High-stability silicon-based samarium nickelate memristor and preparation method thereof

Abstract

The invention relates to a high-stability silicon-based samarium nickelate memristor and a preparation method thereof. Comprising the following steps: (1) pretreating an N-type silicon substrate; (2) growing an amorphous samarium nickelate film on the N-type silicon substrate, and then depositing a palladium metal film on the amorphous samarium nickelate film to obtain the memristor based on the amorphous samarium nickelate; and (3) annealing the memristor based on the amorphous state samarium nickelate at 750-850 DEG C in an oxygen environment to obtain the silicon-based samarium nickelate memristor with high stability. According to the high-stability silicon-based samarium nickelate memristor provided by the invention, the N-type silicon is used as the substrate, and the samarium nickelate thin film is used as the resistive layer, so that the problems of high manufacturing cost and low application value of a perovskite substrate are effectively solved. The invention provides the preparation of the samarium nickelate memristor on the silicon substrate for the first time. And the problems of poor performance, instability and the like of the device caused by mismatching of the N-type silicon substrate and the samarium nickelate film crystal structure are solved through the annealing process.

Description

Technical Field

[0001] The invention belongs to the technical field of non-volatile memory, and particularly relates to a high-stability silicon-based samarium nickelate memristor and a preparation method thereof. Background Art

[0002] As an emerging device, memristor has the advantages of simple structure, low power consumption for reading and writing, high storage density, fast switching speed and compatibility with complementary metal semiconductor processes. It is considered to be the most promising new generation of non-volatile memory. In addition, in-depth research on the modulation of memristor performance will also contribute to the development of materials science, especially in the defects of oxide materials.

[0003] Memristors are usually composed of a two-terminal "metal / resistive functional layer / metal" sandwich structure. In the past few decades, various types of binary transition metal oxides, such as tantalum oxide, aluminum oxide, hafnium oxide, zinc oxide, titanium oxide, magnesium oxide, etc., have been used as the resistive functional layer of memristors due to their low cost, simple preparation, and excellent resistance switching behavior. Compared with binary oxides, perovskite oxides represented by samarium nickelate (SmNiO3) have more complex band structures and stronger electron-lattice correlations, and thus have more flexible electrical adjustability and greater potential in the preparation of high-performance memristors. In addition, compared with other oxides, the smaller oxygen vacancy formation energy of samarium nickelate also gives it an advantage in the preparation of oxygen vacancy-dominated memristor devices.

[0004] At present, most perovskite oxide-based memristors use single crystal films as functional layers. However, in the preparation of single crystal films, the lattice structures of the substrate and the film should be matched as much as possible to ensure high-quality epitaxial growth of the film, thereby reducing the reduction in device reliability caused by stress and defects; but this also leads to the memristor device prepared with this material system as the functional layer being incompatible with the existing silicon-based CMOS process, greatly reducing its potential for large-scale market application. A feasible alternative is to prepare amorphous perovskite oxide films using silicon as a substrate. In literature reports, domestic and foreign researchers have studied the memristor properties of amorphous films in a few perovskite oxides such as strontium titanate (Journal: The Journal of Physical Chemistry Letters, 13 (2022): 884-893) and lanthanum strontium manganese oxide (Journal: Acs Applied Electronic Materials, 1 (2019): 675-683). However, to date, there have been few systematic studies on the performance regulation of amorphous perovskite oxide films and their memristor devices, and there are problems such as small switching window and poor stability. There has been no report on the research on amorphous samarium nickelate-based memristors.

[0005] Therefore, how to further improve the memristive properties of amorphous perovskite oxides in aspects such as switching window and stability is the key to realizing the application of this type of material in the storage field. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a highly stable silicon-based samarium nickelate memristor and a preparation method thereof. The present invention realizes effective regulation of the oxygen vacancy content in the resistive layer by performing a rapid annealing treatment on the silicon-based samarium nickelate memristor, and realizes controllable formation and breaking of oxygen vacancy conductive filaments by changing the distribution of oxygen vacancies, thereby greatly improving the storage characteristics and reliability of this type of memristor.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a high-stability silicon-based samarium nickel oxide memristor comprises the following steps:

[0009] (1) Pre-treating the N-type silicon substrate;

[0010] (2) firstly, an amorphous samarium nickelate film is grown on a pre-treated N-type silicon substrate by a pulsed laser deposition method; then, a palladium metal film is deposited on the amorphous samarium nickelate film by an electron beam evaporation method using a mask to obtain a memristor based on the amorphous samarium nickelate;

[0011] (3) Annealing the amorphous samarium nickelate-based memristor obtained in step (2) at 750-850° C. in an oxygen environment to obtain a highly stable silicon-based samarium nickelate memristor.

[0012] Preferably, in step (1), the pretreatment is as follows: the N-type silicon substrate is cleaned in sequence with acetone solution, ethanol solution, hydrofluoric acid solution and deionized water, and then dried with nitrogen gas.

[0013] Preferably, in step (2) of the present invention, the parameters of the pulsed laser deposition method are: laser power of 80 to 120 W, laser frequency of 2 to 8 Hz;

[0014] The process parameters for growing the amorphous samarium nickelate film are as follows: the growth time is 25 to 35 minutes, the substrate temperature is maintained at 600 to 700° C. during the growth process; oxygen is introduced during the growth process, and the oxygen gas pressure is 0.05 to 0.15 Pa; the thickness of the grown amorphous samarium nickelate film is 75 to 85 nm.

[0015] Further preferably, the parameters of the pulsed laser deposition method are: laser power is 100 W, laser frequency is 5 Hz;

[0016] The process parameters for growing the amorphous samarium nickelate film are as follows: the growth time is 30 minutes, the substrate temperature is maintained at 650° C. during the growth process; oxygen is introduced during the growth process, and the oxygen gas pressure is 0.1 Pa; the thickness of the grown amorphous samarium nickelate film is 80 nm.

[0017] Preferably, according to the present invention, in step (2), the mask is a circular mask with a diameter of 80 to 100 μm; and the thickness of the palladium metal film is 45 to 55 nm.

[0018] Further preferably, the diameter of the mask is 90 μm; and the thickness of the palladium metal film is 50 nm.

[0019] Preferably, according to the present invention, in step (3), the annealing parameters are: annealing temperature is 800° C., annealing time is 10 to 60 min, and oxygen flow rate is 8 L / min.

[0020] A highly stable silicon-based samarium nickel oxide memristor is prepared according to the method.

[0021] Preferably, according to the present invention, the high-stability silicon-based samarium nickelate memristor comprises, from bottom to top, an N-type silicon substrate electrode, a samarium nickelate resistive switching layer and a palladium upper conductive electrode.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Compared with existing perovskite oxides (such as strontium titanate, lanthanum strontium manganese oxide, etc.), samarium nickelate has a weaker chemical bond (Ni-O) and a smaller oxygen vacancy formation energy, and is prone to resistance transformation under specific conditions, making it a more ideal resistive material. However, in the conventional preparation method of samarium nickelate film, oxides with a perovskite structure (such as lanthanum aluminate, strontium titanate, etc.) are usually used as substrate materials, which are incompatible with existing silicon-based CMOS processes and have low application value. Therefore, the present invention selects an N-type silicon substrate to combine with it, and for the first time uses N-type silicon as a substrate and a samarium nickelate film as a resistive layer to prepare a silicon-based memristor. The silicon-based samarium nickelate memristor has the advantages of low cost, good compatibility with CMOS processes and high stability.

[0024] 2. The present invention achieves a highly repeatable method for regulating the change of oxygen vacancy content in the film by strictly controlling the temperature and time of rapid thermal annealing, and effectively regulates the oxygen vacancy content and distribution in the amorphous samarium nickelate film, thereby controlling the formation and breaking process of oxygen vacancy conductive filaments in the memristor device in a controllable manner, further improving the switching ratio and stability of the silicon-based samarium nickelate memristor.

[0025] 3. The high-stability silicon-based SmN memristor provided by the present invention with N-type silicon as substrate and SmN film as resistive switching layer effectively overcomes the problem of high cost and low application value of perovskite substrate. It is the first time to propose the preparation of SmN memristor on silicon substrate. And the present invention solves the defects of poor performance and instability caused by the mismatch of crystal structure between N-type silicon substrate and SmN film through annealing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the samarium nickel oxide silicon-based memristor according to Example 1 of the present invention.

[0027] Figure 2 1 is a logarithmic current-voltage curve of the samarium nickel oxide silicon-based memristor according to Example 1 of the present invention.

[0028] Figure 3 1 is a logarithmic current-voltage curve of the samarium nickel oxide silicon-based memristor according to Example 2 of the present invention.

[0029] Figure 4 1 is a high and low resistance state retention characteristic curve of the samarium nickel oxide silicon-based memristor according to embodiment 2 of the present invention.

[0030] Figure 5 This is the logarithmic current-voltage curve of the samarium nickel oxide silicon-based memristor in comparative example 1 of the present invention. DETAILED DESCRIPTION

[0031] In order to better understand the essence of the present invention, the present invention is further described below in conjunction with the embodiments, but they should not be regarded as limiting the present invention.

[0032] Materials and reagents involved in the examples are common commercially available products unless otherwise specified; experimental operations involved in the examples are performed according to routine operations in the art unless otherwise specified.

[0033] The current-voltage test described in this embodiment is performed according to a conventional method, and is implemented by applying a series of voltages to the memristor device using a conventional digital source meter (such as Keithley 2602B, etc.) at room temperature and measuring the corresponding current.

[0034] Example 1

[0035] A method for preparing a high-stability silicon-based samarium nickel oxide memristor comprises the following steps:

[0036] (1) using an acetone solution, an ethanol solution, a hydrofluoric acid solution and deionized water to clean the N-type silicon substrate in sequence, and drying it with nitrogen gas after cleaning to obtain a pretreated N-type silicon substrate;

[0037] (2) firstly growing an amorphous samarium nickelate thin film on a pretreated N-type silicon substrate by pulsed laser deposition;

[0038] The parameters of the pulsed laser deposition method are as follows: the laser power is 100W, the laser frequency is 5Hz; the time for growing the amorphous samarium nickelate film is 30min, and the substrate temperature is kept at 650℃ during the growth process; oxygen is introduced during the growth process, and the oxygen gas pressure is 0.1Pa. The thickness of the grown amorphous samarium nickelate film is 80nm;

[0039] Then, a circular mask with a diameter of 90 μm was used to deposit a 50 nm thick palladium metal film on the amorphous samarium nickelate film by electron beam evaporation to obtain a memristor based on the amorphous samarium nickelate.

[0040] (3) The amorphous samarium nickelate-based memristor obtained in step (2) is annealed at 800° C. in an oxygen environment for 10 min, with an oxygen flow rate of 8 L / min during the annealing process, to obtain a highly stable silicon-based samarium nickelate memristor.

[0041] The structure of the high-stability Si-based SMO memristor prepared in this embodiment is as follows: Figure 1 As shown, from bottom to top are the N-type silicon substrate electrode, the samarium nickelate resistive layer and the palladium upper conductive electrode.

[0042] The high stability Si-based SmNiO3 memristor prepared in this embodiment was subjected to a current-voltage test. The results are as follows: Figure 2 shown.

[0043] Example 2

[0044] A method for preparing a high-stability silicon-based samarium nickel oxide memristor comprises the following steps:

[0045] (1) using an acetone solution, an ethanol solution, a hydrofluoric acid solution and deionized water to clean the N-type silicon substrate in sequence, and drying it with nitrogen gas after cleaning to obtain a pretreated N-type silicon substrate;

[0046] (2) firstly growing an amorphous samarium nickelate thin film on a pretreated N-type silicon substrate by pulsed laser deposition;

[0047] The parameters of the pulsed laser deposition method are as follows: the laser power is 100W, the laser frequency is 5Hz; the time for growing the amorphous samarium nickelate film is 30min, and the substrate temperature is kept at 650℃ during the growth process; oxygen is introduced during the growth process, and the oxygen gas pressure is 0.1Pa. The thickness of the grown amorphous samarium nickelate film is 80nm;

[0048] Then, a circular mask with a diameter of 90 μm was used to deposit a 50 nm thick palladium metal film on the amorphous samarium nickelate film by electron beam evaporation to obtain a memristor based on the amorphous samarium nickelate.

[0049] (3) The amorphous samarium nickelate-based memristor obtained in step (2) is annealed at 800° C. in an oxygen environment for 60 min, with an oxygen flow rate of 8 L / min during the annealing process, to obtain a highly stable silicon-based samarium nickelate memristor.

[0050] The structure of the high-stability silicon-based samarium nickelate memristor prepared in this embodiment is the same as that in Embodiment 1, which comprises, from bottom to top, an N-type silicon substrate electrode, a samarium nickelate resistive switching layer, and a palladium upper conductive electrode.

[0051] The high stability Si-based SmNiO3 memristor prepared in this embodiment was subjected to a current-voltage test. The results are as follows: Figure 3 shown.

[0052] The high stability silicon-based samarium nickel oxide memristor prepared in this embodiment was subjected to a durability test, and the results are as follows: Figure 4 shown.

[0053] The specific test method is to first modulate the high-stability silicon-based samarium nickel oxide memristor prepared in this embodiment to a high (or low) resistance state, then use a smaller voltage (such as 1V) as a reading voltage, and then continuously measure the change of the device resistance value over time.

[0054] Comparative Example 1

[0055] A method for preparing a memristor based on amorphous samarium nickelate comprises the following steps:

[0056] (1) using an acetone solution, an ethanol solution, a hydrofluoric acid solution and deionized water to clean the N-type silicon substrate in sequence, and drying it with nitrogen gas after cleaning to obtain a pretreated N-type silicon substrate;

[0057] (2) firstly growing an amorphous samarium nickelate thin film on a pretreated N-type silicon substrate by pulsed laser deposition;

[0058] The parameters of the pulsed laser deposition method are as follows: the laser power is 100W, the laser frequency is 5Hz; the time for growing the amorphous samarium nickelate film is 30min, and the substrate temperature is kept at 650℃ during the growth process; oxygen is introduced during the growth process, and the oxygen gas pressure is 0.1Pa. The thickness of the grown amorphous samarium nickelate film is 80nm;

[0059] Then, a circular mask with a diameter of 90 μm was used to deposit a palladium metal film with a thickness of 50 nm on the amorphous samarium nickelate film by electron beam evaporation to obtain a memristor based on the amorphous samarium nickelate.

[0060] The current-voltage test was performed on the amorphous samarium nickelate memristor prepared in this comparative example. The results are as follows: Figure 5 shown.

[0061] Will Figure 2, Figure 3 and Figure 5 After comparing the data, it can be found that the resistivity of the memristor based on amorphous samarium nickelate prepared in Comparative Example 1 is lower, and it does not show two different resistance states of high / low under voltage regulation. This may be due to the presence of a large number of oxygen vacancies in the film, which makes it impossible to produce effective breakage of the conductive filaments.

[0062] Depend on Figure 4 It can be seen that the switching ratio of the SMO Si-based memristor after 60 minutes of annealing in Example 2 is as high as 253. The larger switching ratio is not only conducive to improving the read reliability of the memory, but also conducive to the realization of multi-value storage, thereby significantly improving the storage density. In addition, the high and low resistance values ​​of the SMO Si-based memristor did not fluctuate significantly during the scanning time of 1000s, indicating that it has good stability and durability.

[0063] In summary, compared with the amorphous samarium nickelate-based memristor prepared in Comparative Example 1, Example 1 successfully induced two different resistance states in the amorphous samarium nickelate device by reducing the oxygen vacancy content in the film through annealing treatment.

[0064] Compared with Comparative Example 1 and Example 1, Example 2 further reduces the oxygen vacancy content in the film by extending the time of rapid thermal annealing, so that the storage window of the amorphous samarium nickelate memristor is significantly increased, and an excellent performance of a high-to-low resistance state ratio of 253 is obtained. That is, the present invention strictly controls the temperature and time of rapid thermal annealing to achieve a highly repeatable method for regulating the change of oxygen vacancy content in the film, and effectively regulates the oxygen vacancy content and distribution in the amorphous samarium nickelate film, realizes the formation and fracture process of oxygen vacancy conductive filaments in the memristor device in a controllable manner, and further improves the switching ratio and stability of the silicon-based samarium nickelate memristor.

[0065] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention.

Claims

1. A method for preparing a high-stability samarium nickel oxide silicon-based memristor, characterized in that: The steps include: (1) Pre-treating the N-type silicon substrate; (2) firstly, an amorphous samarium nickelate film is grown on a pre-treated N-type silicon substrate by a pulsed laser deposition method; then, a palladium metal film is deposited on the amorphous samarium nickelate film by an electron beam evaporation method using a mask to obtain a memristor based on the amorphous samarium nickelate; (3) Annealing the amorphous samarium nickelate-based memristor obtained in step (2) at 750-850° C. in an oxygen environment to obtain a highly stable silicon-based samarium nickelate memristor.

2. The preparation method according to claim 1, characterized in that In step (1), the pretreatment specifically comprises: using acetone solution, ethanol solution, hydrofluoric acid solution and deionized water to clean the N-type silicon substrate in sequence, and then blowing it dry with nitrogen gas after cleaning.

3. The preparation method according to claim 1, characterized in that: In step (2), the parameters of the pulsed laser deposition method are: laser power of 80 to 120 W, laser frequency of 2 to 8 Hz; The process parameters for growing the amorphous samarium nickelate film are as follows: the growth time is 25 to 35 minutes, the substrate temperature is maintained at 600 to 700° C. during the growth process; oxygen is introduced during the growth process, and the oxygen gas pressure is 0.05 to 0.15 Pa; the thickness of the grown amorphous samarium nickelate film is 75 to 85 nm.

4. The preparation method according to claim 3, characterized in that: The parameters of the pulsed laser deposition method are: laser power of 100 W, laser frequency of 5 Hz; The process parameters for growing the amorphous samarium nickelate film are as follows: the growth time is 30 minutes, the substrate temperature is maintained at 650° C. during the growth process; oxygen is introduced during the growth process, and the oxygen gas pressure is 0.1 Pa; the thickness of the grown amorphous samarium nickelate film is 80 nm.

5. The preparation method according to claim 1, characterized in that: In step (2), the mask is a circular mask with a diameter of 80 to 100 μm; and the thickness of the palladium metal film is 45 to 55 nm.

6. The preparation method according to claim 5, characterized in that: The diameter of the mask is 90 μm; the thickness of the palladium metal film is 50 nm.

7. The preparation method according to claim 1, characterized in that: In step (3), the annealing parameters are: annealing temperature is 800° C., annealing time is 10 to 60 min, and oxygen flow rate is 8 L / min.

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