A method for preparing Ge3Te7 amorphous germanium telluride nanoparticles

Abstract

The invention relates to a method for preparing amorphous germanium telluride nanoparticles. The method comprises the following steps: mixing germanium halide, amide salt and sodium octanoate in a molar ratio of 1:(0-20):(0-10), dissolving the mixture in a mixed solution of tri-n-octylphosphine and nonanoic acid to obtain a germanium precursor, mixing a tellurium element with the tri-n-octylphosphine solution to obtain a tellurium precursor, vacuumizing the reaction system to remove oxygen and moisture, heating the reaction system within a temperature range of 60-110°C, introducing an inert gas into the reaction system, injecting the tellurium precursor into the germanium precursor in the reaction system within a temperature range of 250-280°C to react for 0.5-60 minutes, and rapidly cooling the reaction system to obtain amorphous germanium telluride nanoparticles.

Description

Technical Field

[0001] The invention relates to a method for preparing nanoparticles, in particular to a method for preparing amorphous germanium telluride nanoparticles. Background Art

[0002] With the rapid development of information technology, the demand for high-density, high-speed, and low-power storage devices is growing. The planar size miniaturization technology of traditional storage devices has gradually approached the physical limit and is difficult to meet the growing demand for information storage, marking that the chip industry has officially entered the "post-Moore era". In this context, phase change memory (PCM) is regarded as an important candidate for the next generation of non-volatile storage technology due to its excellent read and write speed, low power consumption, multi-level storage capability, and three-dimensional integration potential.

[0003] However, PCM still faces many challenges in practical applications, especially how to effectively suppress leakage current crosstalk in three-dimensional integration to improve storage density and overall performance. To this end, 3D X-Point storage technology came into being. Its core lies in the innovative combination of storage cells and gating cells, among which the selection of gating devices is crucial. Among many candidate materials, Ovonic Threshold Switching (OTS) stands out with its unique amorphous semiconductor properties, becoming one of the key technologies for 3D integration with PCRAM and commercialization.

[0004] The core mechanism of OTS devices lies in the reversible change of conductivity of amorphous materials under the action of electric fields. At room temperature, OTS materials behave as high-resistance insulators; when a sufficiently high voltage is applied, the material undergoes a phase change and transforms into a low-resistance conductive state. This phase change is non-permanent and can automatically recover to a high-resistance state after power is cut off. This feature gives OTS devices excellent electrical properties such as high drive current density, low leakage current, large switch selectivity ratio and fast switching speed.

[0005] In the research and development of OTS materials, Te-based compound systems, especially Ge-Te alloys, are favored due to their simple material composition, high current density and good thermal stability. Although Te-based OTS devices have shown excellent performance in many aspects, leakage current is still a major obstacle in their application.

[0006] In view of the performance limitations of current nano-sized OTS devices, such as complex material composition, high leakage current, and small switching ratio, the development of new nano-sized OTS materials has become the key. Compared with standard nanoelectronics manufacturing technology, chemical or physical synthesis of nanoparticles has attracted much attention due to its economy and convenience. However, there are few reports on the chemical synthesis of amorphous germanium telluride nanoparticles, and they have not yet been successfully applied to OTS materials, which provides a broad research space for further exploration and optimization of the nanoscale performance of OTS materials. Summary of the invention

[0007] The present invention provides a method for preparing the amorphous germanium telluride nanoparticles, comprising the following steps:

[0008] The germanium halide, amide salt and sodium octanoate are mixed in a molar ratio of 1:(0-20):(0-10), and dissolved in a mixed solution of tri-n-octylphosphine and nonanoic acid to obtain a germanium precursor;

[0009] Mixing tellurium element with tri-n-octylphosphine solution to obtain a tellurium precursor;

[0010] The reaction system is vacuumed to remove oxygen and moisture, and heated at a temperature range of 60-110°C;

[0011] Inert gas is introduced into the reaction system, and in the temperature range of 250-280° C., the tellurium precursor is injected into the germanium precursor in the reaction system to react for 0.5-60 minutes, and then the reaction system is rapidly cooled to obtain amorphous germanium telluride nanoparticles.

[0012] Preferably, the germanium halide is mixed with an amide salt and sodium octanoate in a molar ratio of 1: (0-20): (0-10), and dissolved in a mixed solution of tri-n-octylphosphine and nonanoic acid to obtain a germanium precursor. Specifically,

[0013] The germanium halide is mixed with amide salt and sodium octanoate in a molar ratio of 1:(0-20):(0-10), and nonanoic acid and / or tri-n-octylphosphine solution is added to promote dissolution.

[0014] Preferably, the germanium halide is GeI2 or GeCl2.

[0015] Preferably, the amide salt is lithium bis(trimethylsilylamide).

[0016] Preferably, the method for preparing amorphous germanium telluride nanoparticles is characterized in that the tellurium precursor is injected into the germanium precursor for reaction, and then rapidly cooled to obtain amorphous germanium telluride nanoparticles, comprising:

[0017] Injecting the tellurium precursor into the germanium precursor for reaction, and then rapidly cooling to form initial amorphous germanium telluride nanoparticles;

[0018] The final amorphous germanium telluride nanoparticles are obtained by centrifugation and washing with cyclohexane and / or alcohol solution.

[0019] Preferably, the centrifugal washing with cyclohexane and / or alcohol solution is specifically: centrifugal washing with a mixed solution of cyclohexane and alcohol, wherein the ratio of cyclohexane to alcohol is 1:1.

[0020] Preferably, the centrifugal washing with cyclohexane and / or alcohol solution comprises: centrifugal washing with cyclohexane and / or alcohol solution at least 3 times.

[0021] Preferably, the centrifugal washing with cyclohexane and / or alcohol solution to obtain the final amorphous germanium telluride nanoparticles is specifically: using cyclohexane and / or alcohol solution, centrifuging at a speed of 7830r / min for 3-4min, repeating the centrifugal washing 3-5 times, and finally obtaining amorphous germanium telluride nanoparticles.

[0022] Preferably, the rapid cooling to obtain the amorphous germanium telluride nanoparticles specifically includes: the solution changes from yellow to brown and then is rapidly cooled to obtain the amorphous germanium telluride nanoparticles.

[0023] Preferably, the solution changes from yellow to brown and then is rapidly cooled to obtain amorphous germanium telluride nanoparticles. Specifically, the solution changes from yellow to brown and then is rapidly cooled in an ice water bath to obtain amorphous germanium telluride nanoparticles.

[0024] The method for preparing crystalline germanium telluride nanoparticles provided in the embodiment of the present invention can achieve uniform nucleation, thereby ensuring the monodispersity of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings required for use in the description of the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0026] Figure 1 is an exemplary TEM image of amorphous Ge3Te7 nanoparticles provided by an embodiment of the present invention;

[0027] Figure 2 is an exemplary XRD image of amorphous Ge3Te7 nanoparticles provided in an embodiment of the present invention;

[0028] Figure 3 is an exemplary electron energy loss spectrum image of amorphous Ge3Te7 nanoparticles provided by an embodiment of the present invention;

[0029] Figure 4This is an exemplary IV image of an OTS device made of amorphous Ge3Te7 nanoparticles provided in an embodiment of the present invention;

[0030] Figure 5 is another exemplary TEM image of crystalline Ge3Te7 nanoparticles provided by an embodiment of the present invention;

[0031] Figure 6 This is another exemplary TEM image of amorphous Ge3Te7 nanoparticles provided in an embodiment of the present invention. Specific embodiments

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0034] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0035] Example 1

[0036] This embodiment describes in detail a specific method for preparing amorphous germanium telluride nanoparticles. First, GeI2 is selected as a germanium halide source, and is mixed with lithium bis(trimethylsilyl)amide (LiN(TMS)2) as an amide salt in a certain molar ratio. Specifically, the germanium halide, amide salt and sodium octanoate are mixed in a molar ratio of 1: (0-20): (0-10), and dissolved in a mixed solution of tri-n-octylphosphine and nonanoic acid in a volume ratio of 1: (2-20), for example, mixed in a molar ratio of 1: 5. The purpose is to obtain a stable and easy-to-control germanium precursor solution.

[0037] In a feasible implementation, an appropriate amount of nonanoic acid and / or tri-n-octylphosphine may be added as a solvent and a co-solvent to promote the dissolution of germanium halide and amide salt to form a uniform germanium precursor solution.

[0038] Next, high-purity tellurium is mixed with tri-n-octylphosphine (TOP) solution in a certain proportion to fully dissolve the tellurium in TOP to form a tellurium precursor solution. In this step, TOP not only acts as a solvent, but also stabilizes the tellurium precursor.

[0039] Subsequently, the reaction vessel containing the germanium precursor solution is strictly vacuumed to completely remove oxygen and moisture in the system to avoid adverse effects on subsequent reactions. Afterwards, the reaction system is heated at 60-110°C.

[0040] When the reaction system reaches the preset temperature, an inert gas (such as argon) is introduced to maintain the oxygen-free state of the reaction environment. Subsequently, the temperature is raised to 250-280°C, and at this temperature, the tellurium precursor solution is quickly injected into the germanium precursor solution. At this time, the two precursors react rapidly at high temperature to generate amorphous germanium telluride nanoparticles. The reaction time is controlled at 0.5-60 minutes to ensure that the reaction is fully carried out and the nanoparticles are uniform.

[0041] Step 1: Preparation of Ge precursor

[0042] First, accurately weigh 0.150 g of GeI2 as a germanium halide source, and weigh 0.05 g of amide salt and 0.100 g of sodium octanoate. Mix GeI2, amide salt, sodium octanoate with 10 mL of tri-n-octylphosphine (TOP) and 2 mL of nonanoic acid, and strictly vacuum the reaction system for 10-20 minutes to completely remove oxygen and moisture from the system to avoid adverse effects on subsequent reactions. Subsequently, heat the mixed solution at 60 ° C for a period of time to ensure that each component is fully dissolved in the solvent to form a uniform and stable germanium precursor solution.

[0043] Step 2: Preparation of Te precursor

[0044] 0.200 g of high-purity tellurium (Te) powder was mixed with 2 mL of TOP solution, and the reaction system was also vacuumed for 10-20 minutes to remove oxygen and moisture. Subsequently, the mixed solution was heated at a temperature range of 60-110°C to fully dissolve Te in TOP to form a uniform Te precursor solution.

[0045] Step 3: Synthesis of Ge3Te7 amorphous nanoparticles

[0046] Under the protection of inert gas of Ar gas (argon), the temperature of the reaction system is raised to 250-280°C. When the temperature reaches the set value, the Te precursor solution prepared in step 2 is quickly injected into the Ge precursor solution obtained in step 1 through a precise injection device. Under high temperature and inert gas atmosphere, the two precursors react rapidly, and the color of the solution gradually changes from light yellow to brown, indicating the formation of Ge3Te7 amorphous nanoparticles. The reaction time is controlled between 0.5-60 minutes to ensure that the reaction is fully carried out and the uniformity of the nanoparticles.

[0047] Step 4: Purification and collection of product

[0048] After the reaction is completed, the reaction product is transferred to a centrifuge tube and centrifuged and washed using a mixed solution of cyclohexane and ethanol in a volume ratio of 1:1. The centrifugal washing operation is repeated 3 times, each time at a speed of 7830r / min for 3-4 minutes. Through multiple centrifugal washings, impurities and unreacted precursors attached to the surface of the nanoparticles can be effectively removed, thereby improving the purity of the product. Finally, the centrifugal washing steps are repeated 3-5 times to obtain Ge3Te7 crystal nanoparticles with uniform dispersion and high purity.

[0049] After the reaction is completed, the reaction system is rapidly cooled to obtain amorphous germanium telluride nanoparticles. Further, pure amorphous germanium telluride nanoparticles can be obtained through centrifugation, washing, drying and other steps.

[0050] The method is based on thermodynamics and molecular dynamics, controls the amount of amide salt, nonanoic acid, sodium octanoate, tri-n-octylphosphine in the solvent, the reaction temperature and the reaction time, and prepares amorphous nanoparticles by hot injection. The precursor solution is quickly injected into the hot reaction solution using a syringe, so that the supersaturation of the solution increases instantly and uniform nucleation occurs, thereby ensuring the monodispersity of the product.

[0051] like Figure 1-4 As shown, the Ge3Te7 nanoparticles synthesized by the above method have uniform morphology and particle size and good dispersibility. And they can be used as OTS gating materials in semiconductor devices.

[0052] Example 2

[0053] After the amorphous germanium telluride nanoparticles are successfully prepared, a centrifugal washing method is used to further improve their purity and dispersibility. The specific operation is as follows: First, the mixed solution obtained after the reaction is quickly cooled to room temperature. At this time, the color of the solution changes from yellow to brown, indicating the initial formation of amorphous germanium telluride nanoparticles. Subsequently, the mixed solution is transferred to a centrifuge tube, a certain volume of cyclohexane and alcohol mixed solution (for example, a ratio of 1:1) is added, and centrifugal treatment is performed at a speed of 7830r / min for 3-4 minutes. Repeat the centrifugal washing 3-5 times to obtain amorphous germanium telluride nanoparticles with uniform dispersion.

[0054] In order to completely remove impurities and unreacted precursors attached to the surface of the nanoparticles, the above steps were repeated at least three times.

[0055] To further optimize the preparation process of amorphous germanium telluride nanoparticles, an ice-water bath was tried for rapid cooling. After the reaction solution completely changed from yellow to brown, the reaction vessel was immediately placed in a pre-cooled ice-water bath to ensure that the solution was quickly cooled to below room temperature in a very short time. This method uses a cold water bath as a rapid cooling method, which can efficiently and uniformly cool the reaction solution, achieve ultrafast thermodynamic control, avoid grain inhomogeneity, and inhibit crystal nucleation growth and particle crystallization.

[0056] The remaining steps are the same as those in Example 1.

[0057] Example 3: A method for preparing Ge3Te7 crystalline nanoparticles.

[0058] This embodiment describes in detail a specific method for preparing Ge3Te7 crystalline nanoparticles, which comprises the following steps:

[0059] Step 1: Preparation of Ge precursor

[0060] First, accurately weigh 0.150 g of GeI2 as a germanium halide source, and weigh 0.0 g of amide salt and 0.100 g of sodium octanoate (amide salt is not added in this example, but the ratio can be adjusted as needed in actual operation). Mix GeI2 and sodium octanoate with 10 mL of tri-n-octylphosphine (TOP) and 2 mL of nonanoic acid, and strictly vacuum the reaction system for 10-20 minutes to completely remove oxygen and moisture from the system to avoid adverse effects on subsequent reactions. Subsequently, heat the mixed solution at 60°C for a period of time to ensure that each component is fully dissolved in the solvent to form a uniform and stable germanium precursor solution.

[0061] Step 2: Preparation of Te precursor

[0062] 0.200 g of high-purity tellurium (Te) powder was mixed with 2 mL of TOP solution, and the reaction system was also vacuumed for 10-20 minutes to remove oxygen and moisture. Subsequently, the mixed solution was heated at a temperature range of 60-110°C to fully dissolve Te in TOP to form a uniform Te precursor solution.

[0063] Step 3: Synthesis of Ge3Te7 crystalline nanoparticles

[0064] In an inert gas atmosphere of Ar gas (argon), the temperature of the reaction system is raised to 250-280°C. When the temperature reaches the set value, the Te precursor solution prepared in step 2 is quickly injected into the Ge precursor solution obtained in step 1 through a precise injection device. At this time, the two precursors react rapidly at high temperature, and the color of the solution gradually changes from light yellow to brown, indicating the formation of Ge3Te7 crystalline nanoparticles. The reaction time is controlled between 0.5-60 minutes to ensure that the reaction is fully carried out and the uniformity of the nanoparticles.

[0065] Step 4: Purification and collection of product

[0066] After the reaction is completed, the reaction product is transferred to a centrifuge tube and centrifuged with a mixed solution of cyclohexane and ethanol (volume ratio of 1:1). The centrifugal washing operation is repeated 3 times, each time at a speed of 7830r / min for 3-4 minutes. Through centrifugal washing, impurities and unreacted precursors attached to the surface of the nanoparticles can be effectively removed, thereby improving the purity of the product. Finally, the centrifugal washing steps are repeated 3-5 times to obtain Ge3Te7 crystal nanoparticles with uniform dispersion and high purity.

[0067] Example 4: Another method for preparing Ge3Te7 amorphous nanoparticles

[0068] This embodiment specifically describes another method for preparing Ge3Te7 amorphous nanoparticles, which comprises the following steps:

[0069] Step 1: Preparation of Ge precursor

[0070] First, accurately weigh 0.15g of GeI2 as a germanium halide source, and weigh 0.1g of amide salt and an appropriate amount of sodium octanoate as a cosolvent. Add GeI2, amide salt and sodium octanoate to a mixed solution containing solvent tri-n-octylphosphine (TOP) and nonanoic acid to ensure that the components are fully mixed in the solvent. Subsequently, the reaction system is vacuumed for 10-20 minutes to completely remove oxygen and moisture in the system to prevent them from having an adverse effect on subsequent reactions. After the vacuuming is completed, the reaction system is heated to 60°C and maintained for a period of time to allow the components to fully react and form a stable Ge precursor solution.

[0071] Step 2: Preparation of Te precursor

[0072] 0.200g of high-purity tellurium (Te) powder was mixed with an appropriate amount of TOP solvent, and the reaction system was also vacuumed for 10-20 minutes to remove oxygen and moisture from the system. Subsequently, the mixed solution was heated at a temperature range of 60-110°C to fully dissolve the Te powder in TOP to form a uniform Te precursor solution.

[0073] Step 3: Synthesis of Ge3Te7 amorphous nanoparticles

[0074] Under the protection of inert gas of Ar gas (argon), the temperature of the reaction system is raised to 250-280°C. When the temperature reaches the set value, the Te precursor solution prepared in step 2 is quickly injected into the Ge precursor solution obtained in step 1 through a precise injection device. Under high temperature and inert gas atmosphere, the two precursors react rapidly, and the color of the solution gradually changes from light yellow to brown, indicating the formation of Ge3Te7 amorphous nanoparticles. The reaction time is controlled between 0.5-60 minutes to ensure that the reaction is fully carried out and the uniformity of the nanoparticles.

[0075] Step 4: Purification and collection of product

[0076] After the reaction is completed, the reaction product is transferred to a centrifuge tube and centrifuged and washed using a mixed solution of cyclohexane and ethanol in a volume ratio of 1:1. The centrifugal washing operation is repeated 3 times, each time at a speed of 7830r / min for 3-4 minutes. Through multiple centrifugal washings, impurities and unreacted precursors attached to the surface of the nanoparticles can be effectively removed, thereby improving the purity of the product. Finally, the centrifugal washing steps are repeated 3-5 times to obtain Ge3Te7 crystal nanoparticles with uniform dispersion and high purity.

[0077] like Figure 1-6As shown, the present invention finds that it is necessary to control the amount ratio of amide salt, nonanoic acid, tri-n-octylphosphine, sodium octanoate in the solvent, the reaction temperature and the reaction time to obtain pure amorphous germanium telluride product. The amount of amide salt affects its morphology and structure, and without adding amide, a crystalline germanium telluride product will be generated.

[0078] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are descriptive and exemplary, rather than restrictive terms. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above-mentioned embodiments are not limited to any of the foregoing details, but should be broadly interpreted within the spirit and scope defined by the appended claims. Therefore, all changes and modifications that fall within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A method for preparing Ge3Te7 amorphous germanium telluride nanoparticles, characterized in that: include: Step 1: weigh 0.150 g of GeI2 as a germanium halide source, and weigh 0.100 g of sodium octanoate and 0.05 g of amide salt, mix the GeI2, sodium octanoate, amide salt with 10 mL of tri-n-octylphosphine and 2 mL of nonanoic acid, and evacuate the reaction system for 10-20 minutes to completely remove oxygen and moisture from the system, and then heat the mixed solution at 60°C for a period of time to ensure that each component is fully dissolved in the solvent to form a uniform and stable germanium precursor solution of germanium; Step 2: 0.200 g of high-purity tellurium powder is mixed with 2 mL of tri-n-octylphosphine, and the reaction system is also vacuumed for 10-20 minutes to remove oxygen and moisture, and the mixed solution is heated at a temperature range of 60-110° C. to fully dissolve tellurium in tri-n-octylphosphine to form a uniform tellurium precursor solution; Step 3: In an inert gas atmosphere of argon, the temperature of the reaction system is raised to 250-280°C. When the temperature reaches the set value, the tellurium precursor solution prepared in step 2 is rapidly injected into the germanium precursor solution obtained in step 1 through a precise injection device. At this time, the two precursors react rapidly at high temperature. The reaction time is controlled between 0.5-60 minutes to ensure that the reaction is fully carried out and the uniformity of the nanoparticles is ensured. When the color of the solution gradually changes from light yellow to brown, Ge3Te7 crystal nanoparticles are formed; Step 4: After the reaction is completed, the reaction product is transferred to a centrifuge tube and centrifuged and washed with a mixed solution of cyclohexane and ethanol, wherein the volume ratio of cyclohexane to ethanol is 1:

1. The centrifugal washing operation is repeated 3 times, each time at a speed of 7830r / min for 3-4 minutes. Through centrifugal washing, impurities and unreacted precursors attached to the surface of the nanoparticles can be effectively removed to improve the purity of the product. The centrifugal washing steps are repeated 3-5 times to obtain Ge3Te7 crystalline nanoparticles with uniform dispersion and high purity. After the reaction is completed, the reaction system is rapidly cooled to obtain Ge3Te7 amorphous germanium telluride nanoparticles.

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