ZnO-CFO / BEFO temperature resistance thin film material and preparation method and application thereof

Abstract

The application provides a ZnO-CFO / BEFO temperature resistance thin film material and a preparation method and application thereof. The temperature resistance thin film material comprises first thin films and second thin films which are alternated with each other. The chemical formula of the first thin film is xZnO-(1-x)CuFe2O4, x=0.3-0.7; the chemical formula of the second thin film is Bi 0.95 Er 0.05 FeO3. The temperature resistance thin film material has the characteristics of high resistance change ratio, change with temperature, high stability and the like, and has excellent repeatable bipolar resistance change switch characteristics.

Description

Technical Field

[0001] This invention belongs to the field of functional materials, specifically relating to a temperature resistive switching film, and more particularly to a ZnO-CFO / BEFO temperature resistive switching film material, its preparation method, and its application. Background Technology

[0002] Temperature-switching (TSS) films are materials whose resistance changes with temperature. Due to their unique electrical properties, they have been widely used in sensors, thermistors, temperature controllers, and temperature compensators. With the deepening research and application of TSS films, more and more materials have been found to possess temperature-dependent switching characteristics. BiFeO3 (BFO) is a rhombic twisted perovskite-type multiferroic material, exhibiting both ferroelectricity (reversible polarization) and ferromagnetism (spin order). This complex charge and spin-ordered structure gives it abundant electronic states, which are significantly affected by temperature, thus exhibiting temperature-dependent switching characteristics. However, pure-phase BFO films have large leakage currents, a small high-to-low resistance window, and poor switching performance. Since structure, defects, and interface effects play a crucial role in determining the switching performance of composite films, doping with lanthanide metals to prepare multilayer composite films, constructing ferroelectric oxide heterojunctions, reducing leakage current, and improving the switching characteristics of BFO films has emerged as a new research area. Tan Guoqiang et al. prepared a BEFMO / ZCO composite film with resistive switching effect (CN 109133667 A). Compared with the BEFMO / ZCO film, which is a two-phase composite film composed of BEFMO and ZCO, the BEFMO / ZCO film is prepared by doping Cu into ZnO solution to prepare ZCO solution. The switching ratio is only 2.63 to 10.30.

[0003] In future development, temperature-switched resistive films will play an even more important role, with broad application prospects and market potential, bringing greater convenience and benefits to human production and life. Therefore, researching temperature-switched resistive films with high resistivity-to-switching ratio, low resistivity, and high stability, and their resistance-tuning characteristics, is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a ZnO-CFO / BEFO temperature resistive switching thin film material, its preparation method and application. The obtained thin film material has the characteristics of high resistive switching ratio, temperature-dependent change and high stability, and has excellent repeatable bipolar resistive switching characteristics.

[0005] This invention is achieved through the following technical solution:

[0006] A ZnO-CFO / BEFO temperature resistive switching thin film material comprises alternating first and second thin films; the chemical formula of the first thin film is xZnO-(1-x)CuFe2O4, where x = 0.3–0.7; the chemical formula of the second thin film is Bi 0.95 Er 0.05 FeO3.

[0007] Preferably, the thickness of the temperature resistive switching film is 260 nm to 450 nm.

[0008] The preparation method of the ZnO-CFO / BEFO temperature resistive switching thin film material includes the following steps:

[0009] Step 1: Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in the first solvent, add pH adjuster, stabilizer and coupling agent, stir to obtain solution 1; dissolve C4H6O4Zn·4H2O in the second solvent, add pH adjuster and viscosity adjuster, stir to obtain solution 2; mix solution 1 and solution 2, and let stand for 12-24 hours to obtain precursor solution A;

[0010] Step 2: Dissolve Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O in a third solvent, add pH adjuster, stabilizer and coupling agent dropwise, and let stand for 12-24 hours to obtain precursor solution B;

[0011] Step 3: Spin-coating the precursor solution A onto the substrate to obtain a wet film of xZnO-(1-x)CFO, baking, and then annealing to obtain a crystalline xZnO-(1-x)CFO thin film;

[0012] Step 4: Spin-coat precursor solution B onto the crystalline xZnO-(1-x)CFO thin film to obtain a BEFO wet film, bake it, and then anneal it to obtain a crystalline BEFO thin film.

[0013] Step 5: Repeat steps 3 and 4 in sequence until the desired thickness of xZnO-(1-x)CFO / BEFO temperature resistive switching film is obtained.

[0014] Preferably, in step 1: the first solvent is ethylene glycol methyl ether and acetic anhydride, the pH adjuster is glacial acetic acid, and the stabilizer and coupling agent are acetylacetone; the second solvent is ethylene glycol methyl ether and anhydrous ethanol, and the viscosity adjuster is ethanolamine.

[0015] Preferably, in step 2: the third solvent is ethylene glycol methyl ether and acetic anhydride, the pH adjuster is glacial acetic acid, and the stabilizer and coupling agent is acetylacetone.

[0016] Preferably, the metal ion concentration in precursor solution A obtained in step 1 is 0.15–0.20 mol / L; and the metal ion concentration in precursor solution B obtained in step 2 is 0.20–0.25 mol / L.

[0017] Preferably, in step 3: baking is performed at a temperature of 200-300°C for 10-20 minutes to obtain a dry film, and annealing is performed at a temperature of 500-590°C for 10-30 minutes.

[0018] Preferably, in step 4: baking is performed at a temperature of 200-300℃ for 5-15 minutes to obtain a dry film, and annealing is performed at a temperature of 500-590℃ for 10-30 minutes.

[0019] Preferably, the substrate is an FTO glass substrate.

[0020] Application of the ZnO-CFO / BEFO temperature resistive switching thin film material in temperature control devices.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] The present invention provides a ZnO-CFO / BEFO temperature resistive switching thin film, comprising a crystalline xZnO-(1-x)CuFe2O4 (xZnO-(1-x)CFO) thin film and a crystalline Bi... 0.95 Er 0.05 Alternating stacks of FeO3 (BEFO) temperature resistive switching films form a near-superlattice structure. Er 3+ Doping is introduced into the BFO layer to replace the volatile Bi. 3+ The site of the site reduces the leakage current of the BFO film, reduces volatility, and improves stability, thereby extending its service life. The xZnO-(1-x)CFO solid solution modulates the crystal structure and defect distribution of the film, regulates the electronic structure of the material, and affects its carrier transport performance, thereby optimizing the switching behavior of the resistive switching film and making it more stable and reliable. The composite of xZnO-(1-x)CFO and BEFO films to construct a heterojunction interface, the resulting interface diffusion, interface ion migration, interface coupling and other heterojunction interface micro-effects improve the resistive switching characteristics of the material. As the temperature increases, the internal molecules of the xZnO-(1-x)CFO / BEFO film become more active after heating, the electronic band structure changes, the electron energy increases, and the electron transition probability increases. The ZnO-CFO / BEFO temperature resistive switching film is prepared by solid solution of CFO and ZnO to form a CFO-ZnO solution, which belongs to a three-phase composite film. This film has a higher on / off ratio (10). 2 ) and excellent fatigue resistance (10 2(No secondary attenuation phenomenon). Furthermore, the ZnO-CFO / BEFO thin film exhibits high temperature sensitivity, with its resistive switching characteristics changing with ambient temperature. The thin film of this invention possesses high resistive switching ratio, temperature-dependent properties, and high stability, making it highly practical and economical. It can be used in temperature-controlled electronic devices, temperature-controlled optoelectronic devices, and temperature-controlled sensors. Additionally, after depositing an Au top electrode on the 0.3ZnO-0.7CFO / BEFO temperature-controlled resistive switching thin film, the difference in thermal expansion coefficients between the Au electrode material and the xZnO-(1-x)CFO / BEFO thin film causes the window ratio to also change with temperature.

[0023] The method for preparing ZnO-CFO / BEFO temperature resistive switching thin films provided by this invention adopts a chemical solution deposition method. The preparation method is simple, the preparation temperature is low, the reaction is easy to carry out, the prepared thin film has good uniformity, and it is easy to realize industrial production. Attached Figure Description

[0024] Figure 1 The 10-layer 0.3ZnO-0.7CFO / BEFO temperature resistive switching film and the 10-layer Cu film prepared in Example 1 and Comparative Example 1 of this invention 0.90 Zn 0.10 XRD pattern of Fe2O4 / BEFO thin film;

[0025] Figure 2 The IV curves of the 10-layer 0.3ZnO-0.7CFO / BEFO temperature resistive switching film prepared in Example 1 of the present invention under linear-linear coordinates [-6V, +6V] at room temperature, 50℃, 75℃, and 100℃.

[0026] Figure 3 The IV curves of the 10-layer 0.3ZnO-0.7CFO / BEFO temperature resistive switching film prepared in Example 1 of the present invention under linear-logarithmic coordinates [-6V, +6V] at room temperature, 50℃, 75℃, and 100℃.

[0027] Figure 4 The 10-layer Cu prepared for Comparative Example 1 of this invention 0.90 Zn 0.10 IV curves of Fe2O4 / BEFO composite films under linear-linear coordinates [-10V, +10V] at room temperature, 50℃, 75℃, and 100℃;

[0028] Figure 5 The 10-layer Cu prepared for Comparative Example 1 of this invention 0.90 Zn 0.10 IV curves of Fe2O4 / BEFO composite films at room temperature, 50℃, 75℃, and 100℃ on linear-logarithmic coordinates [-10V, +10V].

[0029] Figure 6 The fatigue resistance characteristics of the 10-layer 0.3ZnO-0.7CFO / BEFO temperature resistive switching film prepared in Example 1 of this invention are shown in the figure.

[0030] Figure 7 This is a photograph of the 10-layer 0.3ZnO-0.7CFO / BEFO temperature resistive switching film prepared in Example 1 of the present invention after being coated with an Au top electrode. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0032] The ZnO-CFO / BEFO temperature resistive switching thin film material of this invention comprises alternating first and second thin films; the chemical formula of the first thin film is xZnO-(1-x)CuFe2O4(xZnO-(1-x)CFO), where x = 0.3 to 0.7; the chemical formula of the second thin film is Bi 0.95 Er 0.05 FeO3(BEFO).

[0033] The method for preparing the ZnO-CFO / BEFO temperature resistive switching thin film material of the present invention includes the following steps:

[0034] Step 1: Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O according to the molar ratio x:1-x:1-x. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in the first solvent, add pH adjuster, stabilizer and coupling agent, and stir for 1-2 hours to obtain solution 1. Dissolve C4H6O4Zn·4H2O in the second solvent, add pH adjuster and viscosity adjuster, and continue stirring for 5-6 hours to obtain solution 2. Mix solutions 1 and 2, and let stand for 12-24 hours to obtain stable precursor solution A (xZnO-(1-x)CFO).

[0035] Step 2: Dissolve Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O in a third solvent at a molar ratio of 0.95:0.05:1, add glacial acetic acid, stabilizer, and coupling agent dropwise, and let stand for 12-24 hours to obtain a stable precursor solution B (BEFO);

[0036] Step 3: Spin-coating the precursor solution A onto the glass substrate to obtain a wet film of xZnO-(1-x)CFO. After baking at 200-300℃ for 10-20 min, a dry film is obtained. Then, the film is annealed at 500-590℃ for 10-30 min to obtain a crystalline xZnO-(1-x)CFO thin film.

[0037] Step 4: After the xZnO-(1-x)CFO film in the crystalline state cools to room temperature, the precursor solution B is spin-coated onto the crystalline xZnO-(1-x)CFO film to obtain a BEFO wet film. After baking at 200-300℃ for 5-15 minutes, a dry film is obtained. Then, it is annealed at 500-590℃ for 10-30 minutes to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the xZnO-(1-x)CFO film.

[0038] Step 5: After waiting for the BEFO film in the crystalline state to cool to room temperature, repeat steps 3 and 4 in sequence until the desired thickness of xZnO-(1-x)CFO / BEFO temperature resistive switching film is obtained.

[0039] In step 1: the first solvent is ethylene glycol methyl ether and acetic anhydride, the pH adjuster is glacial acetic acid, and the stabilizer and coupling agent is acetylacetone; the volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone is (3-4):1:1:1. The second solvent is ethylene glycol methyl ether and anhydrous ethanol, the pH adjuster is glacial acetic acid, and the viscosity adjuster is ethanolamine; the volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine, and glacial acetic acid is 3:(1-2):(1-2):1.

[0040] In this embodiment of the invention, step 1 specifically includes: dissolving Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stirring evenly, adding acetic anhydride, continuing to stir for 4-7 hours, and finally adding glacial acetic acid and acetylacetone dropwise, stirring for 1-2 hours; dissolving C4H6O4Zn·4H2O in anhydrous ethanol and ethanolamine, heating in a water bath for 30-50 minutes, adding ethylene glycol methyl ether and glacial acetic acid dropwise, continuing to stir for 5-6 hours, mixing the two solutions, and then allowing them to stand and age for 12-24 hours to obtain a stable precursor solution A (xZnO-(1-x)CFO);

[0041] In step 2: the third solvent is ethylene glycol methyl ether and acetic anhydride, the pH adjuster is glacial acetic acid, and the stabilizer and coupling agent is acetylacetone.

[0042] In this embodiment of the invention, step 2 specifically includes: dissolving Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1, stirring evenly, adding acetic anhydride, continuing to stir for 4-7 hours, finally adding glacial acetic acid and acetylacetone dropwise, and then allowing it to stand and age for 12-24 hours to obtain a stable precursor solution B (BEFO).

[0043] The metal ion concentration in the resulting precursor solution A is 0.15–0.20 mol / L; the metal ion concentration in the resulting precursor solution B is 0.20–0.25 mol / L.

[0044] Steps 3 and 4 are performed alternately, and the alternation is repeated 4 to 7 times. The resulting composite film has a thickness of 260 nm to 450 nm.

[0045] The substrate is an FTO glass substrate. The cleaning process of the glass substrate involves ultrasonic cleaning in anhydrous ethanol solution, acetone solution, and deionized water for 10-30 minutes, drying for 15 minutes, and then irradiating under ultraviolet light for 30 minutes to 1 hour to ensure that the surface of the FTO glass substrate can achieve atomic cleanliness before spin coating the precursor solution A.

[0046] Example 1

[0047] 1) Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.3:0.7:0.7. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stir well, add acetic anhydride, and continue stirring for 6 hours. Finally, add glacial acetic acid and acetylacetone dropwise, and stir for 1 hour. The ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and... The volume ratio of acetylacetone was 3:1:1:1. C4H6O4Zn·4H2O was dissolved in a mixture of anhydrous ethanol and ethanolamine. After heating in a water bath for 30 min, ethylene glycol methyl ether and glacial acetic acid were added dropwise, and stirring was continued for 6 h. The volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine, and glacial acetic acid was 3:1:1:1. The two solutions were mixed and then allowed to stand for 24 h to obtain a stable precursor solution A (0.3ZnO-0.7CFO).

[0048] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0049] 3) The precursor solution A was spin-coated onto a glass substrate to obtain a 0.3ZnO-0.7CFO wet film. After baking at 220℃ for 15 min, a dry film was obtained. Then, it was annealed at 570℃ for 30 min to obtain a crystalline 0.3ZnO-0.7CFO thin film.

[0050] 4) After the crystalline 0.3ZnO-0.7CFO film cools to room temperature, the precursor solution B is spin-coated onto the crystalline 0.3ZnO-0.7CFO film to obtain a BEFO wet film. After baking at 220℃ for 15 min, the dry film is obtained. Then, it is annealed at 570℃ for 30 min to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the 0.3ZnO-0.7CFO film.

[0051] 5) After the BEFO film in the crystalline state has cooled to room temperature, repeat steps 3 and 4 for a total of 4 times to obtain 10 layers (300nm) of 0.3ZnO-0.7CFO / BEFO temperature resistive switching film.

[0052] Example 2

[0053] 1) Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.35:0.65:0.65. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stir well, add acetic anhydride, and continue stirring for 6 hours. Finally, add glacial acetic acid and acetylacetone dropwise, and stir for 1 hour. The ethylene glycol methyl ether, acetic anhydride, and glacial acetic acid... The volume ratio of acid to acetylacetone is 3:1:1:1. C4H6O4Zn·4H2O is dissolved in anhydrous ethanol and ethanolamine, heated in a water bath for 30 min, and then ethylene glycol methyl ether and glacial acetic acid are added dropwise. The mixture is stirred for 6 h, with the volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine and glacial acetic acid being 3:1:1:1. The two solutions are mixed and then allowed to stand for 24 h to obtain a stable precursor solution A (0.35ZnO-0.75CFO).

[0054] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0055] 3) The precursor solution A was spin-coated onto a glass substrate to obtain a 0.35ZnO-0.65CFO wet film. After baking at 220℃ for 15 min, a dry film was obtained. Then, it was annealed at 570℃ for 30 min to obtain a crystalline 0.35ZnO-0.65CFO thin film.

[0056] 4) After the crystalline 0.35ZnO-0.65CFO film cools to room temperature, the precursor solution B is spin-coated onto the crystalline 0.35ZnO-0.65CFO film to obtain a BEFO wet film. After baking at 220℃ for 15 min, a dry film is obtained. Then, it is annealed at 570℃ for 30 min to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the 0.35ZnO-0.65CFO film.

[0057] 5) After the BEFO film in the crystalline state has cooled to room temperature, repeat steps 3 and 4 for a total of 4 times to obtain 10 layers (300nm) of 0.35ZnO-0.65CFO / BEFO temperature resistive switching film.

[0058] Example 3

[0059] 1) Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.4:0.6:0.6. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stir well, add acetic anhydride, and continue stirring for 6 hours. Finally, add glacial acetic acid and acetylacetone dropwise, and stir for 1 hour. The ethylene glycol methyl ether, acetic anhydride, and glacial acetic acid... The volume ratio of acid to acetylacetone is 3:1:1:1. C4H6O4Zn·4H2O is dissolved in anhydrous ethanol and ethanolamine, heated in a water bath for 30 min, and then ethylene glycol methyl ether and glacial acetic acid are added dropwise. The mixture is stirred for 6 h, with the volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine and glacial acetic acid being 3:1:1:1. The two solutions are mixed and then allowed to stand for 24 h to obtain a stable precursor solution A (0.4ZnO-0.6CFO).

[0060] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0061] 3) The precursor solution A was spin-coated onto a glass substrate to obtain a 0.4ZnO-0.6CFO wet film. After baking at 220℃ for 15 min, a dry film was obtained. Then, it was annealed at 570℃ for 30 min to obtain a crystalline 0.4ZnO-0.6CFO thin film.

[0062] 4) After the crystalline 0.4ZnO-0.6CFO film cools to room temperature, the precursor solution B is spin-coated onto the crystalline 0.4ZnO-0.6CFO film to obtain a BEFO wet film. After baking at 220℃ for 15 min, the dry film is obtained. Then, it is annealed at 570℃ for 30 min to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the 0.4ZnO-0.6CFO film.

[0063] 5) After the BEFO film in the crystalline state has cooled to room temperature, repeat steps 3 and 4 for a total of 4 times to obtain 10 layers (300nm) of 0.4ZnO-0.6CFO / BEFO temperature resistive switching film.

[0064] Example 4

[0065] 1) Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.45:0.55:0.55. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stir well, add acetic anhydride, and continue stirring for 6 hours. Finally, add glacial acetic acid and acetylacetone dropwise, and stir for 1 hour. The ethylene glycol methyl ether, acetic anhydride, and glacial acetic acid... The volume ratio of acid to acetylacetone is 3:1:1:1. C4H6O4Zn·4H2O is dissolved in anhydrous ethanol and ethanolamine, heated in a water bath for 30 min, and then ethylene glycol methyl ether and glacial acetic acid are added dropwise. The mixture is stirred for 6 h, with the volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine and glacial acetic acid being 3:1:1:1. The two solutions are mixed and then allowed to stand for 24 h to obtain a stable precursor solution A (0.45ZnO-0.55CFO).

[0066] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0067] 3) The precursor solution A was spin-coated onto a glass substrate to obtain a 0.45ZnO-0.55CFO wet film. After baking at 220℃ for 15 min, a dry film was obtained. Then, it was annealed at 570℃ for 30 min to obtain a crystalline 0.45ZnO-0.55CFO thin film.

[0068] 4) After the crystalline 0.45ZnO-0.55CFO film cools to room temperature, the precursor solution B is spin-coated onto the crystalline 0.45ZnO-0.55CFO film to obtain a BEFO wet film. After baking at 220℃ for 15 min, a dry film is obtained. Then, it is annealed at 570℃ for 30 min to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the 0.45ZnO-0.55CFO film.

[0069] 5) After the BEFO film in the crystalline state has cooled to room temperature, repeat steps 3 and 4 for a total of 4 times to obtain 10 layers (300nm) of 0.45ZnO-0.55CFO / BEFO temperature resistive switching film.

[0070] Example 5

[0071] 1) Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.5:0.5:0.5. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stir well, add acetic anhydride, and continue stirring for 6 hours. Finally, add glacial acetic acid and acetylacetone dropwise, and stir for 1 hour. The ethylene glycol methyl ether, acetic anhydride, and glacial acetic acid... The volume ratio of acid to acetylacetone is 3:1:1:1. C4H6O4Zn·4H2O is dissolved in anhydrous ethanol and ethanolamine, heated in a water bath for 30 min, and then ethylene glycol methyl ether and glacial acetic acid are added dropwise. The mixture is stirred for 6 h, with the volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine and glacial acetic acid being 3:1:1:1. The two solutions are mixed and then allowed to stand for 24 h to obtain a stable precursor solution A (0.5ZnO-0.5CFO).

[0072] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0073] 3) The precursor solution A was spin-coated onto a glass substrate to obtain a 0.5ZnO-0.5CFO wet film. After baking at 220℃ for 15 min, a dry film was obtained. Then, it was annealed at 570℃ for 30 min to obtain a crystalline 0.5ZnO-0.5CFO thin film.

[0074] 4) After the crystalline 0.5ZnO-0.5CFO film cools to room temperature, the precursor solution B is spin-coated onto the crystalline 0.5ZnO-0.5CFO film to obtain a BEFO wet film. After baking at 220℃ for 15 min, a dry film is obtained. Then, it is annealed at 570℃ for 30 min to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the 0.5ZnO-0.5CFO film.

[0075] 5) After the BEFO film in the crystalline state has cooled to room temperature, repeat steps 3 and 4 for a total of 4 times to obtain 10 layers (300nm) of 0.5ZnO-0.5CFO / BEFO temperature resistive switching film.

[0076] Example 6

[0077] 1) Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.55:0.45:0.45. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stir well, add acetic anhydride, and continue stirring for 6 hours. Finally, add glacial acetic acid and acetylacetone dropwise, and stir for 1 hour. The ethylene glycol methyl ether, acetic anhydride, and glacial acetic acid... The volume ratio of acid to acetylacetone is 3:1:1:1. C4H6O4Zn·4H2O is dissolved in anhydrous ethanol and ethanolamine, heated in a water bath for 30 min, and then ethylene glycol methyl ether and glacial acetic acid are added dropwise. The mixture is stirred for 6 h, with the volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine and glacial acetic acid being 3:1:1:1. The two solutions are mixed and then allowed to stand for 24 h to obtain a stable precursor solution A (0.55ZnO-0.45CFO).

[0078] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0079] 3) The precursor solution A was spin-coated onto a glass substrate to obtain a 0.55ZnO-0.45CFO wet film. After baking at 220℃ for 15 min, a dry film was obtained. Then, it was annealed at 570℃ for 30 min to obtain a crystalline 0.55ZnO-0.45CFO thin film.

[0080] 4) After the crystalline 0.55ZnO-0.45CFO film cools to room temperature, the precursor solution B is spin-coated onto the crystalline 0.55ZnO-0.45CFO film to obtain a BEFO wet film. After baking at 220℃ for 15 minutes, a dry film is obtained. Then, it is annealed at 570℃ for 30 minutes to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the 0.55ZnO-0.45CFO film.

[0081] 5) After the BEFO film in the crystalline state has cooled to room temperature, repeat steps 3 and 4 for a total of 4 times to obtain 10 layers (300nm) of 0.55ZnO-0.45CFO / BEFO temperature resistive switching film.

[0082] Example 7

[0083] 1) Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.6:0.4:0.4. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stir well, add acetic anhydride, and continue stirring for 6 hours. Finally, add glacial acetic acid and acetylacetone dropwise, and stir for 1 hour. The ethylene glycol methyl ether, acetic anhydride, and glacial acetic acid... The volume ratio of acid to acetylacetone is 3:1:1:1. C4H6O4Zn·4H2O is dissolved in anhydrous ethanol and ethanolamine, heated in a water bath for 30 min, and then ethylene glycol methyl ether and glacial acetic acid are added dropwise. The mixture is stirred for 6 h, with the volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine and glacial acetic acid being 3:1:1:1. The two solutions are mixed and then allowed to stand for 24 h to obtain a stable precursor solution A (0.6ZnO-0.4CFO).

[0084] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0085] 3) The precursor solution A was spin-coated onto a glass substrate to obtain a 0.6ZnO-0.4CFO wet film. After baking at 220℃ for 15 min, a dry film was obtained. Then, it was annealed at 570℃ for 30 min to obtain a crystalline 0.6ZnO-0.4CFO thin film.

[0086] 4) After the crystalline 0.6ZnO-0.4CFO film cools to room temperature, the precursor solution B is spin-coated onto the crystalline 0.6ZnO-0.4CFO film to obtain a BEFO wet film. After baking at 220℃ for 15 min, a dry film is obtained. Then, it is annealed at 570℃ for 30 min to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the 0.6ZnO-0.4CFO film.

[0087] 5) After the BEFO film in the crystalline state has cooled to room temperature, repeat steps 3 and 4 for a total of 4 times to obtain 10 layers (300nm) of 0.6ZnO-0.4CFO / BEFO temperature resistive switching film.

[0088] Example 8

[0089] 1) Take C4H6O4Zn·4H2O, Cu(NO3)3·3H2O, and Fe(NO3)3·9H2O in a molar ratio of 0.7:0.3:0.3. Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in ethylene glycol methyl ether, stir well, add acetic anhydride, and continue stirring for 6 hours. Finally, add glacial acetic acid and acetylacetone dropwise, and stir for 1 hour. The ethylene glycol methyl ether, acetic anhydride, and glacial acetic acid... The volume ratio of acid to acetylacetone is 3:1:1:1. C4H6O4Zn·4H2O is dissolved in anhydrous ethanol and ethanolamine, heated in a water bath for 30 min, and then ethylene glycol methyl ether and glacial acetic acid are added dropwise. The mixture is stirred for 6 h, with the volume ratio of ethylene glycol methyl ether, anhydrous ethanol, ethanolamine and glacial acetic acid being 3:1:1:1. The two solutions are mixed and then allowed to stand for 24 h to obtain a stable precursor solution A (0.7ZnO-0.3CFO).

[0090] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0091] 3) The precursor solution A was spin-coated onto a glass substrate to obtain a 0.7ZnO-0.3CFO wet film. After baking at 220℃ for 15 min, a dry film was obtained. Then, it was annealed at 570℃ for 30 min to obtain a crystalline 0.7ZnO-0.3CFO thin film.

[0092] 4) After the crystalline 0.7ZnO-0.3CFO film cools to room temperature, the precursor solution B is spin-coated onto the crystalline 0.7ZnO-0.3CFO film to obtain a BEFO wet film. After baking at 220℃ for 15 min, the dry film is obtained. Then, it is annealed at 570℃ for 30 min to obtain a crystalline BEFO film. That is, a crystalline BEFO film is prepared on the 0.7ZnO-0.3CFO film.

[0093] 5) After the BEFO film in the crystalline state has cooled to room temperature, repeat steps 3 and 4 for a total of 4 times to obtain 10 layers (300nm) of 0.7ZnO-0.3CFO / BEFO temperature resistive switching film.

[0094] Comparative Example 1

[0095] 1) Cu(NO3)3·3H2O, C4H6O4Zn·4H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.90:0.10:1. After stirring for 1 hour, acetic anhydride was added, and stirring was continued for 5 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 12 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. A stable precursor solution A (Cu(NO3)3·3H2O), with a metal ion concentration of 0.20 mol / L, was obtained. 0.90 Zn 0.10 Fe2O4);

[0096] 2) Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O were dissolved in ethylene glycol methyl ether at a molar ratio of 0.95:0.05:1. After stirring evenly, acetic anhydride was added and stirring was continued for 6 hours. Finally, glacial acetic acid and acetylacetone were added dropwise, and the mixture was allowed to stand for 24 hours. The volume ratio of ethylene glycol methyl ether, acetic anhydride, glacial acetic acid, and acetylacetone was 3:1:1:1. Finally, a stable precursor solution B (BEFO) with a metal ion concentration of 0.2 mol / L was obtained.

[0097] 3) A wet film was prepared by spin-coating precursor solution A onto an FTO glass substrate. The spin-coating speed was 4000 r / min, and the spin-coating time was 10 s. The wet film was baked at 220℃ for 15 min to obtain a dry film, which was then rapidly annealed at 570℃ for 30 min and then cooled to room temperature to obtain a monolayer of Cu. 0.90 Zn 0.10 Fe2O4 film.

[0098] 4) Cu obtained in step 3 using spin coating method 0.90 Zn 0.10 A wet film was prepared by spin-coating precursor solution B onto a Fe2O4 thin film. The wet film was baked at 220℃ for 10 min to obtain a dry film, which was then rapidly annealed at 570℃ for 30 min, and finally cooled to room temperature to obtain Cu. 0.90 Zn 0.10 Fe2O4 / BEFO layer.

[0099] 5) Then repeat steps 3 and 4 in sequence, repeating 4 times in total; to obtain 10 layers of Cu. 0.90 Zn 0.10 Fe2O4 / BEFO thin film.

[0100] X-ray diffraction (XRD) was used to measure the 10-layer 0.3ZnO-0.7CFO / BEFO temperature resistive switching film prepared in Example 1 and the 10-layer Cu film prepared in Comparative Example 1. 0.90 Zn 0.10 The determination results of the structural phases of the Fe2O4 / BEFO composite film are as follows: Figure 1 As shown. (Through) Figure 1The XRD results show that the diffraction peaks of the obtained resistive switching thin film materials indicate that BEFO has a distorted perovskite structure, belonging to the rhombohedral crystal system with space group R3c; CFO has a distorted spinel structure, belonging to the cubic crystal system with space group Fd-3m; and ZnO has a wurtzite structure, belonging to the hexagonal crystal system with space group P63mc. Compared with the BFO standard card (JCPDS No. 86-1518), both Example 1 and Comparative Example 1 have (012), (110), (202), (024), and (300) diffraction peaks. The (110) diffraction peak positions of Example 1 and Comparative Example 1 are 32.231° and 32.386°, respectively, which are shifted from the (110) peak position of 32.078° of the standard card, and the intensity changes. This proves that Er element doping has entered BFO, forming BEFO. Compared with the CFO standard card (JCPDS No. 72-7714), both Example 1 and Comparative Example 1 exhibit (200) and (311) diffraction peaks. Compared with the ZnO standard card (JCPDS No. 76-0704), Example 1 exhibits a (100) diffraction peak, confirming the preparation of a 0.3ZnO-0.7CFO solid solution film. Apart from the substrate peak, no impurity peaks appeared in the XRD patterns, indicating that neither composite film produced any other impurities.

[0101] The IV characteristic curves of the 10-layer 0.3ZnO-0.7CFO / BEFO temperature resistive switching film prepared in Example 1 were measured using a high-precision digital source meter system. The scanning sequence was -6V→0V→6V→0V→-6V. The test results are as follows: Figure 2 , Figure 3 As shown. A high-precision digital source metering system was used to measure the Cu content of the 10-layer Cu prepared in Comparative Example 1. 0.90 Zn 0.10 The IV characteristic curves of the Fe2O4 / BEFO thin film were scanned in the order -10V→0V→10V→0V→-10V, and the test results are as follows: Figure 4 , Figure 5 As shown, the 0.3ZnO-0.7CFO / BEFO thin film exhibits stable bipolar resistive switching behavior at different temperatures. The high-resistivity to low-resistivity ratio (HRS / LRS) changes significantly with temperature. At 25℃, the HRS / LRS is approximately 15, while as the temperature increases to 100℃, the HRS / LRS is approximately 10. 2 It exhibits excellent temperature resistive switching thin film properties. In contrast, Cu... 0.90 Zn 0.10 The high resistivity to low resistivity ratio of the Fe2O4 / BEFO film does not change significantly with temperature, and the HRS / LRS ratio is less than an order of magnitude at all temperatures. This difference is due to the difference between the 0.3ZnO-0.7CFO / BEFO film and the Cu... 0.90 Zn 0.10The composition and crystal structure of Fe2O4 / BEFO films differ. The 0.3ZnO-0.7CFO film is a solid solution, with elements uniformly distributed in the crystal structure, forming a stable crystal structure. In contrast, Cu... 0.90 Zn 0.10 Fe2O4 thin films are doped by introducing Zn into defect sites within the crystal structure, resulting in a less tight bond between the Zn and the main material. Therefore, the 0.3ZnO-0.7CFO / BEFO thin film exhibits a more uniform crystal structure and composition, demonstrating superior temperature-dependent switching properties.

[0102] The fatigue resistance properties of the 10-layer 0.3ZnO-0.7CFO / BEFO temperature resistive switching film prepared in Example 1 were determined using a high-precision digital source meter system. Figure 6 As shown, the 0.3ZnO-0.7CFO / BEFO temperature resistive switching film undergoes 10... 2 After repeated stimulation and working cycles, the resistive switching properties can still maintain high stability.

[0103] This invention employs a simple chemical solution deposition method, selecting an FTO glass substrate, and successfully fabricates an xZnO-(1-x)CFO / BEFO temperature resistive switching thin film through metal ion doping. Using a small ion sputtering instrument, an Au top electrode is deposited on the BEFO temperature resistive switching thin film to obtain an Au / ZnO-CFO / BEFO / FTO structure temperature resistive switching device (e.g., Figure 7 This method requires simple equipment, the experimental conditions are easy to achieve, and the prepared thin film has good uniformity, high resistivity ratio, low resistivity, and high stability, which changes with temperature. It can be used in temperature-sensitive electronic devices, temperature-sensitive optoelectronic devices, temperature sensors, and other fields.

Claims

1. A ZnO-CFO / BEFO temperature-dependent resistive thin film material, characterized in that, The first thin film and the second thin film are alternately arranged; the first thin film has a chemical formula of xZnO-(1-x)CuFe2O4, x=0.3-0.7, and a crystal structure of xZnO-(1-x)CuFe2O4 solid solution; the second thin film has a chemical formula of Bi 0.95 Er 0.05 FeO3.

2. The ZnO-CFO / BEFO temperature-dependent resistive thin film material according to claim 1, characterized in that, The thickness of the temperature resistive switching film is 260nm~450nm.

3. The method of producing a ZnO-CFO / BEFO temperature-dependent resistive thin film material according to claim 1 or 2, characterized in that, Includes the following steps: Step 1: Dissolve Cu(NO3)3·3H2O and Fe(NO3)3·9H2O in the first solvent, add pH adjuster, stabilizer and coupling agent dropwise, stir to obtain solution 1; dissolve C4H6O4Zn·4H2O in the second solvent, add pH adjuster and viscosity adjuster dropwise, stir to obtain solution 2; mix solution 1 and solution 2, and let stand for 12~24h to obtain precursor solution A; Step 2: Dissolve Bi(NO3)3·5H2O, Er(NO3)3·9H2O, and Fe(NO3)3·9H2O in a third solvent, add pH adjuster, stabilizer and coupling agent dropwise, and let stand for 12~24h to obtain precursor solution B; Step 3: Spin-coating the precursor solution A onto the substrate to obtain a wet film of xZnO-(1-x)CFO, baking, and then annealing to obtain a crystalline xZnO-(1-x)CFO thin film; Step 4: Spin-coat precursor solution B onto the crystalline xZnO-(1-x)CFO thin film to obtain a BEFO wet film, bake it, and then anneal it to obtain a crystalline BEFO thin film. Step 5: Repeat steps 3 and 4 in sequence until the desired thickness of xZnO-(1-x)CFO / BEFO temperature resistive switching film is obtained.

4. The method for preparing the ZnO-CFO / BEFO temperature resistive switching thin film material according to claim 3, characterized in that, In step 1: the first solvent is ethylene glycol methyl ether and acetic anhydride, the pH adjuster is glacial acetic acid, and the stabilizer and coupling agent is acetylacetone; the second solvent is ethylene glycol methyl ether and anhydrous ethanol, and the viscosity adjuster is ethanolamine.

5. The method for preparing the ZnO-CFO / BEFO temperature resistive switching thin film material according to claim 3, characterized in that, In step 2: the third solvent is ethylene glycol methyl ether and acetic anhydride, the pH adjuster is glacial acetic acid, and the stabilizer and coupling agent is acetylacetone.

6. The method for preparing the ZnO-CFO / BEFO temperature resistive switching thin film material according to claim 3, characterized in that, The metal ion concentration in precursor solution A obtained in step 1 is 0.15~0.20 mol / L; the metal ion concentration in precursor solution B obtained in step 2 is 0.20~0.25 mol / L.

7. The method for preparing ZnO-CFO / BEFO temperature resistive thin film material according to claim 3, characterized in that, In step 3: baking is done at 200~300℃ for 10~20 minutes to obtain a dry film, and annealing is done at 500~590℃ for 10~30 minutes.

8. The method for preparing the ZnO-CFO / BEFO temperature resistive switching thin film material according to claim 3, characterized in that, In step 4: baking is done at 200~300℃ for 5~15 minutes to obtain a dry film, and annealing is done at 500~590℃ for 10~30 minutes.

9. The method for preparing the ZnO-CFO / BEFO temperature resistive switching thin film material according to claim 3, characterized in that, The substrate is an FTO glass substrate.

10. The application of the ZnO-CFO / BEFO temperature resistive switching thin film material according to claim 1 or 2 in temperature control devices.

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