A wide-band photodetector based on two-dimensional topological material and a preparation method thereof

Abstract

The application discloses a kind of wide-band photodetector based on two-dimensional topological material and preparation method thereof, and the application relates to the technical field of photodetector preparation.The method comprises the following steps: mixing Ni powder, Ta powder and Te powder, grinding;Put into quartz tube, add iodine, heat, while establishing temperature difference, keep a week, cool down, then pick in the crystal material obtained in low temperature zone, get pure phase target single crystal sample;Dissociate to thin layer, and transfer to substrate, then and the mask plate engraved with electrode pattern are pasted and fixed, then Cr / Au electrode is evaporated, and wide-band photodetector based on two-dimensional topological material is prepared.The photodetector based on Ta2Ni3Te5 flake prepared by the application presents fast response time, high responsivity and non-localized photocurrent response in self-powered mode, and the application solves the problem of poor performance of photodetector in the prior art.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of photoelectric detector preparation, in particular to a wide-band photoelectric detector based on two-dimensional topological materials and a preparation method thereof. BACKGROUND

[0002] Due to wide applications in imaging, remote sensing, environmental monitoring, optical communication and analytical applications, the development of room-temperature operated, self-powered, portable light detection devices has high practical significance. Although such photoelectric detectors are mainly based on traditional semiconductor materials such as silicon and InGaAs, they have been commercially used and are quite mature in the visible and near-infrared wavelength regions, while the application of narrow-bandgap photoelectric detectors in the mid-infrared wavelength region is limited by low-temperature operation requirements of semiconductor HgCdTe4 and InSb. So far, the room-temperature operation of mid-infrared photoelectric detectors with high responsivity still presents important technical challenges. Topological quantum materials have unique surface states and low-energy electron transport characteristics, exhibit special topological quantum states (such as Dirac fermions, Weyl fermions and Majorana fermions) and novel physical properties (such as quantum anomalous Hall effect, three-dimensional quantum Hall effect, zero-bandgap topological state and ultra-high carrier mobility) different from conventional semiconductors, and are considered as a major breakthrough in condensed matter physics and materials science in recent years. Therefore, there is an urgent need for a wide-band photoelectric detector based on two-dimensional topological materials, which can greatly improve the output performance of the wide-band photoelectric detector by utilizing the inherent properties of the two-dimensional topological materials and break through the long-term technical bottleneck of self-powered photoelectric detectors. SUMMARY

[0003] The application aims to provide a wide-band photoelectric detector based on two-dimensional topological materials and a preparation method thereof, so as to solve the problem of poor performance of photoelectric detectors in the prior art.

[0004] The technical scheme for solving the above technical problems is as follows: a preparation method of a wide-band photoelectric detector based on two-dimensional topological materials is provided, which comprises the following steps:

[0005] (1) mixing, grinding and preparing Ni powder, Ta powder and Te powder to obtain mixed raw materials;

[0006] (2) putting the mixed raw materials prepared in step (1) into a quartz tube, adding iodine, vacuum sealing, heating to 700-800 / 600-700 DEG C within 8-12 h, establishing a temperature difference of 90-110 DEG C at the same time, maintaining for one week, cooling to room temperature, and then selecting the crystal material obtained in the low-temperature zone to obtain a pure-phase target single crystal sample;

[0007] (3) the target single crystal sample prepared in step (2) is dissociated into a thin layer by a mechanical exfoliation method and transferred to a substrate, then a mask plate with an electrode pattern is adhered and fixed to the target single crystal sample, and then a Cr / Au electrode is evaporated on the surface of the target single crystal sample to prepare a wide-band photodetector based on a two-dimensional topological material.

[0008] Based on the above technical solution, the application can be further improved as follows:

[0009] Further, in step (1), the molar ratio of Ni, Ta and Te is 2.5-3.5:1.5-2.5:4.5-5.5.

[0010] Further, in step (1), the molar ratio of Ni, Ta and Te is 3:2:5.

[0011] Further, in step (2), the mass ratio of the mixed raw materials and iodine is 400-600:40-60.

[0012] Further, in step (2), the mass ratio of the mixed raw materials and iodine is 500:50.

[0013] Further, in step (2), after vacuum sealing, heating and establishing a temperature difference in a double-temperature-zone tube furnace.

[0014] Further, in step (2), heating to 750 / 650 DEG C, while establishing a temperature difference of 100 DEG C.

[0015] Further, in step (2), the target single crystal sample with pure phase is selected from the crystal material obtained in the low temperature zone by XRD.

[0016] Further, in step (2), the diameter of the quartz tube is 1-1.5 cm, and the length is 25-30 cm.

[0017] Further, in step (2), the diameter of the quartz tube is 1.3 cm, and the length is 27 cm.

[0018] Further, in step (3), the substrate is a SiO2 / Si substrate.

[0019] Further, in step (3), the mask plate with the electrode pattern is fixed on the three-dimensional displacement table by a three-dimensional displacement table to complete the adhering and fixing process.

[0020] Further, in step (3), the substrate containing the target single crystal sample is placed on the sample stage, and the sample to be transferred is found under the optical microscope, then the mask plate with the electrode pattern is fixed on the precise three-dimensional displacement stage by vacuum technology, the X-axis and Y-axis of the three-dimensional displacement stage are controlled to align the electrode pattern with the target single crystal sample, and the Z-axis of the three-dimensional displacement stage is controlled to make the mask plate with the electrode pattern adhere to and fix the target single crystal sample.

[0021] Further, in step (3), the Cr / Au electrode is deposited on the surface of the target single crystal sample by electron beam evaporation.

[0022] Further, in step (3), the thickness of Cr in the Cr / Au electrode is 5-10nm, and the thickness of Au is 35-45nm.

[0023] Further, in step (3), the thickness of Cr in the Cr / Au electrode is 8nm, and the thickness of Au is 40nm.

[0024] Further, in step (3), after adhering and fixing, the Cr / Au electrode is deposited in the vacuum chamber.

[0025] The application also provides a two-dimensional topological material-based wide-band photodetector prepared by the preparation method of the two-dimensional topological material-based wide-band photodetector.

[0026] The application has the following beneficial effects:

[0027] 1. The two-dimensional topological quantum material prepared by the application has unique surface state and low-energy consumption electronic transport characteristics, exhibits special topological quantum state and novel physical characteristics different from conventional semiconductors, and has important value in the fields of basic research of condensed matter physics and wide-spectrum photodetector devices.

[0028] 2. The application first prepares a Ta2Ni3Te5 crystal by a chemical vapor transmission method. The resistivity of the Ta2Ni3Te5 single crystal sample increases first, then decreases, and then increases again with the decrease of temperature, and presents a rare negative magnetoresistance effect under a weak magnetic field in the transition temperature region (about 20-50K), which is due to the thermal activation of impurities in the crystal. Interestingly, the magnetoresistance of Ta2Ni3Te5 at low temperature shows a good linear correlation with the applied magnetic field, which is related to its second-order topological nature and Luttinger liquid behavior.

[0029] 3. The photodetector prepared based on the Ta2Ni3Te5 flake presents a fast response time (21.25 s) and a high responsivity (110 A W -1) and non-localized photocurrent response, which is consistent with that observed in photodetectors based on topological materials. The photodetector prepared by the present application exhibits fast response time (0.605 ms), high responsivity (0.26 A W -1 ) and broadband spectral response up to 10.6 m in conventional mode, showing great application potential in the field of electronics and optoelectronics. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Crystal structure diagram of Ta2M'3Te5 prepared by the present application;

[0031] Figure 2 XRD spectrum of Ta2Ni3Te5 prepared in Example 1;

[0032] Figure 3 HAADF image of Ta2Ni3Te5 prepared in Example 1 in (010) crystal plane projection;

[0033] Figure 4 SEM image of Ta2Ni3Te5 prepared in Example 1

[0034] Figure 5 Mapping image of Ta, Ni and Te elements in Ta2Ni3Te5 prepared in Example 1;

[0035] Figure 6 Temperature dependence curve of resistivity of Ta2Ni3Te5 prepared in Example 1;

[0036] Figure 7 Temperature dependence curve of ln( r xx ) of Ta2Ni3Te5 prepared in Example 1;

[0037] Figure 8 Field dependence curve of magnetoresistance of Ta2Ni3Te5 prepared in Example 1 in transition temperature region;

[0038] Figure 9 Field dependence curve of Ta2Ni3Te5 prepared in Example 1 in low temperature region;

[0039] Figure 10 Photocurrent time resolution curve of the photodetector prepared in Example 1;

[0040] Figure 11 Scanning photocurrent image of the photodetector prepared in Example 1;

[0041] Figure 12 Light power dependence curve of photocurrent generated by the photodetector prepared in Example 1;

[0042] Figure 13 The chopped frequency dependent photocurrent response of the photodetector prepared in Example 1;

[0043] Figure 14 The photocurrent distribution of the photodetector prepared in Example 1 across the channel; I ph - V ds Curve;

[0044] Figure 15 The time resolved photocurrent curve of the photodetector prepared in Example 1 for one cycle of amplification;

[0045] Figure 16 The photocurrent distribution of the photodetector prepared in Example 1 across the channel;

[0046] Figure 17 The power density dependence curve of responsivity and detectivity of the photodetector prepared in Example 1;

[0047] Figure 18 The time resolved photocurrent curve of the photodetector prepared in Example 1 at 405 nm;

[0048] Figure 19 The time resolved photocurrent curve of the photodetector prepared in Example 1 at 639 nm;

[0049] Figure 20 The time resolved photocurrent curve of the photodetector prepared in Example 1 at 980 nm;

[0050] Figure 21 The time resolved photocurrent curve of the photodetector prepared in Example 1 at 10.6 μm. DETAILED DESCRIPTION

[0051] The principles and features of the present application are described below in conjunction with the accompanying drawings, in which the examples are used to explain the present application and are not intended to limit the scope of the present application. The specific conditions not mentioned in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased on the market.

[0052] Example 1:

[0053] A wide-band photodetector based on two-dimensional topological material, the preparation comprising the following steps:

[0054] (1) In the glove box, according to the molar ratio of 3:2:5, mix Ni powder, Ta powder and Te powder, grind in the agate mortar, and prepare 500 mg of mixed raw materials;

[0055] (2) Put the mixed raw material prepared in step (1) into a quartz tube (diameter 1.3 cm, length 27 cm), add 50 mg of iodine as a transport agent, vacuum seal the quartz tube, place it in a double-temperature zone tube furnace, heat to 750 / 650°C within 10 h, at the same time establish a temperature difference of 100°C, keep for a week, after the reaction is completed, take the quartz tube out of the tube furnace and cool it to room temperature quickly, transfer the quartz tube to a fume hood, and use a tube breaking tool to open the quartz tube, then select the target single crystal sample with pure phase from the crystal material obtained in the low temperature zone by XRD;

[0056] (3) Dissociate the target single crystal sample (Ta2Ni3Te5) prepared in step (2) into a thin layer using a mechanical exfoliation method, and transfer it to a SiO2 / Si substrate. Place the substrate containing the target single crystal sample on a sample stage, and find the sample to be transferred under an optical microscope. Then fix the mask plate with electrode patterns on the precise three-dimensional displacement stage by vacuum technology. Align the electrode patterns with the target single crystal sample by controlling the X and Y axes of the three-dimensional displacement stage. Control the Z axis of the three-dimensional displacement stage to make the mask plate with electrode patterns adhere to and fix the target single crystal sample. Transfer to the vacuum cavity, use electron beam evaporation, and evaporate Cr / Au (8 / 40 nm) electrodes on the surface of the target single crystal sample to prepare a wide-band photodetector based on two-dimensional topological materials.

[0057] Example 2:

[0058] A wide-band photodetector based on two-dimensional topological materials, its preparation includes the following steps:

[0059] (1) In a glove box, mix Ni powder, Ta powder and Te powder according to a molar ratio of 2.5:1.5:4.5, and grind them in an agate mortar to prepare 400 mg of mixed raw material;

[0060] (2) Put the mixed raw material prepared in step (1) into a quartz tube (diameter 1.3 cm, length 27 cm), add 50 mg of iodine as a transport agent, vacuum seal the quartz tube, place it in a double-temperature zone tube furnace, heat to 750 / 650°C within 10 h, at the same time establish a temperature difference of 100°C, keep for a week, after the reaction is completed, take the quartz tube out of the tube furnace and cool it to room temperature quickly, transfer the quartz tube to a fume hood, and use a tube breaking tool to open the quartz tube, then select the target single crystal sample with pure phase from the crystal material obtained in the low temperature zone by XRD;

[0061] (3) The target single crystal sample (Ta2Ni3Te5) prepared in step (2) is dissociated into a thin layer by a mechanical exfoliation method and transferred to a SiO2 / Si substrate. The substrate containing the target single crystal sample is placed on a sample stage, and the sample to be transferred is found under an optical microscope. Then, a mask plate with an electrode pattern is fixed on a precise three-dimensional displacement stage by vacuum technology. The electrode pattern is aligned with the target single crystal sample by controlling the X-axis and Y-axis of the three-dimensional displacement stage. The mask plate with the electrode pattern is adhered and fixed to the target single crystal sample by controlling the Z-axis of the three-dimensional displacement stage. The mask plate with the electrode pattern is transferred into a vacuum chamber, and an electron beam evaporation is used. Then, a Cr / Au (5 / 35 nm) electrode is evaporated on the surface of the target single crystal sample to prepare a wide-band photodetector based on a two-dimensional topological material.

[0062] Example 3

[0063] A wide-band photodetector based on a two-dimensional topological material is prepared, including the following steps:

[0064] (1) In a glove box, Ni powder, Ta powder and Te powder are mixed in a molar ratio of 3.5:2.5:5.5, and are ground in an agate mortar to prepare 600 mg of mixed raw materials;

[0065] (2) The mixed raw materials prepared in step (1) are put into a quartz tube (diameter 1.3 cm, length 27 cm), and 60 mg of iodine is added as a transport agent. The quartz tube is vacuum sealed and placed in a double-temperature zone tube furnace. It is heated to 800 / 700°C within 10 hours, while a temperature difference of 100°C is established. The reaction is maintained for one week. After the reaction is completed, the quartz tube is removed from the tube furnace and quickly cooled to room temperature. The quartz tube is transferred to a fume hood and opened using a tube breaking tool. Then, the crystal material obtained in the low temperature zone is selected by XRD to obtain a pure phase target single crystal sample;

[0066] (3) The target single crystal sample (Ta2Ni3Te5) prepared in step (2) is dissociated into a thin layer by a mechanical exfoliation method and transferred to a SiO2 / Si substrate. The substrate containing the target single crystal sample is placed on a sample stage, and the sample to be transferred is found under an optical microscope. Then, a mask plate with an electrode pattern is fixed on a precise three-dimensional displacement stage by vacuum technology. The electrode pattern is aligned with the target single crystal sample by controlling the X-axis and Y-axis of the three-dimensional displacement stage. The mask plate with the electrode pattern is adhered and fixed to the target single crystal sample by controlling the Z-axis of the three-dimensional displacement stage. The mask plate with the electrode pattern is transferred into a vacuum chamber, and an electron beam evaporation is used. Then, a Cr / Au (10 / 45 nm) electrode is evaporated on the surface of the target single crystal sample to prepare a wide-band photodetector based on a two-dimensional topological material.

[0067] Test Example

[0068] I. Crystal Structure and Material Characterization

[0069] 1. The crystal structure of M2M′3Te5 is shown in [reference needed]. Figure 1 .

[0070] Depend on Figure 1 It can be seen that the central M atom coordinates with five Te atoms to form a tetragonal pyramid. The formed MTe5 tetragonal pyramid is formed by sharing their edges along... b The axes form a one-dimensional chain. M′ atoms occupy the interstitial sites between the chains, obtained through tetrahedral coordination of Te atoms. The resulting M2M′3Te5 layer is formed along the chain by weak van der Waals interactions between Te atoms. c It is made by stacking shafts.

[0071] 2. The Ta2Ni3Te5 prepared in Example 1 was subjected to XRD analysis. The specific method was as follows: the prepared single crystal sample... a-b The XRD patterns collected using a powder crystal diffractometer when the surface was exposed to X-rays are shown in the figure. Figure 2 .

[0072] Depend on Figure 2 As can be seen, the spectrum shows sharp and high-intensity Bragg diffraction peaks, and all diffraction peaks correspond to the information of the (001) crystal plane, which can be labeled as ( 00l This is consistent with the diffraction pattern calculated through crystal structure. No diffraction peaks were found for any other impurity phases, indicating that the prepared Ta2Ni3Te5 single crystal material has good crystallinity and purity. The inset shows an optical image of the Ta2Ni3Te5 single crystal; the prepared single crystal has a flat surface, and the preferred lattice orientation of the material can be roughly observed.

[0073] 3. The Ta2Ni3Te5 single crystal material prepared in Example 1 was collected using high-angle annular dark-field imaging (HAADF) projected onto the (010) crystal plane. The results are shown in [Figure 1]. Figure 3 .

[0074] Depend on Figure 3 It can be seen that the formed five-layer Te-Ni-Ta-Ni-Te structure is stacked along the c-axis through weak van der Waals interactions, with an interlayer spacing of approximately 1.6 Å. The arrangement of all Ta, Ni, and Te atoms can be clearly seen in... a-c Crystal planes are resolvable. Interestingly, the microstructure of the prepared Ta2Ni3Te5 crystal is slightly different from that of the previously reported Ta2Pd3Te5 material. The prepared Ta2Ni3Te5 exhibits a monoclinic crystal structure, with lattice parameters labeled as follows. a =17.9Å, c =7.8Å, =117 o It has a crystal structure somewhat similar to that of TaTe2.

[0075] 4. The Ta2Ni3Te5 prepared in Example 1 was subjected to SEM analysis, and the results are shown in the figure. Figure 4 .

[0076] Depend on Figure 4 As can be seen, a flat surface structure is observed. Clear linear protrusions can be observed on the crystal surface, indicating that the prepared Ta2Ni3Te5 crystal has a quasi-one-dimensional crystal structure similar to that of Ta2NiSe5.

[0077] 5. The Ta2Ni3Te5 prepared in Example 1 was subjected to EDX elemental analysis, and the results are shown in the figure. Figure 5 (e) is the element Ta, (f) is the element Ni, and (g) is the element Te.

[0078] Depend on Figure 5 It can be seen that the elements are uniformly distributed in the Ta2Ni3Te5 crystal. The atomic proportions of Ta, Ni and Te in the prepared Ta2Ni3Te5 crystal are 20.04%, 28.98% and 50.99%, respectively, with an uncertainty of less than 3%, which is consistent with the crystal structure analysis.

[0079] II. The transport properties of the two-dimensional material Ta2Ni3Te5 prepared in Example 1 were tested, and the results are shown in [the table below]. Figure 6-9 .

[0080] Depend on Figure 6 It is known that the room temperature resistivity of Ta2Ni3Te5 is as low as 0.01 Ω cm. Within the temperature range of 300-80 K, its resistivity exhibits a monotonically increasing trend with decreasing temperature, consistent with intrinsic semiconductor characteristics. In the temperature range of 50-80 K, the resistivity of Ta2Ni3Te5 shows a slightly decreasing trend with decreasing temperature, exhibiting metallic conductivity. This transition is attributed to the thermal activation of impurities, leading to a slight disorder in the prepared Ta2Ni3Te5 sample within this temperature range. With further decreasing temperature, the impurities are frozen, and the resistivity of Ta2Ni3Te5 once again exhibits typical semiconductor characteristics.

[0081] The bandgap of a semiconductor ( E g This can be described by the following formula:

[0082]

[0083] In the formula, a 0 is a constant. xx Transverse resistivity, kB is the Boltzmann constant.

[0084] From Figure 7 we can see that in the high temperature region, ln( xx )- T -1 shows a good linear curve, and the calculated E g is about 0.09 eV. When the impurities are frozen out (below 40 K), ln( xx )- T -1 shows a good linear correlation again, and the slope is smaller than that in the high temperature region, corresponding to a smaller band gap energy, about 0.7 meV.

[0085] According to the classical Hall effect theory, in a conventional system with only one type of carrier (hole), the electric field induced by the Hall voltage balances the Lorentz force generated by the carrier motion. Therefore, the carriers can maintain a straight-line motion in the system. Generally, the carrier motion will form a closed orbit after a large magnetic field is applied, i.e. wt > 1, where w is the Larmor frequency, t is the collision time. In this region, the magnetoresistance is mainly formed by the carrier transfer between the closed orbits, resulting in a good linear magnetoresistance. Therefore, the field-dependent curve of the magnetoresistance changes from H 2 dependence to H dependence.

[0086] From Figure 8 we can see that the Ta2Ni3Te5 crystal prepared in the transition temperature region shows weak negative magnetoresistance at low magnetic fields. This is due to the change in disorder caused by the thermal activation of impurities. With the increase of the magnetic field, a clear transition from negative magnetoresistance to positive magnetoresistance is shown. This transition can be explained by the wave function contraction model and the forward scattering model. At this time, the magnetoresistance is considered to be the superposition of positive and negative magnetoresistance, and the contraction of the electron wave function at the impurity center in the strong magnetic field leads to a decrease in the hopping length between two sites, making the positive magnetoresistance of the material more prominent.

[0087] From Figure 9It is known that when the temperature is further reduced to below the transition temperature range (10K), the magnetoresistance of Ta2Ni3Te5 single crystal again presents a monotonic change with the magnetic field, which is associated with impurity freezing. Interestingly, the magnetoresistance at low temperature shows a good linear correlation with the applied magnetic field, which is contrary to the traditional magnetoresistance theory. The theory of linear magnetoresistance can be divided into two categories: classical theory and quantum theory. The classical theory shows that when the current is bent in the low carrier mobility region (caused by low conductivity impurities), the linear magnetoresistance is mostly contributed by the Hall effect, which is obviously contrary to the Hall resistance. The quantum model shows that linear magnetoresistance occurs in systems with open Fermi surface or in the ultra-quantum limit of narrow band gap semiconductors, and this quantum magnetoresistance remains linear in very small magnetic fields. In recent years, people have made additional considerations on the linear magnetoresistance phenomenon in topological systems. Therefore, the interesting electrical transport properties of Ta2Ni3Te5 are related to the predicted second-order topological nature and Luttinger liquid behavior.

[0088] Thirdly, the Ta2Ni3Te5 material prepared by the present application has the above-mentioned excellent electron transport properties (narrow band gap electronic structure and second-order topological nature), and has potential research value in wide wavelength photodetection. In combination with Example 1, a Ta2Ni3Te5 two-electrode photodetector is prepared, and the output performance of the photodetector in a self-powered mode is tested by using a lock-in amplifier and a chopper, and the chopping frequency is 232Hz, and the results are shown in Figure 10-13 .

[0089] From Figure 10 it can be seen that the Ta2Ni3Te5 photodetector prepared in Example 1 has a stable photocurrent response in a self-powered mode.

[0090] From Figure 11 it can be seen that the photocurrent of the Ta2Ni3Te5 photodetector prepared in Example 1 does not show obvious region dependence. The contact region far away from the metal electrode-Ta2Ni3Te5 shows a stable non-local photocurrent, which means that the photothermal effect (PTE, i.e. Seebeck effect) plays a crucial role in the process of photocurrent generation. Moreover, the photocurrent generation of the photothermal effect does not depend on the distance from the contact region, which is somewhat similar to the Shockley-Ramo mechanism found in graphene and the charge separation mechanism provided by topological materials. The photovoltaic effect or the photo-Dember effect both depend on the contact between the metal electrode and the channel material (the built-in electric field generated in the contact region facilitates the separation of carriers), therefore, the generated photocurrent is highly localized and occurs in the contact region of the metal electrode and the channel material.

[0091] From Figure 12It can be seen that the photocurrent generated by the Ta2Ni3Te5 photodetector prepared in Example 1 exhibits a good linear correlation with the laser power in self-powered mode (power range: 0.1-1.8mW). The responsivity of the Ta2Ni3Te5 photodetector is approximately 110. AW -1 It shows potential application value in the field of self-powered photoelectric detection.

[0092] Depend on Figure 13 It can be seen that the photoelectric response time of the photodetector prepared by this invention, which is related to the chopping frequency, is approximately 21.25 seconds. s.

[0093] IV. The photoelectric characteristics of the photodetector prepared in Example 1 were detected using a semiconductor analyzer in conventional mode. The results are shown in [Figure 1]. Figure 14-17 .

[0094] Depend on Figure 14 As can be seen, the Ta2Ni3Te5 photodetector prepared in Example 1 exhibits a significant positive photocurrent response throughout the entire voltage test range, and the generated photocurrent shows a good linear relationship with the external bias voltage. With the gradual increase of light intensity, the generated positive photocurrent shows a significant increasing trend.

[0095] Depend on Figure 15 It can be seen that the photocurrent of the Ta2Ni3Te5 photodetector under the traditional mode originates from the entire channel, which is consistent with the photoconductivity mechanism.

[0096] Depend on Figure 16 It can be seen that the Ta2Ni3Te5 photodetector exhibits an ultrafast response speed (defined as the time taken for the maximum photocurrent to change between 10% and 90%): the rise time is approximately 605 seconds. The descent time was approximately 653 seconds. s.

[0097] Depend on Figure 17 It can be seen that, with an external bias voltage of 2.0V, the Ta2Ni3Te5 photodetector achieves a maximum responsivity of 0.26AW at room temperature. -1 This is comparable to broadband photodetectors based on two-dimensional materials. However, due to the large dark current of the Ta2Ni3Te5 photodetector, the corresponding specific detectivity is only 2.8 × 10⁻⁶. 5 Jones' performance in low-light detection is mediocre. Constructing pn, pin, or Schottky junctions can create junction barriers and built-in electric fields, potentially leading to a significant reduction in dark current and a substantial improvement in photoelectric detection performance.

[0098] V. The time-resolved photocurrent curves of the photodetector prepared in Example 1 at different laser wavelengths were detected, and the results are shown in [the table below]. Figure 18-21 . ( Figure 18 405nm@0.53W cm -2 ; Figure 19 639nm@0.16W cm -2 ; Figure 20 980nm@0.31W cm -2 ; Figure 21 10.6m@0.23W cm -2 )

[0099] Depend on Figure 18-21 It can be seen that the photocurrent response of the photodetector based on Ta2Ni3Te5 thin film exhibits a wide wavelength distribution. Figure 18-21 The photocurrent time-resolved curves of the Ta2Ni3Te5 photodetector at different laser wavelengths ranging from 405 nm to 10.6 μm are presented. The Ta2Ni3Te5 photodetector prepared in Example 1 exhibits a light response at longer wavelengths that is no weaker than that in the visible light region. Due to different laser spot sizes and instantaneous excitation energies, the photocurrent time-resolved curves at different wavelengths show different morphologies. Due to the significant thermal effect radiation in the infrared region (980 nm), the internal hot carriers of the Ta2Ni3Te5 photodetector are activated under continuous laser irradiation, increasing the photocurrent output of the prepared photodetector. When the laser is turned off, the photocurrent of the detector also shows a slow decrease, which is also attributed to the slow response or gradual quenching of hot carriers. When the excitation energy is as low as 0.12 eV (10.6 μm), the excitation energy is close to the bandgap of Ta2Ni3Te5, and the thermal effect of the detector is more obvious. Based on the analysis of electrical transport characteristics, Ta2Ni3Te5 exhibits a narrower bandgap (70meV) and lower dark current at low temperatures. The Ta2Ni3Te5 photodetector prepared in this invention will exhibit excellent photoelectric properties and a wider spectral response.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for fabricating a broadband photodetector based on two-dimensional topological materials, characterized in that, Includes the following steps: (1) Mix Ni powder, Ta powder and Te powder, grind them to obtain a mixed raw material; (2) The mixed raw materials obtained in step (1) are put into a quartz tube, iodine is added, vacuum is applied and sealed, and the mixture is heated to 750 / 650℃ within 8-12 hours. At the same time, a temperature difference of 100℃ is established and maintained for one week. The mixture is then cooled to room temperature, and then selected from the crystal materials obtained in the low temperature region to obtain the target single crystal sample of the pure phase. (3) The target single crystal sample obtained in step (2) is dissected into a thin layer by mechanical peeling and transferred to the substrate. Then, the mask with the electrode pattern is attached and fixed to the target single crystal sample. Then, Cr / Au electrodes are deposited on the surface of the target single crystal sample to obtain a wideband photodetector based on two-dimensional topological materials. In step (1), the molar ratio of Ni, Ta, and Te is 3:2:5; In step (2), the mass ratio of the mixed raw materials to iodine is 400-600:40-60; In step (2), XRD is used to select pure phase target single crystal samples from the crystal materials obtained in the low-temperature region; In step (3), the substrate is a SiO2 / Si substrate; In step (3), the mask with the electrode pattern is fixed on the three-dimensional displacement stage to complete the bonding and fixing process. In step (3), Cr / Au electrodes are deposited on the surface of the target single crystal sample by electron beam evaporation.

2. The broadband photodetector based on two-dimensional topological materials prepared by the fabrication method of the broadband photodetector based on two-dimensional topological materials as described in claim 1.

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