CN113328036B - Ag/[ SnS 2 /PMMA]/Cu low-power-consumption resistive random access memory and preparation method thereof - Google Patents

Abstract

Translated fromChinese

本发明涉及二维材料与器件技术领域，具体涉及一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器及其制备方法。其公开了一种水热法合成SnS₂六方结构纳米片，并将其与PMMA高分子材料复合制备SnS₂/PMMA薄膜，将复合薄膜作为阻变功能层材料制备Ag/[SnS₂/PMMA]/Cu阻变存储器的方法。其开关比约为10⁶，耐受性达到了10⁴，上述两项参数在二维材料阻变存储器中已达到较优水平的基础上，Set/Reset电压只有‑0.1V/0.14V，远低于现有技术制备出的RRAM,有利于其未来在可穿戴设备方面的应用，当器件从高阻转变为低阻时对应的Set电流为2.6×10^‑9A，Set功率仅为3.6×10^‑10W,因此器件的功耗极低。

The invention relates to the technical field of two-dimensional materials and devices, in particular to an Ag/[SnS₂ /PMMA]/Cu low power consumption resistive memory and a preparation method thereof. It discloses a hydrothermal method to synthesize SnS₂ hexagonal structure nanosheets, compound it with PMMA polymer material to prepare SnS₂ /PMMA thin film, and use the composite thin film as a resistive functional layer material to prepare Ag/[SnS₂ /PMMA] /Cu resistive memory method. Its on-off ratio is about 10⁶ , and its tolerance reaches 10⁴ . On the basis that the above two parameters have reached a better level in 2D material resistive memory, the Set/Reset voltage is only ‑0.1V/0.14V, which is far It is lower than the RRAM prepared by the existing technology, which is beneficial to its application in wearable devices in the future. When the device changes from high resistance to low resistance, the corresponding Set current is 2.6×10^‑9 A, and the Set power is only 3.6× 10^‑10 W, so the power consumption of the device is extremely low.

Description

Translated fromChinese

一种Ag/[SnS2/PMMA]/Cu低功耗阻变存储器及其制备方法A kind of Ag/[SnS2/PMMA]/Cu low-power resistive memory and its preparation method

技术领域technical field

本发明涉及二维材料与器件技术领域，具体涉及一种Ag/[SnS₂/PMMA]/Cu 低功耗阻变存储器及其制备方法。The invention relates to the technical field of two-dimensional materials and devices, in particular to an Ag/[SnS₂ /PMMA]/Cu low-power resistive memory and a preparation method thereof.

背景技术Background technique

随着电子信息行业的快速发展，低成本、高性能、非易失性存储器在电子器件和逻辑存储单元中的应用需求越来越大，而传统的硅基信息存储技术面临着理论与物理上的限制。With the rapid development of the electronic information industry, the application requirements of low-cost, high-performance, non-volatile memory in electronic devices and logic storage units are increasing, while the traditional silicon-based information storage technology faces theoretical and physical challenges. limits.

在众多类型的非易失性存储器中，阻变存储器(Resistive Random AccessMemory,RRAM)具有耐受性好、密度高、写入速度快、保持时间长、工作电压低等优点，成为了下一代信息存储设备的理想替代品。寻找合适的功能材料来改善RRAM的存储特性是一个重要的研究领域。Among many types of non-volatile memory, resistive random access memory (RRAM) has the advantages of good endurance, high density, fast writing speed, long retention time, and low operating voltage, and has become the next generation of information technology. Ideal replacement for storage devices. Finding suitable functional materials to improve the storage properties of RRAM is an important research area.

绝缘过渡金属氧化物是最常见的阻变材料，但是因为其柔韧性差，因此不利于应用在柔性器件领域。二维材料由于其柔性、超薄、具有晶体结构等特点，在过去十几年的研究表现出了独特的电学、化学、力学和物理性能。二维材料，如石墨烯、氧化石墨烯、还原氧化石墨烯、过渡金属二卤化物和MXenes已经被引入作为阻变层，在柔性或刚性衬底上制备RRAM器件。尽管基于二维材料的RRAM器件表现出了优异的性能，但是实现一种具有所有参数均优异的功能性记忆材料仍然是一项具有挑战性的工作。功能层的复合是提高其性能的有效途径之一，与石墨烯、GO、RGO、TaOx、MoS₂等单活性层相比，基于复合功能层的RRAM性能得到了较大幅度的提高。Insulating transition metal oxides are the most common resistive switching materials, but because of their poor flexibility, they are not conducive to application in the field of flexible devices. Due to its flexibility, ultra-thin, and crystal structure, two-dimensional materials have shown unique electrical, chemical, mechanical, and physical properties in the past ten years of research. Two-dimensional materials such as graphene, graphene oxide, reduced graphene oxide, transition metal dichalcogenides, and MXenes have been introduced as resistive switching layers to fabricate RRAM devices on flexible or rigid substrates. Although RRAM devices based on 2D materials have shown excellent performance, it is still a challenging work to realize a functional memory material with excellent performance in all parameters. Combination of functional layers is one of the effective ways to improve its performance. Compared with single active layers such as graphene, GO, RGO, TaOx, and MoS2, the performance of RRAM based_on composite functional layers has been greatly improved.

商用柔性可穿戴器件的发展需要较低的RRAM工作电压。为了推进可穿戴技术的应用，需要电源电压小于1V的RRAM。然而，当开关比大于10⁶、耐受性大于10⁴且Set电流小于10^-8A时，几乎所有基于绝缘过渡金属氧化物和二维材料的RRAM的Set都高于1V。The development of commercial flexible wearable devices requires lower RRAM operating voltage. In order to advance the application of wearable technology, RRAM with supply voltage less than 1V is required. However, the Set of almost all RRAMs based on insulating transition metal oxides and 2D materials is higher than 1 V when the on-off ratio is greater than 10⁶ , the endurance is greater than 10⁴ , and the Set current is less than 10⁻⁸ A.

调节限制电流可以改变阻变存储器导通时的低阻值，从而实现RRAM的多级存储特性。如果器件的开关比较低，调控低阻值的范围就越窄，所以高开关比的RRAM将有利于实现多级存储功能。然而，当Set电压小于1V、耐受性大于10⁴、Set电流小于10^-8A且限制电流调控开关比的变化范围大于5×10²时，几乎所有基于绝缘过渡金属氧化物和二维材料的RRAM的开关比都小于10⁶。Adjusting the limiting current can change the low resistance value of the RRAM when it is turned on, thereby realizing the multi-level storage characteristics of the RRAM. If the switching ratio of the device is relatively low, the range of adjusting the low resistance value will be narrower, so RRAM with high switching ratio will be beneficial to realize multi-level storage function. However, when the Set voltage is less than 1V, the tolerance is greater than 10⁴ , the Set current is less than 10^-8 A, and the variation range of the limiting current regulation switching ratio is greater than 5×10² , almost all insulating transition metal oxides and two-dimensional materials based on The on-off ratios of the RRAMs are less than 10⁶ .

发明内容Contents of the invention

有鉴于此，本发明提供一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器及其制备方法，其制备出的阻变存储器具有低操作电压、低功耗、高耐受性、高开关比的特点。In view of this, the present invention provides a Ag/[SnS₂ /PMMA]/Cu low-power resistive memory and a preparation method thereof, and the prepared resistive memory has low operating voltage, low power consumption, and high tolerance , High switching ratio characteristics.

为解决现有技术存在的问题，本发明的技术方案是：一种 Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器，其特征在于：所述Ag/[SnS₂/PMMA]/Cu 阻变存储器包括自下而上依次设置的衬底、底电极、阻变层和顶电极。In order to solve the problems existing in the prior art, the technical solution of the present invention is: an Ag/[SnS₂ /PMMA]/Cu low-power resistive memory, characterized in that: said Ag/[SnS₂ /PMMA]/ The Cu resistive variable memory includes a substrate, a bottom electrode, a resistive variable layer and a top electrode arranged sequentially from bottom to top.

进一步，衬底为玻璃衬底。Further, the substrate is a glass substrate.

进一步，底电极为Ag，电极的厚度为100～300nm；顶电极为Cu，电极的厚度为100～300nm，直径250μm。Further, the bottom electrode is Ag, and the thickness of the electrode is 100-300 nm; the top electrode is Cu, and the thickness of the electrode is 100-300 nm, and the diameter of the electrode is 250 μm.

进一步，阻变层材料为SnS₂/PMMA复合薄膜。Further, the material of the resistance variable layer is a composite film of SnS₂ /PMMA.

一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法，其特征在于：所述的方法步骤为：A preparation method of Ag/[SnS₂ /PMMA]/Cu low-power resistive memory, characterized in that: the method steps are:

1)将硫代乙酰胺、五水四氯化锡溶解在去离子水中，滴加冰乙酸，搅拌均匀直至形成透明溶液后放入反应釜内；1) Dissolve thioacetamide and tin tetrachloride pentahydrate in deionized water, add glacial acetic acid dropwise, stir evenly until a transparent solution is formed, and then put it into the reaction kettle;

2)维持反应釜温度150～200℃，进行水热反应6～24h；2) Maintain the temperature of the reactor at 150-200°C, and carry out the hydrothermal reaction for 6-24 hours;

3)反应结束后，将产物用无水乙醇、去离子水分别清洗3-5次，然后80℃恒温烘干，得到产物SnS₂；3) After the reaction is finished, the product is washed with absolute ethanol and deionized water for 3-5 times, and then dried at a constant temperature of 80° C. to obtain the product SnS₂ ;

4)称取步骤3)制得的1～2g SnS₂加入10～100mL的N-N二甲基甲酰胺中，采用超声法制备SnS₂悬浮液；4) Weighing_1-2 g of SnS2 prepared in step₃ ) and adding it to 10-100 mL of NN dimethylformamide, and preparing SnS2 suspension by ultrasonic method;

5)采用真空蒸发镀膜法在玻璃衬底上蒸镀厚度为100～300nm的Ag底电极；5) Evaporating an Ag bottom electrode with a thickness of 100-300 nm on the glass substrate by vacuum evaporation coating method;

6)将步骤4)制得的SnS₂悬浮液采用真空抽滤法在底电极上制备SnS₂薄膜，并采用旋转涂胶法在SnS₂薄膜表面旋涂一层PMMA；6) the SnS2 suspension prepared in step₄ ) is prepared on the bottom electrode by a vacuum filtration method to prepare a SnS2 film, and a layer of PMMA is spin_- coated on the surface of the SnS2 film by a spin coating method_;

7)在PMMA薄膜上表面真空蒸镀直径250μm、厚度100～300nm的Cu 作为顶电极。7) Vacuum-deposit Cu with a diameter of 250 μm and a thickness of 100-300 nm on the upper surface of the PMMA film as the top electrode.

进一步，步骤1)中五水四氯化锡与硫代乙酰胺的摩尔比为1:2.5，去离子水体积为50～150mL，冰乙酸体积为1～10mL。Further, in step 1), the molar ratio of tin tetrachloride pentahydrate to thioacetamide is 1:2.5, the volume of deionized water is 50-150 mL, and the volume of glacial acetic acid is 1-10 mL.

进一步，步骤4)中超声法的时间为1～4h，超声功率为150～250W。Further, the ultrasonic method in step 4) takes 1-4 hours, and the ultrasonic power is 150-250W.

进一步，步骤5)中真空蒸发镀膜法的条件为：蒸镀速率为

本底真空小于5×10^-4Pa、蒸镀功率为130～160W。Further, in step 5), the condition of the vacuum evaporation coating method is: the evaporation rate is

The background vacuum is less than 5×10^-4 Pa, and the evaporation power is 130-160W.

进一步，步骤6)中SnS₂悬浮液体积为0.5～3ml，旋转涂胶法的转速为4000 ～8000rpm，旋涂时间为60～120s。Further, in step 6), the volume of the SnS₂ suspension is 0.5-3ml, the rotational speed of the spin-coating method is 4000-8000rpm, and the spin-coating time is 60-120s.

进一步，步骤7)中，所述真空蒸镀的条件为：蒸镀速率为

本底真空小于5×10^-4Pa、蒸镀功率为160～190W。Further, in step 7), the conditions of the vacuum evaporation are: the evaporation rate is

The background vacuum is less than 5×10^-4 Pa, and the evaporation power is 160-190W.

与现有技术相比，本发明的优点如下：Compared with prior art, advantage of the present invention is as follows:

1)本发明采用水热法制备的SnS₂作为阻变材料制备Ag/[SnS₂/PMMA]/Cu 阻变存储器，开关比约为10⁶，耐受性达到了10⁴，这两项参数在二维材料阻变存储器中已达到较优水平的基础上，Set/Reset电压只有0.14V/-0.1V，远低于现有技术制备出的RRAM，有利于其未来在可穿戴设备方面的应用；当器件从高阻态转变为低阻态时对应的Set电流为2.6×10^-9A，Set功率仅为3.6×10^-10W，说明器件的功耗极低。1) In the present invention, SnS₂ prepared by hydrothermal method is used as the resistive switch material to prepare Ag/[SnS₂ /PMMA]/Cu resistive switch memory, the switch ratio is about 10⁶ , and the tolerance reaches 10⁴ . These two parameters On the basis that the two-dimensional material resistive variable memory has reached a better level, the Set/Reset voltage is only 0.14V/-0.1V, which is far lower than the RRAM prepared by the existing technology, which is conducive to its future development in wearable devices. Application; when the device changes from a high-resistance state to a low-resistance state, the corresponding Set current is 2.6×10^-9A , and the Set power is only 3.6×10^-10 W, indicating that the power consumption of the device is extremely low.

2)本发明利用Ag/[SnS₂/PMMA]/Cu阻变存储器表现出的高开关比，通过限制电流改变器件的低阻值，调控开关比的变化范围高达5×10²，可以较好的实现多级存储功能；2) The present invention utilizes the high switching ratio exhibited by the Ag/[SnS₂ /PMMA]/Cu resistive variable memory, changes the low resistance value of the device by limiting the current, and regulates the variation range of the switching ratio up to 5×10² , which can be better The realization of multi-level storage function;

3)本发明将SnS₂与PMMA形成复合功能层制备Ag/[SnS₂/PMMA]/Cu阻变存储器，SnS₂薄膜中SnS₂纳米片之间存在空隙，蒸镀顶部Cu电极时Cu沿空隙沉积，造成顶部Cu电极与底部Ag电极贯通，SnS₂层上旋涂上PMMA层后，PMMA层可将SnS₂层封装在衬底上，阻断了SnS₂层与外界的接触，不仅防止了顶部Cu电极蒸镀时其与底部Ag电极的贯通，也提高了阻变存储器的耐受性。3) In the present invention, SnS₂ and PMMA form a composite functional layer to prepare Ag/[SnS₂ /PMMA]/Cu resistive memory, there are gaps between SnS₂ nanosheets in the SnS₂ film, and Cu along the gap when the top Cu electrode is evaporated Deposition, causing the top Cu electrode and the bottom Ag electrode to penetrate, after the PMMA layer is spin-coated on the SnS₂ layer, the PMMA layer can encapsulate the SnS₂ layer on the substrate, blocking the contact between the SnS₂ layer and the outside world, not only preventing The penetration of the top Cu electrode and the bottom Ag electrode during evaporation also improves the resistance of the RRAM.

附图说明：Description of drawings:

图1是实施例1中合成的SnS₂纳米片在扫描电镜(SEM)和透射电镜(TEM) 下的形貌和结构；图中(a)SEM,(b)TEM,(c)和(d)HRTEM；Fig. 1 is the morphology and the structure of the SnS synthesized in embodiment₁ nanosheets under scanning electron microscope (SEM) and transmission electron microscope (TEM); Among the figure (a) SEM, (b) TEM, (c) and (d )HRTEM;

图2是实施例1中合成的SnS₂纳米片的XRD、EDX、XPS和拉曼光谱分析结果；图中(a)XRD,(b)和(c)XPS,(d)拉曼光谱；Fig. 2 is the XRD, EDX, XPS and Raman spectrum analysis result of the SnS synthesized in the embodiment₁ nanosheet; Among the figure (a) XRD, (b) and (c) XPS, (d) Raman spectrum;

图3是实施例1中Ag/[SnS₂/PMMA]/Cu阻变存储器的结构与性能；图中(a) 结构的示意图，(b)器件的侧切面SEM图，(c)I-V曲线，(d)正向双对数I-V曲线，(e)反向双对数I-V曲线，(f)高低阻值统计图；Fig. 3 is the structure and performance of Ag/[SnS₂ /PMMA]/Cu resistive memory inembodiment 1; Among the figure (a) the schematic diagram of structure, (b) the side section SEM picture of device, (c) IV curve, (d) forward double logarithmic IV curve, (e) reverse double logarithmic IV curve, (f) high and low resistance statistical chart;

图4是实施例1中Ag/[SnS₂/PMMA]/Cu阻变存储器的多级阻变特性；图中 (a)不同限制电流下的I-V曲线图，(b)不同限制电流下的高低阻值统计图；Fig. 4 is the multilevel resistive change characteristic of Ag/[SnS₂ /PMMA]/Cu resistive change memory inembodiment 1; Among the figure (a) IV curve figure under different limiting currents, (b) high and low under different limiting currents Resistance chart;

图5是实施例2中Ag/[SnS₂/PMMA]/Cu阻变存储器的阻变特性；图中(a)I-V 曲线图，(b)高低阻值统计图。Fig. 5 is the resistive switching characteristics of the Ag/[SnS₂ /PMMA]/Cu resistive memory in Example 2; in the figure (a) IV curve, (b) high and low resistance statistics.

具体实施方式Detailed ways

为了进一步理解本发明，下面结合实施例对本发明提供的技术方案进行详细说明，本发明的保护范围不受以下实施例的限制。In order to further understand the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with the examples, and the protection scope of the present invention is not limited by the following examples.

本发明一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器，如图3的(a)和(b)，包括自下而上依次设置的衬底、底电极、阻变层和顶电极；An Ag/[SnS₂ /PMMA]/Cu low-power resistive variable memory of the present invention, as shown in (a) and (b) of Figure 3, includes a substrate, a bottom electrode, and a resistive variable layer arranged in sequence from bottom to top and the top electrode;

上述衬底为玻璃衬底；底电极为Ag，电极的厚度为100～300nm；阻变层材料为SnS₂/PMMA复合薄膜；顶电极为Cu，电极的厚度为100～300nm，直径 250μm。The above substrate is a glass substrate; the bottom electrode is Ag, and the thickness of the electrode is 100-300nm; the material of the resistive layer is SnS₂ /PMMA composite film; the top electrode is Cu, the thickness of the electrode is 100-300nm, and the diameter is 250μm.

实施例1：Example 1:

一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法的步骤为：The steps of a preparation method of Ag/[SnS₂ /PMMA]/Cu low-power resistive memory are as follows:

1)称取5.0mmol的五水四氯化锡(SnCl₄·5H₂O)溶解在70mL的稀冰乙酸溶液(3mL冰乙酸+67mL去离子水)中，均匀搅拌；1) Dissolve 5.0 mmol of tin tetrachloride pentahydrate (SnCl₄ 5H₂ O) in 70 mL of dilute glacial acetic acid solution (3 mL of glacial acetic acid + 67 mL of deionized water), and stir evenly;

2)加入12.5mmol的硫代乙酰胺(CH₃CSNH₂)后继续搅拌10min，将搅拌好的透明溶液转移至100mL的聚四氟衬里的不锈钢高压反应釜内，密封好，放入电热恒温鼓风干燥箱中，180℃反应12h；2) After adding 12.5mmol of thioacetamide (CH₃ CSNH₂ ), continue to stir for 10 minutes, transfer the stirred transparent solution to a 100mL stainless steel autoclave with PTFE lining, seal it well, and put it into an electric heating constant temperature drum In an air drying oven, react at 180°C for 12 hours;

3)反应结束后自然冷却至室温，用去离子水和无水乙醇反复超声洗涤3次后离心，将样品在80℃的真空条件下烘干，即可得到SnS₂纳米片；3) Naturally cool to room temperature after the reaction, repeat ultrasonic washing with deionized water and absolute ethanol for 3 times, then centrifuge, and dry the sample under vacuum conditions at 80°C to obtain SnS₂ nanosheets;

4)称取1g SnS₂样品加入到100ml的N,N-二甲基甲酰胺中，采用超声法将SnS₂粉末分散制备SnS₂悬浮液，超声时间3h、超声功率为250W；4) Weigh 1g of SnS₂ sample and add it to 100ml of N,N-dimethylformamide, and disperse the SnS₂ powder by ultrasonic method to prepare SnS₂ suspension, the ultrasonic time is 3h, and the ultrasonic power is 250W;

5)采用真空蒸发镀膜法在玻璃衬底上蒸镀厚度为220nm的Ag作为底电极，真空蒸镀条件为：蒸镀速率为

本底真空小于5×10^-4Pa、蒸镀功率为 140W；5) Ag with a thickness of 220nm is evaporated on the glass substrate by the vacuum evaporation coating method as the bottom electrode, and the vacuum evaporation conditions are: the evaporation rate is

The background vacuum is less than 5×10^-4 Pa, and the evaporation power is 140W;

6)取1ml的SnS₂悬浮液采用真空抽滤法在底电极上制备SnS₂阻变层薄膜，并采用旋转涂胶法在SnS₂薄膜表面在6000rpm转速和70s时间的条件下旋涂一层PMMA；₆ ) Take 1ml of the SnS2 suspension and prepare a SnS2 resistive layer film_on the bottom electrode by vacuum filtration, and spin coat a layer_on the surface of the SnS2 film under the conditions of 6000rpm and 70s by spin coating method PMMA;

7)在SnS₂/PMMA阻变层薄膜上采用真空抽滤法蒸镀直径250μm、厚度220nm 的Cu作为顶电极，真空蒸镀的条件为：蒸镀速率为

本底真空小于 5×10^-4Pa、蒸镀功率为180W。最后采用吉利时(keithely)4200-SCS半导体特性分析仪进行阻变特性测试，限制电流为1×10^-3A。7) On the SnS₂ /PMMA resistive layer film, Cu with a diameter of 250 μm and a thickness of 220 nm was evaporated as the top electrode by vacuum filtration method. The conditions of vacuum evaporation were: the evaporation rate was

The background vacuum is less than 5×10^-4 Pa, and the evaporation power is 180W. Finally, a keithely 4200-SCS semiconductor characteristic analyzer was used to test the resistive switching characteristics, and the limiting current was 1×10^-3 A.

本实施例提供制备低操作电压、高耐受性、高开关比的Ag/[SnS₂/PMMA]/Cu 阻变存储器的方法。为本发明的最优实施例，This embodiment provides a method for preparing an Ag/[SnS₂ /PMMA]/Cu RRAM with low operating voltage, high endurance, and high switching ratio. For the best embodiment of the present invention,

图1是实施例1中水热法制备的SnS₂粉体在扫描电镜(SEM)和透射电镜 (TEM)下的形貌和结构，可以看出制备的SnS₂粉体为边长等于20～50nm的六角形纳米片，层数约为15层(厚度约为10nm)，其原子结构为蜂窝状排列的 2H结构。Fig. 1 is the SnS prepared by the hydrothermal method in embodiment₁ The morphology and structure of the powder under the scanning electron microscope (SEM) and the transmission electron microscope (TEM), it can be seen that the prepared SnS_The powder has a side length equal to 20～ The 50nm hexagonal nanosheet has about 15 layers (thickness is about 10nm), and its atomic structure is a 2H structure arranged in a honeycomb shape.

图2是实施例1中合成的SnS₂粉末的成分；通过图2(a)的XRD图谱，可以看出所制备SnS₂纳米片的主要衍射峰与标准卡中的六方结构SnS₂(JCPDS No.23-0677)的相一致，这表明所制备SnS₂纳米片具有六方结构。采用x光电子能谱(XPS)分析了所制备SnS₂纳米片的化学组成和键合结构，如图2(b)和(c) 所示。由于Sn元素强烈的自旋轨道分裂，Sn 3d_5/2和Sn3d_3/2两个主要能级峰分别位于486.59eV和495.03eV，见图2(b)，图中两个主要能级峰之差表示Sn 的自旋轨道分裂能，可以算出Sn的自旋轨道分裂能为8.44eV，是SnS₂中Sn⁴⁺轨道的典型值。而S 2p_3/2和S 2p_1/2两个主要能级峰分别位于161.94eV和163.03 eV，见图2(c)，可以算出S的自旋轨道分裂能约为1.09eV。拉曼光谱可用于定量分析SnS₂纳米片的层数。一层、二层、三层、四层和块体SnS₂的A_1g拉曼频率分别为304.6、307.0、308.9、309.5和310.8cm^-1。图2(d)为所制备SnS₂纳米片的拉曼光谱，可以看出其拉曼光谱图上只在311.1cm^-1处出现了一个特征峰，这一特征峰应是SnS₂的A_1g峰。制备SnS₂纳米片的层数为15层左右，其 A_1g峰对应的拉曼频率与块体SnS₂的(310.8cm^-1)几乎完全相同。Fig.₂ is the composition of the SnS2 powder synthesized inembodiment 1; By the XRD pattern of Fig.₂ (a), it can be seen that the main diffraction peaks of the prepared SnS2 nanosheets are consistent with the hexagonal structure SnS2 in the standard card (JCPDS_No. 23-0677), which indicates that the as_- prepared SnS2 nanosheets have a hexagonal structure. The chemical composition and bonding structure of the as_- prepared SnS2 nanosheets were analyzed by x-ray photoelectron spectroscopy (XPS), as shown in Figure 2(b) and (c). Due to the strong spin-orbit splitting of the Sn element, the two main energy level peaks of Sn 3d_5/2 and Sn3d_3/2 are located at 486.59eV and 495.03eV, respectively, as shown in Figure 2(b). The difference between the two main energy level peaks in the figure is Indicates the spin-orbit splitting energy of Sn, and it can be calculated that the spin-orbit splitting energy of Sn is 8.44eV, which is a typical value of Sn⁴⁺ orbital in SnS₂ . The two main energy level peaks of S 2p_3/2 and S 2p_1/2 are located at 161.94eV and 163.03 eV, respectively, as shown in Figure 2(c), and the spin-orbit splitting energy of S can be calculated to be about 1.09eV. Raman spectroscopy can be used to quantitatively analyze the layer number of_SnS2 nanosheets. The A_1g Raman frequencies of one-layer, two-layer, three-layer, four-layer and bulk SnS₂ are 304.6, 307.0, 308.9, 309.5 and 310.8cm^-1 , respectively. Figure 2(d) is the Raman spectrum of the prepared SnS₂ nanosheets. It can be seen that there is only one characteristic peak at 311.1cm^-1 in the Raman spectrum, which should be the A_1g of SnS₂ peak. The number of layers for preparing SnS₂ nanosheets is about 15, and the Raman frequency corresponding to the A_1g peak is almost the same as that of bulk SnS₂ (310.8cm^-1 ).

本发明将水热法制备的SnS₂纳米片与PMMA薄膜进行复合形成SnS₂/PMMA复合薄膜作为阻变层，制备了Ag/[SnS₂/PMMA]/Cu阻变存储器。In the present invention, SnS₂ nanosheets prepared by a hydrothermal method are combined with PMMA films to form a SnS₂ /PMMA composite film as a resistive variable layer, and an Ag/[SnS₂ /PMMA]/Cu resistive variable memory is prepared.

图3是实施例1中RRAM的阻变特性。图3(a)为器件的示意图，器件从下至上分别是Ag电极、SnS₂薄膜、PMMA薄膜以及Cu电极。图3(b)是器件的侧切面SEM图，Ag/[SnS₂/PMMA]/CuAg电极的厚度约为250nm，SnS₂薄膜的厚度约为900nm、PMMA薄膜的厚度约为180nm，Cu电极的厚度约为250nm。图3(c) 为I-V曲线图，器件的Set电压为0.14V，Reset电压为-0.1V，操作电压远小于1V。器件从高阻转变为低阻时的Set电流为2.6×10^-9A，Set功率仅为 3.6×10^-10W,说明器件的功耗极低。图3(d)和(e)是正偏压区和负偏压区的双对数坐标I-V曲线图，Ag/[SnS₂/PMMA]/Cu阻变存储器的双对数坐标I–V曲线的斜率值～1，表明高阻态(HRS)与低阻态(LRS)的转换是由导电细丝模型控制的。图3(f)为高低阻值统计图，从图中可以看出其在高阻态(HRS)和低阻态(LRS)之间可以进行稳定的电阻切换。在约1×10⁴次开/关循环后，开/关电阻比基本保持稳定，约集中在1×10⁶左右。综合考虑器件的开关比、耐受性、功耗和Set/Reset电压,实施例1中的Ag/[SnS₂/PMMA]/Cu阻变存储器的综合性能十分优异。FIG. 3 is the resistive switching characteristic of the RRAM in the first embodiment. Figure 3(a) is a schematic diagram of the device, and the device is Ag electrode, SnS₂ film, PMMA film and Cu electrode from bottom to top. Figure 3(b) is a side-section SEM image of the device. The thickness of the Ag/[SnS₂ /PMMA]/CuAg electrode is about 250nm, the thickness of the SnS₂ film is about 900nm, and the thickness of the PMMA film is about 180nm. The thickness is about 250nm. Figure 3(c) is the IV curve. The Set voltage of the device is 0.14V, the Reset voltage is -0.1V, and the operating voltage is much less than 1V. When the device changes from high resistance to low resistance, the Set current is 2.6×10^-9 A, and the Set power is only 3.6×10^-10 W, indicating that the power consumption of the device is extremely low. Figure 3(d) and (e) are the log-log coordinate IV curves of the positive bias region and the negative bias region, and the log-log coordinate I-V curve of the Ag/[SnS₂ /PMMA]/Cu resistive memory The slope value ~1 indicates that the transition from the high resistance state (HRS) to the low resistance state (LRS) is controlled by the conductive filament model. Figure 3(f) is a statistical diagram of high and low resistance values, from which it can be seen that it can perform stable resistance switching between the high resistance state (HRS) and the low resistance state (LRS). After about 1×10⁴ on/off cycles, the on/off resistance ratio remains basically stable, centered around 1×10⁶ . Comprehensively considering the switching ratio, tolerance, power consumption and Set/Reset voltage of the device, the comprehensive performance of the Ag/[SnS₂ /PMMA]/Cu resistive memory in Example 1 is very excellent.

将实施例1制备的阻变存储器采用吉利时(keithely)4200-SCS半导体特性分析仪进行阻变特性测试时限制电流的设置范围为1×10^-5～5×10^-3A。The setting range of the limiting current is 1×10^-5 to 5×10^-3 A when the resistive switching memory prepared in Example 1 is tested using a Keithely 4200-SCS semiconductor characteristic analyzer.

改变限制电流的大小可以调控RRAM低阻值，图5是实施例2中 Ag/[SnS₂/PMMA]/Cu阻变存储器的多级阻变特性，图5(a)是不同限制电流下的 I-V曲线图，可以看出器件在1×10^-5A、5×10^-4A、5×10^-3A限制电流条件下都表现出了良好的阻变存储特性，Set/Reset电压低。图5(b)是不同限制电流下的高低阻值统计图，可以看出器件在不同参数的限制电流下，未导通时的高阻值基本保持不变，而导通后的低阻值会发生改变。六个不同的低阻态仍然可以被明显的区分开，这说明了通过限制电流调控Ag/[SnS₂/PMMA]/Cu阻变存储器低阻值的可行性。最高限制电流(5×10^-3A)和最低限制电流(1×10^-5A)条件下，低阻值的比值约为5×10²，限制电流调控开关比的变化范围约为5×10²，可以较好的实现多级存储功能。Changing the size of the limiting current can regulate the low resistance value of RRAM, and Fig. 5 is the multi-level resistive switching characteristic of Ag/[SnS₂ /PMMA]/Cu resistive switching memory inembodiment 2, and Fig. 5 (a) is under different limiting currents From the IV curve, it can be seen that the device exhibits good resistive memory characteristics under the condition of 1×10^-5 A, 5×10^-4 A, and 5×10^-3 A limited current, and the Set/Reset voltage is low. Figure 5(b) is a statistical chart of high and low resistance values under different limiting currents. It can be seen that under the limiting current of different parameters, the high resistance value when the device is not turned on remains basically unchanged, while the low resistance value after the conduction There will be changes. Six different low-resistance states can still be clearly distinguished, which demonstrates the feasibility of regulating the low-resistance value of Ag/[SnS₂ /PMMA]/Cu RRAM by limiting the current. Under the conditions of the highest limiting current (5×10^-3 A) and the lowest limiting current (1×10^-5 A), the ratio of the low resistance value is about 5×10² , and the variation range of the limiting current control switching ratio is about 5× 10² , can better realize the multi-level storage function.

实施例2：Example 2:

一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法的步骤为：The steps of a preparation method of Ag/[SnS₂ /PMMA]/Cu low-power resistive memory are as follows:

1)称取8.0mmol的四氯化锡(SnCl₄·5H₂O)溶解在100mL的稀冰乙酸溶液(5mL冰乙酸+112mL去离子水)中，均匀搅拌；1) Dissolve 8.0 mmol of tin tetrachloride (SnCl₄ 5H₂ O) in 100 mL of dilute glacial acetic acid solution (5 mL of glacial acetic acid + 112 mL of deionized water), and stir evenly;

2)加入20mmol的硫代乙酰胺(CH₃CSNH₂)后继续搅拌10min，将搅拌好的透明溶液转移至150mL的聚四氟衬里的不锈钢高压反应釜内，密封好，放入电热恒温鼓风干燥箱中，190℃反应10h；2) After adding 20mmol of thioacetamide (CH₃ CSNH₂ ), continue to stir for 10 minutes, transfer the stirred transparent solution to a 150mL stainless steel autoclave lined with polytetrafluoroethylene, seal it well, and put it into an electric heating constant temperature blasting In a drying oven, react at 190°C for 10h;

3)反应结束后自然冷却至室温，用去离子水和无水乙醇反复超声洗涤5次后离心，将样品在80℃的真空条件下烘干，即可得到SnS₂纳米片；3) Naturally cool to room temperature after the reaction, ultrasonically wash with deionized water and absolute ethanol for 5 times, centrifuge, and dry the sample under vacuum at 80°C to obtain SnS₂ nanosheets;

4)称取1g SnS₂样品加入到100ml的N,N-二甲基甲酰胺中，采用超声法将SnS₂粉末分散制备SnS₂悬浮液，超声时间3h、超声功率为250W；4) Weigh 1g of SnS₂ sample and add it to 100ml of N,N-dimethylformamide, and disperse the SnS₂ powder by ultrasonic method to prepare SnS₂ suspension, the ultrasonic time is 3h, and the ultrasonic power is 250W;

5)采用真空蒸发镀膜法在玻璃衬底上蒸镀厚度为200nm的Ag作为底电极，真空蒸镀条件为：蒸镀速率为

本底真空小于5×10^-4Pa、蒸镀功率为150 W；5) The vacuum evaporation coating method is used to evaporate Ag with a thickness of 200nm on the glass substrate as the bottom electrode. The vacuum evaporation conditions are: the evaporation rate is

The background vacuum is less than 5×10^-4 Pa, and the evaporation power is 150 W;

6)取2ml的SnS₂悬浮液采用真空抽滤法在底电极上制备SnS₂阻变层薄膜。并采用旋转涂胶法在SnS₂薄膜表面在7000rpm转速和60s时间的条件下旋涂一层PMMA；6) Take 2ml of the SnS₂ suspension and prepare a SnS₂ resistive layer film on the bottom electrode by vacuum filtration. And adopt the spin-coating method to spin_- coat a layer of PMMA on the SnS2 film surface under the condition of 7000rpm rotating speed and 60s time;

7)在SnS₂/PMMA阻变层薄膜上采用真空抽滤法蒸镀直径250μm、厚度200nm 的Cu作为顶电极，真空蒸镀的条件为：蒸镀速率为

本底真空小于5×10^-4 Pa、蒸镀功率为170W。最后采用吉利时(keithely)4200-SCS半导体特性分析仪进行阻变特性测试，，限制电流为1×10^-3A。7) On the SnS₂ /PMMA resistive layer film, Cu with a diameter of 250 μm and a thickness of 200 nm was evaporated as the top electrode by vacuum filtration method. The conditions of vacuum evaporation were: the evaporation rate was

The background vacuum is less than 5×10^-4 Pa, and the evaporation power is 170W. Finally, a keithely 4200-SCS semiconductor characteristic analyzer is used to test the resistive switching characteristics, and the limiting current is 1×10^-3 A.

图5是实施例2中Ag/[SnS₂/PMMA]/Cu阻变存储器的阻变特性。图5(a) 为I-V曲线图，器件的Set电压为0.16V，Reset电压为-0.09v，操作电压远小于 1V。图5(b)为高低阻值统计图，从图中可以看出其在高阻态(HRS)和低阻态(LRS)之间可以进行稳定的电阻切换。在约1400次开/关循环后，开/关电阻比保持稳定。Ag/[SnS₂/PMMA]/Cu阻变存储器的高低阻开关比值在约为10⁶。FIG. 5 shows the resistive switching characteristics of the Ag/[SnS₂ /PMMA]/Cu resistive memory in Example 2. FIG. Figure 5(a) is the IV curve. The Set voltage of the device is 0.16V, the Reset voltage is -0.09v, and the operating voltage is far less than 1V. Figure 5(b) is a statistical diagram of high and low resistance values, from which it can be seen that it can perform stable resistance switching between the high resistance state (HRS) and the low resistance state (LRS). The on/off resistance ratio remained stable after about 1400 on/off cycles. The high-to-low resistance switching ratio of the Ag/[SnS₂ /PMMA]/Cu RRAM is about 10⁶ .

以上所述仅是本发明的优选实施例，并非用于限定本发明的保护范围，应当指出，对本技术领域的普通技术人员在不脱离本发明原理的前提下，对其进行若干改进与润饰，均应视为本发明的保护范围。The above is only a preferred embodiment of the present invention, and is not intended to limit the protection scope of the present invention. It should be pointed out that those skilled in the art can make some improvements and modifications to it without departing from the principles of the present invention. All should be regarded as the protection scope of the present invention.

Claims (6)

Translated fromChinese

1.一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法，其特征在于：所述Ag/[SnS₂/PMMA]/Cu阻变存储器包括自下而上依次设置的衬底、底电极、阻变层和顶电极；所述的衬底为玻璃衬底；所述的底电极为Ag，电极的厚度为100～300nm；顶电极为Cu，电极的厚度为100～300nm，直径250μm；所述的阻变层材料为SnS₂/PMMA复合薄膜；1. A preparation method of Ag/[SnS₂ /PMMA]/Cu low-power resistive variable memory, characterized in that: the Ag/[SnS₂ /PMMA]/Cu resistive variable memory includes sequentially setting from bottom to top The substrate, the bottom electrode, the resistive layer and the top electrode; the substrate is a glass substrate; the bottom electrode is Ag, and the thickness of the electrode is 100-300nm; the top electrode is Cu, and the thickness of the electrode is 100 nm. ~300nm, diameter 250μm; the material of the resistive layer is SnS₂ /PMMA composite film;所述的方法步骤为：Described method step is:1)将硫代乙酰胺、五水四氯化锡溶解在去离子水中，滴加冰乙酸，搅拌均匀直至形成透明溶液后放入反应釜内；1) Dissolve thioacetamide and tin tetrachloride pentahydrate in deionized water, add glacial acetic acid dropwise, stir evenly until a transparent solution is formed, and then put it into the reaction kettle;2)维持反应釜温度150～200℃，进行水热反应6～24h；2) Maintain the temperature of the reactor at 150-200°C, and carry out the hydrothermal reaction for 6-24 hours;3)反应结束后自然冷却至室温，用去离子水和无水乙醇反复超声洗涤3-5次后离心，将样品在80℃的真空条件下烘干，即可得到SnS₂纳米片；3) Naturally cool to room temperature after the reaction, repeat ultrasonic washing with deionized water and absolute ethanol for 3-5 times, then centrifuge, and dry the sample under vacuum conditions at 80°C to obtain SnS₂ nanosheets;4)称取步骤3)制得的1～2g SnS₂加入10～100mL的N-N二甲基甲酰胺中，采用超声法制备SnS₂悬浮液；4) Weighing_1-2 g of SnS2 prepared in step₃ ) and adding it to 10-100 mL of NN dimethylformamide, and preparing SnS2 suspension by ultrasonic method;5)采用真空蒸发镀膜法在玻璃衬底上蒸镀厚度为100～300nm的Ag底电极；5) Evaporating an Ag bottom electrode with a thickness of 100-300 nm on the glass substrate by vacuum evaporation coating method;6)将步骤4)制得的SnS₂悬浮液采用真空抽滤法在底电极上制备SnS₂薄膜，并采用旋转涂胶法在SnS₂薄膜表面旋涂一层PMMA；6) the SnS2 suspension prepared in step₄ ) is prepared on the bottom electrode by a vacuum filtration method to prepare a SnS2 film, and a layer of PMMA is spin_- coated on the surface of the SnS2 film by a spin coating method_;7)在PMMA薄膜上表面真空蒸镀直径250μm、厚度100～300nm的Cu作为顶电极。7) Vacuum-deposit Cu with a diameter of 250 μm and a thickness of 100-300 nm on the upper surface of the PMMA film as the top electrode.2.根据权利要求1所述的一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法，其特征在于：步骤1)中五水四氯化锡与硫代乙酰胺的摩尔比为1:2.5，去离子水体积为50～150mL，冰乙酸体积为1～10mL。2. the preparation method of a kind of Ag/[SnS₂ /PMMA]/Cu low power consumption resistive variable memory according to claim 1, is characterized in that: in step 1) tin tetrachloride pentahydrate and thioacetamide The molar ratio is 1:2.5, the volume of deionized water is 50-150mL, and the volume of glacial acetic acid is 1-10mL.3.根据权利要求1或2所述的一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法，其特征在于：步骤4)中超声法的时间为1～4h，超声功率为150～250W。3. A method for preparing Ag/[SnS₂ /PMMA]/Cu low-power resistive memory according to claim 1 or 2, characterized in that: the time of the ultrasonic method in step 4) is 1 to 4 hours, The ultrasonic power is 150-250W.4.根据权利要求3所述的一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法，其特征在于：步骤5)中真空蒸发镀膜法的条件为：蒸镀速率为

本底真空小于5×10^-4Pa、蒸镀功率为130～160W。4. the preparation method of a kind of Ag/[SnS₂ /PMMA]/Cu low power consumption resistive memory according to claim 3, is characterized in that: the condition of vacuum evaporation coating method in step 5) is: evaporation rate for

The background vacuum is less than 5×10^-4 Pa, and the evaporation power is 130-160W.5.根据权利要求4所述的一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法，其特征在于：步骤6)中SnS₂悬浮液体积为0.5～3mL，旋转涂胶法的转速为4000～8000rpm，旋涂时间为60～120s。5. A kind of preparation method of Ag/[SnS₂ /PMMA]/Cu low power consumption resistive memory according to claim 4, it is characterized in that: in step 6), the volume of SnS₂ suspension is 0.5～3mL, rotate The rotational speed of the gluing method is 4000-8000rpm, and the spin-coating time is 60-120s.6.根据权利要求5所述的一种Ag/[SnS₂/PMMA]/Cu低功耗阻变存储器的制备方法，其特征在于：步骤7)中，所述真空蒸镀的条件为：蒸镀速率为

本底真空小于5×10^-4Pa、蒸镀功率为160～190W。6. a kind of preparation method of Ag/[SnS₂ /PMMA]/Cu low power consumption resistive memory according to claim 5, it is characterized in that: in step 7), the condition of described vacuum evaporation is: evaporation Plating rate is

The background vacuum is less than 5×10^-4 Pa, and the evaporation power is 160-190W.

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