Method for regulating and controlling phase transition temperature of 1T-phase tantalum disulfide through surface oxidation

Abstract

The invention relates to the technical field of nano materials, and discloses a method for regulating and controlling the phase change temperature of 1T-phase tantalum disulfide through surface oxidation, which at least comprises the following steps: bombarding oxygen plasma onto a 1T-phase tantalum disulfide material, so that the phase change temperature of the 1T-phase tantalum disulfide material for indicating phase change into 2T-phase tantalum disulfide can be increased; and a 1T phase tantalum disulfide material having a high phase transition temperature; the invention further discloses application of the method for regulating and controlling the phase transition temperature of the 1T-phase tantalum disulfide through surface oxidation. According to the method, the phase change temperature of the tantalum disulfide is increased, and the phase change temperature of the 1T-phase tantalum disulfide can be regulated and controlled by changing the oxygen plasma treatment time, so that the 1T-phase tantalum disulfide material with the high phase change temperature is obtained, and the application range of the 1T-phase tantalum disulfide material in the fields of heterogeneous material heterojunctions and the like is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation. Background Art

[0002] Transition metal dichalcogenide (TMD) material is a typical van der Waals layered material, whose single layer is formed by stacking three subatomic layers from top to bottom in the form of XMX. Among them, M is a transition metal element and X is a chalcogen element. According to the relative positions of the X elements in the upper and lower subatomic layers, TMD materials can usually form two thermodynamically stable structures: H phase and T phase. In the H phase structure, the X elements in the upper and lower subatomic layers are completely aligned to form a triangular prism structure with hexagonal symmetry. In the T phase structure, the X elements in the upper and lower subatomic layers are misaligned to form an octahedral structure with tetragonal symmetry.

[0003] As a typical TMD material, TaS2 also has two structures, H phase and T phase, and the electronic properties of the two are quite different. TaS2 materials of different phases can exhibit completely different electronic properties. By regulating the phase structure of TaS2 materials, their electronic properties can be effectively regulated.

[0004] 1T-TaS2 exhibits metallic properties when the temperature is higher than 543K, the non-commensurate charge density wave phase (ICCDW) between 543K and 350K, the nearly commensurate charge density wave phase (NCCDW) between 350K and 200K, and the commensurate charge density wave phase (CCDW) below 180K. However, completely different from 1T-TaS2, 2H-TaS2 has a CCDW phase below 75K and superconducting properties below 0.8K.

[0005] However, due to the small difference in thermodynamic energy between the two phase structures of TaS2, 1T-TaS2 is more likely to undergo phase transitions. For example, under high temperature, the surface of 1T-TaS2 can partially transform into 2H-TaS2, which makes the material not able to withstand high temperatures well. Because the electronic properties before and after the phase transition are quite different, the performance of electronic devices based on this material changes significantly.

[0006] At the same time, in the actual application process of TaS2, it is often necessary to prepare heterostructures, which requires that the preparation temperature and phase change temperature between different heterojunction components cannot differ too much. The too low phase change temperature of 1T-TaS2 material is not conducive to expanding the preparation selection range of heterojunctions.

[0007] Therefore, there is a need for a method that can easily regulate the phase transition temperature of 1T-TaS2 materials so that they can adapt to higher temperature operation and expand the application of 1T-TaS2 materials. Summary of the invention

[0008] The purpose of the present invention is to provide a method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation, so as to solve the technical problem in the prior art that the phase transition temperature of 1T-TaS2 material is low and not conducive to use.

[0009] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0010] The present invention provides a method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation, which at least comprises the following steps: bombarding oxygen plasma onto a 1T phase tantalum disulfide material, thereby increasing the phase transition temperature of the 1T phase tantalum disulfide material to transform the surface of the 1T phase tantalum disulfide into a 2T phase tantalum disulfide.

[0011] As a preferred solution of the present invention, the phase transition temperature of the 1T phase tantalum disulfide material can be controlled by changing the bombardment time of the oxygen plasma on the 1T phase tantalum disulfide material.

[0012] As a preferred embodiment of the present invention, the bombardment time is 7-14s.

[0013] As a preferred solution of the present invention, the bombardment time is positively correlated with the phase transition temperature of the 1T phase tantalum disulfide material.

[0014] As a preferred embodiment of the present invention, the method comprises the following steps:

[0015] S100, placing the 1T phase tantalum disulfide material in an oxygen plasma chamber, and evacuating the chamber to a vacuum environment;

[0016] S200, introducing oxygen into the chamber at a preset flow rate;

[0017] S300, after the oxygen flow rate is stabilized, turning on the radio frequency power supply and maintaining a preset power to generate oxygen plasma in the chamber, and bombarding the 1T phase tantalum disulfide material with the oxygen plasma within the bombardment time to obtain the 1T phase tantalum disulfide material with a high phase transition temperature.

[0018] As a preferred solution of the present invention, in step S100, the air pressure of the vacuum environment is less than 100 Pa.

[0019] As a preferred solution of the present invention, in step S200, the flow rate is 600 sccm.

[0020] As a preferred solution of the present invention, in step S300, the preset power is 100W.

[0021] The present invention also provides a 1T phase tantalum disulfide material with a high phase transition temperature, which is prepared according to the above method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation.

[0022] The present invention provides an application of a method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation in heterojunction preparation.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention can increase the phase transition temperature of 1T phase tantalum disulfide material to 2T phase tantalum disulfide material through oxygen plasma bombardment to obtain 1T phase tantalum disulfide material with higher phase transition temperature, so that TaS2 material can have better high temperature resistance, is not easy to completely phase change in a high temperature environment, and has a shallow surface oxide layer, which does not affect the properties of 1T phase tantalum disulfide;

[0025] The present invention can regulate the phase transition temperature of 1T-phase tantalum disulfide material by changing the bombardment time of oxygen plasma on the 1T-phase tantalum disulfide material, which is beneficial to the compatibility of the preparation temperature and phase transition temperature of TaS2 with other materials and expands the preparation selection range of its heterojunction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0027] Figure 1 A schematic diagram of the oxidation process of 1T phase tantalum disulfide provided by the present invention after being bombarded by plasma;

[0028] Figure 2 Provided for the present invention are optical microscope images of 1T phase tantalum disulfide treated with oxygen plasma for 7s as shown in Example 1, and optical microscope images after annealing at 350°C and after annealing at 550°C;

[0029] Figure 3 The present invention provides Raman spectra after annealing at 350°C, 400°C, 450°C and 500°C as shown in Example 1;

[0030] Figure 4Provided for the present invention are optical microscope images of 1T phase tantalum disulfide treated with oxygen plasma for 14 seconds, optical microscope images after annealing at 350° C. and after annealing at 550° C. as shown in Example 2;

[0031] Figure 5 The present invention provides Raman spectra after annealing at 350°C, 400°C, 450°C, 500°C, and 550°C as shown in Example 2;

[0032] Figure 6 The present invention provides a schematic diagram of the phase change process effect of Comparative Example 1;

[0033] Figure 7 The present invention provides Raman spectra of the 1T phase tantalum disulfide sample of Comparative Example 1 after annealing at 200° C., 250° C., 300° C., 350° C. and 400° C.;

[0034] Figure 8 The present invention provides X-ray photoelectron spectra of tantalum atom 3d orbitals of tantalum disulfide materials in Comparative Example 1, Example 1, and Example 2;

[0035] Fig. 9 The present invention provides X-ray photoelectron spectra of the 2p orbital of the sulfur atom of tantalum disulfide materials of Comparative Example 1, Example 1 and Example 2. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, the present invention provides a method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation, which mainly includes: bombarding oxygen plasma onto the 1T phase tantalum disulfide material.

[0038] After oxygen plasma bombards the 1T phase tantalum disulfide material, an oxide film will be produced on the surface of the 1T phase tantalum disulfide material. This oxide film can protect the surface layer of the 1T phase tantalum disulfide material from being easily transformed into 2H phase tantalum disulfide, thereby increasing the phase transition temperature of the 1T phase tantalum disulfide material.

[0039] Moreover, the oxide film has little effect on the 1T phase tantalum disulfide material, and the surface oxide layer is very shallow, which basically does not affect the properties of the 1T phase tantalum disulfide and will not affect its chemical performance when the material is used.

[0040] It can be seen that oxygen plasma bombardment can increase the phase transition temperature of 1T phase tantalum disulfide material to 2H phase tantalum disulfide material.

[0041] Furthermore, by changing the bombardment time of oxygen plasma on the 1T phase tantalum disulfide material, the phase transition temperature of the 1T phase tantalum disulfide material can be controlled.

[0042] The present invention can regulate the phase transition temperature of TaS2 by oxygen plasma bombardment, which is beneficial to the compatibility of the preparation temperature and phase transition temperature of TaS2 with other materials and expands the preparation selection range of its heterojunction.

[0043] Furthermore, the present invention provides a 1T phase TaS2 material with a high phase transition temperature. This 1T phase TaS2 material can have better high temperature resistance and is not prone to complete phase change in a high temperature environment.

[0044] The following examples are provided for illustration:

[0045] Embodiment 1:

[0046] The 1T phase tantalum disulfide material (this material uses silicon as a substrate) is placed in an oxygen plasma chamber, and the chamber is evacuated to a vacuum environment with a gas pressure of less than 100 Pa;

[0047] Oxygen was introduced into the chamber, and the oxygen flow rate was controlled to be 600 sccm;

[0048] After the oxygen flow rate stabilizes, the RF power is turned on to generate oxygen plasma in the chamber, and the 1T phase tantalum disulfide is bombarded with oxygen plasma for a period of time. The RF power is 100 W and the bombardment time is 7 seconds.

[0049] The schematic diagram of the surface oxidation process effect of this embodiment is as follows Figure 1 shown.

[0050] Figure 1 It is shown that after oxygen plasma bombardment, an oxide layer (preliminarily identified as TaO x ), it can be seen that plasma bombardment of the 1T phase tantalum disulfide material in a vacuum environment and maintaining the bombardment time for 7s can form an oxide layer on the surface of the 1T phase tantalum disulfide material.

[0051] Furthermore, the surface-oxidized 1T phase tantalum disulfide is placed in a vacuum annealing chamber, and the vacuum annealing chamber is evacuated to an ultra-high vacuum environment, and the pressure of the chamber is not greater than 5×10 -7 Pa;

[0052] The 1T phase tantalum disulfide was annealed at 350°C for 30 minutes, and then the 1T phase tantalum disulfide was taken out and characterized by Raman spectroscopy to determine whether a phase change occurred;

[0053] Subsequently, the above steps were repeated and the annealing temperature was changed to prepare samples annealed at 400°C, 450°C and 500°C and characterized by Raman spectroscopy.

[0054] Characterization of Example 1:

[0055] The Raman spectra of the above samples are characterized as follows Figure 3 As shown, the optical microscope image of the surface oxidation process is Figure 2 shown.

[0056] Depend on Figure 3 The Raman spectra of 1T phase TaS2 after oxygen plasma bombardment for 7s and annealing at 350℃ and 400℃ are shown at 64cm -1 、240.5cm -1 、382cm- 1 The Raman spectra of the samples annealed at 450℃ and 500℃ show the characteristic Raman peaks of 1T phase tantalum disulfide, while the Raman spectra of the samples annealed at 450℃ and 500℃ show the characteristic Raman peaks at 286cm -1 、400cm -1 Additional characteristic peaks appeared, indicating that a phase transition occurred in 1T phase tantalum disulfide, and its surface was transformed into 2H phase.

[0057] At the same time, it can be seen from the Raman spectrum after oxidation that its Raman spectrum after oxidation still conforms to the 1T phase tantalum disulfide, that is, it has the same properties as before oxidation. At the same time, it is confirmed from the Raman spectrum that the oxidized 2H-TaS2 has the same Raman peak as the unoxidized 2H-TaS2, which will not affect its chemical performance when the material is used.

[0058] In summary, after 7s of oxygen plasma bombardment, the phase transition temperature of 1T phase tantalum disulfide is 450℃.

[0059] Embodiment 2:

[0060] The 1T phase tantalum disulfide is placed in an oxygen plasma chamber, and the chamber is evacuated to a vacuum environment, and the gas pressure of the chamber is below 100 Pa;

[0061] Then, oxygen gas was introduced into the chamber at a flow rate of 600 sccm;

[0062] After the oxygen flow rate stabilizes, the RF power is turned on to generate oxygen plasma in the chamber, and the 1T phase tantalum disulfide is bombarded with oxygen plasma for a period of time, wherein the RF power is 100 W and the bombardment time is 14 s.

[0063] The surface-oxidized 1T phase tantalum disulfide was placed in a vacuum annealing chamber, and the vacuum annealing chamber was evacuated to an ultra-high vacuum environment, and the pressure of the chamber was no more than 5×10 -7 Pa;

[0064] The 1T phase tantalum disulfide was annealed at 350°C for 30 minutes, and then the 1T phase tantalum disulfide was taken out and characterized by Raman spectroscopy to determine whether a phase change occurred;

[0065] Subsequently, the above steps were repeated and the annealing temperature was changed to prepare samples annealed at 400°C, 450°C, 500°C, 550°C and 600°C and characterized by Raman spectroscopy.

[0066] Characterization of Example 2:

[0067] The electron microscope image of the surface oxidation process of Example 2 is Figure 4 As shown, Figure 4 It shows that plasma bombardment of 1T phase tantalum disulfide material in a vacuum environment and maintaining the bombardment time for 14s can increase the phase transition temperature of the 1T phase tantalum disulfide material.

[0068] The Raman spectra of the above samples are characterized as follows Figure 5 As shown in the figure, the Raman spectra of 1T phase tantalum disulfide after oxygen plasma bombardment for 14s and annealing at 350℃, 400℃, 450℃ and 500℃ are at 64cm -1 、240.5cm -1 、382cm -1 The Raman spectra of the samples annealed at 550℃ and 600℃ show the characteristic Raman peaks of 1T phase tantalum disulfide. -1 、400cm -1 Additional characteristic peaks appeared, indicating that a phase transition occurred in 1T phase tantalum disulfide, and its surface was transformed into 2H phase.

[0069] It can be seen that the phase transition temperature of 1T phase tantalum disulfide can be increased to 550℃ by oxygen plasma bombardment for 14s.

[0070] Comparative Example 1:

[0071] The 1T phase tantalum disulfide is placed in a vacuum annealing chamber, and the vacuum annealing chamber is evacuated to an ultra-high vacuum environment, and the pressure of the chamber is not greater than 5×10 -7 Pa;

[0072] The 1T phase tantalum disulfide was annealed at 200°C for 30 minutes, and then the 1T phase tantalum disulfide was taken out and characterized by Raman spectroscopy to determine whether a phase change occurred;

[0073] Subsequently, the above steps were repeated and the annealing temperature was changed to prepare samples annealed at 200°C, 250°C, 300°C, 350°C and 400°C and characterized by Raman spectroscopy.

[0074] The schematic diagram of the phase change process effect of comparative example 1 is as follows Figure 6 As shown, the upper part of the figure shows the 1T phase tantalum disulfide on the silicon dioxide / silicon substrate, the middle figure shows the tantalum disulfide after annealing at 350°C for 30 minutes, and its surface has undergone partial phase change, and the lower part of the figure shows the 1T phase tantalum disulfide after annealing at 400°C for 30 minutes, and its surface has completely changed to 2H phase.

[0075] The Raman spectra of the above samples are characterized as follows Figure 7 The Raman spectra of 1T phase tantalum disulfide after annealing at 200℃, 250℃ and 300℃ are shown in Figure 64cm -1 、240.5cm -1 、382cm -1 The Raman spectra of the samples annealed at 350℃ and 400℃ show the characteristic Raman peak of 1T phase tantalum disulfide at 286cm -1 、400cm -1 Additional characteristic peaks appeared, indicating that a phase transition occurred in 1T phase tantalum disulfide, and its surface was transformed into 2H phase.

[0076] According to Comparative Example 1, the phase transition temperature of 1T phase tantalum disulfide without surface oxidation treatment is 400°C.

[0077] The materials in Example 1, Example 2 and Comparative Example 1 were further characterized:

[0078] The 1T phase tantalum disulfide without annealing treatment in Example 1 and the tantalum disulfide after oxygen plasma bombardment in Examples 2 and 3 were characterized by X-ray photoelectron spectroscopy.

[0079] Figure 8 , Fig. 9 The energy spectra of the 3d orbital of Ta atoms and the 2p orbital of S atoms of untreated 1T phase tantalum disulfide, tantalum disulfide treated with oxygen plasma for 7s and tantalum disulfide treated with oxygen plasma for 14s are shown.

[0080] For the 3d orbital energy spectrum of Ta atoms, after oxygen plasma treatment, the intensity of the oxidation peak of 1T phase tantalum disulfide is enhanced, and as the oxygen plasma treatment time increases, the intensity of the oxidation peak becomes stronger. This indicates that tantalum oxide is formed on the surface of 1T phase tantalum disulfide after oxygen plasma treatment. For the 2p orbital energy spectrum of S atoms, after oxygen plasma treatment, the oxidation peak of S appears in 1T phase tantalum disulfide, and as the oxygen plasma treatment time increases, the intensity of the oxidation peak becomes stronger. This indicates that sulfur oxide is formed on the surface after oxygen plasma treatment.

[0081] In summary, Example 1 and Example 2 jointly confirm that the surface oxidation of 1T-phase tantalum disulfide can be achieved by bombarding 1T-phase tantalum disulfide with surface oxygen plasma to increase its phase transition temperature without affecting the properties of the 1T-phase tantalum disulfide itself. The phase transition temperature of 1T-phase tantalum disulfide can be regulated by changing the oxygen plasma bombardment time, thereby achieving the purpose of regulating the phase transition temperature of 1T-phase tantalum disulfide by surface oxidation.

[0082] The comparison between Comparative Example 1 and Examples 1 and 2 confirms that surface oxygen plasma bombardment can increase the phase transition temperature of 1T phase tantalum disulfide, and after surface oxygen plasma bombardment, 1T phase tantalum disulfide can be transformed into a material with a higher phase transition temperature.

[0083] By means of the method of regulating the phase transition temperature of 1T-phase tantalum disulfide by surface oxidation in this embodiment, the phase transition temperature of tantalum disulfide can be increased, and the phase transition temperature of 1T-phase tantalum disulfide can be regulated by changing the time of oxygen plasma treatment, so as to obtain 1T-phase tantalum disulfide material with a high phase transition temperature, thereby broadening the application scope of 1T-phase tantalum disulfide material in the fields of heterogeneous material heterojunction and the like.

[0084] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation, characterized in that: The method comprises at least the following steps: bombarding the 1T phase tantalum disulfide material with oxygen plasma, so as to increase the phase transition temperature of the 1T phase tantalum disulfide material to transform into the 2T phase tantalum disulfide.

2. The method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation according to claim 1, characterized in that: By changing the bombardment time of the oxygen plasma on the 1T phase tantalum disulfide material, the phase transition temperature of the 1T phase tantalum disulfide material can be adjusted.

3. The method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation according to claim 2, characterized in that: The bombardment time is 7-14 s.

4. The method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation according to claim 2, characterized in that: The bombardment time is positively correlated with the phase transition temperature of the 1T phase tantalum disulfide material.

5. The method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation according to claim 3, characterized in that: The steps include: S100, placing the 1T phase tantalum disulfide material in an oxygen plasma chamber, and evacuating the chamber to a vacuum environment; S200, introducing oxygen into the chamber at a preset flow rate; S300, after the oxygen flow rate is stabilized, turning on the radio frequency power supply and maintaining a preset power to generate oxygen plasma in the chamber, and bombarding the 1T phase tantalum disulfide material with the oxygen plasma within the bombardment time to obtain the 1T phase tantalum disulfide material with a high phase transition temperature.

6. The method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation according to claim 5, characterized in that: In step S100, the air pressure of the vacuum environment is less than 100 Pa.

7. The method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation according to claim 5, characterized in that: In step S200, the flow rate is 600 sccm.

8. The method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation according to claim 5, characterized in that: In step S300, the preset power is 100W.

9. A 1T phase tantalum disulfide material with a high phase transition temperature, characterized in that: It is prepared by the method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation according to any one of claims 1 to 8.

10. Use of the method for regulating the phase transition temperature of 1T phase tantalum disulfide by surface oxidation as claimed in any one of claims 1 to 8 in the preparation of heterojunction.

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