JP6656848B2 - Method for manufacturing oxide semiconductor secondary battery - Google Patents

Description

  The present invention relates to an oxide semiconductor secondary battery and a method for manufacturing the same.

  A battery (hereinafter, referred to as a quantum battery) utilizing a photoexcitation structure change of a metal oxide due to ultraviolet irradiation has been filed (Patent Document 1). The secondary battery disclosed in Patent Literature 1 is safe in that it is an all-solid-state battery and does not use a chemical reaction in a charge / discharge process. Also, this secondary battery is expected as a technology that surpasses a lithium ion battery in terms of output density and power density. The secondary battery of Patent Document 1 has a structure in which a first electrode, an n-type metal oxide semiconductor layer, a charge layer, a p-type semiconductor layer, and a second electrode are stacked on a substrate.

International Publication No. 2012/046325

In Patent Document 1, titanium dioxide (TiO ₂ ), tin oxide (SnO ₂ ), or zinc oxide (ZnO) is used as an n-type metal oxide semiconductor layer. As the first electrode, a metal electrode such as a silver (Ag) alloy film containing aluminum (Al) is used. Patent Document 1 discloses that a metal electrode is formed by an electrolytic plating method or an electroless plating method. Further, as the metal used for plating, there is generally a description of a value at which copper, copper alloy, nickel, aluminum, silver, gold, zinc, tin, or the like can be used.

  In the quantum battery, development of a secondary battery having better characteristics is desired.

  The present invention has been made in view of the above problems, and has as its object to provide an oxide semiconductor secondary battery having favorable characteristics and a method for manufacturing the same.

  The oxide semiconductor secondary battery according to one embodiment of the present embodiment includes a first electrode, an n-type metal oxide semiconductor layer formed over the first electrode, and an n-type metal oxide semiconductor layer. A charging layer formed of a material containing an n-type metal oxide semiconductor and an insulating material; a p-type metal oxide semiconductor layer formed on the charging layer; and a p-type metal oxide semiconductor layer A second electrode formed thereon, wherein the n-type metal oxide semiconductor layer contains titanium dioxide having an anatase structure or an amorphous structure.

  In the above oxide semiconductor secondary battery, it is preferable that the n-type metal oxide semiconductor layer is the titanium dioxide having the anatase structure.

  In the above oxide semiconductor secondary battery, it is preferable that the outermost layer of the first electrode is formed of a chromium film, and the n-type metal oxide semiconductor layer is in contact with the chromium film.

  In the above oxide semiconductor secondary battery, it is preferable that the outermost layer of the first electrode is formed of a titanium film, and the n-type metal oxide semiconductor layer is in contact with the titanium film.

  In the above oxide semiconductor secondary battery, in the X-ray diffraction pattern obtained by performing the X-ray diffraction measurement on the n-type metal oxide semiconductor layer by the θ-2θ method, the diffraction of the anatase (101) plane is obtained. The intensity is preferably higher than the diffraction intensity of the rutile (110) plane.

  In the method for manufacturing an oxide semiconductor secondary battery according to one embodiment of the present embodiment, a step of forming a first electrode and a step of forming an n-type metal oxide semiconductor layer made of titanium dioxide over the first electrode Forming a charge layer made of a material containing an n-type metal oxide semiconductor and an insulating material on the n-type metal oxide semiconductor layer; and forming a p-type metal oxide semiconductor on the charge layer Forming a layer and forming a second electrode on the p-type metal oxide semiconductor layer, wherein the n-type metal oxide semiconductor layer comprises titanium dioxide having an anatase structure or an amorphous structure. Includes

  In the above manufacturing method, it is preferable that the n-type metal oxide semiconductor layer is titanium dioxide having the anatase structure.

  In the above manufacturing method, it is preferable that the outermost layer of the first electrode is formed of a chromium film, and the n-type metal oxide semiconductor layer is in contact with the chromium film.

  In the above manufacturing method, it is preferable that the outermost layer of the first electrode is formed of a titanium film, and the n-type metal oxide semiconductor layer is in contact with the titanium film.

  In the above manufacturing method, it is preferable that, after forming the n-type metal oxide semiconductor layer, the n-type metal oxide semiconductor layer is heated to form the titanium dioxide having the anatase structure.

  In the above manufacturing method, in the X-ray diffraction pattern obtained by performing X-ray diffraction measurement on the n-type metal oxide semiconductor layer by the θ-2θ method, the diffraction intensity of the anatase (101) plane is rutile. Preferably, the diffraction intensity is higher than the diffraction intensity of the (110) plane.

  According to the present invention, an oxide semiconductor secondary battery having good characteristics and a method for manufacturing the same can be provided.

FIG. 1 is a diagram illustrating a cross-sectional structure of an oxide semiconductor secondary battery 10. FIG. 2 is a diagram schematically illustrating a configuration of a sample analyzed by X-ray diffraction. FIG. 3 shows an X-ray diffraction pattern showing the difference in the crystal structure of titanium dioxide depending on the underlying film. FIG. 4 shows an X-ray diffraction pattern when the underlying layer is a chromium film. FIG. 5 shows an X-ray diffraction pattern when the base is a palladium film. FIG. 6 shows an X-ray diffraction pattern when a titanium film is used as a base. FIG. 7 is a flowchart illustrating a method for manufacturing an oxide semiconductor secondary battery. FIG. 8 is a flowchart showing details of the charging layer forming process. FIG. 9 is a table showing X-ray diffraction data of titanium dioxide having an anatase structure. FIG. 10 is a table showing X-ray diffraction data of rutile titanium dioxide. FIG. 11 is a table showing chromium X-ray diffraction data. FIG. 12 is a table showing X-ray diffraction data of palladium.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. The following description shows a preferred embodiment of the present invention, and the technical scope of the present invention is not limited to the following embodiment.

  The present invention relates to a quantum battery based on a new charging principle (hereinafter referred to as “oxide semiconductor secondary battery”) and a method for manufacturing an oxide semiconductor secondary battery. An oxide semiconductor secondary battery is a chargeable and dischargeable secondary battery.

  Specifically, in an oxide semiconductor secondary battery, the charge layer is irradiated with ultraviolet light to change the conductivity of the charge layer.

(Battery structure)
FIG. 1 is a diagram showing a cross-sectional structure of the oxide semiconductor secondary battery according to the present embodiment.

  In FIG. 1, an oxide semiconductor secondary battery 10 has a conductive first electrode 14, an n-type metal oxide semiconductor layer 16, a charging layer 18 for charging energy, and a p-type metal oxide semiconductor layer on a substrate 12. 20 and the second electrode 22 have a stacked structure in which the layers are stacked in this order.

  The material of the substrate 12 may be an insulating substance or a conductive substance. For example, as a material of the substrate 12, a glass substrate, a resin sheet of a polymer film, a metal foil sheet, or the like can be used.

  On the first electrode 14 and the second electrode 22, as a conductive film, a film such as a laminated film of Cr and Pd or an Al film that can reduce the resistance is formed. For example, as the first electrode 14, a metal electrode containing chromium (Cr), titanium (Ti), or the like can be used. Alternatively, an alloy containing chromium or titanium as a main component can be used. The first electrode 14 may have a laminated structure in which different metals are laminated. Further, as the second electrode, a metal electrode such as chromium (Cr) or copper (Cu) can be used. Other metal electrodes include a silver (Ag) alloy film containing aluminum (Al). Examples of the formation method include a vapor phase film formation method such as sputtering, ion plating, electron beam evaporation, vacuum evaporation, and chemical vapor deposition. The metal electrode can be formed by an electrolytic plating method, an electroless plating method, or the like. Generally, copper, copper alloy, nickel, aluminum, silver, gold, zinc, tin or the like can be used as the metal used for plating.

As a material of the n-type metal oxide semiconductor layer 16, for example, titanium dioxide (TiO ₂ ) can be used. Furthermore, in this embodiment, anatase type or amorphous (amorphous) type titanium dioxide is used for the n-type metal oxide semiconductor layer 16. Note that a suitable combination of the materials of the first electrode 14 and the n-type metal oxide semiconductor layer 16 will be described later.

  As a material of the charging layer 18, a fine-particle n-type metal oxide semiconductor can be used. The n-type metal oxide semiconductor changes its photoexcited structure by irradiation with ultraviolet light, and becomes a layer having a charging function. The charging layer 18 is made of a material containing an n-type metal oxide semiconductor and an insulating material. As the n-type metal oxide semiconductor material that can be used in the charging layer 18, titanium dioxide, tin oxide, and zinc oxide are preferable. It is possible to use a material combining any two of titanium dioxide, tin oxide, and zinc oxide, or a material combining three.

The p-type metal oxide semiconductor layer 20 formed on the charging layer 18 is provided to prevent electrons from being injected from the upper second electrode 22 into the charging layer 18. As a material of the p-type metal oxide semiconductor layer 20, nickel oxide (NiO), copper aluminum oxide (CuAlO ₂ ), or the like can be used.

  Note that the stacking order on the substrate 12 in the present embodiment may be reversed. That is, a stacked structure in which the first electrode 14 is the uppermost layer and the second electrode 22 is the lowermost layer may be used. Next, an example of an actual prototype is shown.

(Structure of charging layer 18)
The charging layer 18 contains an insulating substance and an n-type metal oxide semiconductor. Hereinafter, the charging layer 18 will be described in detail. The charging layer 18 uses silicone oil as a material of an insulating substance. In addition, titanium dioxide is used as a material of the n-type metal oxide semiconductor.

  As a material of the n-type metal oxide semiconductor used for the charge layer 18, titanium dioxide, tin oxide, and zinc oxide are used. The n-type metal oxide semiconductor is generated by decomposing in a manufacturing process from an aliphatic acid salt of these metals. For this reason, as a metal aliphatic acid salt, those which can be decomposed or burned by irradiating ultraviolet rays or calcination in an oxidizing atmosphere to be converted into metal oxides are used.

  Aliphatic acid salts are easily decomposed or burned by heating, have high solvent solubility, have a dense film composition after being decomposed or burned, are easy to handle and are inexpensive, and are easy to synthesize salts with metals. For some reasons, salts of aliphatic acids with metals are preferred.

  Next, materials and combinations of the first electrode 14 and the n-type metal oxide semiconductor layer 16 will be described in detail. The inventors of the present application have conducted various experiments and found the material of the first electrode 14 and the n-type metal oxide semiconductor layer 16 exhibiting good battery characteristics.

  Specifically, in the present embodiment, as the material of the n-type metal oxide semiconductor layer 16 in contact with the charge layer 18, titanium dioxide having an anatase-type crystal structure is used. Anatase type titanium dioxide has a tetragonal crystal structure, and changes to a rutile type when heated to 900 ° C. or higher. When the n-type metal oxide semiconductor layer 16 is made of anatase-type titanium dioxide, good battery characteristics can be obtained.

  As a base film for forming anatase type titanium dioxide, a chromium film or a titanium film is preferable. Therefore, the first electrode 14 has a three-layer structure of Cr / Pd / Cr. That is, as shown in FIG. 2, the first electrode 14 has a chromium (Cr) film 14a, a palladium (Pd) film 14b, and a chromium (Cr) film 14c. In the first electrode 14, a chromium film 14a, a palladium film 14b, and a chromium film 14c are stacked in order from the bottom. Therefore, the chromium film 14c is the outermost layer of the first electrode 14.

  Then, an n-type metal oxide semiconductor layer 16 made of anatase type titanium dioxide is formed on the chromium film 14c. Therefore, the interface of the first electrode 14 in contact with the n-type metal oxide semiconductor layer 16 is the chromium film 14c. That is, the chromium film 14c is provided so as to be in contact with the n-type metal oxide semiconductor layer 16, and the palladium film 14b is not in contact with the n-type metal oxide semiconductor layer 16.

  Thus, the n-type metal oxide semiconductor layer 16 containing anatase-type titanium dioxide can be formed on the first electrode 14. Here, a difference in crystal structure of the n-type metal oxide semiconductor layer 16 depending on the base (the first electrode 14) will be described with reference to FIGS.

  FIG. 3 shows an X-ray diffraction pattern showing the difference in the crystal structure of titanium dioxide depending on the underlying film.

  That is, FIG. 3 is a diagram showing data (hereinafter, XRD data) of an X-ray diffraction pattern (X-ray diffraction spectrum) in a state where the first electrode 14 and the n-type metal oxide semiconductor layer 16 are formed.

  In FIG. 3, the horizontal axis is the diffraction angle 2θ (the angle between the incident X-ray direction and the diffracted X-ray direction), and the vertical axis is the diffraction intensity (cps). In the present embodiment, X-ray diffraction measurement is performed by the θ-2θ method using CuKα radiation having a wavelength of 1.5418 angstroms.

  When the lattice spacing of the crystal is d and the X-ray wavelength is λ, a peak appears in the X-ray diffraction pattern when 2d sin θ = nλ is satisfied (n is an integer of 1 or more). Therefore, the crystal structure of titanium dioxide can be specified from the peak value of 2θ. For example, in anatase (101), a peak appears when 2θ = 25.3 °, and in rutile (110), a peak appears when 2θ = 27.4 °.

  FIG. 3 shows a result of performing an X-ray diffraction analysis on the sample before forming the charging layer 18 as shown in FIG. That is, FIG. 3 shows a result of performing X-ray diffraction analysis in a state where the n-type metal oxide semiconductor layer 16 is exposed. Here, the n-type metal oxide semiconductor layer 16 is annealed at the same temperature as the baking step of the charging layer 18. Specifically, X-ray diffraction is performed on a sample annealed at 350 ° C.

  The lower part of FIG. 3 shows XRD data when the first electrode 14 has a three-layer structure of Cr / Pd / Cr (that is, when the underlayer is the chromium film 14c). The upper part of FIG. 3 shows XRD data when the first electrode 14 has a two-layer structure of Cr / Pd. Accordingly, the upper side of FIG. 3 shows a measurement result in a configuration without the chromium film 14c in FIG. 2, that is, a configuration in which the base is the palladium film 14b.

  When the base is the chromium film 14c, a peak of the anatase (101) plane appears at 2θ = 25.3 ° (see the lower graph in FIG. 3). On the other hand, when the base is the palladium film 14b, a peak of the rutile (110) plane appears at 2θ = 27.4 ° (see the upper graph in FIG. 3). Thus, the peak position in the X-ray diffraction differs depending on the base of the n-type metal oxide semiconductor layer 16. In other words, the crystal structure of the n-type metal oxide semiconductor layer 16 changes depending on the base material of the n-type metal oxide semiconductor layer 16. Furthermore, the inventors of the present application have found a material for the n-type metal oxide semiconductor layer 16 that provides good battery characteristics.

  Next, the difference in crystal structure due to the presence or absence of annealing and the difference in base will be described with reference to FIGS. FIG. 4 is a diagram showing XRD data when the first electrode 14 has a three-layer structure of Cr / Pd / Cr. FIG. 5 is a diagram showing XRD data when the first electrode 14 has a two-layer structure of Cr / Pd. FIG. 6 is a diagram showing XRD data when the first electrode 14 has a two-layer structure of Cr / Ti. 4 to 6, the horizontal axis represents the diffraction angle 2θ (the angle between the incident X-ray direction and the diffracted X-ray direction), and the vertical axis represents the diffraction intensity (cps).

  That is, FIG. 4 shows an X-ray diffraction pattern when the base is a chromium film. FIG. 5 shows an X-ray diffraction pattern when the base is a palladium film. FIG. 6 shows an X-ray diffraction pattern when a titanium film is used as a base.

  4 to 6 show the results of performing X-ray diffraction on the configuration before forming the charging layer 18 (the sample before forming the charging layer 18), as in FIG. 4 to 6, XRD data without annealing is shown on the upper side, and XRD data with annealing is shown on the lower side. The annealing temperature is set at 350 °, which is the same as the firing step of the charging layer.

  Here, when the base is a chromium film or a titanium film, a peak (2θ = 25.3 °) of the anatase (101) plane appears (see FIG. 4 or FIG. 6). When the underlayer is made of chromium, the peak (2θ = 25.3 °) on the anatase (101) plane is increased by annealing (see FIG. 4). Therefore, the annealing promotes the crystallization of titanium dioxide.

  When the base is a palladium film, a peak (2θ = 27.4 °) on the rutile (110) plane appears (see FIG. 5). As described above, the crystal structure of the n-type metal oxide semiconductor layer 16 changes depending on the base film. Specifically, in the lower part of FIG. 5, the diffraction intensity at 2θ = 27.4 ° is higher than the diffraction intensity at 2θ = 25.3 °.

(Battery characteristics)
A description will be given of battery characteristics when samples of an oxide semiconductor secondary battery in which a base is a chromium film, a palladium film, and a titanium film are respectively formed.

  Oxide semiconductor secondary batteries (Cr), oxide semiconductor secondary batteries (Pd), and oxide semiconductor secondary batteries were used as samples of the oxide semiconductor secondary batteries when the base was a chromium film, a palladium film, and a titanium film, respectively. (Ti). The oxide semiconductor secondary battery (Cr) is a sample of an oxide semiconductor secondary battery in which the first electrode 14 has a three-layer structure of Cr / Pd / Cr. Similarly, the oxide semiconductor secondary battery (Pd) is a sample of an oxide semiconductor secondary battery in which the first electrode 14 has a two-layer structure of Cr / Pd, and is an oxide semiconductor secondary battery (Ti). Is a sample of an oxide semiconductor secondary battery in which the first electrode 14 has a two-layer structure of Cr / Ti.

  In the oxide semiconductor secondary battery (Pd), charging was hardly performed, and sufficient battery characteristics could not be obtained. Specifically, in an oxide semiconductor secondary battery (Pd), a charging current flows too much, and a charging voltage cannot be applied. On the other hand, in the oxide semiconductor secondary battery (Cr) and the oxide semiconductor secondary battery (Ti), it was possible to appropriately charge and to obtain sufficient battery characteristics. That is, since the charging current does not flow too much, the charging voltage can be appropriately applied to the charging layer 18.

  Therefore, it is preferable that the base film of the n-type metal oxide semiconductor layer 16 be a chromium film or a titanium film. That is, it is preferable that the outermost layer of the first electrode 14 be a chromium film or a titanium film.

  The chromium film or the titanium film of the first electrode 14 is in contact with the lowermost layer of the n-type metal oxide semiconductor layer 16. Thereby, the n-type metal oxide semiconductor layer 16 having the anatase structure can be formed on the first electrode 14, and good battery characteristics can be obtained.

  In order to determine whether titanium dioxide has an anatase structure or a rutile structure, X-ray diffraction may be used as described above. For example, in X-ray diffraction, the diffraction intensity on the anatase (101) plane (2θ = 25.3 °) is higher than the diffraction intensity on the rutile (110) plane at (2θ = 27.4). In other words, the X-ray diffraction pattern obtained by performing X-ray diffraction analysis on the n-type metal oxide semiconductor layer 16 by the θ-2θ method shows that the diffraction intensity of the anatase (101) plane is rutile (110). It is higher than the diffraction intensity of the surface. That is, using this characteristic, it can be determined whether titanium dioxide has an anatase structure or a rutile structure.

(Method of Manufacturing Charge Layer 18)
Next, a method for manufacturing the oxide semiconductor secondary battery 10 will be described with reference to FIG. FIG. 7 is a flowchart showing a method for manufacturing a secondary battery. In the following description, FIGS. 1 and 2 are referred to as appropriate for the configuration of the oxide semiconductor secondary battery 10.

  First, the first electrode 14 is formed on the substrate 12 (S1). As shown in FIG. 2, the first electrode 14 has a three-layer structure of a chromium film 14a, a palladium film 14b, and a chromium film 14c. Alternatively, the first electrode 14 may have a two-layer structure of Cr / Ti. Of course, the structure and the number of layers of the first electrode 14 are not limited to the above structure and the number of layers. For example, since the outermost layer of the first electrode 14 may be a chromium film or a titanium film, the first electrode 14 can have a single-layer structure of a chromium film or a titanium film. Alternatively, the lower layer of the chromium film or the titanium film of the first electrode 14 may be another metal film.

  In addition, as a material of the substrate 12, for example, a glass substrate or a polyimide (PI) sheet can be used. By using a polyimide resin sheet for the substrate 12 to provide flexibility, the usability can be improved. In addition, as a pretreatment before forming the first electrode 14, the surface of the substrate 12 may be subjected to a surface treatment such as ultraviolet irradiation, plasma treatment, or ion treatment. By doing so, the adhesion can be improved.

Next, the n-type metal oxide semiconductor layer 16 is formed on the first electrode 14 (S2). The n-type metal oxide semiconductor layer 16 is formed so as to be in contact with the chromium film or the titanium film which is the outermost layer of the first electrode 14. For example, a TiO ₂ film having a thickness of 50 nm to 200 nm is formed on the first electrode 14 by a sputtering method.

  Note that the first electrode 14 and the n-type metal oxide semiconductor layer 16 can be formed by the sputtering method or the like as described above. The method for forming the first electrode 14 and the n-type metal oxide semiconductor layer 16 is not limited to the sputtering method, and a thin film forming method such as an evaporation method, an ion plating method, and an MBE (Molecular Beam Epitaxy) method is used. be able to. Further, the first electrode 14 and the n-type metal oxide semiconductor layer 16 may be formed by using a coating method such as a printing method or a spin coating method.

  Then, the charge layer 18 is formed on the n-type metal oxide semiconductor layer 16 (S3). FIG. 8 shows an example of the step of forming the charging layer 18 (S3). FIG. 8 is a flowchart illustrating an example of a process of forming the charging layer 18.

  First, a fatty acid titanium and a silicone oil are mixed in a solvent and stirred to prepare a coating liquid (S31). Next, the coating liquid is spin-coated on the n-type metal oxide semiconductor layer 16 by a spinner while rotating the prepared substrate 12 (S32). The rotation of the substrate forms a thin layer of 0.3 to 1 μm. This layer contains a mixture of silicone and titanium dioxide. Note that the coating film is formed on the n-type metal oxide semiconductor layer 16 by not only the spin coating method but also a dip coating method, a die coating method, a slit coating method, a gravure coating method, a spray coating method, a curtain coating method, or the like. Is also good. Note that, before the coating step, a surface treatment may be performed on the n-type metal oxide semiconductor layer 16 by ultraviolet irradiation or the like.

  After the application, a drying process is performed (S33). For example, the substrate 12 is placed on a hot plate and heated at a predetermined temperature for a predetermined time to volatilize the solvent in the coating film. The drying method is not limited to a hot plate, and a heating method using far infrared rays or a drying method using hot air circulation can be used.

  After the drying process, the charging layer 18 is fired (S34). The firing temperature is preferably set to 300 ° C to 400 ° C. Here, the firing temperature is 350 ° C. The firing time is 10 minutes to 1 hour.

  The above-described manufacturing method for forming the charging layer 18 in which an insulating material and titanium dioxide are mixed is a method called a coating thermal decomposition method. It is preferable to use a silicon compound such as a silicon oxide as the insulating substance.

  The next manufacturing step is an ultraviolet irradiation step (S35). In this step, the charged layer is irradiated with ultraviolet rays to change the conductivity of the charged layer.

  Then, the p-type metal oxide semiconductor layer 20 is formed on the charging layer 18 (S4). For example, a NiO film having a thickness of 120 to 300 nm is formed as the p-type metal oxide semiconductor layer 20 by a sputtering method. Note that the method for forming the p-type metal oxide semiconductor layer 20 is not limited to the sputtering method, and a thin film forming method such as an evaporation method, an ion plating method, and an MBE method can be used. Further, the P-type metal oxide semiconductor layer 20 may be formed by using a coating method such as a printing method or a spin coating method.

  Next, the second electrode 22 is formed on the p-type metal oxide semiconductor layer 20 (S5). For example, an Al film having a thickness of 100 to 300 nm is formed by a sputtering method. The second electrode 22 is preferably made of a material having a high conductivity, that is, a material having a low resistivity, for example, a material having a resistivity of 100 μΩ · cm or less.

  The method of forming the second electrode 22 is not limited to the sputtering method, and a thin film forming method such as a vapor deposition method, an ion plating method, and an MBE (Molecular Beam Epitaxy) method can be used. Further, the second electrode 22 may be formed by using a coating method such as a printing method or a spin coating method.

  Thus, the oxide semiconductor secondary battery 10 is completed. As described above, the n-type metal oxide semiconductor layer 16 is titanium dioxide having an anatase structure. Therefore, good battery characteristics can be obtained.

  Note that the n-type metal oxide semiconductor layer 16 may be changed to an anatase structure during the manufacturing process. For example, the formation process (S2) of the n-type metal oxide semiconductor layer 16 has an amorphous structure, and the baking process (S35) may change the amorphous structure into an anatase structure. For example, as shown in FIG. 4, the n-type metal oxide semiconductor layer 16 after annealing has a higher diffraction intensity on the anatase (101) plane than before annealing. Therefore, by forming the n-type metal oxide semiconductor layer 16 and then heating the n-type metal oxide semiconductor layer 16, titanium dioxide having an anatase structure can be formed. In other words, the manufacturing process of the oxide semiconductor secondary battery 10 may include a heating process of changing titanium dioxide into an anatase structure.

  As described above, the base of the n-type metal oxide semiconductor layer 16 is a chromium film or a titanium film. By doing so, the n-type metal oxide semiconductor layer 16 can be made of titanium dioxide having an anatase structure.

  In the above description, the n-type metal oxide semiconductor layer 16 is described as titanium dioxide having an anatase structure, but the n-type metal oxide semiconductor layer 16 may be titanium dioxide having an amorphous structure. Even when the n-type metal oxide semiconductor layer 16 is made of titanium dioxide having an amorphous structure, good battery characteristics can be obtained.

  FIGS. 9 and 10 show XRD data when the n-type metal oxide semiconductor layer 16 is titanium dioxide having an anatase structure and a rutile structure. FIG. 9 is a table showing XRD data of the anatase structure. FIG. 10 is a table showing XRD data having a rutile structure. For reference, FIG. 11 shows XRD data of chromium, and FIG. 12 shows XRD data of palladium.

  FIG. 9 shows data from the publication Natl. Bur. Stand. (U.S.) Monogr. 25, detail volume. 7, page 82 (1969). FIG. 10 shows data from the publication Natl. Bur. Stand. (U.S.) Monogr. 25, detail volume. 7, page 83 (1969). FIG. 11 shows data from the publication Natl. Bur. Stand. (U.S.), Circ. 539, detail volume. V, page 20 (1955), creator Swanson et al. FIG. 12 shows data of Natl. Bur. Stand. (U.S.), Circ. 539, details volume. I, page 21 (1953), and creator Swanson, Tatge.

  In the case of an anatase structure, a peak exists when 2θ = 25.281 °. In the amorphous structure and the anatase structure, the battery shows good battery characteristics. In the rutile structure, a peak exists at 2θ = 27.447. The rutile structure does not exhibit good battery characteristics. Therefore, if the titanium dioxide has a structure other than the rutile structure, good battery characteristics can be obtained. For example, the X-ray diffraction intensity at 2θ = 27.4 ° for rutile (110) is lower than the X-ray diffraction intensity at 2θ = 25.3 ° corresponding to anatase (101).

  As described above, an example of the embodiment of the present invention has been described. However, the present invention includes appropriate modifications without impairing the object and advantages, and is not limited by the above embodiment.

Reference Signs List 10 oxide semiconductor secondary battery 12 substrate 14 first electrode 16 n-type metal oxide semiconductor layer 18 charging layer 20 p-type metal oxide semiconductor layer 22 second electrode

Claims (3)

Forming a first electrode;
Forming an n-type metal oxide semiconductor layer made of titanium dioxide on the first electrode;
Forming a charge layer made of a material containing an n-type metal oxide semiconductor and an insulating material on the n-type metal oxide semiconductor layer;
Forming a p-type metal oxide semiconductor layer on the charging layer;
Forming a second electrode on the p-type metal oxide semiconductor layer,
An outermost layer of the first electrode is formed of a titanium film;
The n-type metal oxide semiconductor layer is in contact with the titanium film,
The n-type metal oxide semiconductor layer contains titanium dioxide having an anatase structure or an amorphous structure ,
In the step of forming the n-type metal oxide semiconductor layer, an amorphous titanium dioxide film is formed,
In the step of forming the charging layer, a method for manufacturing an oxide semiconductor secondary battery in which the amorphous titanium dioxide is heated to change the titanium dioxide into an anatase structure . In the step of forming the charging layer,
2. The oxide semiconductor according to claim 1 , wherein a coating liquid containing the n-type metal oxide semiconductor and the insulating material is applied on the n-type metal oxide semiconductor layer, and then baked at 350 ° C. to 400 ° C. 3. A method for manufacturing a secondary battery. In the X-ray diffraction pattern obtained by performing X-ray diffraction measurement on the n-type metal oxide semiconductor layer by the θ-2θ method, the diffraction intensity of the anatase (101) plane is smaller than that of the rutile (110) plane. The method for manufacturing an oxide semiconductor secondary battery according to claim 1, wherein the strength is higher than the strength.

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