Self-supporting thin film high-voltage electricity transport measuring device and preparation method and application of self-supporting thin film high-voltage electricity transport measuring device

Abstract

The invention discloses a self-supporting film high-voltage electric transport measurement device and a preparation method and application thereof, and relates to the technical field of electric transport measurement, and the self-supporting film high-voltage electric transport measurement device comprises a diamond anvil cell and a micro-nano structure device constructed on the lower anvil surface of the diamond anvil cell; the micro-nano structure device comprises an electrode circuit constructed by taking a self-supporting film as a structural material; and the electrode assembly is connected with the electrode circuit and is used for leading the electrode circuit out of the diamond anvil cell. According to the invention, the self-supporting film is completely and uniformly stripped from the substrate without cracks through a wet etching technology, and then the self-supporting film is transferred to the anvil surface of the diamond anvil cell through a heat release polymer transfer technology, so that the electric transport measurement device based on the self-supporting film is constructed. And an effective research means is provided for researching the physical characteristics of flexible electron oxide materials including self-supporting films under high pressure.

Description

Technical Field

[0001] The present invention relates to the technical field of electric transport measurement, and in particular to a self-supporting thin film high voltage electric transport measurement device and a preparation method and application thereof. Background Art

[0002] Oxide films represent a large class of quantum materials with excellent physical properties such as superconductivity, various long-range (antiferroic) orders, and quantized states. In addition, due to the strong chemical bonding between them and the substrate, oxide films become an ideal platform for synthesizing and designing metastable phases, which are usually not available in conventional bulk materials. However, oxide films often have millimeter-thick substrates, which greatly limits the means of regulating the physical properties of oxide films. For example, when a portable high-pressure device is used to regulate the pressure of an oxide film with a substrate, the maximum pressure can only reach 3GPa, which is far lower than the critical pressure required for the current regulation of the physical properties of bulk materials.

[0003] Over the past few decades, there have been many studies devoted to separating oxide films from substrates by using soluble buffer layers during film growth. Researchers have found that self-supporting films have comparable or even better functional properties than epitaxial films. Thanks to the reduction in the size of self-supporting films, higher pressures can theoretically be applied to self-supporting films to study their physical properties under extreme high-pressure conditions. However, it is still extremely challenging to transfer self-supporting films of nanometer thickness to diamond anvils, apply high pressure and perform electrical transport property measurements. For example, a large number of cracks will appear in the film during transfer, it is difficult to make lead electrodes for nanometer-thick films, and the film and lead electrodes may be damaged by high pressure after pressurization. Therefore, it is very necessary to invent a technology that can transfer self-supporting films relatively intact to the anvil surface of diamond anvils, and make reliable lead electrodes through micro-nano processing, so as to stably carry out electrical transport measurements under higher pressures. Summary of the invention

[0004] The object of the present invention is to provide a self-supporting thin film high voltage electric transport measuring device and a preparation method and application thereof.

[0005] The present invention is achieved through the following technical solutions:

[0006] As a first aspect of the present invention, a self-supporting thin film high voltage electric transport measuring device is provided, comprising a diamond anvil and a micro-nano structure device constructed on the lower anvil surface of the diamond anvil;

[0007] The micro-nano structure device includes an electrode circuit constructed with a self-supporting film as a structural material; and

[0008] An electrode assembly connected to the electrode circuit for leading the electrode circuit out of the diamond anvil.

[0009] As a further optimization solution of the present invention, the self-supporting film is an oxide film.

[0010] As a further optimization solution of the present invention, the structure of the self-supporting film is a three-layer structure film protected by a ferroelectric interlayer.

[0011] As a further optimization scheme of the present invention, the electrode circuit is constructed by first peeling the self-supporting film with a substrate from the substrate, then transferring the self-supporting film to the lower anvil surface of the diamond anvil, and finally performing thermal evaporation gold plating on the surface of the self-supporting film.

[0012] As a second aspect of the present invention, there is also provided a method for preparing a self-supporting thin film high voltage electric transport measuring device, comprising the following steps:

[0013] (1) preparing a flat substrate, growing a sacrificial layer film on the substrate and growing a self-supporting film on the sacrificial layer film by pulsed laser deposition, separating the self-supporting film from the substrate by wet etching, and transferring the self-supporting film to the center of the lower anvil surface of a diamond anvil by thermal release polymer transfer technology;

[0014] (2) The electrode circuit is constructed by thermal evaporation gold plating on the surface of the self-supporting film through micro-nano processing and electron beam etching technology, and the electrode assembly is connected to the electrode circuit to obtain a micro-nano structure device, thereby obtaining the self-supporting film high-voltage electric transport measurement device.

[0015] Furthermore, in the step (2), the specific process of transferring the self-supporting film to the center of the lower anvil surface of the diamond anvil by using the thermal release polymer transfer technology is as follows:

[0016] First, polydimethylsiloxane (PDMS) is attached to the surface of the self-supporting film, and then one side of the self-supporting film is placed directly above the lower anvil surface of the diamond anvil. After heating, the viscosity of the polydimethylsiloxane is ineffective, and the self-supporting film is separated from the polydimethylsiloxane and transferred to the lower anvil surface of the diamond anvil.

[0017] As the third aspect of the present invention, a method for measuring the electrical transport of a self-supporting film is also provided. The test method is: constructing an electrical transport measurement device as described in any of the above, placing the measurement device in a comprehensive physical property measurement system, and using the comprehensive physical property measurement system to measure the electrical transport properties of the self-supporting film to obtain the electrical transport measurement results of the self-supporting film.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] (1) The present invention uses a wet etching technique to completely, evenly, and crack-free peel off the self-supporting film from the substrate, and then uses a thermal release polymer transfer technique to transfer the self-supporting film to the anvil surface of a diamond anvil, thereby constructing an electrical transport measurement device based on the self-supporting film, which provides an effective research method for studying the physical properties of flexible electronic oxide materials including self-supporting films under high pressure.

[0020] (2) The electrical transport measurement device proposed in the present invention can accurately detect the dependence of the electrical signal of the self-supporting film on the diamond anvil cell (DAC) pressure under different temperatures and magnetic fields, providing key experimental data for in-depth research on the change law of the electrical properties of the self-supporting film under high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the electrical structure of diamond anvil cell;

[0022] Figure 2 BaTiO with a size of millimeters 3 -SrIrO 3 -BaTiO 3 membrane;

[0023] Figure 3 To utilize 1uc thick BaTiO 3 -SrIrO 3 -BaTiO 3 Schematic diagram of the structure of the electrical transport measurement device obtained by membrane preparation;

[0024] Figure 4 Based on BaTiO 3 -SrIrO 3 -BaTiO 3 Scanning electron microscope schematic diagram of the membrane's micro-nanostructure device;

[0025] Figure 5 Based on BaTiO 3 -SrIrO 3 -BaTiO 3 Schematic diagram of the membrane's micro-nanostructure device;

[0026] Figure 6 This is a diagram of a self-supporting thin film high voltage electrical transport device;

[0027] Figure 7 BaTiO 3 -SrIrO 3 -BaTiO 3 Electrical transport data of the membrane at different temperatures. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Technicians in this field can make some non-essential improvements and adjustments to the present invention based on the above application content.

[0029] The self-supporting thin film high voltage electric transport measuring device provided by the present invention comprises a diamond anvil and a micro-nano structure device constructed on the lower anvil surface of the diamond anvil;

[0030] Specifically, the micro-nano structure device includes an electrode circuit constructed with a self-supporting film as a structural material; and

[0031] An electrode assembly connected to the electrode circuit for leading the electrode circuit out of the diamond anvil.

[0032] Among them, the anvil surface of the diamond anvil has extremely high flatness and smoothness, and the surface roughness reaches the nanometer level, which can meet the requirements of microstructure, ensure the tightness of the interface and the high efficiency of electrical signal transmission. In addition, it can make the transferred self-supporting film uniform and stress-free, and make the adhesion of the evaporated electrode assembly more solid and firm.

[0033] In addition, the diamond anvil has a low thermal expansion coefficient and high thermal conductivity, which can effectively reduce the stress effect caused by slight stretching of the self-supporting film due to heating, and has the excellent performance of quickly conducting away the thermal effect of the electrode, ensuring that stable physical properties can be maintained under different temperature conditions and reducing measurement errors caused by thermal effects.

[0034] The method for preparing the self-supporting thin film high voltage electric transport measuring device comprises the following steps:

[0035] (1) preparing a flat substrate, growing a sacrificial layer film on the substrate by pulsed laser deposition, and growing a self-supporting film on the sacrificial layer film;

[0036] During the growth of the sacrificial layer film and the self-supporting film, the thickness of each film can be further monitored by using a reflection high energy electron diffractometer (RHEED) oscillation.

[0037] (2) separating the self-supporting film from the substrate by wet etching technology, and then transferring the self-supporting film to the center of the lower anvil surface of the diamond anvil by thermal release polymer transfer technology;

[0038] The excess non-central film on the anvil surface of the diamond anvil is precisely removed using an atomic force microscope (AFM) probe, and the resulting debris is adhered to the anvil surface by a polymer to avoid contamination or interference with subsequent processes;

[0039] Before the self-supporting film is transferred to the lower anvil surface of the diamond anvil, the size of the self-supporting film can be processed to the millimeter level or tens of micrometers;

[0040] In order to maintain a good electrical contact signal, the channel can be deeply etched by argon ionization. Furthermore, the electrode assembly includes a platinum bar and an enameled copper wire. The electrode line is extended with a cut platinum bar by utilizing the good conductivity of platinum and gold and the reliable ohmic contact characteristics between the two, and the platinum bar is then led out to the outside of the diamond anvil with an enameled copper wire.

[0041] (3) The electrode circuit is constructed by thermal evaporation gold plating on the surface of the self-supporting film through micro-nano processing and electron beam etching technology, and the electrode assembly is connected to the electrode circuit to obtain a micro-nano structure device, thereby obtaining a self-supporting thin film high-voltage electrical transport measurement device.

[0042] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following specific embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0043] 1. Preparation of self-supporting thin film high voltage electrical transport measurement devices

[0044] 1.1. Preparation of free-standing films

[0045] (1) SrTiO 3 ) The single crystal substrate was placed in a tube furnace and annealed in a flowing air atmosphere at a temperature of 1050°C for 120 min. After the annealing was completed, the substrate was slowly cooled to room temperature to obtain SrTiO 3 (001) single crystal substrate, SrTiO 3 (001) single crystal substrate was used as the substrate.

[0046] (2) Pulsed laser deposition (PLD) was used to deposit SrTiO 3 ) substrate to grow strontium aluminate (Sr 3 Al 2 O 6 ) sacrificial layer film, and then grow BaTiO 3 -SrIrO 3 -BaTiO 3 The overall structure grows in a two-dimensional layered pattern, and the film thickness is monitored by reflection high energy electron diffraction (RHEED) oscillation during the growth process. After the deposition is completed, the film is placed at 5.5×10 4 The temperature was slowly lowered to room temperature at a rate of 10° C. / min under an oxygen pressure of Pa to obtain a self-supporting film used in this embodiment.

[0047] The growth parameters are as follows:

[0048] ①Sr 3 Al 2 O 6 The energy density of the film growth is 1.2 J / cm 2 , the laser frequency is 1 Hz, and the deposition oxygen pressure is 5.7×10 -3 Pa, the deposition temperature is 850℃ and the thickness is 16nm.

[0049] ② Upper and lower BaTiO 3 The film growth conditions are the same, with an energy density of 1J / cm 2 , the laser frequency is 2Hz, the deposition oxygen pressure is 3Pa, the deposition temperature is 750℃, and the thickness is 2nm.

[0050] ③SrIrO 3 The energy density of the film growth is 1.1 J / cm 2 , the laser frequency is 4 Hz, the deposition oxygen pressure is 10 Pa, the deposition temperature is 700 ° C, and the thickness is 12 nm.

[0051] 1.2. Transferring the self-supporting film to the lower anvil surface of the diamond anvil

[0052] Specifically, first, a 500 μm thick polydimethylsiloxane (hereinafter referred to as PDMS) is attached to the surface of the self-supporting film (the structural schematic diagram is shown in FIG. Figure 1 The free-standing film was released by wet etching, that is, the whole structure was immersed in deionized water at room temperature until the sacrificial layer of strontium aluminate (Sr 3 Al 2 O 6 ) is completely dissolved (this process takes about 12 hours), and the BaTiO 3 -SrIrO 3 -BaTiO 3 The membrane and substrate were completely separated and removed from the water.

[0053] Subsequently, the BaTiO 3 -SrIrO 3 -BaTiO 3 The film is transferred to the anvil surface, which will be attached with BaTiO 3 -SrIrO 3 -BaTiO 3 The PDMS film was fixed on the transfer platform clip, and the diamond lower anvil was placed directly below it. After 10 minutes of heating at 80°C, the PDMS viscosity gradually failed, and the BaTiO 3 -SrIrO 3 -BaTiO 3The film gradually detaches from the PDMS and falls onto the anvil surface.

[0054] Furthermore, in BaTiO 3 -SrIrO 3 -BaTiO 3 Before the film is transferred to the lower anvil surface of the diamond anvil, the BaTiO 3 -SrIrO 3 -BaTiO 3 The film is processed to size. Figure 2 The figure shows BaTiO at millimeter scale. 3 -SrIrO 3 -BaTiO 3 membrane.

[0055] Furthermore, BaTiO 3 -SrIrO 3 -BaTiO 3 During the film growth process, the film thickness can be controlled to 1uc by monitoring the film thickness using reflection high energy electron diffraction (RHEED) oscillation. Figure 3 To utilize 1uc thick BaTiO 3 -SrIrO 3 -BaTiO 3 Schematic diagram of the structure of the electrical transport measurement device obtained by membrane preparation.

[0056] In addition, in addition to the above-mentioned BaTiO 3 -SrIrO 3 -BaTiO 3 The present invention also grows BaTiO according to the above preparation process. 3 -SrTiO 3 -BaTiO 3 Film, except SrTiO 3 The energy density of the film growth is 1.1 J / cm 2 , the laser frequency is 4 Hz, and the deposition oxygen pressure is 5.1×10 -3 The other growth parameters except the deposition temperature of 700°C and the thickness of 24 nm are consistent with the above preparation process.

[0057] 1.3. Preparation of electrode circuit

[0058] (1) Place the diamond anvil surface firmly on the coating machine, evenly drop a few drops of photoresist on it for spin spraying and heating. The spraying speed is 4000r / min and the heating temperature is 120℃. The heating time is 5min. Place the coated film under an optical microscope and measure the film to be 40μm long and 25μm wide.

[0059] (2) Import the directional cross exposure pattern into the control terminal computer of the electron beam exposure system, place the anvil surface with glue uniformly in vacuum for 2 hours, and then put it into the vacuum chamber of the electron microscope, and the vacuum degree reaches 2x10 -5 After mbar, the electron beam finds the anvil surface, determines the center and starts exposure. After exposure, it is developed and fixed, and placed in a thermal evaporation coater for evaporation. After evaporation, it is immersed in acetone to remove the glue.

[0060] (3) The anvil surface with the thin film is evenly coated and placed under a microscope. With the help of the microscope's fine-tuning device, the photo is aligned and photographed. The photograph is imported into the layout drawing tool klayout software to pre-draw the electrode. The thin film device is placed in the electron microscope cavity. The pre-steamed cross electrode is aligned with the center of the electron beam scanning area, and the overall electrode pattern is exposed to the anvil surface photoresist.

[0061] (4) Development and fixing are then performed to evaporate the titanium / gold alloy, with the titanium thickness being 10 nm and the gold thickness being 120 nm, and finally forming the required electrode circuit on the anvil surface.

[0062] 1.4. Use the cut platinum strips to extend the electrode lines on the electrode circuit, and then use the enameled copper wires as pins to lead the platinum strips to the outside of the diamond anvil to obtain the electrical transport measurement device. The schematic diagram of the constructed electrical transport measurement device is shown in Figure 4-5 shown.

[0063] 2. BaTiO 3 -SrIrO 3 -BaTiO 3 Electrical transport measurements in membranes

[0064] 2.1. Instrument inspection

[0065] Check whether all parts of the comprehensive physical property measurement system (PPMS-9T) are working properly, including superconducting magnets, refrigeration systems, control systems, etc. Confirm whether the temperature control, magnetic field control and other functions are stable, check whether the various parameter settings of the instrument are within the normal range, and adjust the system's temperature and magnetic field to the initial values.

[0066] 2.2. Standard pressure

[0067] The BaTiO-based 3 -SrIrO 3 -BaTiO 3 Membrane electrical transport measurement devices ( Figure 6 ) is placed in a pressure standard system and the ruby ​​fluorescence spectrum is used for pressure standardization. The wavelength of the spectrum red shifts as the pressure increases. The pressure standard formula is as follows:

[0068]

[0069] In the formula, λ p and λ0 are the wavelengths of the spectrum at a specific pressurized pressure value and a standard atmospheric pressure, respectively, and p is the standard pressure.

[0070] 2.3. Electrical transport measurements

[0071] Under the set temperature and magnetic field conditions, the prepared electric transport measurement device was inserted into the pin of the comprehensive physical property measurement system (PPMS-9T) and connected. The compressor was used to extract the exchange gas for cooling and electric transport measurement. After measuring a pressure point, the device was taken out and placed on the standard pressure system for pressurization and standard pressure, and then placed in the comprehensive physical property measurement system to measure BaTiO 3 -SrIrO 3 -BaTiO 3 The membranes were tested for electrical transport under different pressures.

[0072] 2.4.Data recording and monitoring

[0073] During the measurement process, the measured data is recorded in real time, including current, voltage, resistance, temperature, magnetic field and other parameters. At the same time, the changes in the data are observed to ensure the stability and rationality of the data.

[0074] 2.5. Multi-parameter scanning

[0075] If you need to study the electrical transport properties of the film under different temperatures and magnetic fields, you can perform temperature scanning or magnetic field scanning measurements. During the temperature scanning process, the magnetic field strength needs to be fixed and the temperature needs to be gradually changed according to the set temperature step length to measure the electrical transport parameters at different temperatures. During the magnetic field scanning process, similarly, the temperature conditions need to be fixed and the magnetic field strength needs to be gradually changed to measure the electrical transport parameters under different magnetic fields.

[0076] Figure 7 The results are shown for BaTiO under the conditions of magnetic field strength of 0Oe and measurement pressure of 0GPa and 15.2GPa. 3 -SrIrO 3 -BaTiO 3 The electrical transport data of the film at different temperatures. It can be seen that BaTiO 3 -SrIrO 3 -BaTiO 3 The film can still stably exist at 15.2 GPa to measure the electrical transport data. In addition, BaTiO 3 -SrIrO 3 -BaTiO 3 The change in the behavior of the film resistance indicates that the film band gap has changed.

[0077] The present invention provides key experimental data for in-depth research on the changing rules of the electrical properties of self-supporting films under high voltage.

[0078] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A self-supporting thin film high voltage electric transport measuring device, characterized in that: The electrical transport measurement device comprises a diamond anvil and a micro-nano structure device constructed on the lower anvil surface of the diamond anvil; The micro-nano structure device includes an electrode circuit constructed with a self-supporting film as a structural material; as well as An electrode assembly connected to the electrode circuit for leading the electrode circuit out of the diamond anvil.

2. A self-supporting thin film high voltage electric transport measuring device according to claim 1, characterized in that: The self-supporting film is an oxide film.

3. A self-supporting thin film high voltage electric transport measuring device according to claim 1, characterized in that: The structure of the self-supporting film is a three-layer structure film protected by a ferroelectric interlayer.

4. A self-supporting thin film high voltage electric transport measuring device according to claim 1, characterized in that: The electrode circuit is constructed by first peeling the self-supporting film with a substrate from the substrate, then transferring the self-supporting film to the lower anvil surface of the diamond anvil, and finally performing thermal evaporation gold plating on the surface of the self-supporting film.

5. A method for preparing a self-supporting thin film high voltage electric transport measuring device according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) preparing a flat substrate, growing a sacrificial layer film on the substrate and growing a self-supporting film on the sacrificial layer film by pulsed laser deposition, separating the self-supporting film from the substrate by wet etching, and transferring the self-supporting film to the center of the lower anvil surface of a diamond anvil by thermal release polymer transfer technology; (2) The electrode circuit is constructed by thermal evaporation gold plating on the surface of the self-supporting film through micro-nano processing and electron beam etching technology, and the electrode assembly is connected to the electrode circuit to obtain a micro-nano structure device, thereby obtaining the self-supporting film high-voltage electric transport measurement device.

6. The method for preparing a self-supporting thin film high voltage electric transport measuring device according to claim 5, characterized in that: In the step (2), the specific process of transferring the self-supporting film to the center of the lower anvil surface of the diamond anvil by using the thermal release polymer transfer technology is as follows: First, polydimethylsiloxane is attached to the surface of the self-supporting film, and then one side of the self-supporting film is placed directly above the lower anvil surface of the diamond anvil. After heating, the viscosity of the polydimethylsiloxane is ineffective, and the self-supporting film is separated from the polydimethylsiloxane and transferred to the lower anvil surface of the diamond anvil.

7. A method for measuring electrical transport of a self-supporting film, characterized in that: Construct an electric transport measurement device as described in any one of claims 1 to 4, place the measurement device in a comprehensive physical property measurement system, use the comprehensive physical property measurement system to measure the electric transport properties of the self-supporting film, and obtain the electric transport measurement results of the self-supporting film.

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