A method for phase regulation of a Bi-Te-O ternary system

Abstract

This invention discloses a method for controlling the phases of a Bi-Te-O ternary system, belonging to the field of two-dimensional semiconductor material preparation technology. Using Bi₂Te₃ and Bi₂O₃ powders as reaction sources, controllable growth is achieved on a mica substrate using CVD. By adjusting the growth temperature and system pressure to construct a pressure-temperature synergistic phase diagram, the growth windows for four different phases—elemental Te, Bi₂Te₃, Bi₂TeO₅, and Bi₂O₂Te—were determined and controlled. By utilizing the modulation of the vapor pressure and chemical potential of the precursors by temperature and pressure, the problem of low phase purity caused by differences in precursor reaction concentration and activity in the ternary system is solved, successfully preparing ultrathin two-dimensional Bi₂TeO₅ crystals with a thickness of 3.0–5.7 nm. The preparation method provided by this invention is simple and highly controllable, offering a new technological paradigm for the large-scale and precise preparation of complex ternary two-dimensional systems.

Description

Technical Field

[0001] This invention relates to the fields of two-dimensional material preparation and semiconductor material technology, specifically to a chemical vapor deposition method based on the synergistic effect of temperature and pressure, which enables precise control of different phases in the preparation of a Bi-Te-O ternary system. Background Technology

[0002] The bismuth-tellurium-oxygen (Bi-Te-O) ternary system, as a promising and versatile material system, plays a crucial role in microelectronics, thermoelectric conversion, and optoelectronic devices. This system encompasses a range of functional materials with diverse properties. For example, elemental Te possesses excellent p-type carrier transport characteristics; Bi₂Te₃ is a high-performance room-temperature thermoelectric material and an important carrier for studying topological insulators. Bi₂O₂Te is an emerging two-dimensional semiconductor with high carrier mobility, air stability, and a suitable band gap, making it one of the core materials for novel electronic devices. Bi₂TeO₅ exhibits good dielectric properties, unique ferroelectricity, and nonlinear optical characteristics, making it suitable for use in optoelectronic modulation devices.

[0003] However, when preparing specific phases in this system using chemical vapor deposition (CVD), especially large-area, high-quality single-crystal products, the challenge of competitive growth between different phases remains constant. This is because the thermodynamic Gibbs free energies of the various compounds in the Bi-Te-O system, such as elements, oxides, tellurides, and telluroxides, are very close, resulting in a relatively narrow phase space window during growth. In actual growth, this often leads to the disordered nucleation of multiple phases on the substrate, making it difficult to obtain a single pure phase.

[0004] To address the aforementioned issues, it is necessary to regulate the growth parameters of chemical vapor deposition (CVD). Generally, the reaction temperature affects the precursor volatilization rate, determining the saturated vapor concentration of the gaseous precursor and the rate of the chemical reaction, among other microscopic processes. The system pressure affects the mass transfer process of the gaseous precursor. Both factors jointly influence the precursor source supply flux, the thermodynamic energy barrier of the reaction, and the kinetic rate. Therefore, achieving a proper match between the system pressure, precursor temperature, substrate temperature, and precursor flux is crucial. Taking the CVD preparation of Bi2O2Te as an example, patent CN115041677B discloses a method for preparing Bi2O2Te nanosheets on a mica substrate using bismuth telluride and bismuth oxide as precursors. Although this technology has achieved the growth of Bi2O2Te nanosheets, it can only prepare a single phase of Bi2O2Te and cannot cover the multi-phase preparation requirements of the Bi-Te-O ternary system. Moreover, its parameter control is only focused on the physical characteristics of Bi2O2Te nanosheets such as thickness, morphology, and size. It does not carry out synergistic coupling design of core parameters such as reaction temperature and system pressure, nor does it carry out precise control on the problem of narrow phase space window. At the same time, the technology uses pure argon inert atmosphere as carrier gas and protective gas, which further limits the possibility of phase control. Even for the preparation of Bi2O2Te single phase, this technology still has the problem of insufficient parameter matching: for example, if the pressure inside the tube furnace is too high, the mean free path of Te vapor will be limited, and insufficient Te flux on the substrate surface will easily lead to the formation of Bi-rich impurity phase; if the pressure is too low, the high saturated vapor pressure of Te will cause it to volatilize and be lost from the lattice, resulting in the oxidation and decomposition of the target product, which will ultimately affect the phase purity and crystal quality of the product.

[0005] Based on the above analysis, traditional single-parameter control lacks precise control over complex growth kinetics and cannot meet current requirements for phase purity, crystal quality, and uniformity of two-dimensional and ternary materials. Therefore, developing a chemical vapor deposition (CVD) process capable of achieving multi-parameter synergistic coupling has become a key scientific problem urgently needing to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for preparing Bi-Te-O ternary system phases based on dual-parameter control of temperature and pressure. This invention utilizes chemical vapor deposition (CVD) to achieve precise control of the concentration field and kinetic processes of the gaseous precursor by synergistically adjusting the temperature of the central heating zone of a tubular furnace and the total system pressure.

[0007] To achieve the above objectives, the present invention first provides a method for phase control of a Bi-Te-O ternary system, specifically comprising the following steps: (1) The reaction source Bi2Te3 powder, Bi2O3 powder and mica substrate are placed sequentially in the upstream, center and downstream heating zones of the tube furnace; (2) Introduce carrier gas into the tubular furnace and use a vacuum pump and flow controller to adjust the pressure of the tubular furnace to the preset value; (3) Set the heating program to make the temperature of the central heating zone (Bi2O3 powder) of the tube furnace reach the preset temperature. The temperature of the upstream heating zone (Bi2Te3 powder) and the downstream heating zone (mica substrate) is controlled by their distance from the central heating zone. (4) By adjusting the pressure and temperature, a Bi-Te-O ternary system material with tunable phase is deposited on the substrate surface; wherein the carrier gas is an argon / hydrogen mixture.

[0008] In one embodiment of the present invention, the pressure of the tubular furnace and the temperature of the central region are synergistically controlled to controllably prepare the following four target phases: (1) When the target phase is elemental Te, the growth parameter range is: central region temperature is 510-550 ℃, and tube furnace pressure is 100-500 Torr; (2) When the target phase is Bi2Te3, the growth parameters are: central temperature of 580-620 ℃ and tube furnace pressure of 50-200 Torr; (3) When the target phase is Bi2TeO5, the growth parameter range is: the temperature in the central region is 630-670 ℃, and the pressure in the tube furnace is 200-450 Torr; (4) When the target phase is Bi2O2Te, the growth parameters are: the temperature in the central region is 680-720 ℃ and the pressure in the tubular furnace is 10-100 Torr.

[0009] In one embodiment of the present invention, the mass ratio of Bi2Te3 powder to Bi2O3 powder is 1:2 to 2:1.

[0010] In one embodiment of the present invention, the distance between the upstream position of the Bi2Te3 powder and the center position of the tube furnace is 8-12 cm, and the distance between the downstream position of the mica substrate and the center position of the tube furnace is 12-18 cm.

[0011] In one embodiment of the present invention, the temperature and pressure control mechanism is as follows: by changing the pressure of the tubular furnace and its heating temperature, the partial pressure of the precursor (Bi2Te3 vapor, Bi2O3 vapor) and its mean free path on the substrate surface are adjusted, thereby controlling the adsorption / desorption rate of each component atom, and realizing controllable preparation between multiple thermodynamically similar phases.

[0012] In one embodiment of the present invention, the growth conditions for Te, Bi2Te3, Bi2O2Te, and Bi2TeO5 are as follows: (1) When growing Te, Bi2Te3 is placed 10cm upstream of the central heating zone, and the mica substrate is placed 15cm downstream of the central heating zone. The heating temperature is 520℃ and the pressure of the tube furnace is 320 Torr. (2) When growing Bi2Te3, Bi2Te3 is placed 8 cm upstream of the central heating zone, and the mica substrate is placed 12 cm downstream of the central heating zone. The heating temperature is 620℃ and the pressure of the tube furnace is 180 Torr. (3) When growing Bi2O2Te, Bi2Te3 is placed 10cm upstream of the central heating zone, and the mica substrate is placed 15cm downstream of the central heating zone. The heating temperature is 720℃ and the pressure of the tube furnace is 30 Torr. (4) When growing Bi2TeO5, Bi2Te3 is placed 12cm upstream of the central heating zone, and the mica substrate is placed 18cm downstream of the central heating zone. The heating temperature is 650℃ and the pressure of the tube furnace is 350 Torr.

[0013] In one embodiment of the present invention, the volume fraction of hydrogen in the carrier gas is 2%-20%, and the reduction intensity of the reaction environment is controlled by adjusting this volume fraction to achieve fine adjustment of the oxygen partial pressure of the reaction system.

[0014] In one embodiment of the present invention, the flow rate of the carrier gas is 10-100 sccm. The pressure of the tube furnace is adjusted by the carrier gas flow rate and the vacuum pump valve, thereby achieving the adjustment of the free path of the gas phase precursor.

[0015] In one embodiment of the present invention, the heating rate of the tube furnace is 30-50 °C / min, and the isothermal growth time is 10-60 min.

[0016] The present invention also provides a Bi-Te-O ternary system phase prepared according to the above method.

[0017] In one embodiment of the present invention, the phase has the following physical characteristics: (1) When the phase is elemental Te, it has a density of 120 cm⁻¹ -1 and 141 cm -1 The Raman peak has a thickness of 78-86 nm; (2) When the phase is Bi2Te3, it has a density of 100 cm⁻¹ -1 and 133 cm -1 Raman Peak; (3) When the phase is Bi2TeO5, it has a density of 103 cm⁻¹. -1 The Raman peaks have a thickness of 3.0-5.7 nm; (4) When the phase is Bi2O2Te, it has a thickness of 146 cm⁻¹. -1 Mount Raman.

[0018] The present invention also provides an application of the above-mentioned Bi-Te-O ternary system phase in the fields of microelectronics, thermoelectric conversion and optoelectronic devices.

[0019] Beneficial effects: This invention enables the controllable growth of elements, binary compounds, and ternary compounds within the same apparatus by adjusting only two core physical parameters: temperature (precursor temperature and substrate temperature) and reaction pressure, without requiring replacement of the reaction source. The grown crystalline phases exhibit high crystallinity and regular morphology, especially the ternary phase Bi₂TeO₅, which achieves two-dimensional growth of 3.0-5.7 nm. The invention provides a clear process window, detailing the pressure and temperature ranges for each phase, demonstrating good operability and repeatability. Furthermore, by employing a common tube furnace and solid powder, the equipment requirements are low, providing clear parameter guidance for the large-scale preparation of Bi-Te-O ternary systems. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a general growth apparatus for the Bi-Te-O ternary system and its reaction source layout.

[0021] Figure 2 The images show the growth curve, OM image, and Raman curve of the Te element obtained in Example 1.

[0022] Figure 3 The image shows the AFM diagram and height diagram of elemental Te obtained in Example 1.

[0023] Figure 4 The images show the growth curve, OM image, and Raman curve of Bi2Te3 obtained in Example 2.

[0024] Figure 5 The growth curve, OM image, and Raman curve of Bi2O2Te obtained in Example 3 are shown.

[0025] Figure 6 The images show the growth curve, OM image, and Raman curve of Bi2TeO5 obtained in Example 4.

[0026] Figure 7 The image shows the AFM diagram and height map of Bi2TeO5 obtained in Example 4. Detailed Implementation

[0027] The following will clearly and completely describe the concept of the present invention and its resulting technical effects with reference to embodiments. The described embodiments are only for illustrating the present invention and are not intended to limit the scope of protection of the invention.

[0028] Example 1: Growth regulation of elemental Te Bi₂Te₃ powder and Bi₂O₃ powder were placed in a tube furnace at a mass ratio of 1:1. Bi₂O₃ was placed in the center of the furnace, Bi₂Te₃ was placed 10 cm upstream of the center, and the mica substrate was placed 15 cm downstream of the center. An argon / hydrogen mixed carrier gas (containing 5% hydrogen by volume) was introduced at a flow rate of 50 sccm. Simultaneously, the vacuum pump valve was adjusted to stabilize the system pressure at 300 Torr. The central heating zone was heated to 530 °C at a rate of 40 °C / min. At this point, the temperature of the upstream Bi₂Te₃ region was approximately 400-450 °C, and the temperature of the downstream substrate region was approximately 300-350 °C. The temperature was maintained at this constant level for 30 min for growth.

[0029] At 530 °C, Bi₂O₃ exhibits low chemical reactivity, while the upstream Bi₂Te₃ undergoes partial decomposition under higher pressure (300 Torr), releasing Te vapor. Due to the higher pressure, the Te molecules have a shorter mean free path and a higher collision frequency, rapidly reaching supersaturation and crystallizing on the substrate surface. Figure 2 and Figure 3 As can be seen, the obtained Te single crystal product exhibits a distinct metallic luster under an optical microscope. Raman spectroscopy reveals its 120 cm⁻¹... -1 and 141 cm -1 Characteristic peaks, measured by atomic force microscopy (AFM), show that its thickness is approximately 82 nm and its morphology is a regular nanoribbon.

[0030] Example 2: Growth Regulation of Bi2Te3 Bi₂Te₃ powder and Bi₂O₃ powder were placed in a tube furnace at a mass ratio of 2:1. Bi₂O₃ was placed in the center of the furnace, Bi₂Te₃ was placed 8 cm upstream of the center, and the mica substrate was placed 12 cm downstream of the center. An argon / hydrogen mixed carrier gas (containing 10% hydrogen by volume) was introduced at a flow rate of 50 sccm. Simultaneously, the vacuum pump valve was adjusted to stabilize the system pressure at 150 Torr. The central heating zone was heated to 600 °C at a rate of 40 °C / min and held at this temperature for 20 min for growth.

[0031] At 600 °C, the volatilization of Bi₂Te₃ increased significantly. Lowering the pressure to 150 Torr increased the diffusion rate of precursor molecules, allowing Bi and Te atoms to reach the substrate in a near 2:3 stoichiometric ratio. Due to the low hydrogen concentration and the temperature not yet reaching the range where the oxide reacts significantly, pure-phase Bi₂Te₃ was ultimately formed. Figure 4 It can be seen that the obtained Bi₂Te₃ nanosheets have a typical hexagonal morphology, and Raman spectroscopy at 100 cm⁻¹...-1 and 133 cm -1 Characteristic peaks, corresponding to the standard vibration mode of Bi2Te3.

[0032] Example 3: Growth Regulation of Bi2O2Te Bi₂Te₃ powder and Bi₂O₃ powder were placed in a tube furnace at a mass ratio of 1:1. Bi₂O₃ was placed in the center of the furnace, Bi₂Te₃ was placed 10 cm upstream of the center, and the mica substrate was placed 15 cm downstream of the center. An argon / hydrogen mixed carrier gas (containing 20% ​​hydrogen by volume) was introduced at a flow rate of 50 sccm. Simultaneously, the vacuum pump valve was adjusted to stabilize the system pressure at 50 Torr. The central heating zone was heated to 700 °C at a rate of 40 °C / min and held at this temperature for 45 min for growth.

[0033] The high temperature of 700 °C ensured the complete dissociation of Bi₂O₃, while the low pressure of 50 Torr increased the molecular free path, allowing precursor molecules to diffuse over long distances and seek the lowest energy sites on the substrate surface. The high concentration of hydrogen gas helped regulate the oxygen partial pressure, preventing excessive oxidation and the formation of the Bi₂O₃ impurity phase. Figure 5 It can be seen that the Raman spectrum of the obtained sample is at 146 cm⁻¹. -1 The peaks are sharp and symmetrical.

[0034] Example 4: Growth Regulation of Bi2TeO5 Bi₂Te₃ powder and Bi₂O₃ powder were placed in a tube furnace at a mass ratio of 1:2. Bi₂O₃ was placed in the center of the furnace, Bi₂Te₃ was placed 12 cm upstream of the center, and the mica substrate was placed 18 cm downstream of the center. An argon / hydrogen mixed carrier gas (containing 2% hydrogen by volume) was introduced at a flow rate of 50 sccm. Simultaneously, the vacuum pump valve was adjusted to stabilize the system pressure at 350 Torr. The central heating zone was heated to 650 °C at a rate of 40 °C / min and held at this temperature for 60 min for growth.

[0035] At 650 °C, Bi₂O₃ begins to partially participate in the reaction. A pressure of 350 Torr significantly reduces the mean free path of the molecules, increasing the collision probability of Bi, Te, and O atoms on the substrate surface, thus promoting the nucleation of the complex ternary phase. Simultaneously, the downstream 18 cm spacing provides a suitable temperature gradient, suppressing longitudinal growth and favoring two-dimensional lateral growth. Figure 6 and 7 It can be seen that the product is a triangular or polygonal thin sheet, and the Raman spectrum is at 103 cm⁻¹. -1 A strong peak appears at this point, and AFM characterization shows that its average thickness is only 4.5 nm.

[0036] Example 5: Growth Regulation of Four Phases Bi₂Te₃ powder and Bi₂O₃ powder were placed in a tube furnace at a mass ratio of 1:1. Bi₂O₃ was placed in the center of the furnace, Bi₂Te₃ upstream, and the mica substrate downstream. An argon / hydrogen mixed carrier gas (containing 2% hydrogen by volume) was introduced at a flow rate of 50 sccm. Simultaneously, the vacuum pump valve was adjusted to stabilize the system pressure at a preset value. The central heating zone was heated to the preset value at a rate of 40 °C / min and held at this temperature for 30 min to grow elemental Te, Bi₂Te₃, Bi₂O₂Te, and Bi₂TeO₅, respectively. The growth conditions for Te, Bi₂Te₃, Bi₂O₂Te, and Bi₂TeO₅ are as follows: (1) When growing Te, Bi2Te3 is placed 10cm upstream of the central heating zone, and the mica substrate is placed 15cm downstream of the central heating zone. The heating temperature is 520℃ and the pressure of the tube furnace is 320 Torr. (2) When growing Bi2Te3, Bi2Te3 is placed 8 cm upstream of the central heating zone, and the mica substrate is placed 12 cm downstream of the central heating zone. The heating temperature is 620℃ and the pressure of the tube furnace is 180 Torr. (3) When growing Bi2O2Te, Bi2Te3 is placed 10cm upstream of the central heating zone, and the mica substrate is placed 15cm downstream of the central heating zone. The heating temperature is 720℃ and the pressure of the tube furnace is 30 Torr. (4) When growing Bi2TeO5, Bi2Te3 is placed 12cm upstream of the central heating zone, and the mica substrate is placed 18cm downstream of the central heating zone. The heating temperature is 650℃ and the pressure of the tube furnace is 350 Torr.

[0037] Experiments showed that the nanosheets of each phase prepared in Example 5 had good morphology, similar to the morphology of the corresponding substances in Examples 1-4, and their Raman spectra also showed that the corresponding substances were prepared.

[0038] Based on the experimental conditions and the experimental results of the embodiments, it was found that in this invention, in addition to the carrier gas containing a reducing gas, the parameters that have the greatest impact on the morphology, uniformity and purity of each phase are temperature and pressure. Secondly, the placement of the raw material precursor and the substrate is also a necessary factor affecting the formation of phases. The main reason is that for different phases, the heating temperature of Bi2Te3 is different as the heating temperature of Bi2O3 is different. Different phase synthesis requires control of the volatilization amount and dissociation degree of Bi2Te3. Similarly, the temperature of the substrate position will also change accordingly. Different phase synthesis also requires control of the substrate position.

[0039] Comparative Example 1 The difference between Comparative Example 1 and Example 5 is that the carrier gas was replaced with pure argon.

[0040] Experiments revealed that without a carrier gas containing reducing gases, a large amount of oxygen would remain inside the tube furnace, resulting in the presence of impurity phases such as Bi₂O₃ in the prepared material, making it difficult to generate a single phase with high purity. Furthermore, if pure argon is used as the carrier gas, it is difficult to synthesize pure phases of Bi₂O₂Te and Bi₂Te₃, thus hindering the control of different phases in the material.

[0041] Comparative Example 2 The difference between Comparative Example 2 and Example 5 is that only the temperature is adjusted, not the pressure.

[0042] Experiments revealed that temperature is a crucial parameter for phase control. Adjusting only the temperature based on Example 5 without regulating the pressure also fails to achieve the control of all four phases. This is because higher pressure during the growth of Bi₂Te₃ and Bi₂O₂Te affects precursor diffusion, resulting in a higher concentration of impurities in the prepared phases, making it difficult to synthesize a single phase with high purity.

[0043] In this invention, temperature and pressure do not act independently on the phase regulation of the Bi-Te-O system, but rather influence the phase synergistically through chemical potential. The carrier gas flow rate is not only a transport medium but also a means of pressure regulation; with a constant pump speed, a higher flow rate results in a higher static pressure inside the tube. Since the Bi-Te-O ternary system is highly sensitive to oxygen concentration, hydrogen concentration is crucial. The upstream (8-12 cm) and downstream (12-18 cm) spacing of the tubular furnace center utilizes the natural temperature drop curve of a single-temperature zone furnace. This spatial gradient ensures that each precursor can be continuously supplied at a stable ratio and rate.

[0044] As can be seen from the above embodiments, the method provided by this invention overcomes the problem of disordered phases in traditional ternary system synthesis. Through the coordinated dual-parameter control of temperature and pressure, the controllable preparation of the Bi-Te-O system phases is achieved. This provides a material foundation for subsequent research on the application of these two-dimensional materials in high-performance semiconductor devices.

[0045] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for phase modulation of a Bi-Te-O ternary system, characterized in that, The method includes the following steps: (1) The reaction source Bi2Te3 powder, Bi2O3 powder and mica substrate are placed sequentially in the upstream heating zone, the central heating zone and the downstream heating zone of the tube furnace; (2) A carrier gas is introduced into the tube furnace, and a phase-tunable Bi-Te-O ternary system material is deposited on the substrate surface by adjusting the pressure of the tube furnace and the temperature of the central heating zone. The phase-tunable Bi-Te-O ternary system material includes elemental Te, Bi2Te3, Bi2TeO5 and Bi2O2Te. The temperature of the upstream heating zone and the downstream heating zone is controlled by their distance from the central heating zone. The carrier gas is a mixture of inert gas and reducing gas.

2. The method according to claim 1, characterized in that, The pressure and temperature of the tubular furnace are synergistically controlled to controllably prepare the following four target phases: (1) When the target phase is elemental Te, the temperature of the central heating zone is 510-550 ℃ and the pressure of the tube furnace is 100-500 Torr; (2) When the target phase is Bi2Te3, the temperature of the central heating zone is 580-620 ℃ and the pressure of the tube furnace is 50-200 Torr; (3) When the target phase is Bi2TeO5, the temperature of the central heating zone is 630-670 ℃ and the pressure of the tube furnace is 200-450 Torr; (4) When the target phase is Bi2O2Te, the temperature of the central heating zone is 680-720 ℃ and the pressure of the tubular furnace is 10-100 Torr.

3. The method according to claim 1, characterized in that, The distance between the upstream heating zone of the tube furnace containing the Bi2Te3 powder and the central heating zone is 8-12 cm, and the distance between the downstream position of the tube furnace containing the mica substrate and the center position is 12-18 cm.

4. The method according to claim 1, characterized in that, The mass ratio of Bi2Te3 powder to Bi2O3 powder is 1:2 to 2:

1.

5. The method according to claim 1, characterized in that, The inert gas is argon, the reducing gas is hydrogen, and the volume fraction of the reducing gas in the carrier gas is 2-20%.

6. The method according to claim 1, characterized in that, The volume fraction of reducing gas in the carrier gas is 2-5%, and the flow rate of the carrier gas is 10-100 sccm.

7. The method according to claim 1, characterized in that, The heating rate of the tube furnace is 30-50 ℃ / min, and the isothermal growth time is 10-60 min.

8. The phase-tunable Bi-Te-O ternary system material prepared by the method according to any one of claims 1 to 7, wherein the phase-tunable Bi-Te-O ternary system material comprises elemental Te, Bi2Te3, Bi2TeO5 and Bi2O2Te.

9. The phase-tunable Bi-Te-O ternary system material according to claim 8, characterized in that, The obtained phase has the following physical characterization features: (1) When the phase is elemental Te, it has a density of 120 cm⁻¹ -1 and 141 cm -1 The Raman peak has a thickness of 78-86 nm; (2) When the phase is Bi2Te3, it has a density of 100 cm⁻¹ -1 and 133 cm -1 Raman Peak; (3) When the phase is Bi2TeO5, it has a density of 103 cm⁻¹. -1 The Raman peaks have a thickness of 3.0-5.7 nm; (4) When the phase is Bi2O2Te, it has a thickness of 146 cm⁻¹. -1 Mount Raman.

10. The application of the phase-tunable Bi-Te-O ternary system material as described in claim 8 or 9 in the fields of microelectronics, thermoelectric conversion and optoelectronic devices.

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