Tellurium nanowire preparation method based on chemical vapor deposition method and application thereof

Abstract

The invention discloses a tellurium nanowire preparation method based on a chemical vapor deposition method and application thereof, and belongs to the field of one-dimensional nano material preparation, the preparation method comprises the following steps: placing lead telluride powder in a source region of a chemical vapor deposition system, and placing a substrate in a downstream deposition region of the source region; vacuumizing the chemical vapor deposition system, and introducing inert protective gas; the source area is heated to the growth temperature, meanwhile, the temperature of a deposition area where the substrate is located is kept at a certain temperature, and heat preservation growth is carried out under the condition; and after the growth is finished, naturally cooling the chemical vapor deposition system, and obtaining the tellurium nanowire on the surface of the substrate. According to the method disclosed by the invention, the high-purity single-crystal Te nanowire can be directly and efficiently grown on the substrate.

Description

Technical Field

[0001] This invention relates to the field of one-dimensional nanomaterial preparation, and in particular to a method for preparing tellurium nanowires based on chemical vapor deposition and its application. Background Technology

[0002] Tellurium nanowires, as an important quasi-one-dimensional semiconductor material, have shown great application potential in thermoelectric conversion, photoelectric detection, gas sensing, and phase-change memory. Their unique helical chain-like crystal structure leads to significant anisotropy, resulting in excellent optoelectronic and thermoelectric properties.

[0003] Currently, common methods for preparing tellurium nanowires include hydrothermal methods, solution methods, template methods, and physical vapor deposition (PVD). However, these methods typically have limitations, such as complex processes, the need for organic surfactants leading to contamination, low product purity, or poor nanowire crystal quality. While chemical vapor deposition (CVD) can prepare high-quality nanowires, traditional CVD methods for preparing Te nanowires usually require high-purity elemental Te as the evaporation source. Elemental Te has extremely high vapor pressure at high temperatures, making precise control difficult, and the process is also costly.

[0004] Therefore, developing a new method that is simple, low-cost, and can obtain high-purity, high-crystallinity Te nanowires is of great scientific significance and industrial value. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for preparing tellurium nanowires based on chemical vapor deposition, in order to solve the problems in the prior art where the vapor pressure of elemental Te is extremely high at high temperatures, making it difficult to control precisely and resulting in high costs.

[0006] This invention is achieved through the following technical solution: a method for preparing tellurium nanowires based on chemical vapor deposition, comprising the following steps: S100, placing lead telluride powder in the source region of a chemical vapor deposition system, and placing a substrate in the downstream deposition region of the source region; S200, evacuating the chemical vapor deposition system, introducing an inert protective gas, and maintaining the working pressure within the system in the range of 1.0 Pa-10 Pa; S300, heating the source region to a growth temperature of 580 °C-620 °C, while maintaining the temperature of the deposition region where the substrate is located at 200 °C, and performing heat preservation growth under these conditions for 30-50 min; S400, after growth, allowing the chemical vapor deposition system to cool naturally, and obtaining tellurium nanowires on the surface of the substrate.

[0007] Furthermore, in S100, the distance between the substrate and the lead telluride powder in the source region is 10 cm to 20 cm.

[0008] Furthermore, the preparation method also includes a step of pre-treating the substrate after S100 and before S200: ultrasonically cleaning the substrate sequentially with acetone, ethanol and deionized water, and drying it with nitrogen gas.

[0009] Further, in S200, the vacuuming process specifically involves: activating a mechanical pump to evacuate the basic vacuum level of the chemical vapor deposition system to... Pa level.

[0010] Furthermore, in S200, the inert protective gas is argon, and the gas flow rate is 50 sccm-70 sccm.

[0011] Furthermore, in S300, the heating rate is 5 °C / min.

[0012] Furthermore, in S300, the growth temperature of the source region is 600 °C, and the growth time is 40 minutes.

[0013] Furthermore, in S400, the natural cooling is carried out while the inert protective gas is continuously introduced until the system temperature drops to room temperature.

[0014] Furthermore, the substrate is selected from silicon oxide wafers, quartz, glass, or sapphire; preferably a glass substrate.

[0015] In another aspect, the present invention provides a tellurium nanowire based on chemical vapor deposition, which is prepared according to the preparation method described above.

[0016] Another aspect of the present invention provides an application of tellurium nanowires based on chemical vapor deposition. Tellurium nanowires prepared according to the above steps have the following applications: (1) application in photoelectric detection; (2) application in thermoelectric conversion; (3) application in the preparation of gas sensors.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] 1. This invention utilizes the 'self-sacrificing template' effect of compound precursors and the principle of gas phase component separation to provide a new idea and technical path for the preparation of other single-element nanomaterials. The source material used in this invention is inexpensive. For the first time, commercial PbTe powder is used as a single precursor, which provides Te vapor and Pb catalyst through its own decomposition. There is no need to introduce additional elemental Te source or external metal catalyst, which significantly reduces the cost of raw materials and the complexity of the process.

[0019] 2. This invention adopts a one-step direct growth method, which utilizes the self-decomposition characteristics of the precursor to achieve in-situ catalyst formation, avoiding complex catalyst pre-preparation steps. By precisely controlling the temperature gradient between the source region and the deposition region, the system pressure, and the carrier gas flow rate, the diameter, length, and distribution density of the nanowires can be effectively controlled, which has the advantages of simplicity and outstanding controllability.

[0020] 3. The Te nanowires prepared by the present invention based on the VLS growth mechanism have a complete single crystal structure, are oriented along the

[001] direction, have high crystal purity, few defects and clean surface, which provides a material basis for their application in nanoscale thermoelectric converters, photodetectors and other devices, and the final crystal quality is excellent.

[0021] 4. This invention reveals an innovative pathway for VLS growth through autocatalysis using compound precursors. This 'self-supplying catalyst' mechanism provides new technical ideas and theoretical references for the controllable synthesis of other single-element nanomaterials, and its principle and mechanism have universal significance. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of the Te nanowire growth process provided in Embodiment 1 of the present invention.

[0024] Figure 2 This is a metallographic microscope image of Te nanowires on a silicon oxide substrate provided in Example 1 of the present invention.

[0025] Figure 3 This is a metallographic microscope image of Te nanowires on a glass slide substrate provided in Embodiment 2 of the present invention.

[0026] Figure 4 This is a metallographic microscope image of Te nanowires on a quartz substrate provided in Example 3 of the present invention.

[0027] Figure 5 This is a metallographic microscope image of Te nanowires on a sapphire substrate provided in Example 4 of the present invention.

[0028] Figure 6 Scanning electron microscope image provided for experimental examples of the present invention.

[0029] Figure 7 The energy dispersive X-ray spectrum analysis diagram provided for the experimental example of the present invention.

[0030] Figure 8 The SEM and EDS images of the Te nanowires provided for experimental examples of this invention are shown.

[0031] Figure 9 The Raman spectrum of the Te nanowires provided as an experimental example of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated herein by reference to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. The terms “comprising,” “including,” “having,” “containing,” etc., as used herein are open-ended terms, meaning that they include but are not limited to. Unless the context clearly indicates otherwise, the expressions “a” and “an” as used herein include plural references. It should be noted that “first,” “second,” etc., are used merely for convenience of description and distinction and should not be construed as indicating or implying relative importance. The term “about” as used herein indicates a range of ±20% of the following numerical value. In some embodiments, the term “about” indicates a range of ±10% of the following numerical value. In some embodiments, the term “about” indicates a range of ±5% of the following numerical value.

[0034] Example 1

[0035] This embodiment aims to illustrate the process of preparing high-purity, high-crystallinity tellurium nanowires on a silicon oxide substrate under the most optimized process parameters. Figure 1 A schematic diagram of the Te nanowire growth process in this embodiment is shown. As can be seen from the figure, this embodiment includes the following steps:

[0036] Step 1: Source Material and Substrate Preparation. Accurately weigh 100 mg of high-purity (99.99%) PbTe powder and place it in a clean corundum boat. Push the boat into the central high-temperature zone (source zone) of a dual-temperature zone tubular chemical vapor deposition (CVD) furnace. Select a 1 cm × 2 cm silicon oxide (SiO2 / Si) wafer as the substrate. Sonicately clean the substrate for 15 minutes each with acetone, anhydrous ethanol, and deionized water, then dry it with high-purity nitrogen. Place the cleaned substrate in another corundum boat and position it in the downstream low-temperature zone of the CVD furnace tube, 15 cm downstream of the source zone.

[0037] Step 2: System Sealing and Venting: Seal the flanges at both ends of the furnace tube, start the mechanical pump to evacuate the quartz furnace tube until the system background vacuum is better than [previous value]. .

[0038] Step 3: Growth Atmosphere Control: High-purity argon gas (99.999%) is introduced into the furnace tube as both carrier and protective gas. The gas flow rate is stabilized at 60 sccm using a mass flow controller (MFC). Simultaneously, the growth working pressure inside the furnace tube is dynamically stabilized at 1.0 Pa by adjusting the downstream valves.

[0039] Step 4: Heating and Growth: Set the program to heat the source region to 600 °C at a heating rate of 5 °C / min. Due to the natural thermal field distribution of the furnace, the temperature in the low-temperature region where the substrate is located stabilizes at approximately 200 °C. Under these conditions, maintain the temperature for 40 minutes to grow the nanowires.

[0040] Step 5: Cooling and Sampling: After growth, turn off the heating power and allow the furnace to cool naturally to room temperature under a protective atmosphere of continuously supplied argon gas (60 sccm). After cooling, turn off the gas source and vacuum pump, open the furnace tube, and remove the sample. It can be observed that a uniform silver-gray velvety film covers the surface of the silicon oxide substrate.

[0041] Figure 2 The image shown is a metallographic microscope image of the Te nanowires prepared in this embodiment on the silicon oxide substrate in this embodiment.

[0042] Example 2

[0043] This embodiment illustrates the process of fabricating tellurium nanowires on a glass substrate, which is a common glass slide.

[0044] Except for replacing the substrate with a regular glass slide (glass substrate), all other experimental steps and process parameters (such as the amount of source material, the distance between the source region and the substrate, the vacuum level, the argon flow rate, the working pressure, the heating program, the growth temperature and time, etc.) are exactly the same as in Example 1.

[0045] After growth, the sample was removed, and the resulting metallographic micrograph is shown below. Figure 3 As shown, optical microscopy revealed that a large number of dispersed tellurium nanowires were successfully grown on the glass substrate. Compared with other substrates, the individual nanowires grown on the glass substrate were longer, more dispersed, and had higher morphological quality.

[0046] Example 3

[0047] This embodiment illustrates the process of fabricating tellurium nanowires on a quartz substrate.

[0048] Except for replacing the substrate with a quartz sheet, all other experimental steps and process parameters in this embodiment are exactly the same as in Example 1.

[0049] After growth, the sample was removed, and the resulting metallographic micrograph is shown below. Figure 4 As shown in the optical microscope image, a cluster-like structure composed of a large number of tellurium nanowires has formed on the surface of the quartz substrate, with a high coverage density.

[0050] Example 4

[0051] This embodiment illustrates the process of fabricating tellurium nanowires on a sapphire substrate.

[0052] In this embodiment, the substrate is replaced with sapphire ( Except for the substrate, all other experimental steps and process parameters are exactly the same as in Example 1.

[0053] After growth, the sample was removed, and the resulting metallographic micrograph is shown below. Figure 5 As shown in the optical microscope images, high-density tellurium nanowires were also grown on the sapphire substrate surface, with morphology similar to that on the quartz substrate.

[0054] Example 5

[0055] To verify the performance of the scheme in Example 1 with different parameter ranges, this example adjusts the parameter range.

[0056] The specific process parameters are adjusted as follows:

[0057] Distance between source material and substrate: 10 cm;

[0058] Working pressure: 10 Pa;

[0059] Source region growth temperature: 580 °C;

[0060] Incubation period: 30 minutes.

[0061] All other conditions remained the same as in Example 1. After the experiment, SEM characterization confirmed that high-purity elemental tellurium nanowires were successfully obtained on the substrate. However, compared to Example 1, the average length of the nanowires was shorter and the density was slightly lower. This result demonstrates that the technical solution of this invention is still feasible within the parameter range given in this example.

[0062] Example 6

[0063] To verify the performance of the scheme in Example 1 with different parameter ranges, this example adjusts the parameter range.

[0064] The specific process parameters are adjusted as follows:

[0065] Distance between source material and substrate: 20 cm;

[0066] Operating pressure: maintained at 5.0 Pa;

[0067] Source region growth temperature: 620 °C;

[0068] Incubation period: 50 minutes.

[0069] All other conditions remained the same as in Example 1. After the experiment, SEM characterization confirmed that high-purity elemental tellurium nanowires were successfully obtained on the substrate, with a slightly increased average diameter and still high coverage. This result demonstrates that the technical solution of this invention is also feasible within the parameter range given in this example.

[0070] Example 7

[0071] Source material and substrate preparation: Take 100 mg of high-purity (99.99%) PbTe powder, place it in a small corundum boat, and put it into the isothermal center zone of the tube CVD furnace. Clean different substrates (including silicon oxide, quartz, glass, and sapphire) with acetone, ethanol, and deionized water for 15 minutes, respectively, dry them with nitrogen, and place them in another corundum boat, which is positioned approximately 15 cm downstream of the source region.

[0072] System sealing and venting:

[0073] Seal the furnace tubes, turn on the vacuum system, and evacuate the furnace to a basic vacuum of 1×10⁻⁶. -1 Pa.

[0074] Growth atmosphere control: High-purity argon gas (99.999%) is introduced into the furnace tube at a flow rate of 60 sccm. The working pressure inside the furnace is stabilized at about 1.0 Pa by adjusting the gate valve.

[0075] Heating and growth: The source region was heated to 600 °C at a heating rate of 5 °C / min, while the substrate temperature was approximately 200 °C. Growth was carried out at this temperature for 40 minutes.

[0076] Cooling and Sampling: After growth is complete, turn off the heating power and allow the furnace to cool naturally to room temperature under an argon atmosphere. Remove the silicon substrate; a uniform silver-gray velvety film can be observed covering its surface.

[0077] This embodiment cleverly utilizes the instability of PbTe compounds under specific CVD environments and the differences in volatility of each component.

[0078] The method in this embodiment includes several core processes:

[0079] Precursor decomposition and gas phase generation: High-purity PbTe powder is placed in the high-temperature source zone (approximately 600 °C) of a CVD furnace. Under this temperature and low oxygen partial pressure environment, PbTe undergoes a thermal decomposition reaction, generating a mixed precursor of gaseous Pb, PbO, and Te.

[0080] Gas phase transport and droplet formation: such as Figure 1 As indicated by the arrows, the gaseous precursor is transported to the downstream low-temperature substrate region (approximately 200 °C) by an inert carrier gas. At a deposition temperature higher than the melting point of lead, the gaseous Pb / PbO first condenses on the substrate surface to form liquid catalyst particles, providing nucleation sites for subsequent growth.

[0081] VLS (Vapor-Liquid-Solid) Growth and Selective Deposition: Te vapor dissolves in Pb-based catalyst droplets on the substrate surface, forming a Pb-Te alloy. When the Te concentration in the alloy reaches supersaturation, it precipitates along the

[001] crystal orientation via the droplet interface, epitaxially growing into single-crystal Te nanowires. Simultaneously, gaseous Pb / PbO that did not participate in the catalytic reaction is carried away from the reaction zone by the carrier gas due to the mismatch in deposition conditions, thus achieving efficient gas-phase separation of Te and Pb and directional, selective growth of Te nanowires.

[0082] Experimental Example

[0083] from Figures 2-5 The metallographic microscopy images show that, under an optical microscope, rod-shaped nanowire structures are grown uniformly over a large area on the substrate surface using the scheme described in this application. Observation under low magnification using a metallographic microscope confirms that Te nanowires have achieved large-area and uniform growth on different substrates, forming high-quality Te nanowires. The nanowires grown on different substrates have different morphologies. It can be seen that Te nanowires grow best on glass substrates, and can grow single Te nanowires of high quality.

[0084] The Te nanowires prepared in Example 1 were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Figure 6 The image shows a scanning electron microscope image. It can be seen from the image that the method in Example 1 successfully prepared a high-density, uniformly distributed cluster nanowire structure with a length of tens of micrometers, exhibiting excellent aspect ratio and morphological consistency. Furthermore, high-magnification SEM-EDS analysis of the ends of individual nanowires revealed significant Pb enrichment at the nanowire tips. Figure 6 The green highlight area is in the middle, while the nanowire body contains almost no Pb.

[0085] Energy-dispersive X-ray spectroscopy analysis of clustered nanowires, such as Figure 7 As shown in the figure, Te is uniformly distributed in the main body of the nanowire, while a significant Pb signal is detected at the top cap. Quantitative analysis indicates that Te accounts for approximately 99.97% of the overall elemental composition of the nanowire, and Pb accounts for approximately 0.03% (e.g., ...). Figure 7 (As shown). This result has three important implications:

[0086] 1. Confirmed that the main component of the product is high-purity elemental tellurium;

[0087] 2. The enrichment of Pb at the tip is in perfect agreement with the spatial distribution characteristics of the catalyst droplets in the VLS growth mechanism;

[0088] 3. The extremely low Pb content (0.03%) demonstrates that highly efficient gas-phase separation was achieved during the reaction process, with the vast majority of the Pb components successfully separated. This series of findings provides direct morphological and compositional evidence for the VLS growth mechanism employed in this invention.

[0089] Figure 8 SEM images and EDS spectra of densely grown Te nanowires are shown. Scanning electron microscopy images reveal a large number of uniformly distributed and densely packed nanostructures grown on a silicon oxide substrate. The nanowires have diameters between 50 and 150 nanometers and lengths reaching tens of micrometers, exhibiting a large aspect ratio and excellent morphology. EDS spectra: Elemental analysis of the nanowire region shows strong characteristic peaks for Te in energy-dispersive X-ray spectroscopy, while the characteristic peaks for Pb are extremely weak or undetectable. This result directly proves that the main component of the product is elemental tellurium, rather than lead telluride.

[0090] Finally, the product prepared in Example 1 was subjected to Raman spectroscopy, and the Raman spectrum analysis diagram is shown below. Figure 9 As shown, the product is at approximately 120 cm. -1 and 140 cm -1 The positions showed clear and sharp characteristic scattering peaks, corresponding to the A1 and E2 vibrational modes of trigonal elemental Te, respectively. This result corroborates the EDS analysis, further confirming that the prepared nanowires are well-crystallized elemental Te.

[0091] Summarize

[0092] The results of Examples 1-7 and the experimental examples above fully demonstrate that the method claimed in this invention can successfully prepare single-crystal tellurium nanowires with extremely high purity (>99.9%) and excellent crystallinity by using PbTe powder as the sole precursor, within a wide process window (source temperature 580-620 °C, pressure 1.0-10 Pa, growth time 30-50 minutes, source-substrate distance 10-20 cm) and on various inert substrates with different properties (such as silicon oxide, glass, quartz, and sapphire) through a cleverly designed VLS growth mechanism. This invention overcomes the problems existing in the prior art, with a simple process, low cost, and high product purity, and has significant inventiveness and practicality.

[0093] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing tellurium nanowires based on chemical vapor deposition, characterized in that, The preparation method includes: S100: Place lead telluride powder in the source region of the chemical vapor deposition system, and place the substrate in the downstream deposition region of the source region; S200. The chemical vapor deposition system is evacuated, an inert protective gas is introduced, and the working pressure in the system is maintained in the range of 1.0 Pa to 10 Pa. S300: Heat the source region to a growth temperature of 580 °C-620 °C, while maintaining the temperature of the deposition region where the substrate is located at 200 °C. Under these conditions, perform heat preservation growth for 30-50 minutes. S400 After growth is complete, the chemical vapor deposition system is allowed to cool naturally to obtain tellurium nanowires on the substrate surface.

2. The method for preparing tellurium nanowires based on chemical vapor deposition according to claim 1, characterized in that, In S100, the distance between the substrate and the lead telluride powder in the source region is 10 cm to 20 cm.

3. The method for preparing tellurium nanowires based on chemical vapor deposition according to claim 1, characterized in that, The preparation method further includes: The pretreatment step of the substrate after S100 and before S200: The substrate was ultrasonically cleaned sequentially with acetone, ethanol and deionized water, and then dried with nitrogen.

4. The method for preparing tellurium nanowires based on chemical vapor deposition according to claim 1, characterized in that, In step S200, the vacuuming process specifically includes: Turn on the mechanical pump to evacuate the basic vacuum level of the chemical vapor deposition system to [value missing]. Pa level.

5. The method for preparing tellurium nanowires based on chemical vapor deposition according to claim 1, characterized in that, In S200, the inert protective gas is argon, and the gas flow rate is 50 sccm-70 sccm.

6. The method for preparing tellurium nanowires based on chemical vapor deposition according to claim 1, characterized in that, In S300, the heating rate is 5 °C / min.

7. The method for preparing tellurium nanowires based on chemical vapor deposition according to claim 1, characterized in that, In S300, the growth temperature of the source region is 600 °C and the growth time is 40 minutes.

8. The method for preparing tellurium nanowires based on chemical vapor deposition according to claim 1, characterized in that, The substrate is selected from silicon dioxide wafers, quartz, glass, or sapphire.

9. A tellurium nanowire based on chemical vapor deposition, characterized in that, The tellurium nanowires are prepared by the preparation method according to any one of claims 1 to 8.

10. An application of tellurium nanowires based on chemical vapor deposition, characterized in that, The tellurium nanowires are prepared according to the preparation methods described in claims 1 to 8. Including the following applications: (1) Applications in photoelectric detection; (2) Applications in thermoelectric conversion; (3) Application in the fabrication of gas sensors.

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