Terahertz detector and preparation method thereof

Abstract

The invention discloses a terahertz detector and a preparation method thereof. The terahertz detector comprises a substrate; the TaNiTe5 layer is positioned on the substrate; the electrode is located on the substrate, and the electrode comprises a source electrode and a drain electrode which are electrically connected with the two ends of the TaNiTe5 layer respectively. According to the terahertz detector, the TaNiTe5 layer of the quasi-one-dimensional topological structure serves as the channel material layer of the terahertz detector, the unique double Dirac surface state and the quasi-one-dimensional structure of the TaNiTe5 layer can bring high carrier mobility, and effective detection of terahertz waves at the room temperature is achieved through a photoconductive response mechanism.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, specifically relating to a terahertz detector and its fabrication method. Background Technology

[0002] Terahertz (THz) waves are electromagnetic waves with frequencies ranging from 0.1 THz to 10 THz. Due to their unique advantages, they hold significant promise for applications in non-destructive imaging, high-speed, high-capacity communication, biomedicine, and scientific instruments. Among these, real-time terahertz imaging and high-speed communication are transformative for the future development of smart healthcare and artificial intelligence, thus creating an urgent need for miniaturized integrated terahertz detection chips. Current terahertz detectors mainly include cooled terahertz detectors such as superconducting detectors, quantum well detectors, and blocking impurity band detectors. However, these cooled terahertz detectors rely on large cryogenic cooling systems, hindering their application in miniaturized integrated systems. Therefore, the development of uncooled terahertz detection technology is crucial for realizing miniaturized integrated terahertz detection chips. However, the energy of terahertz photons is in the range of 0.42 meV to 42 meV, comparable to room temperature thermal energy (~26 meV), posing a significant challenge to achieving effective detection of terahertz waves at room temperature.

[0003] Existing uncooled terahertz detectors include field-effect transistor (FET) detectors, Schottky barrier diode (SPD) detectors, and photothermal detectors, which achieve terahertz detection based on plasma wave oscillation, metal-semiconductor rectification effect, and hot carrier photothermal effect, respectively. Since these uncooled terahertz detectors do not directly rely on terahertz photon excitation, they can overcome the limitations of traditional photogenerated carriers and achieve uncooled terahertz detection. However, FET detectors typically require high-mobility materials and field-effect structures, limiting further improvements in their detection performance; Schottky diode detectors exhibit an exponential decrease in detection sensitivity with increasing frequency, and their delicate air-bridge structure hinders their application in large-scale array integrated systems; furthermore, photothermal detectors require the design of additional asymmetric structures, and their response speed is relatively slow due to lattice thermal vibrations. Furthermore, terahertz detectors with subwavelength gap metal-semiconductor-metal structures developed in recent years are based on an electromagnetically induced potential well mechanism. Under terahertz irradiation, a potential well is generated to trap charge carriers in the metal, thereby changing the channel resistance and achieving terahertz photon detection through a mechanism similar to conventional photoconductivity. However, this mechanism is limited to semiconductor materials, and their high internal resistance leads to significant thermal noise, restricting further improvements in the sensitivity of such terahertz detectors.

[0004] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a terahertz detector and its fabrication method. Summary of the Invention

[0005] The purpose of this invention is to provide a terahertz detector and its fabrication method, which can detect terahertz waves at high speed and high sensitivity at room temperature.

[0006] To achieve the above objectives, an embodiment of the present invention provides the following technical solution:

[0007] A terahertz detector, the terahertz detector comprising:

[0008] Substrate;

[0009] A TaNiTe5 layer is located on the substrate;

[0010] An electrode is located on the substrate, and the electrode includes a source and a drain that are electrically connected to both ends of the TaNiTe5 layer, respectively.

[0011] In one embodiment, the TaNiTe5 layer has two Dirac surface states.

[0012] In one embodiment, the thickness of the TaNiTe5 layer is 5nm to 50nm.

[0013] In one embodiment, the source and drain constitute an antenna structure, the source includes a first side and a second side disposed opposite to each other, and the drain includes a third side and a fourth side disposed opposite to each other, the first side and the third side being opposite to each other and respectively in contact with the TaNiTe5 layer.

[0014] In one embodiment, the width of the source electrode increases first and then remains constant from the first side to the second side, and the width of the drain electrode increases first and then remains constant from the third side to the fourth side.

[0015] In one embodiment, the spacing between the first side of the source and the third side of the drain is 30 nm to 4 μm; and / or,

[0016] The distance between the second side of the source electrode and the fourth side of the drain electrode is 80μm~200μm, the width of the source electrode on the second side is 60μm~140μm, and the width of the drain electrode on the fourth side is 60μm~140μm.

[0017] In one embodiment, the substrate includes an intrinsic silicon layer and a silicon oxide layer located on the intrinsic silicon layer.

[0018] In one embodiment, the resistivity of the intrinsic silicon layer is greater than or equal to 20,000 Ω·cm.

[0019] Another embodiment of the present invention discloses the following technical solution:

[0020] A method for fabricating a terahertz detector, the method comprising the following steps:

[0021] Provide substrate;

[0022] A TaNiTe5 layer was prepared on the substrate;

[0023] Source and drain electrodes electrically connected to the TaNiTe5 layer were fabricated on substrates at both ends of the TaNiTe5 layer.

[0024] In one embodiment, fabricating a TaNiTe5 layer on a substrate includes:

[0025] TaNiTe5 crystals were prepared by a fluxing method.

[0026] The TaNiTe5 layer was transferred from the TaNiTe5 crystal to the substrate by mechanical exfoliation.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention uses a TaNiTe5 layer with a quasi-one-dimensional topological structure as the channel material layer of a terahertz detector. Its unique dual Dirac surface states and quasi-one-dimensional structure can bring high carrier mobility and achieve effective detection of terahertz waves at room temperature through a photoconductive response mechanism.

[0029] This invention constructs the source and drain as an antenna structure and integrates it with the TaNiTe5 layer, which can obtain stronger terahertz optical field coupling, which is beneficial to realizing high-sensitivity terahertz wave detection at room temperature. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the terahertz detector in Embodiment 1 of the present invention;

[0032] Figure 2 This is the band structure diagram of the TaNiTe5 layer obtained by angle-resolved photoelectron spectroscopy in Example 2 of the present invention;

[0033] Figure 3 This is a schematic diagram of the photoconductive mechanism of the terahertz detector in Embodiment 1 of the present invention;

[0034] Figure 4 This is an optical microscope characterization image of the terahertz detector prepared in Example 1 of the present invention;

[0035] Figure 5 This is a terahertz field distribution diagram of the electrodes of the antenna structure in Embodiment 1 of the present invention;

[0036] Figure 6 This is a graph showing the relationship between photocurrent and bias voltage measured by the terahertz detector at different incident frequencies in Embodiment 1 of the present invention.

[0037] Figure 7 The above are response waveforms of the terahertz detector measured under different bias voltages in Embodiment 1 of the present invention.

[0038] Figure 8 This is a graph showing the relationship between photocurrent and incident power measured by the terahertz detector under different bias voltages in Embodiment 1 of the present invention.

[0039] Figure 9 This is a graph showing the relationship between the photocurrent responsivity and bias voltage measured by the terahertz detector at different incident frequencies in Embodiment 1 of the present invention.

[0040] Figure 10 This is a graph showing the relationship between the noise equivalent power and the bias voltage measured by the terahertz detector at different incident frequencies in Embodiment 1 of the present invention.

[0041] Figure 11 The photoresponse time of the terahertz detector in Embodiment 1 of the present invention is measured at an incident frequency of 0.11 THz.

[0042] Figure 12 This is a graph showing the relationship between the photocurrent and the modulation frequency measured by the terahertz detector at a bandwidth of -3dB in Embodiment 1 of the present invention.

[0043] Explanation of key figure labels:

[0044] 10 - Substrate, 101 - Intrinsic silicon layer, 102 - Silicon oxide layer, 20 - TaNiTe5 layer, 301 - Source, 302 - Drain. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0046] This invention discloses a terahertz detector, comprising:

[0047] Substrate;

[0048] The TaNiTe5 layer is located on the substrate;

[0049] An electrode is located on a substrate. The electrode includes a source electrode and a drain electrode that are electrically connected to both ends of the TaNiTe5 layer respectively.

[0050] The present invention also discloses a preparation method of a terahertz detector, including the following steps:

[0051] Provide a substrate;

[0052] Prepare a TaNiTe5 layer on the substrate;

[0053] Prepare a source electrode and a drain electrode that are electrically connected to the TaNiTe5 layer on the substrate at both ends of the TaNiTe5 layer respectively.

[0054] Quasi-one-dimensional Dirac semimetal TaNiTe5 provides a new platform for the research of new topological phenomena and terahertz optoelectronic devices due to its unique electronic structure, energy band characteristics and electrical transport properties. The double Dirac surface states of TaNiTe5 material will trigger a strong photocell-like effect, enabling broadband and highly sensitive terahertz detection. In addition, the topological protected edge states generated by the quasi-one-dimensional structure of TaNiTe5 material will bring low scattering and high mobility, enabling high responsivity and fast response. This provides new possibilities for the research of photocell-like effect-driven room-temperature terahertz detection and new non-cooled terahertz detection technologies.

[0055] The following further illustrates the present invention with specific examples.

[0056] Example 1:

[0057] As shown in the figure, the terahertz detector in this example includes: Figure 1 As shown in the figure, the terahertz detector in this example includes:

[0058] A substrate 10;

[0059] A TaNiTe5 layer 20, located on the substrate 10;

[0060] An electrode is located on the substrate 10. The electrode includes a source electrode 301 and a drain electrode 302 that are electrically connected to both ends of the TaNiTe5 layer respectively.

[0061] Among them, the substrate 10 includes an intrinsic silicon layer 101 and a silicon oxide layer 102 located on the intrinsic silicon layer 101.

[0062] Specifically, the intrinsic silicon layer 101 in this example is a high-resistance intrinsic silicon layer with a resistivity greater than or equal to 20000 Ω·cm to ensure that the terahertz detector has low leakage current and high signal-to-noise ratio. Preferably, the thickness of the silicon oxide layer 102 is 285 nm.

[0063] Furthermore, in this embodiment, the TaNiTe5 layer is used as the channel material layer of the terahertz detector. Its dual Dirac surface states can induce a strong photoelectric effect, thereby achieving high-sensitivity broadband terahertz detection.

[0064] Specifically, the thickness of the TaNiTe5 layer 20 is 5nm~50nm.

[0065] Furthermore, in this embodiment, the source electrode 301 and the drain electrode 302 constitute an antenna structure, which efficiently couples the incident terahertz radiation. The source electrode 301 includes a first side and a second side arranged opposite to each other, and the drain electrode 302 includes a third side and a fourth side arranged opposite to each other. The first side and the third side are opposite to each other and are in contact with the TaNiTe5 layer 20, respectively.

[0066] By constructing the source and drain into a subwavelength planar metal antenna structure and integrating it with a TaNiTe5 layer, stronger terahertz optical field coupling is obtained, achieving efficient utilization of terahertz waves from both material and device levels, which is more conducive to realizing room temperature high-sensitivity terahertz detection.

[0067] It is worth noting that the source and drain of the antenna structure can be partially covered on the TaNiTe5 layer, or the sidewalls of the source and drain can be in contact with the TaNiTe5 layer to ensure that the source and drain of the antenna structure are in contact with the TaNiTe5 layer and achieve electrical connection.

[0068] Specifically, the distance between the first side of the source and the third side of the drain is 30nm~4μm. The distance between the first side of the source and the third side of the drain is reasonably designed according to actual needs so that the antenna structure can achieve a suitable local field enhancement effect.

[0069] In this embodiment, the source and drain form a butterfly antenna structure. The width of the source increases first and then remains constant from the first side to the second side, and the width of the drain increases first and then remains constant from the third side to the fourth side.

[0070] More specifically, the distance between the second side of the source and the fourth side of the drain is 80 μm to 200 μm, preferably 80 μm, the width of the source on the second side is 60 μm to 140 μm, preferably 60 μm, and the width of the drain on the fourth side is 60 μm to 140 μm, preferably 60 μm.

[0071] It should be understood that in other embodiments, the source and drain may also form other shapes of butterfly antenna structures or adopt other antenna structures, and their specific parameters should be adjusted accordingly based on the requirements of the response frequency band.

[0072] In this embodiment, the quasi-one-dimensional Dirac semimetal TaNiTe5 layer is used as the channel material layer of the terahertz detector. Compared with two-dimensional and three-dimensional systems, it has a lower dimension, and the influence of its confinement effect produces richer topological properties, such as topological surface states, low effective mass, nontrivial Berry phase, and smaller Fermi pockets, etc. These unique electronic properties endow it with low scattering and high carrier mobility protected by topological edge states, which is beneficial to high responsivity and high-speed photoelectric detection. At the same time, the unique double Dirac surface states and Dirac cones near the Fermi surface of the TaNiTe5 layer can provide a stronger photoconductance-like effect, thereby enabling high-performance uncooled terahertz detection.

[0073] As shown in Figure 2 Figure [Reference not provided], the energy band structure of the TaNiTe5 layer was analyzed by angle-resolved photoemission spectroscopy, demonstrating the existence of double Dirac surface states in TaNiTe5.

[0074] As shown in Figure 3 Figure [Reference not provided], the terahertz response mechanism of the terahertz detector in this embodiment was demonstrated. When terahertz radiation reaches the channel material, non-equilibrium electrons are excited to occupy higher energy states. At the same time, these non-equilibrium electrons drift unidirectionally under an external electric field, generating a photocurrent whose direction is determined by the direction of the applied electric field, similar to the classical photoconductance effect.

[0075] The preparation method of the terahertz detector in this embodiment includes the following steps:

[0076] S1. Provide a substrate.

[0077] The substrate in this embodiment includes an intrinsic silicon layer and a silicon oxide layer located on the intrinsic silicon layer.

[0078] Specifically, first, a high-resistivity intrinsic silicon substrate with a resistivity greater than or equal to 20000 Ω·cm is provided, and a 285-nm-thick silicon oxide layer is formed on the high-resistivity intrinsic silicon substrate through a thermal oxidation process; then, the substrate is successively ultrasonically cleaned with acetone, isopropyl alcohol, and deionized water; after that, the substrate is blown clean with a nitrogen gun to remove impurities and adhesives on the substrate surface.

[0079] S2. Prepare a TaNiTe5 layer on the substrate.

[0080] Specifically, this step includes:

[0081] (1) Prepare high-quality TaNiTe5 crystals by the flux method.

[0082] First, tantalum (Ta), nickel (Ni), and tellurium (Te) powders were placed in an alumina crucible at a molar ratio of Ta:Ni:Te = 1:1:12, with a total weight of 2g. Excess tellurium powder was used as a flux for the mixed powder. The alumina crucible containing the mixed powder was then placed in a quartz tube, with a crucible filled with quartz wool placed on top to remove excess flux in the subsequent centrifugation step. The quartz tube was then vacuum-sealed and placed in a pit furnace, where it was slowly heated to 950°C at a rate of 1°C per minute and held at that temperature for seven days to allow the mixed powder to fully melt. The temperature was then lowered to 500°C at a rate of 2°C per hour. The quartz tube was then quickly removed, and excess flux was removed using a high-temperature centrifuge to obtain high-quality TaNiTe5 crystals with a metallic luster.

[0083] (2) The TaNiTe5 layer is separated from the TaNiTe5 crystal by mechanical peeling and transferred to the substrate.

[0084] Specifically, the thin TaNiTe5 layer is first separated from the TaNiTe5 crystal using a conventional mechanical peeling method, and a TaNiTe5 layer of appropriate thickness is selected under an optical microscope. Then, the peeled TaNiTe5 layer is transferred to the substrate using a dry transfer process or a wet transfer process.

[0085] S3. On the substrates at both ends of the TaNiTe5 layer, source and drain electrodes electrically connected to the TaNiTe5 layer are respectively fabricated.

[0086] Specifically, in this embodiment, the source and drain form a butterfly antenna structure, and this step includes:

[0087] (1) A patterned photoresist layer was formed on a substrate with a TaNiTe5 layer using a standard electron beam exposure process to define the position and shape of the source and drain.

[0088] (2) A 10 nm titanium metal layer and a 90 nm gold metal layer were sequentially deposited on the substrate and the photoresist layer using an electron beam evaporation process.

[0089] (3) The photoresist layer and the titanium and gold metal layers on it are removed by a solvent extraction process, and the source and drain electrodes constituting the butterfly antenna structure are formed on the substrates at both ends of the TaNiTe5 layer.

[0090] In addition, after the fabrication of the terahertz detector is completed, the process also includes wire-wrap testing of the fabricated terahertz detector.

[0091] Compared to the uncooled terahertz detector structure in the prior art, the terahertz detector in this embodiment is composed of a simple photoconductive structure, which makes it easier to achieve miniaturized array integration.

[0092] As shown in Figure 4 and in combination with Figure 5 shown, in this embodiment, constructing the source and drain into an antenna structure can effectively converge terahertz radiation into the TaNiTe5 layer, achieving local enhancement of the terahertz electric field.

[0093] In addition, the relationship between the terahertz photocurrent and the applied bias voltage and incident power of the terahertz detector in this embodiment was tested at different incident frequencies. As shown in Figure 6 shown, the terahertz response photocurrent measured at frequencies of 0.03 THz, 0.11 THz, and 0.29 THz increases linearly with the increase of the bias voltage, and its direction is consistent with the direction of the applied bias voltage. As shown in Figure 7 shown, the measured terahertz wave response waveform is consistent with the direction of the applied bias voltage. These results indicate that the terahertz response process of the terahertz detector in this embodiment is dominated by a photoconductivity-like mechanism mediated by the double Dirac surface states of the TaNiTe5 layer. As shown in Figure 8 shown, the terahertz response photocurrent measured at different bias voltages shows a linear dependence on the incident power, demonstrating the free carrier absorption mechanism mediated by the double Dirac surface states in the TaNiTe5 layer, thus further demonstrating its photoconductivity-like response mechanism.

[0094] As shown in Figure 9 shown, at room temperature, the terahertz detector in this embodiment shows strong responses to sub-terahertz waves and terahertz waves in different frequency bands, with frequencies of 0.03 THz, 0.11 THz, and 0.29 THz respectively. In combination with Figure 10 shown, at room temperature, the photocurrent responsivity of the terahertz detector in this embodiment measured at a frequency of 0.29 THz can reach 2.06 A / W, and the noise equivalent power reaches 11 pW / Hz 0.5 .

[0095] As shown in Figure 11 and in combination with Figure 12 shown, according to the response waveform extracted by a high-precision oscilloscope and the 3 dB bandwidth calculation, the response time of the terahertz detector in this embodiment at a frequency of 0.11 THz can reach 9 us. The above results indicate that the terahertz detector in this embodiment can achieve high-sensitivity detection of terahertz waves at room temperature, indicating that the photoconductivity-like effect mediated by double Dirac surface states has great application prospects in the terahertz field.

[0096] From the above technical solutions, it can be seen that the present invention has the following beneficial effects:

[0097] This invention uses a TaNiTe5 layer with a quasi-one-dimensional topological structure as the channel material layer of a terahertz detector. Its unique dual Dirac surface states and quasi-one-dimensional structure can bring high carrier mobility and achieve effective detection of terahertz waves at room temperature through a photoconductive response mechanism.

[0098] This invention constructs the source and drain as an antenna structure and integrates it with the TaNiTe5 layer, which can obtain stronger terahertz optical field coupling, which is beneficial to realizing high-sensitivity terahertz wave detection at room temperature.

[0099] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0100] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A terahertz detector, characterized in that, The terahertz detector includes: Substrate; A TaNiTe5 layer is located on the substrate; An electrode is located on the substrate, and the electrode includes a source and a drain that are electrically connected to both ends of the TaNiTe5 layer, respectively.

2. The terahertz detector according to claim 1, characterized in that, The TaNiTe5 layer has two Dirac surface states.

3. The terahertz detector according to claim 1, characterized in that, The thickness of the TaNiTe5 layer is 5nm~50nm.

4. The terahertz detector according to claim 1, characterized in that, The source and drain constitute an antenna structure. The source includes a first side and a second side arranged opposite to each other, and the drain includes a third side and a fourth side arranged opposite to each other. The first side and the third side are opposite to each other and are in contact with the TaNiTe5 layer respectively.

5. The terahertz detector according to claim 4, characterized in that, The width of the source electrode increases first and then remains constant from the first side to the second side, and the width of the drain electrode increases first and then remains constant from the third side to the fourth side.

6. The terahertz detector according to claim 5, characterized in that, The distance between the first side of the source electrode and the third side of the drain electrode is 30 nm to 4 μm; and / or, The distance between the second side of the source electrode and the fourth side of the drain electrode is 80μm~200μm, the width of the source electrode on the second side is 60μm~140μm, and the width of the drain electrode on the fourth side is 60μm~140μm.

7. The terahertz detector according to claim 1, characterized in that, The substrate includes an intrinsic silicon layer and a silicon oxide layer located on the intrinsic silicon layer.

8. The terahertz detector according to claim 1, characterized in that, The resistivity of the intrinsic silicon layer is greater than or equal to 20000 Ω·cm.

9. A method for fabricating a terahertz detector, characterized in that, The preparation method includes the following steps: Provide substrate; A TaNiTe5 layer was prepared on the substrate; Source and drain electrodes electrically connected to the TaNiTe5 layer were fabricated on substrates at both ends of the TaNiTe5 layer.

10. The method for fabricating a terahertz detector according to claim 9, characterized in that, The fabrication of the TaNiTe5 layer on the substrate includes: TaNiTe5 crystals were prepared by a fluxing method. The TaNiTe5 layer was dissociated from the TaNiTe5 crystal by mechanical exfoliation and transferred to the substrate.

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