is the same as that in Embodiment 1 except that it includes 8 composite layers.

[0097] Comparative Example 1

[0098] This comparative example provides a multilayer thin-film capacitor, which includes an NdScO3 substrate and 20nm Ba2O3. 0.5 Sr 0.5 The electrode layer consists of a RuO3 layer and a 150nm PMN-0.3PT layer, where PMN is Pb(Mg) 1 / 3 Nb 2 / 3 )O3, PT is PbTiO3;

[0099] The method for preparing the multilayer thin-film capacitor includes the following steps:

[0100] Ba was sequentially deposited on the substrate surface using pulsed laser deposition. 0.5 Sr 0.5 The stacked thin-film capacitor is obtained by adding a RuO3 electrode layer and a PMN-0.3PT layer.

[0101] Comparative Example 2

[0102] This comparative example provides a multilayer film capacitor, which is the same as that in Example 1 except that y=1.2×x=14.4.

[0103] Comparative Example 3

[0104] This comparative example provides a multilayer film capacitor, which is the same as that in Example 1 except that y=0.3×x=3.6.

[0105] Comparative Example 4

[0106] This comparative example provides a multilayer film capacitor, which is identical to that of Example 1 except that it includes two composite layers.

[0107] The thin-film capacitors obtained in the above embodiments and comparative examples were first subjected to a temperature T1 (T1 is 25°C) from 1 MV·cm -1 up to 2MV·cm -1 An electric field is applied, and the temperature is raised to T2 (T2 is 75°C). Then, the electric field is removed, and the temperature is lowered to T1. This process releases pyroelectric current and voltage. The energy density (i.e., pyroelectric conversion energy density) and relative conversion efficiency (efficiency relative to an ideal Carnot cycle) are calculated using the area of ​​the hysteresis loop obtained by a ferroelectric testing instrument. The hysteresis loop in Example 1 is shown below. Figure 1 As shown in the diagram, the pyroelectric cycle is as follows: Figure 2 As shown.

[0108] The energy density and relative conversion efficiency of the thin-film capacitors obtained in the above embodiments and comparative examples are shown in Table 1:

[0109] Table 1

[0110]

[0111] As can be seen from Table 1:

[0112] As shown in Example 1 and Comparative Example 1, the present invention can obtain a pyroelectric multilayer thin film capacitor with excellent pyroelectric performance by constructing a superlattice structure. As shown in Example 1 and Comparative Examples 2-3, the y=(0.5~1)×x of the present invention can maintain a certain ferroelectricity in the ferroelectric layer, giving it a wave-shaped polarization structure without forming vortex domains, thereby improving the pyroelectric performance of the capacitor. As shown in Example 1 and Comparative Example 4, the present invention preferably includes more than 3 composite layers to ensure the pyroelectric performance of the pyroelectric multilayer thin film capacitor. As shown in Example 1 and Examples 6-8, as x changes, y also changes accordingly, thereby changing the performance of the pyroelectric multilayer thin film capacitor. As shown in Example 1 and Example 9, n≥3 of the present invention, but n should not be too large, thereby further improving the pyroelectric performance.

[0113] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A pyroelectric multilayer thin-film capacitor, characterized in that, The pyroelectric multilayer thin film capacitor includes a substrate, a first electrode layer, an n-layer composite layer, and a second electrode layer stacked sequentially, wherein n≥3; The composite layer has a superlattice structure and includes a ferroelectric layer and a paraelectric layer stacked together, wherein the ferroelectric layer is close to the substrate; The number of unit cells in the ferroelectric layer is x, and the number of unit cells in the paraelectric layer is y, where y = (0.5~1) × x.

2. The pyroelectric multilayer thin-film capacitor according to claim 1, characterized in that, 10＜x＜20。 3. The pyroelectric multilayer thin-film capacitor according to claim 1 or 2, characterized in that, The ferroelectric layer includes KNbO3 and Pb(Ti) 0.8 Zr 0.2 Any one or at least a combination of O3 or BiFeO3.

4. The pyroelectric multilayer thin-film capacitor according to claim 1 or 2, characterized in that, The paraelectric layer comprises KTaO3 and / or SrTiO3.

5. The pyroelectric multilayer thin-film capacitor according to claim 1 or 2, characterized in that, The substrate comprises SrTiO3 and / or DyScO3; The first electrode layer comprises Nb-doped SrTiO3 and / or Nb-doped SrRuO3; The second electrode layer comprises Pt and / or Au.

6. The pyroelectric multilayer thin-film capacitor according to claim 1 or 2, characterized in that, The thickness of the first electrode layer is 5-25 nm; The thickness of the second electrode layer is 5-25 nm.

7. A method for preparing a pyroelectric multilayer thin-film capacitor as described in any one of claims 1-6, characterized in that, The preparation method includes the following steps: A first electrode layer and an n-layer composite layer are sequentially grown on the substrate surface, and finally a second electrode layer is formed to obtain the pyroelectric multilayer thin film capacitor.

8. The preparation method according to claim 7, characterized in that, The method for growing the first electrode layer includes pulsed laser deposition. The method for growing the n-layer composite layer includes pulsed laser deposition. Methods for setting a second electrode layer include vapor deposition.

9. An application of the pyroelectric multilayer thin-film capacitor as described in any one of claims 1-6, characterized in that, The applications include those for electrothermal conversion.

10. The application according to claim 9, characterized in that, The method of using a pyroelectric multilayer thin-film capacitor for the electrothermal conversion includes the following steps: An electric field is applied to the pyroelectric multilayer thin film capacitor as described in any one of claims 1-6, and then the temperature is increased. After the temperature increase is completed, the electric field is removed and the temperature is reduced to achieve electrothermal conversion.

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