CN108232011B - Amorphous strontium titanate thin-film device and preparation method thereof - Google Patents
Amorphous strontium titanate thin-film device and preparation method thereof Download PDFInfo
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Abstract
本发明提供了一种非晶钛酸锶薄膜器件的制备方法，包括：在基底表面旋涂底电极溶液后退火，形成底电极；在所述底电极表面旋涂钛酸锶溶液后进行烘烤，形成酸锶薄膜；将所述钛酸锶薄膜进行退火处理，形成非晶薄膜；在所述非晶薄膜表面进行电子束蒸发溅射形成顶电极，得到非晶钛酸锶薄膜器件。本发明提供的非晶钛酸锶薄膜器件的最大的创新点在器件的主体氧化物薄膜层为非晶薄膜，并且制备方法工艺简单，制备过程中对温度的要求较低，能够进行批量生产，而且制备得到的钛酸锶薄膜器件的稳定性好、耐疲劳能够循环使用，开关比大，400℃退火时开关比达到103，应用领域广泛。
The invention provides a preparation method of an amorphous strontium titanate thin film device, which includes: spin-coating a bottom electrode solution on the surface of a substrate and then annealing to form a bottom electrode; and baking the bottom electrode after spin-coating the strontium titanate solution on the surface of the bottom electrode , forming a strontium acid film; annealing the strontium titanate film to form an amorphous film; performing electron beam evaporation and sputtering on the surface of the amorphous film to form a top electrode to obtain an amorphous strontium titanate film device. The biggest innovation of the amorphous strontium titanate thin film device provided by the present invention is that the main oxide thin film layer of the device is an amorphous thin film, and the preparation method is simple, the temperature requirement in the preparation process is low, and mass production can be carried out. In addition, the prepared strontium titanate thin film device has good stability, fatigue resistance and can be used cyclically, and has a large on - off ratio.
Description
Technical Field
The invention relates to the technical field of functional thin-film devices, in particular to an amorphous strontium titanate thin-film device and a preparation method thereof.
Background
In recent decades, continuous optimization of electronic computer technology has marked rapid development of modern information technology, and the life style of people is continuously changed. Memory is an indispensable carrier for information technology and one of the most important technologies in the field of integrated circuits. When the size of a Flash memory device is below 65nm, the further optimization of the device is limited by the contradiction between the erasing speed and the reliability of the traditional Flash memory with a polysilicon floating gate structure, the problems of gate dielectric leakage and the like. Liu et al, at the university of Houston, USA, discovered Pr in 20000.7Ca0.3MnO3The resistance change phenomenon in the thin film lifts up the resistance change memory to study the hot tide, and the resistance change memory becomes a new generation memory device with considerable prospect at the present stage due to high storage density, more repeated times and multi-value storage.
Under the action of an external electric field, the resistance value of the resistive random access memory can be switched between a high resistance state and a low resistance state, wherein the storage state of the resistive random access memory is 0 in the high resistance state, and the storage state of the resistive random access memory is 1 in the low resistance state. The ratio of the high and low impedance states is called the on-off ratio. The resistive random access memory is generally of a sandwich structure and consists of an upper electrode, a lower electrode and a middle resistive layer. Currently, the resistance-change layers having resistance-change characteristics studied and reported are roughly classified into the following three types from the material viewpoint: organic materials, solid electrolyte materials, and oxide materials.
The organic resistance change material mainly comprises PMMA (polymethyl methacrylate), PEDOT: PSS (3, 4-ethylenedioxythiophene monomer: polystyrene sulfonate), PVK (polyvinylcarbazole), etc., are typically some small organic molecules. The solid electrolyte material mainly refers to a sulfur compound containing Ag or Cu, and the resistance change mechanism of the solid electrolyte material is a conductive filament formed by redox reaction of an easily-oxidized metal electrode and migration of cations. The oxide resistance change material can be subdivided into multi-element oxide and binary oxide resistance change materials, and mainly comprises SrTiO3、SrZrO3Strontium zirconate, SrRuO3Isopoly oxide and HfO2(hafnium oxide), TiO2(titanium oxide) ZrO2(zirconia) and the like.
In the prior art, the resistive random access memory device is prepared from expensive raw materials, high in preparation required temperature, complex in process, poor in stability, easy to fatigue and difficult to carry out large-scale industrial production.
Disclosure of Invention
In view of the above, the present invention provides an amorphous strontium titanate thin film device and a method for manufacturing the same, and the amorphous strontium titanate thin film device provided by the present invention has an obvious diode resistance change effect, and has the advantages of simple manufacturing process, short period, significant resistance change performance, and convenience for mass production.
The invention provides an amorphous strontium titanate thin film device, comprising:
a substrate;
a bottom electrode disposed on the substrate surface;
the amorphous strontium titanate film is arranged on the surface of the bottom electrode;
and the top electrode is arranged on the surface of the amorphous strontium titanate film.
In the present invention, the substrate is preferably Glass (Glass), silicon wafer (Si wafer), LaNiO3/Si、SrRuO3/Si、LaRuO3/Si、LaMnO3/Si、SrMnO3titanium/Si/magnesium oxide (MgO)Strontium sulfate niobium (SrTiO)3Nb) or platinum/titanium/silica/silicon (100) (Pt/Ti/SiO)2Si (100)) (commercial substrate). In the present invention, the Glass is preferably FTO conductive Glass (ITO/Glass).
In the present invention, the bottom electrode is preferably platinum or lanthanum nickelate (LaNiO)3) Strontium ruthenate (SrRuO)3) Lanthanum ruthenate (LaRuO)3) Lanthanum manganate (LaMnO)3) Strontium manganate (SrMnO)3) ITO (indium doped tin oxide film) or FTO (fluorine doped tin oxide film).
In the present invention, the strontium titanate has a chemical formula of SrTiO3Abbreviated STO. In the present invention, the thickness of the strontium titanate thin film is preferably 200nm to 350 nm.
In the present invention, the top electrode is preferably gold, platinum, tungsten, silver or aluminum. In the present invention, the top electrode is preferably a plurality of dot-shaped electrodes, and in the present invention, a plurality of dot-shaped electrodes arranged regularly are preferably provided on the surface of the amorphous thin film, and the diameter of the dot-shaped electrodes is preferably 0.25 to 2.5mm, and more preferably 0.25 to 0.5 mm.
The invention provides a preparation method of an amorphous strontium titanate thin-film device in the technical scheme, which comprises the following steps:
carrying out annealing after spin-coating a bottom electrode solution on the surface of the substrate to form a bottom electrode;
spin-coating a strontium titanate solution on the surface of the bottom electrode and then baking to form a strontium titanate film;
annealing the strontium titanate film to form an amorphous film;
and carrying out electron beam evaporation sputtering on the surface of the amorphous film to form a top electrode, thus obtaining the strontium titanate film device.
In the present invention, the bottom electrode solution is preferably lanthanum nickelate (LaNiO)3) Solution, strontium ruthenate (SrRuO)3) Solution, lanthanum ruthenate (LaRuO)3) Solution, lanthanum manganate (LaMnO)3) Solution or strontium manganate (SrMnO)3) And (3) solution.
In the invention, the surface of a substrate is preferably baked after being coated with a bottom electrode solution in a spinning mode, and the baking temperature is preferably 280-300 ℃; the baking time is preferably 9-10 min; the temperature for annealing after the bottom electrode solution is coated on the surface of the substrate in a spinning mode is preferably 400-550 ℃, more preferably 400-520 ℃, more preferably 400-500 ℃, and most preferably 400-480 ℃; the annealing time is preferably 10-12 min.
In the present invention, the method of spin-coating the strontium titanate solution is preferably:
and spin-coating the strontium titanate solution at a first speed for a first time, then spin-coating at a second speed for a second time, baking the obtained wet film at the first temperature for a third time to remove moisture in the wet film, then baking at the second temperature for a fourth time to decompose organic matters in the film, and repeatedly coating for 2-3 times to obtain the strontium titanate film with the required thickness.
In the present invention, the spin coating apparatus is preferably a spin coater. In the invention, the first speed is preferably 700-800 r/min, more preferably 720-780 r/min, and most preferably 740-760 r/min; the first time is preferably 10-12 s. In the present invention, the second speed is preferably 2800 to 3000r/min, more preferably 2850 to 2950r/min, and most preferably 2900 r/min. In the present invention, the second time is preferably 20 to 30 seconds, more preferably 22 to 28 seconds, and most preferably 24 to 26 seconds. In the invention, the first temperature is preferably 180-200 ℃, and more preferably 190 ℃; the third time is preferably 9-10 min. In the invention, the second temperature is preferably 280-300 ℃, and more preferably 290 ℃; the fourth time is preferably 9-10 min.
In the invention, the concentration of the strontium titanate solution is preferably 0.25-0.3 mol/L.
In the present invention, the preparation method of the strontium titanate solution is preferably:
and mixing the strontium nitrate solution and the butyl titanate solution to obtain the strontium titanate solution.
In the present invention, it is preferable that the solution of butyl titanate is dropwise added to the solution of strontium nitrate to obtain a solution of strontium titanate.
In the invention, the mixing is preferably carried out under stirring, and the mixing time is preferably 4.5-5 hours.
In the invention, after the strontium nitrate solution and the butyl titanate solution are mixed, if no precipitate is generated, preferably acetylacetone is added into the mixed solution, and the concentration of the obtained strontium titanate solution is adjusted to be 0.25-0.3 mol/L.
In the present invention, the molar ratio of strontium nitrate to butyl titanate is preferably 1: 1. In order to ensure that the molar ratio of strontium nitrate to butyl titanate is 1:1, the butyl titanate solution remained in the beaker is preferably washed by acetylacetone for a plurality of times in a small amount in the mixing process, and the washing liquid is transferred to the mixed solution of strontium nitrate and butyl titanate by the same method every time.
In the present invention, the preparation method of the strontium nitrate solution is preferably:
dissolving strontium nitrate in ethylene glycol, and mixing to obtain a strontium nitrate solution.
In the present invention, the purity of the strontium nitrate is preferably 99.5%. In the invention, the mixing is preferably carried out under stirring, and the mixing temperature is preferably 40-60 ℃, more preferably 45-55 ℃, and most preferably 50 ℃; the stirring time is preferably 4 to 5 hours.
In the present invention, the method for preparing the butyl titanate solution is preferably:
and mixing the butyl titanate and the acetylacetone to obtain a butyl titanate solution.
In the present invention, the purity of the butyl titanate is preferably 99%. In the invention, the mixing temperature is preferably 20-30 ℃; the mixing is preferably carried out under stirring; the stirring time is preferably 2-2.5 hours.
In the invention, after the strontium nitrate solution and the butyl titanate solution are obtained, the two solutions are preferably kept still for 2-3 days, and the observation shows that if the precipitate is generated and needs to be reconfigured, the reason for separating out the precipitate may be water in an experimental container in the configuration process, or poor tightness in the solution storage process, or separation out caused by the solubility of a solute.
In the present invention, the strontium titanate solution is preferably filtered with filter paper after it is obtained to reduce dust pollution in the air.
In the invention, the annealing treatment temperature of the strontium titanate film is preferably 400-550 ℃, and more preferably 450-500 ℃; the time for annealing the strontium titanate film is preferably 10-12 min.
In the invention, a template covering method is preferably adopted, and a top electrode is formed on the surface of the amorphous film by electron beam evaporation sputtering; the granularity of the material in the top electrode is preferably 0.25-2.5 mm. The specific method of electron beam evaporation sputtering is not particularly limited in the present invention, and the technical scheme of electron beam evaporation sputtering known to those skilled in the art can be adopted.
In the invention, the electrical property of the amorphous strontium titanate thin film device is influenced by the atmosphere environment, the substrate temperature and the vacuum degree, and the air atmosphere and the substrate temperature are selected to keep the room temperature in the process of preparing the strontium titanate thin film device.
The amorphous strontium titanate thin-film device provided by the invention has a diode resistance change effect, and the on-off ratio can reach 103. The preparation method of the amorphous strontium titanate thin-film device provided by the invention has the advantages that the process is simple, the requirement on temperature in the preparation process is low, the batch production can be realized, the prepared amorphous strontium titanate thin-film device has good stability, fatigue resistance and large on-off ratio, and the application field is wide.
According to the invention, the I-V curves (I and V respectively represent current and voltage, the I-V curves represent the change of the current along with the test voltage, and the curves can represent the output electrical property of the material) of the amorphous strontium titanate thin-film device prepared by testing are found that the thin-film device provided by the invention has obvious unidirectional conductivity similar to a rectifier diode and remarkable rectification characteristic. In addition, by testing the I-V cycle curve, the test voltage is from 0V to the maximum value (+ V) of the test voltagemax) To 0V and then to the negative maximum (-V) of the test voltagemin) And when the voltage reaches a certain value, the current is not increased, and the device jumps from the high-resistance state to the low-resistance state. When the voltage is reduced from the positive maximum to 0V, the current is also gradually reduced, but the device is combinedWithout returning to the original high resistance state. In the negative voltage region, when the voltage reaches the negative maximum, the device returns to another high-resistance state from the low-resistance state. Test results show that the on-off ratio of the amorphous strontium titanate thin-film device provided by the invention can reach 103. And when the I-V cycle test reaches 30 times, the switching ratio hardly changes greatly, which indicates that the device belongs to nonvolatile storage. Finally, the fatigue resistance of the device is shown by measuring I-T characteristics (the change of the current I along with the time T), and the result shows that the change of the current along with the time hardly fluctuates, which shows that the amorphous strontium titanate thin film device provided by the invention has good stability and fatigue resistance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic structural diagram of an amorphous strontium titanate thin-film device prepared according to an embodiment of the present invention;
FIG. 2 is an I-V diagram of an amorphous strontium titanate thin film device fabricated according to an embodiment of the present invention;
FIG. 3 is an I-V cycle plot of an amorphous strontium titanate thin film device made in accordance with an embodiment of the present invention;
FIG. 4 is an I-T diagram of an amorphous strontium titanate thin film device prepared according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
With strontium nitrate Sr (NO)3)2(99.5%) as a starting material; ethylene glycol is used as a solvent. Strontium nitrate Sr (NO)3)2(99.5%) is dissolved in ethylene glycol, and stirred for 4-5 hours at 50 ℃ until the strontium nitrate is fully dissolved, so as to obtain the strontium nitrate solution.
With butyl phthalate Ti (OC)4H9)4(99%) as starting material; acetylacetone as a solvent. Butyl phthalate Ti (OC) was weighed so that the molar ratio of the stoichiometric ratio to strontium nitrate was 1:14H9)4(99%) is dissolved in acetylacetone, and stirred for 2-2.5 hours at normal temperature until the solution is fully dissolved, so as to obtain a butyl phthalate solution.
And dropwise adding the butyl titanate solution into the strontium nitrate solution, stirring at a constant speed for 5 hours, and adjusting the concentration of the solution to be 0.25mol/L by using acetylacetone to obtain the strontium titanate solution.
Mixing SrTiO3(STO) solution is coated on FTO conductive glass in a rotating mode, the FTO conductive glass is coated on a spin coater at a low speed of 800r/min for 15s in a spinning mode, then the coating is kept for 20s at a speed of 3000r/min, each layer is coated, the wet film is baked on a heating table at 180 ℃ for 20min to remove moisture in the film, then the wet film is baked at 300 ℃ for 10min to decompose organic matters in the film, and the process is repeated for 3 times to obtain the strontium titanate film with the thickness of about 300 nm.
And annealing the strontium titanate film at the temperature of 400 ℃ for 12min to obtain the amorphous film.
And sputtering the surface of the amorphous film by an electron beam evaporation sputtering method and a template covering method to obtain a layer of dot-shaped gold electrodes with the diameter of 0.5mm in a regular arrangement, forming a top electrode and obtaining the amorphous strontium titanate film device.
Fig. 1 is a schematic structural diagram of an amorphous strontium titanate thin-film device prepared in embodiment 1 of the present invention, which includes a substrate layer Glass, an FTO bottom electrode (FTO is a fluorine-doped tin oxide film, the FTO/Glass bottom electrode/substrate is commercially available, and is obtained by purchase) disposed on a surface of the substrate layer, an amorphous strontium titanate thin-film layer disposed on a surface of the bottom electrode, and a gold top electrode disposed on a surface of the amorphous strontium titanate thin-film layer (the gold top electrode is sputtered by an electron beam evaporation sputtering method in combination with a template masking method to obtain a layer of dot-shaped electrode with a diameter of 0.5mm, which is regularly arranged).The amorphous strontium titanate thin-film device provided by the invention has a simple structure and only needs to be made of FTO conductive glass (fluorine-doped SnO)2Transparent conductive glass) is prepared with a layer of SrTiO3The (STO) film is only needed, and is convenient for large-scale production.
Fig. 2 is an I-V diagram of an amorphous strontium titanate thin film device prepared in example 1 of the present invention. The test voltage is gradually increased from negative-2V to positive +3V, the current is obviously changed near negative voltage-1.8V and positive voltage +2V, and the current tends to be stable in the range of-1.8V to + 2V. Fig. 2 shows that the amorphous strontium titanate thin-film device prepared by the invention has a remarkable diode effect, and the open-circuit voltage reaches 2.1V. And the difference of the test results after the cycle test is extremely small, which shows that the diode rectification characteristic of the device is stable and nonvolatile.
Fig. 3 is an I-V cycle diagram of an amorphous strontium titanate thin film device prepared in example 1 of the present invention. In the test process, the voltage is increased from 0V to the maximum positive test voltage, then is decreased to the maximum negative voltage, and finally 0V is detected again. When annealing is carried out at 400 ℃, when the voltage is increased from 0V to +2V and then decreased from +2V to 0V, the result of the first cycle test shows that the device is initially in a high-resistance state, the current is increased along with the increase of the external voltage, when the voltage reaches 1.1V, the current intensity jumps, the current gradually becomes stable, and the device jumps from the high-resistance state to the low-resistance state. When the voltage is reduced from the positive maximum to 0V, the current is also gradually reduced, but the device does not return to the original high-resistance state. In the negative voltage region, when the voltage reaches negative maximum-2V and then increases from-2V to 0V, the current jumps again at-1.1V, and the device also returns to another high-resistance state from the low-resistance state. Test results show that the on-off ratio of the device can reach 103. And when the I-V cycle test reaches 30 times, the switching ratio hardly changes greatly, which indicates that the device belongs to nonvolatile storage.
FIG. 4 is an I-T diagram of an amorphous strontium titanate thin film device prepared in example 1 of the present invention. Under the condition that the test voltage is 1V, the current of the device is tested, the single test time is 0.1s, the continuous measurement is carried out for 100 times, and the total time consumption is 20 s. The test result shows that the amorphous strontium titanate thin film device prepared by the invention has excellent stability and fatigue resistance.
The invention provides amorphous SrTiO with a diode resistance change effect3The (STO) thin film device and the preparation method thereof solve the defect of complex manufacturing process of the thin film material of the electronic device. The simple and convenient preparation process, and the excellent, stable and nonvolatile memory device undoubtedly have the application prospect which cannot be underestimated in the field of electronic devices.
Example 2
With strontium nitrate Sr (NO)3)2(99.5%) as a starting material; ethylene glycol is used as a solvent. Strontium nitrate Sr (NO)3)2(99.5%) was dissolved in ethylene glycol and stirred at 50 ℃ for 4.5 hours until fully dissolved to give a strontium nitrate solution.
With butyl phthalate Ti (OC)4H9)4(99%) as starting material; acetylacetone as a solvent. Butyl phthalate Ti (OC) was weighed so that the molar ratio of the stoichiometric ratio to strontium nitrate was 1:14H9)4(99%) dissolved in acetylacetone, and stirred at room temperature for 2 hours until the solution is sufficiently dissolved to obtain a butyl phthalate solution.
And dropwise adding the butyl titanate solution into the strontium nitrate solution, stirring at a constant speed for 5 hours, and adjusting the concentration of the solution to be 0.25mol/L by using acetylacetone to obtain the strontium titanate solution.
Mixing SrTiO3(STO) solution is coated on FTO conductive glass in a rotating mode, the FTO conductive glass is coated on a spin coater at a low speed of 800r/min for 15s in a spinning mode, then the coating is kept for 20s at a speed of 3000r/min, each layer is coated, the wet film is baked on a heating table at 180 ℃ for 20min to remove moisture in the film, then the wet film is baked at 300 ℃ for 10min to decompose organic matters in the film, and the process is repeated for 3 times to obtain the strontium titanate film with the thickness of about 300 nm.
And annealing the strontium titanate film at the temperature of 550 ℃ for 13min to obtain the amorphous film.
And sputtering the surface of the amorphous film by an electron beam evaporation sputtering method and a template covering method to obtain a layer of dot-shaped gold electrodes with the diameter of 0.5mm in a regular arrangement, forming a top electrode and obtaining the amorphous strontium titanate film device.
Junction of amorphous strontium titanate thin-film device prepared in embodiment 2 of the present inventionThe structure includes: the electrode comprises a substrate layer Glass, an FTO bottom electrode (FTO is a fluorine-doped tin oxide film, the FTO/Glass bottom electrode/substrate is commercially available and is obtained), an amorphous strontium titanate thin film layer arranged on the surface of the bottom electrode, and a gold top electrode (the gold top electrode is sputtered by an electron beam evaporation sputtering method and a template covering method to obtain a layer of round dot-shaped electrode with the diameter of 0.5mm in a regular arrangement). The amorphous strontium titanate thin-film device provided by the embodiment 2 of the invention has a simple structure, and only needs to be made of FTO conductive glass (SnO doped with fluorine)2Transparent conductive glass) is prepared with a layer of SrTiO3The (STO) film is only needed, and is convenient for large-scale production.
In the I-V cycle test process of the amorphous strontium titanate thin film device prepared in embodiment 2 of the invention, the voltage is increased from 0V to the maximum test positive voltage +3V and then decreased to the maximum negative voltage-3V, and then returned to 0V. The cycle test is carried out for 50 times, the IV cycle diagram of the device has slight change in high and low resistance states along with the increase of the test times, and the switching ratio can reach 10 at most2. The small change of the switching ratio indicates that the device belongs to a nonvolatile memory.
Example 3
With strontium nitrate Sr (NO)3)2(99.5%) as a starting material; ethylene glycol is used as a solvent. Strontium nitrate Sr (NO)3)2(99.5%) was dissolved in ethylene glycol and stirred at 50 ℃ for 5 hours to be sufficiently dissolved, to obtain a strontium nitrate solution.
With butyl phthalate Ti (OC)4H9)4(99%) as starting material; acetylacetone as a solvent. Butyl phthalate Ti (OC) was weighed so that the molar ratio of the stoichiometric ratio to strontium nitrate was 1:14H9)4(99%) dissolved in acetylacetone, and stirred at room temperature for 2 hours until the solution is sufficiently dissolved to obtain a butyl phthalate solution.
And dropwise adding the butyl titanate solution into the strontium nitrate solution, stirring at a constant speed for 5 hours, and adjusting the concentration of the solution to be 0.25mol/L by using acetylacetone to obtain the strontium titanate solution.
Mixing SrTiO3(STO) solution spin coating on SiO2(silicon oxide/silicon wafers are commercially available substrates) low on spin coatersAnd at the speed of 900r/min, carrying out spin coating for 15s, then keeping the spin coating at 3200r/min for 20s, coating one layer each time, baking the wet film on a heating table at 180 ℃ for 20min to remove moisture in the film, then baking the film at 300 ℃ for 10min to decompose organic matters in the film, and repeating the steps for 3 times to obtain the strontium titanate film with the thickness of about 300 nm.
And finally, annealing the strontium titanate film at 600 ℃ for 14min to obtain the amorphous strontium titanate film.
And sputtering the surface of the amorphous strontium titanate film by an electron beam evaporation sputtering method and a template covering method to obtain a layer of dot-shaped gold electrodes with the diameter of 1mm in a regular arrangement, and forming a top electrode to obtain the amorphous strontium titanate film device.
The structure of the amorphous strontium titanate thin-film device prepared in embodiment 3 of the present invention includes: a base layer Si (silicon wafer), and SiO arranged on the surface of the base layer2The bottom electrode (the bottom electrode/substrate is commercially available and purchased), the amorphous strontium titanate film layer arranged on the surface of the bottom electrode, and the gold top electrode arranged on the surface of the amorphous strontium titanate film layer (the gold top electrode is sputtered by combining an electron beam evaporation sputtering method with a template covering method to obtain a layer of dot-shaped electrode with the diameter of 1mm and arranged regularly). The amorphous strontium titanate thin-film device prepared in embodiment 3 of the invention has a simple structure, and only a layer of SrTiO is required to be prepared on a silicon oxide/silicon wafer3The (STO) film is only needed, and is convenient for large-scale production.
The voltage of the I-V characteristic curve of the amorphous strontium titanate thin film device prepared in example 3 gradually increases from negative-6 to positive +8V, the current significantly changes in the vicinity of negative-4V and positive +7.8V, the current tends to be stable in the range of-1.8V to +2V, the magnitude of the current is extremely small, the resistance is extremely large, and the device is in an insulating state. The amorphous strontium titanate film device prepared by the invention has obvious diode effect, and the open-circuit voltage reaches 7.8V. And the difference of the test results after the cycle test is extremely small, which shows that the diode rectification characteristic of the device is stable and nonvolatile. The switch ratio of the device is close to 10 by testing the IV cycle chart2。
From the above embodiments, the present invention provides a method for manufacturing an amorphous strontium titanate thin film device, including: spin-coating a bottom electrode solution on the surface of the substrate and then annealing to form a bottom electrode; spin-coating a strontium titanate solution on the surface of the bottom electrode and then baking to form a strontium titanate film; annealing the strontium titanate film to form an amorphous film; and carrying out electron beam evaporation sputtering on the surface of the amorphous film to form a top electrode, thereby obtaining the amorphous strontium titanate film device. The preparation method of the amorphous strontium titanate thin-film device provided by the invention has the advantages that the process is simple, the requirement on temperature in the preparation process is low, the batch production can be realized, the prepared amorphous strontium titanate thin-film device has good stability, fatigue resistance and large on-off ratio, and the application field is wide.
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