WO2012021006A2 - Double-layer metal thin film type electric power generator, and integrated electric power generator using same - Google Patents

Abstract

The invention relates to a double-layer metal thin film type electric power generator, comprising a substrate, a first metal thin film formed on the substrate, an insulation film formed on the substrate such that the insulation film contacts the first metal thin film, and a second metal thin film formed on the first metal thin film and on the insulation film. According to the double-layer metal thin film type electric power generator of the present invention, thermal energy and radiant energy applied from respective external sources to the first and second metal thin films are simultaneously converted into electric energy.

Description

Double metal thin film generator and integrated generator using the same

The present invention relates to an electric power generator with a bi-layered metallic thin films using a thermoelectric effect and a photovoltaic effect, and more particularly, electrical energy by simultaneously using naturally or artificially generated light or heat. The present invention relates to a double metal thin film generator having a nonmagnetic (or magnetic) / magnetic (or nonmagnetic) structure which is suitable for generating s, and an integrated electrical power generator using the same.

In recent years, researches on the development of environment-friendly energy have been actively conducted all over the world in order to solve the problem of environmental pollution and energy depletion. In particular, many studies on generators using light energy or heat energy that can be easily obtained from the surrounding area and Attention is focused.

As is well known, the technique of converting light energy into electrical energy utilizes a photovoltaic effect, in which when photons above a certain energy are absorbed at the interface between two different materials, they are bound to the nucleus at the junction. Electrons are excited, and these excited electrons move by the energy potential in two different material junctions, forming photovoltaic power.

For example, in the metal-to-metal junction, electrons excited by the potential due to the difference in work function between the metals move to form photovoltaic power. The contact or Schottky contact is determined, and the potential between them separates the pair of electrons excited from the metal and the electrons and holes excited from the semiconductor to form photovoltaic power.

In the PN junction, which is a semiconductor-semiconductor junction, as shown in FIG. 1, electron and hole pairs generated by light are separated by internal potential to form photovoltaic power.

In Fig. 1, reference numeral EC denotes an energy level of a conduction band of a silicon semiconductor, EF ( _Equilibrium) denotes a Fermi energy level in a thermal equilibrium state, and E _V denotes a valence band of a silicon semiconductor. Where E _FP represents the Fermi energy level of the P-type semiconductor, and E _FN represents the Fermi energy level of the N-type semiconductor.

Here, as a typical photovoltaic device using the photovoltaic effect, for example, a solar cell is mentioned, such a solar cell is a semiconductor device, a semiconductor solar cell using a bulk silicon, thin film silicon, a compound is typical, in addition, dye-sensitized Type solar cells and solar cells using organic / inorganic materials have been studied.

On the other hand, the technology of converting thermal energy into electrical energy is based on the thermoelectric effect of converting thermal energy into electrical energy, which is based on the Fermi Energy Model theory and diffusion potential. Potential theory.

As an example, as shown in FIG. 2 showing a schematic diagram of a single magnetic / nonmagnetic double thin film electromechanical device, two metal materials M1 and M2 having different coefficients of thermal expansion, thermal conductivity, and Seebeck coefficient are bonded (M1 / When the M2 junction is formed and an open circuit is formed on the electrodes M1 contact and M2 contact of each material, when the heat from the outside is applied to the junction part of the two metal materials M1 and M2, the junction part and the electrode part ( The temperature difference between M1 contact and M2 contact generates electromotive force. At this time, the temperature of the electrode portion can be cooled by the temperature of the reference by connecting the same metal material (M1, M2, respectively) or a material of low resistance as a reference and being exposed to room temperature.

Therefore, according to the Fermi energy model theory, the temperature difference between the junction portion and the electrode portion respectively changes the Fermi energy level in the metal material, and as shown in Equation 1 below, the thermoelectric power is generated in proportion to the Fermi energy change amount. do.

[Equation 1]

In Equation 1, E _F (T) is a Fermi energy according to the temperature (T), E _F (0) is a Fermi energy at the absolute temperature OK (Zero Kelvin), N (E) is the energy The number of electrons accordingly is shown, respectively. That is, the above E _F (T) equation is obtained by subtracting the absolute temperature 0K, that is, the Fermi energy value (E _F (0)) inherent in a material that has not received any external energy, minus the energy level produced or destroyed by the temperature, In other words, it means the Fermi energy value that is changed by the thermal energy.

In addition, the Fermi potential value ΔV _F according to the Fermi level may be expressed by Equation 2 below.

[Equation 2]

In Equation 2, P _S is a Seebeck coefficient, that is, a material-specific value (Unit: V / K) representing an electromotive force value according to thermal energy, and ΔP _S is a difference value of Seebeck coefficient of two metal materials in contact ( ΔP _S = P _{S (Material 1)} − P _{S (Material 2)} ).

That is, ΔV _F is equal to the product of the Seebeck coefficient value and the temperature change (ΔT) value, and the Seebeck coefficient is a value unique to a material and represents an electromotive force value according to thermal energy (Unit: V / K), Depending on the material, it may have a (+) or (-) value and may also be expressed as a Fermi energy change value per unit electron.

In addition, the diffusion potential theory suggests that when the temperature rises in the metal, this temperature difference cancels out the average speed of electrons and phonons, so that the changed electron and phonon densities form diffusion potentials. Since is opposite to the direction of the thermoelectric power, the actual thermoelectric effect occurs by the difference between the potential value and the diffusion potential value according to the amount of change in the Fermi energy level.

This thermoelectric phenomenon, as shown in Equation 3 below, occurs when there is a temperature difference between two junction parts and a reference part in any type of heat, and this effect is applied to the Seebeck coefficient of the two metal materials. Linearly proportional. In particular, the thermoelectric effect is very easy to convert the thermal energy into electrical energy, there is an advantage that can generate high-efficiency electrical energy because there is no need for an external voltage for device (Device) operation.

[Equation 3]

In Equation 3, reference numeral Ps denotes the Seebeck coefficient of the metal 1 (M1) and the metal 2 (M2), and Ve.mf denotes the difference between the Seebeck coefficient of the two materials in contact with the temperature change (ΔT). Electromotive force, ΔPS is the Seebeck coefficient difference value of the two materials in contact (△ P _S = P _{S (Material 1)} -P _{S (Material 2)} ), P _M1 is the Seebeck coefficient value of the metal 1 (M1), P _M2 represents the Seebeck coefficient value of the metal 2 (M2), T _junction represents the temperature value at the metal junction, and T _reference represents the Referece temperature value.

However, the semiconductor-based solar cell technology among the photovoltaic devices using the photovoltaic effect has a relatively high initial installation cost compared to other renewable energy, is sensitive to the use environment, has a disadvantage in terms of durability, A sufficient power generation efficiency can be obtained only during the day time, and due to the inherent characteristics of the semiconductor material, the power generation efficiency is lowered due to a rise in temperature of the solar panel when exposed to light for a long time.

In addition, the next generation solar cell using organic / inorganic materials is expected to have many applications due to the transparent and low-cost production, but the power generation efficiency is not only relatively low compared to the conventional silicon solar cell, but also the durability is verified. There is not a problem.

In this regard, many companies and university research institutes at home and abroad are conducting researches to improve solar cell power generation efficiency and reduce manufacturing costs, but most of them are limited to generators that generate a large amount of electricity using solar light. . Recently, the combination of LED and solar cells, application to electronic devices such as solar cell phones, solar chargers, and miniaturized applications have been attempted, but the application is limited due to the limitation of solar cell size and power generation efficiency. It is true.

On the other hand, in relation to the research on the development of power generation technology using thermoelectric phenomenon, many companies at home and abroad have been developing various types of thermoelectric power generators for several decades. Low efficiency to convert into electrical energy, large size of devices to increase power generation efficiency, high thermal conductivity, low electrical reliability, and device integration Technical problems still exist, such as poor integration, which is practically very limited in scope and particularly in various portable (or mobile) electrical and electronic devices (e.g., portable computers, portable terminals, cellular phones, smartphones, electrical Automotive battery, etc.) is bound to have a limit.

First, the present invention uses a structure and a material capable of simultaneously using the thermoelectric effect and the photovoltaic effect.

To this end, the present invention includes a substrate, a first metal thin film formed on the substrate, and a second metal thin film formed on an upper portion of the substrate and an upper portion of the first metal thin film according to one aspect; The present invention provides a dual metal thin film type generator that simultaneously converts thermal energy and light energy applied to the first and second metal thin films from the outside into electrical energy.

Here, the first metal thin film is a non-magnetic metal thin film having a low resistance value and a Seebeck coefficient, that is, a thermoelectric effect, to maintain ohmic contact with a substrate, thereby inducing photovoltaic effect-induced current. Reduces the loss and smooths the flow. The second metal thin film is a magnetic thin film having a relatively high resistance value, a lateral photovoltaic effect, and a high light absorption rate among the magnetic metal thin films. In addition, the second metal thin film has a Seebeck coefficient opposite to that of the first metal thin film and is partially in contact with the first metal thin film to exhibit an efficient thermoelectric effect as a thermocouple structure, and at the same time induce a Schottky junction with the substrate. By maintaining the electromotive force by suppressing the shunting of the current due to the photovoltaic effect induced in the interface between the first metal thin film and the second metal thin film, and the substrate and the first and second metal thin films, respectively. The second magnetic metal thin film has a spin seebeck effect or a spin-photovoltaic effect due to a quantum mechanical effect as well as a general thermoelectric effect or photovoltaic effect when fabricating a nano patterning structure. effect) can be induced to increase the power generation efficiency.

According to another aspect of the present invention, a substrate, a first metal thin film formed on the substrate, an insulating film formed on the substrate in contact with the first metal thin film, an upper portion of the first metal thin film, and the insulating film It includes a second metal thin film formed on the top of the, and provides a double metal thin film type generator for converting the thermal energy and light energy applied to the first and second metal thin film from the outside at the same time into electrical energy. Here, the insulating film further increases the electromotive force by suppressing the shunt of the thermal or photovoltaic effect-induced current induced by light or heat.

According to another aspect of the present invention, a plurality of unit cells having a structure in which a first metal thin film and a second metal thin film having different Seebeck coefficients are sequentially stacked on a substrate are connected in series, and each unit is connected from the outside. An integrated generator using a double metal thin film for simultaneously converting thermal energy and light energy applied to the first and second metal thin films of a cell into electrical energy is provided. This series connection can be applied to environments where high electromotive force is required.

According to another aspect of the present invention, a plurality of unit cells having a structure in which a first metal thin film and a second metal thin film having different Seebeck coefficients are sequentially stacked on a substrate are connected in parallel, and each unit is connected from the outside. An integrated generator using a double metal thin film for simultaneously converting thermal energy and light energy applied to the first and second metal thin films of a cell into electrical energy is provided. This parallel connection can be applied in environments where high current is required.

According to another aspect of the present invention, a first unit cell group in which a plurality of unit cells each having a structure in which a first metal thin film and a second metal thin film having different Seebeck coefficients are sequentially stacked on a substrate is connected to each other in series And a plurality of unit cells each having a same structure as the first unit cell group in series, and each having a second unit cell group connected in parallel to the first unit cell group. An integrated generator using a double metal thin film for simultaneously converting thermal energy and light energy applied to the first and second metal thin films into electrical energy is provided. This series / parallel connection is useful for devices requiring high voltages and large currents (high voltage / high current generators).

According to the present invention, a first metal thin film (nonmagnetic or magnetic) and a second metal thin film (magnetic) having different Seebeck coefficients are sequentially formed on the substrate, and the thermal energy applied to the first and second metal thin films from the outside and By adopting a structure that converts light energy into electrical energy at the same time, the size of the power generating element can be manufactured according to the purpose and space, so its application range is wide, especially the material inherent in the generator using only conventional light or heat By overcoming the limitations of miniaturization and low heat due to characteristics, it can be easily applied to small electronic devices, home and office electronic devices.

In addition, the present invention can significantly reduce the manufacturing cost of the power generation device by manufacturing in a simplified process such as sputtering, without the need for a separate patterning process, it is possible to realize low-cost mass production.

Furthermore, the present invention can be used semi-permanently, environmentally friendly, and versatile because it simultaneously uses heat energy generated from electronic devices and light energy such as the sun, fluorescent lamps, incandescent lamps, and LEDs.

1 is an exemplary diagram for explaining a photovoltaic effect;

2 is a schematic diagram of a single magnetic / nonmagnetic dual thin film power generation device;

3 is a cross-sectional view of a double metal thin film generator according to Embodiment 1 of the present invention;

4A and 4B are band diagrams at junctions of a double metal thin film structure as the temperature rises in the p-type substrate and the n-type substrate, respectively;

5 is a cross-sectional view of a double metal thin film generator according to Embodiment 2 of the present invention;

6 is a diagram showing the configuration of an integrated generator in which a plurality of unit cells (power generation elements) each having a double metal thin film are connected in series in a planar structure;

7 is a diagram illustrating a configuration of an integrated generator in which a plurality of unit cells (power generation elements) each having a double metal thin film are connected in parallel in a planar structure;

8 is a cross-sectional view of an integrated generator fabricated in the form of connecting each unit cell group produced by connecting a plurality of single cells each having a double metal thin film in series;

9A and 9B are views illustrating a method of measuring electromotive force in a double metal thin-film generator manufactured according to the present invention;

10A and 10B are graphs showing voltage and current change results when external heat and various light are applied to a metal thin film device having a Si (p-type) / Cu / (MgO) Co structure, which was tested according to the present invention.

FIG. 10C is a table numerically displaying the results of FIGS. 10A and 10B;

FIG. 11A is a graph showing light intensity and relative light intensity of a human eye according to light wavelengths of a white LED; FIG.

11b is a graph showing the intensity of light according to the wavelength of each light;

12 is a graph showing the result of the voltage change according to the application of light / heat energy using a conventional solar cell,

13 is a schematic diagram of an experimental apparatus for measuring electromotive force of each device by connecting two single cells in series;

14 is a graph showing the results of experiments in which electromotive force is measured by connecting two single cells in series;

15A and 15B are graphs of experimental results of measuring voltage changes according to application of thermal energy in Si (p type) / Cu / Co and Si (p type) / Cu / (MgO) Co structures, respectively;

16A and 16B are graphs of experimental results of measuring voltage changes according to application of halogen light energy in Si (p type) / Cu / Co and Si (p type) / Cu / (MgO) Co structures,

17 is a graph of the results of experiments measuring the temperature change with heating time using daylight, halogen, heat, LED,

18A and 18B are graphs of experimental results of measuring changes in voltage and current according to the distance between halogen and LED light sources in Si (p type) / Cu / (MgO) Co structures, respectively.

18C is a table showing numerical values of the experimental results of FIGS. 18A and 18B;

19a and 19b are voltage variations of thermal energy applied at 5 nm (± 10%) and 20 nm (± 10%) of Cu thickness in Si (p-type) / Cu (t) / (MgO) Co structures, respectively. Graph of the experimental results measured.

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

In the following description of the present invention, if it is determined that a detailed description of known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may be changed according to intention or custom of a user, an operator, or the like. Therefore, the definition should be made based on the technical idea described throughout this specification.

Example 1

3 is a cross-sectional view of a double metal thin film generator according to Embodiment 1 of the present invention.

Referring to FIG. 3, in the generator of the present embodiment, a first metal thin film 304 is formed on a substrate 302, for example, a silicon substrate, and an upper part of the substrate 302 and an upper part of the first metal thin film 304. And a double metal thin film structure in which a second metal thin film 306 is formed. The double metal thin film structure includes any of a nonmagnetic metal / magnetic metal structure, a magnetic metal / magnetic metal structure, and a magnetic metal / nonmagnetic metal structure. It can be formed in one structure.

Here, it is necessary to select the first and second metal thin films 304 and 306 as materials capable of simultaneously obtaining a thermoelectric effect (or a thermoelectric effect) and a photovoltaic effect. That is, the generator of the present exemplary embodiment may simultaneously convert thermal energy and light energy applied to the first and second metal thin films 304 and 306 from the outside into electrical energy. That is, when thermal energy is applied to the junction portions of the first and second metal thin films 304 and 306, thermoelectric power is generated by the thermoelectric effect due to the temperature difference between the junction portion and the first and second metal thin film portions, When applied, photovoltaic power is generated by the photovoltaic effect at the metal-metal contact surface and the first and second metal-substrate contact surfaces of the first and second metal thin film junctions. The heat energy applied to the double metal thin film structure may be, for example, heat energy generated from an electronic device equipped with a generator, and the light energy may be, for example, a sun, a fluorescent lamp, an incandescent lamp, an LED, or the like.

At this time, in order to generate an efficient thermoelectric power, the first metal thin film 304 and the second metal thin film 306 have different Seebeck coefficients, which is a thermoelectric effect due to the temperature difference between the junction portion and the metal portion of the metal. This is to generate thermal power through. That is, the thermoelectric effect requires a combination of metal thin film materials having a large difference between the Seebeck coefficients of the first and the second metal thin films (ΔP _S = P _{S (material 1)} -P _{S (material 2)} ). When the Seebeck coefficient values of the first and second metal thin films are one positive, the other has a negative value to induce high efficiency. At the same time the Seebeck coefficient values of the substrate and the first metal thin film material deposited thereon must be both positive or both negative.

To this end, when the substrate 302 is a p-type silicon substrate having a positive Seebeck coefficient, the first metal thin film 304 is formed of a metal having a positive Seebeck coefficient, and the second metal thin film 306 The first metal thin film 304 is formed of a metal having a (-) Seebeck coefficient, whereas the substrate 302 is an n-type silicon substrate having a (-) Seebeck coefficient. The second metal thin film 306 may be formed of a metal having a (+) Seebeck coefficient.

That is, when heat is applied to the junction portion of the double metal thin film employed in the device (generator) of the present embodiment, thermoelectric power is generated due to the thermoelectric effect caused by the temperature difference between the junction portion and the two electrode portions. Silver is affected by the presence or absence of the substrate and the type of the substrate.

For example, a double metal thin film on which a first metal thin film M1 having a (+) Seebeck coefficient and a second metal thin film (M2) having a (−) Seebeck coefficient are sequentially formed on a P-type silicon substrate having a (+) Seebeck coefficient. As the temperature of the junction portion rises in the structure, it has a stepped band diagram, as shown in FIG. 4A as an example. At this time, in the first metal thin film M1, as the Fermi energy level decreases as the temperature increases at the junction, electrons are collected, and the electrons exit to the P-type silicon. Each electrode part is connected to the substrate as well as the junction, so that the substrate and the electrons circulate, and thermal power is generated.

In addition, a temperature in a double-film structure in which a first metal thin film M1 having a (-) Seebeck coefficient and a second metal thin film M2 having a (+) Seebeck coefficient are formed on an N-type silicon substrate having a (-) Seebeck coefficient. When is raised, as shown in Figure 4b, it has a stepped band diagram can generate the thermoelectric power.

4A and 4B, _{EF (Equilibrium)} is a Fermi energy level in the thermal equilibrium state, and E _{F (M1)} is a Fermi energy level of the first metal thin film changed after applying thermal energy, E _{F (M2)} Is the Fermi energy level of the second metal thin film changed after applying the thermal energy, E _{F (Si)} is the Fermi energy level of the silicon substrate changed after applying the thermal energy, E _C is the energy level of the conduction band of the silicon substrate, E _V represents the energy level of the valence band of the silicon substrate, and E _{F (Intrinsic)} represents the Fermi energy level of the intrinsic semiconductor.

On the other hand, the non-magnetic metal thin film having a relatively low resistance value and the magnetic metal thin film having a large resistance value can maintain a large potential difference in the power generation element, thereby realizing high power generation efficiency. ) And the second metal thin film are schottky contacted to maintain a large potential difference in the power generating element, thereby improving power generation efficiency. In addition, magnetic (non-magnetic) / non-magnetic (magnetic) or magnetic / magnetic selective double metal thin film structure and nano patterning structure through the spin, thermoelectric effect (Spin) Seebeck effect or spin-photovoltaic effect can be induced.

In addition, the ohmic contact and the Schottky contact are determined by the work function of the substrate and the metal according to the type of the substrate (n-type or p-type), and the Schottky contact is generally φm (metal Is formed when the work function of > > However, this is a general model and in practice the Schottky barrier must be adjusted in consideration of the interface level. In addition, a Schottky barrier may be formed by inserting a thin insulator between the semiconductor substrate and the second metal thin film, which may be used to create a Schottky contact by tunneling or adjusting the barrier depending on the thickness of the insulator or the band gap of the insulator. Can be.

In general, a method for forming an ohmic contact includes controlling the work affinity of a metal and the electron affinity of a semiconductor to sufficiently reduce the barrier energy (φ m (work function of a metal)-φ s (electron affinity of a semiconductor)) or There is a method of increasing the impurity doping or thinning the metal to produce quantum mechanical tunneling. In the case of impurity doping, a diffusion process or an ion implantation process commonly used in a general semiconductor process may be used.

The photovoltaic effect is related to the work function difference between the first and second metal thin film materials and the work function difference between the substrate (eg, silicon substrate) and the first and second metal thin film materials. The larger the work function difference between the second metal thin film materials, the higher the photovoltaic power can be obtained, and the photovoltaic effect-induced current must be achieved when the first metal thin film material deposited directly on the substrate forms an ohmic contact. Can be induced into the metal thin film material without loss by the barrier at the interface between the substrate and the metal thin film. This principle can be equally applied to not only the current formed by the light energy but also the thermal effect-induced current.

More specifically, when the double metal thin film is a p-type substrate having a nonmagnetic / magnetic structure and has a (+) Seebeck coefficient, considering the thermoelectric effect, since the cancellation should not occur in the device, the (+) Seebeck coefficient is sequentially The first metal thin film (non-magnetic) material having a branch and the second metal thin film (magnetic) material having a (-) Seebeck coefficient may be deposited on a substrate to obtain good power generation efficiency. In addition, considering the photovoltaic effect, in order for the p-type substrate and the first metal thin film material to form ohmic contact, the work function of the first metal thin film should be basically larger than the work function of the p-type substrate (φps = 5.05 eV). (φm (work function of metal)> φps (work function of p-type silicon semiconductor)). The larger the work function difference between the two metal thin film materials and the larger the work function difference between the substrate and each metal thin film material is better.

First, considering only Seebeck coefficients, the first metal thin film material (nonmagnetic) in a p-type substrate is, for example, Al, Cu, Ag, Au, Ta, Sb, W, Cd, Mo having a (+) Seebeck coefficient. Pt with a Seebeck coefficient of 0 can be used since the work function (φps = 5.65 eV) is larger than the work function of the p-type substrate to form ohmic contact.

That is, the first metal thin film material available should have a work function value that is relatively larger than the work function value of the p-type substrate for ohmic contact with the p-type substrate. However, since this work function may induce quantum mechanical tunneling by controlling impurity doping into the p-type substrate (high concentration impurity doping) to make ohmic contacts or to reduce the thickness of the first metal thin film material, 4.0 to 5.65 A metal material having a work function range of about eV may be used as the first metal thin film material.

As the second metal thin film material in the case of a p-type substrate, for example, an alloy such as Ni, Co having a (-) Seebeck coefficient, as well as Constantan or Alumel containing magnetic materials, etc. Series (ie, all magnetic materials having a (-) Seebeck coefficient and alloy series containing magnetic materials) and the like.

In addition, when the double metal thin film is an n-type substrate having a nonmagnetic / magnetic structure and has a negative (-) Seebeck coefficient, the first metal thin film having a (−) Seebeck coefficient and a positive (+) Seebeck coefficient Two metal thin film (magnetic) materials must be deposited on the substrate in order to achieve good power generation efficiency. In addition, in order for the n-type substrate and the first metal thin film material to form ohmic contact, basically, the work function of the first metal thin film material should be smaller than the work function (φps = 4.52 eV) of the n-type substrate (that is, φ m (metal Work function) <φns (work function of n-type silicon semiconductor))

Thus, for the n-type substrate, as the first metal thin film material, for example, Pd having a negative (-) Seebeck coefficient may be used, and Ti, which has a work function smaller than that of the n-type substrate and has little Seebeck coefficient, is also in ohmic contact Formation is possible and can use. As the second metal thin film material, for example, Fe having a (+) Seebeck coefficient may be used, and all magnetic materials having an alloy series (that is, having a (+) Seebeck coefficient including Chrommel, etc., containing a magnetic material). Alloy series containing a magnetic material) and the like. Although the work function of Pd is larger than the work function of the n-type substrate to form a Schottky contact, it can be used through the method described above.

Next, when the double metal thin film is a magnetic / magnetic structure and is a p-type substrate, as the first metal thin film material (magnetic), for example, Fe having a positive Seebeck coefficient may be used and chromium containing magnetic material. Alloy series such as all magnetic materials having a (+) Seebeck coefficient and an alloy series including the magnetic materials may be used. As the second metal thin film material (magnetic), not only Ni and Co having a (-) Seebeck coefficient but also all alloy series (i.e., having a (-) Seebeck coefficient including magnetic or constantan or aamel) Magnetic materials and alloy series containing magnetic materials) and the like.

And when the double metal thin film is a magnetic / magnetic structure and is an n-type substrate, as the first metal thin film (magnetic) material, for example, Constantan containing magnetic material as well as Ni, Co having a (-) Seebeck coefficient or Alloy series (ie, all magnetic materials having a (−) Seebeck coefficient and an alloy series containing magnetic materials), such as aamel, etc., may be used.

As the second metal thin film (magnetic) material, for example, Fe having a (+) Seebeck coefficient may be used, and all magnetic materials and magnetic materials having an alloy series (i.e., having a (+) Seebeck coefficient including chrome mel etc. containing magnetic materials). This included alloy series) and the like can be used. Here, the first metal thin film material and the second metal thin film material should not be the same material.

On the other hand, when the double metal thin film is a magnetic / nonmagnetic structure and is a p-type substrate, for example, Fe having a (+) Seebeck coefficient may be used as the first metal thin film (magnetic) material. Alloys such as chromemel and the like containing magnetic materials (ie, all magnetic materials having a (+) Seebeck coefficient and alloys containing magnetic materials), and the like, and a second metal thin film material (nonmagnetic). As the above, for example, Pd having a (-) Seebeck coefficient can be used.

In addition, when the double metal thin film is a magnetic / nonmagnetic structure and is an n-type substrate, the first metal thin film (magnetic) material having a (-) Seebeck coefficient may be, for example, Constantan or a magnetic material as well as Ni or Co. Alloy series (ie, all magnetic materials having a (-) Seebeck coefficient and an alloy series including the magnetic materials), and the like, may be used, and as the second metal thin film (nonmagnetic) material, for example, a (+) Seebeck coefficient Al, Cu, Ag, Au, Ta, Sb, W, Cd, Mo, or Rh may be used.

Here, the selection of the metal thin film material in consideration of the photovoltaic effect is basically preferred as the work function difference between the first and second metal thin film materials and the substrate is larger, and the first metal thin film is preferably in ohmic contact with the substrate. In addition, materials such as Cu, Co, or Ti are materials that can expect a photovoltaic effect because they can see the lateral photovoltaic effect.

On the other hand, when light is applied to the double metal thin film structure, a current is generated by the photovoltaic effect at the metal-metal contact surface and the metal-substrate contact surface of the double metal thin film junction, wherein light is absorbed from the surface according to the metal surface state of the top layer. The degree of transmission or reflection varies. That is, if the surface is rough or uneven, diffuse reflection occurs, thereby reducing the amount of transmitted light. At this time, since the surface roughness varies according to grain size and grain shape according to the thickness of the metal thin film, power generation efficiency can be increased by adjusting the grain size and grain shape according to the thickness of the metal thin film. have.

That is, the control of grain size and grain shape according to the thickness of the metal thin film can be described as a thin film formation process based on the crystal growth theory. The thin film growth starts after the cluster of critical size is formed, and the initial thin film When formed, the deposition material begins to form very small grains of island form, and as the deposition proceeds, the island form grains become larger during the fusion process. it becomes a columnar grain structure and grows roughly on the surface.

Through this change, a continuous film is formed, so that the grain size and grain shape vary according to the thickness.To make the grain size and shape small and uniform, 1) Ar pressure (the grain size decreases and decreases when the Ar partial pressure increases. 2) Input sputtering power (increasing, increasing the movement of deposited target atoms to form a smooth surface), and 3) substrate biasing (DC / RF bias applied). In addition, the chemical potential is increased to suppress grain migration and to form a smooth surface. Nevertheless, various external factors may cause the surface roughness of the metal to be deteriorated.

Therefore, when the contact surface between the metal thin films is discontinuous or rough, and the diffuse reflection becomes large, the light absorption is less, resulting in less photovoltaic effect. To this end, in the present invention, after forming the first metal thin film, a surface treatment using sputtering etching, an ashing process, or an ion-cluster in which a gas and ions are condensed instead of a single ion is made to collide with the metal surface. The physical interface state of the surface of the first metal thin film may be improved through a gas-cluster ion beam process that softens the metal surface.

On the other hand, the thickness of the first metal thin film 304 employed in the generator using the double metal thin film of the present embodiment is the photovoltaic-induced current and the ohmic contact between the metal thin film and the substrate 302 and the light generated. Given the flow of thermoelectric-induced currents, it should be formed at least thinner than the thickness of the second metal thin film 306, for example, 20 nm (± 10%) for the first metal thin film 304. A thickness range of about) is preferable, and in the case of the second metal thin film 306, a thickness range of about 50 nm (± 10%) is preferable. Of course, the generator using the double metal thin film of the present invention is not necessarily limited to the thickness of each metal thin film formed on the substrate, and may be formed thinner or thicker in consideration of the use of the generator, power generation capacity and the like. Of course.

As the method for forming the first and second metal thin films 304 and 306 on the substrate 302, for example, any one of a DC sputtering process, an RF sputtering process, an ion beam sputtering process, and a photolithography process can be used. have.

For example, the pre ^- designed shadow mask (the first metal thin film shadow mask) is subjected to a DC sputtering process under vacuum conditions in which a vacuum degree of 2X10 ^-7 Torr is maintained and 2X10 ^-3 Torr of Ar working gas is injected. The first metal thin film 304 is formed (deposited) on the substrate 302 without a separate patterning process. Of course, when manufacturing a metal film of a relatively smaller size, patterning may be performed by a photolithography process mainly used in a conventional semiconductor process using an immersion mask manufactured by an ion beam or the like.

Next, a DC sputtering process using a shadow mask for the second metal thin film is performed so that the second metal thin film is spread over the upper portion of the substrate 302 and the upper portion of the first metal thin film 304 without a separate patterning process. By forming (depositing) 306, the production of a generator using a double metal thin film is completed. Of course, like the first metal thin film 304, the second metal thin film 306 may also be patterned by a photolithography process using an immersion mask.

Example 2

5 is a cross-sectional view of a double metal thin film generator according to Embodiment 2 of the present invention.

Referring to FIG. 5, the generator of the present embodiment may be regarded as the same as the first embodiment from the structural point of view of sequentially forming the first metal thin film 504 and the second metal thin film 508 on the substrate 502. However, there is a difference in that an insulating film 506 is further formed between the substrate 502 and the second metal thin film 508.

Here, each of the substrate 502, the first metal thin film 504, and the second metal thin film 508 has a corresponding structural member of the first embodiment shown in FIG. Since they are substantially the same, the detailed description herein is omitted for the sake of brevity of the specification.

That is, the insulating film 506 formed between the substrate 502 and the second metal thin film 508 is a kind of barrier to control the flow of current from the second metal thin film 508 to the substrate 502 to light or thermal energy. By suppressing the shunt of the current formed by the current can be increased the electromotive force value applied to the both ends of the first metal thin film 504 and the second metal thin film 508. This further enhances power generation efficiency (power generation efficiency by thermal energy and light energy). Here, the insulating film 506 is preferably a thickness range of about 30 nm (± 10%), but may be formed thinner or thicker in consideration of the use of the generator, power generation capacity, and the like.

The insulating layer 506 may be formed to have the same thickness to be in contact with the first metal thin film 504 without a separate patterning process, for example, through a sputtering process using a shadow mask for an RF insulating film, and may include MgO, SiO ₂ , and the like. Si ₃ N ₄ and other available insulating thin films can be used.

Therefore, the double metal thin film type generator of the present embodiment further includes an insulating film 506 serving as a barrier layer between the substrate 502 and the second metal thin film 508, thereby further improving power generation compared to the generator of the first embodiment. Efficiency can be realized.

Meanwhile, in the first and second embodiments of the present invention, one unit cell (power generation device) having a double metal thin film has been described by way of example, but the present invention is not limited thereto, and n unit cells may be arranged in series in a planar structure. An integrated generator may be manufactured in a parallel connection, or an integrated generator may be manufactured in which two or more unit cell groups in which n unit cells are connected in series are connected in parallel.

6 illustrates a configuration of an integrated generator in which a plurality of unit cells each having a double metal thin film are connected in series in a planar structure.

Referring to FIG. 6, the integrated generator or the series integrated generator of the present invention connects single cells each having a first metal thin film M1 and a second metal thin film M2 having different Seebeck coefficients in series in a planar structure. It is configured in a form, such a series integrated generator can be usefully used as a high voltage generator that requires a relatively high voltage. Of course, more generators can be integrated in series, depending on the needs or applications.

That is, the series integrated generator has a structure in which a plurality of unit cells each having a structure in which a first metal thin film and a second metal thin film having different Seebeck coefficients are sequentially stacked on a substrate are connected in series, and each unit is externally connected. The first and second metal thin films in the cell function to simultaneously convert heat and light energy into electrical energy when applied.

Here, each unit cell constituting the series integrated generator may further include an insulating film formed between the upper portion of the substrate and the portion of the second metal electrode as in the second embodiment.

7 illustrates a configuration of an integrated generator in which a plurality of unit cells each having a double metal thin film are connected in parallel in a planar structure.

Referring to FIG. 7, the integrated generator of the present invention is configured to connect single cells each having a first metal thin film M1 and a second metal thin film M2 having different Seebeck coefficients in parallel in a planar structure. Such a parallel integrated generator can be usefully used as a high current generator requiring a relatively large current. Of course, more generators can be integrated in parallel, depending on the needs or applications.

That is, the parallel integrated generator has a structure in which a plurality of unit cells each having a structure in which a first metal thin film and a second metal thin film having different Seebeck coefficients are sequentially stacked on the substrate are connected in parallel, and each unit is connected from the outside. The first and second metal thin films in the cell function to simultaneously convert heat and light energy into electrical energy when applied.

Here, each unit cell constituting the parallel integrated generator may further include an insulating film formed between the upper portion of the substrate and a portion of the second metal electrode as in the series integrated generator described above.

FIG. 8 illustrates a configuration of an integrated generator fabricated in such a manner that each unit cell group manufactured by connecting a plurality of single cells each having a double metal thin film in series is connected in parallel.

Referring to FIG. 8, the integrated generator (serial / parallel integrated generator) of the present invention connects single cells each having a first metal thin film M1 and a second metal thin film M2 having different Seebeck coefficients in series. Two unit cell groups 802 and 804 are connected in parallel to each other. This series / parallel integrated generator is useful as a device (high voltage / high current generator) requiring a relatively high voltage and a large current. Can be utilized.

That is, the serial / parallel integrated generator includes a first unit cell group in which a plurality of unit cells each having a structure in which a first metal thin film and a second metal thin film having different Seebeck coefficients are sequentially stacked on the substrate are connected in series. 802 and a plurality of unit cells having the same structure as that of the first unit cell group, each of which is connected in series and includes a second unit cell group 804 connected in parallel to the first unit cell group, each unit cell from outside The first and second metal thin films therein serve to simultaneously convert thermal energy and light energy into electrical energy when applied.

Here, each unit cell constituting the series / parallel integrated generator may further include an insulating film formed between the upper portion of the substrate and the portion of the second metal electrode as in the series or parallel integrated generator described above. Can be.

In addition, after constructing an integrated generator for each purpose, a thin film such as ITO (InSbO) and ZnO is deposited on a double metal junction portion of the uppermost second metal thin film surface to prevent heat emission and to concentrate light. Thermal and Optical Window 806 can be used to further increase power generation efficiency.

FIG. 9A is a view illustrating a method of measuring electromotive force in a double metal thin-film generator manufactured according to the present invention, and FIG. 9B is a view schematically illustrating an electromotive force measuring method.

The measuring device M, such as a multimeter, measures photovoltaic-thermoelectric effect-induced voltage generated when simultaneously applying thermal energy and light energy to the junction portions M1 / M2 of the device. In the measurement, when heat is applied through a thermal heat source, only heat is applied to the junction portions M1 / M2 of the device. At this time, the metal thin film on the device is directly exposed to the air to cover the phenomenon of heat loss to put a glass substrate (Cover Glass) that can act as a kind of passivation (Passivation).

In the actual device fabrication, a thin film such as ITO (InSbO) and ZnO is deposited on the top surface of the second metal thin film to prevent heat emission and to concentrate light for thermal protection. ) Can be used. In addition, the interconnect and the electrode parts are blocked with a black cover so that only the junction parts M1 / M2 of the device can apply light energy by the light source.

For electromotive force measurement, the same ambient temperature (Ambient Temperature: 50 ° C.) was applied to the entire device in an oven, and light was applied to the entire device by attaching a light source at a distance (12 cm). At this time, an experiment was performed to measure the electromotive force by using a white LED (wavelength band energy 1.93 ~ 2.19 eV, 2.6 eV) and a halogen lamp (frequency band energy 1.88 ~ 2.35 eV) to see the electromotive force generated according to the light energy. .

10A and 10B illustrate changes in voltage and current measured by exposing a metal thin film device having a Si (p-type) / Cu / (MgO) Co structure manufactured according to the present invention to various light sources / heat sources including sunlight. 10C is a graph showing numerical results of the results of FIGS. 10A and 10B.

10A, 10B, and 10C, it can be seen from the results of this experiment that the electromotive force value is maintained even after a predetermined time has elapsed after applying external heat and light to the metal thin film device. It can be seen that it has an advantage that is clearly distinguished from the conventional solar cell in which the power generation efficiency is reduced. As a result, it was found that voltage of 90.74mV in sunlight, 33.58mV in halogen lamp, and 14.13mV in white LED were generated.

This is shown in FIG. 11A and a graph showing the light intensity according to the light wavelength of the white LED (bold line) and the relative intensity of the human eye (dotted line) and the light intensity according to the wavelength of each light. As shown in FIG. 11B, which shows a graph, the light energy transmitted varies according to the wavelength distribution of each light source. In other words, sunlight with a broad wavelength range delivers the highest energy, and halogen lamps in the visible region used indoors deliver relatively low energy, and LEDs that emit light closer to three natural colors deliver the lowest energy. .

12 is a graph showing the result of the voltage change according to the application of light / heat energy using a solar cell.

Referring to FIG. 12, it can be seen that the solar cell generating solar electromotive force completely disappears when the applied light is removed, and through this, the generator of the present invention using heat energy and light energy is superior. It can be seen that it has power generation efficiency.

FIG. 13 is a schematic diagram of an experimental apparatus for measuring electromotive force of each device by connecting two single cells in series.

Referring to FIG. 13, after two single cells are connected in series, heat and light (halogen lamps) are applied to measure an electromotive force using a multimeter. As shown in FIG. 14, the electromotive force of each device is shown. It can be seen that this shows a tendency to sum, which is a result showing the possibility of integration.

These results indicate that multipurpose high-efficiency devices can be integrated at least using nanopattern technology to increase their electromotive force by several or tens of volts (V). Therefore, through the design of various types of junction structures to obtain such high integration and high efficiency, it is possible to manufacture a generator applicable to various electronic devices.

15A and 15B are graphs of experimental results of measuring voltage changes according to application of thermal energy in Si (p type) / Cu / Co and Si (p type) / Cu / (MgO) Co structures, respectively. FIG. 16B is a graph showing experimental results of measuring voltage changes according to application of halogen light energy in Si (p type) / Cu / Co and Si (p type) / Cu / (MgO) Co structures, respectively.

15 and 16, it can be seen that power generation efficiency due to thermal energy and light energy varies according to the presence or absence of an insulator (insulation film), that is, power generation efficiency is increased when an insulator is inserted between the substrate and the second metal thin film. .

17 is a graph showing experimental results of measuring temperature change according to heating time using daylight, halogen, heat, and LED.

18A and 18B are graphs of experimental results of measuring changes in voltage and current according to the distance between halogen and LED light sources in Si (p-type) / Cu / (MgO) Co structures, respectively. Figure 18b shows the numerical results of the experiment.

Referring to FIG. 18, it can be seen that the closer the distance to the substrate, the higher the density of incident light per unit area of the device, so that the closer the density is, the higher the density of light is.

19A and 19B show the voltage change according to the application of thermal energy for Cu thickness 5 nm (± 10%) and 20 nm (± 10%) in Si (p-type) / Cu (t) / (MgO) Co structures. It is a graph of the measured experimental result.

Referring to FIG. 19, it can be seen that power generation efficiency varies depending on the thickness of the metal thin film 1 in the structure of the second embodiment of the present invention (the structure employing the insulating film). In FIGS. 19A and 19B, the first metal thin film The thicknesses are 5 nm (± 10%) and 20 nm (± 10%), respectively, and at 5 nm (± 10%), the metal is not formed on the substrate in a continuous thin film form but is discontinuous like an island shape. Roughness is formed, which increases the diffuse reflection at the contact surface between the metal thin films and reduces the amount of light absorbed or transmitted, thereby reducing the photovoltaic effect. In addition, as the thickness of the first metal thin film becomes thinner, the number of electrons of the first metal thin film contributing to the photovoltaic effect between the first and second metal thin film junctions and between the first metal thin film and the substrate decreases and is discontinuous. Due to the thin and coarse thin film form, it is difficult to form ohmic contacts, which reduces the photovoltaic effect. This means that the ohmic contact formation can be controlled when the first metal thin film is formed in consideration of thickness. In addition, the discontinuity of the thin film at the contact surface increases resistance, which means that the heat dissipation caused by the hot electrons is reduced, thereby increasing the thermoelectric effect.

On the other hand, as the metal thin film 1 having a thickness of 20 nm (± 10%) becomes relatively thick, the number of electrons contributing to the photovoltaic power is increased and the ohmic contact formation is relatively easy, so the photovoltaic effect is increased. do. However, due to its relatively low resistance, the thermoelectric effect is reduced compared to that of metal films of 5 nm (± 10%). The results of this experiment show that the device's power generation efficiency can be further improved by controlling the thickness, interface state and light absorption technology of the material.

In the above description has been described by presenting a preferred embodiment of the present invention, but the present invention is not necessarily limited to this, and those skilled in the art to which the present invention pertains within a range without departing from the technical spirit of the present invention It will be readily appreciated that branch substitutions, modifications and variations are possible.

Claims (34)

1. Substrate,

   A first metal thin film formed on the substrate,

   A second metal thin film formed on an upper portion of the substrate and an upper portion of the first metal thin film,

   The dual metal thin film type generator which simultaneously converts thermal energy and light energy applied to the first and second metal thin films into electrical energy.
2. According to claim 1,

   The generator generates thermoelectric power by a Seebeck effect due to a temperature difference between a junction portion and two metal thin film portions when the thermal energy is applied to the junction portions of the first and second metal thin films, and when the optical energy is applied, A dual metal thin film type generator that generates photovoltaic power by the photovoltaic effect on the metal-metal contact surface and the metal-substrate contact surface of a metal thin film junction.
3. According to claim 1,

   Wherein the first metal thin film is a nonmagnetic metal thin film, and the second metal thin film is a magnetic metal thin film.
4. The method of claim 1,

   Wherein said first metal thin film is a magnetic metal thin film and said second metal thin film is a magnetic metal thin film.
5. The method of claim 1,

   Wherein the first metal thin film is a magnetic metal thin film, and the second metal thin film is a non-magnetic metal thin film.
6. The method according to any one of claims 1 to 5,

   The first and second metal thin film, the double metal thin film type generator having a different Seebeck coefficient (seebeck coefficient).
7. The method of claim 6,

   When the substrate is a p-type silicon substrate having a positive Seebeck coefficient, the first metal thin film is a metal having a positive Seebeck coefficient, and the second metal thin film is a metal having a negative Seebeck coefficient. Thin film generator.
8. The method of claim 6,

   When the substrate is an n-type silicon substrate having a negative Seebeck coefficient, the first metal thin film is a metal having a negative Seebeck coefficient, and the second metal thin film is a metal having a positive Seebeck coefficient. Thin film generator.
9. The method according to any one of claims 1 to 5,

   The first metal thin film is a metal material having a work function relatively smaller than the work function of the substrate when the substrate is an n-type silicon substrate, and is larger than the work function of the substrate when the substrate is a p-type silicon substrate. Double-metal thin-film generator, which is a metal material with a relatively large work function.
10. The method of claim 9,

    Wherein said first metal thin film is in ohmic contact on said substrate and a portion of said second metal thin film is in schottky contact on said substrate.
11. The method of claim 10,

    The first metal thin film has a relatively small resistance value, the second metal thin film has a relatively large resistance value.
12. The method according to any one of claims 1 to 5,

    The first metal thin film is a double metal thin film generator is a metal material having a work function in the range of 4.0 to 5.65eV.
13. The method according to any one of claims 1 to 5,

    The thickness of the said 1st metal thin film is a double metal thin film type | mold generator of at least thinner than the thickness of the said 2nd metal thin film.
14. The method of claim 13,

    The thickness range of the first metal thin film is 20 nm (± 10%), the thickness of the second metal thin film is 50 nm (± 10%) of a double metal thin film generator.
15. The method according to any one of claims 1 to 5,

    Each of the first and second metal thin films may be formed by any one of a DC sputtering process, an RF sputtering process, an ion beam sputtering process, and a photolithography process.
16. Substrate,

    A first metal thin film formed on the substrate;

    An insulating film formed on the substrate in contact with the first metal thin film;

    A second metal thin film formed on an upper portion of the first metal thin film and an upper portion of the insulating film,

    The double metal thin film type generator which converts thermal energy and light energy applied to the first and second metal thin films from the outside into electrical energy at the same time.
17. The method of claim 16,

    Wherein the first metal thin film is a nonmagnetic metal thin film, and the second metal thin film is a magnetic metal thin film.
18. The method of claim 16,

    Wherein the first metal thin film is a magnetic metal thin film, and the second metal thin film is a magnetic metal thin film.
19. The method of claim 16,

    Wherein the first metal thin film is a magnetic metal thin film, and the second metal thin film is a non-magnetic metal thin film.
20. The method of claim 16,

    The insulating film is a double metal thin film type generator that functions to increase the potential difference between the first metal film and the second metal film by controlling the flow of current from the second metal film to the substrate.
21. The method of claim 16,

    The insulating film is a double metal thin film generator of any one of MgO, SiO ₂ , Si ₃ N ₄ .
22. The method of claim 16,

    The insulating film is a double metal thin film type generator formed by an RF sputtering process.
23. The method according to any one of claims 16 to 22,

    The first and second metal thin film, the double metal thin film type generator having a different Seebeck coefficient (seebeck coefficient).
24. The method of claim 23,

    When the substrate is a p-type silicon substrate having a positive Seebeck coefficient, the first metal thin film is a metal having a positive Seebeck coefficient, and the second metal thin film is a metal having a negative Seebeck coefficient. Thin film generator.
25. The method of claim 23,

    When the substrate is an n-type silicon substrate having a negative Seebeck coefficient, the first metal thin film is a metal having a negative Seebeck coefficient, and the second metal thin film is a metal having a positive Seebeck coefficient. Thin film generator.
26. The method according to any one of claims 16 to 22,

    The first metal thin film is a metal material having a work function relatively smaller than the work function of the substrate when the substrate is an n-type silicon substrate, and is larger than the work function of the substrate when the substrate is a p-type silicon substrate. Double-metal thin-film generator, which is a metal material with a relatively large work function.
27. The method of claim 26,

    Wherein said first metal thin film is in ohmic contact on said substrate and a portion of said second metal thin film is in schottky contact on said substrate.
28. The method of claim 27,

    The first metal thin film has a relatively small resistance value, the second metal thin film has a relatively large resistance value.
29. A plurality of unit cells each having a structure in which a first metal thin film and a second metal thin film having different Seebeck coefficients are sequentially stacked on the substrate are connected in series,

    An integrated generator using a double metal thin film which simultaneously converts thermal energy and light energy applied to the first and second metal thin films of each unit cell from the outside into electrical energy.
30. The method of claim 29,

    Each of the plurality of unit cells further comprises an insulating film formed between an upper portion of the substrate and a portion of the second metal electrode.
31. A plurality of unit cells each having a structure in which the first metal thin film and the second metal thin film having different Seebeck coefficients are sequentially stacked on the substrate are connected in parallel, respectively.

    An integrated generator using a double metal thin film which simultaneously converts thermal energy and light energy applied to the first and second metal thin films of each unit cell from the outside into electrical energy.
32. The method of claim 31, wherein

    Each of the plurality of unit cells further includes an insulating film formed between an upper portion of the substrate and a portion of the second metal electrode.
33. A first unit cell group in which a plurality of unit cells each having a structure in which a first metal thin film and a second metal thin film having different Seebeck coefficients are sequentially stacked are respectively connected in series;

    A plurality of unit cells having the same structure as the first unit cell group are connected in series, and each includes a second unit cell group connected in parallel to the first unit cell group,

    An integrated generator using a double metal thin film which simultaneously converts thermal energy and light energy applied to the first and second metal thin films of each unit cell from the outside into electrical energy.
34. The method of claim 33, wherein

    Each of the plurality of unit cells,

    And an insulating film formed between the upper portion of the substrate and the portion of the second metal electrode.

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