Terahertz detector and preparation method and application thereof

Abstract

The application discloses a terahertz detector and a preparation method and application thereof, and the preparation method comprises the following steps: providing a first substrate; preparing a graphene layer on the first substrate; providing a second substrate; preparing an electrode structure on the second substrate, wherein the electrode structure comprises a source electrode and a drain electrode; and transferring the electrode structure from the second substrate to the first substrate by a transfer process, so that the source electrode and the drain electrode are electrically connected to two ends of the graphene layer, respectively. The terahertz detector is prepared in situ by using a low-energy van der Waals metal integration technology, the influence of the preparation of the electrode structure on the graphene layer is effectively avoided, the excellent intrinsic performance of the graphene layer is maintained, and the high-performance terahertz detector is obtained.

Description

Technical Field

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

[0002] With the further development of communication technology, 6G application scenarios (such as immersive communication, ultra-large-scale connectivity, ultra-reliable low-latency communication, the convergence of artificial intelligence and communication, the convergence of sensing and communication, and ubiquitous connectivity) place higher demands on wireless communication, requiring Tbps-level data transmission rates, millisecond-level latency, and centimeter-level sensing accuracy. Terahertz (THz) waves, due to their high bandwidth and abundant spectrum resources, can meet the bandwidth and data transmission rate requirements of future wireless communication, making them an ideal frequency band for future wireless communication. Simultaneously, their sub-millimeter to millimeter wavelengths offer high-precision sensing capabilities, providing possibilities for the development of IMT-2030.

[0003] Terahertz detectors are an important component of terahertz communication. Currently, terahertz detectors based on low-dimensional materials such as graphene have attracted widespread attention due to their ability to achieve terahertz detection without intrinsic links. However, in existing graphene-based terahertz detectors, the intrinsic properties of the graphene layer are easily damaged during the fabrication of the electrode structure, preventing the full utilization of its excellent performance.

[0004] Furthermore, in the field of terahertz communication, room-temperature terahertz detectors such as heterodyne detection and Schottky barrier diode detectors are mainly used, achieving communication transmission rates exceeding 100 Gbps. However, these terahertz detectors are limited by non-flat frequency response, bandwidth, and nonlinear response, making it difficult to further improve communication performance. At the same time, communication systems using these terahertz detectors require additional components such as intrinsic links, frequency multipliers, and mixers, resulting in a large overall size and cost, making it difficult to meet the requirements of future miniaturized integrated communication systems.

[0005] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a terahertz detector, its fabrication method, and its applications. Summary of the Invention

[0006] The purpose of this invention is to provide a terahertz detector, its preparation method, and its application, which can maintain the excellent intrinsic properties of the graphene layer and integrate a high-performance, miniaturized terahertz communication system.

[0007] To achieve the above objectives, an embodiment of the present invention provides the following technical solution:

[0008] A method for fabricating a terahertz detector, the method comprising the following steps:

[0009] Provide a first substrate;

[0010] A graphene layer is prepared on a first substrate;

[0011] Provide a second substrate;

[0012] An electrode structure is fabricated on a second substrate, the electrode structure comprising a source and a drain.

[0013] The electrode structure is transferred from the second substrate to the first substrate using a transfer process, so that the source and drain are electrically connected to the two ends of the graphene layer, respectively.

[0014] In one embodiment, the step of transferring the electrode structure onto the first substrate using a transfer process, so that the source and drain are electrically connected to the two ends of the graphene layer, respectively, includes:

[0015] Provide substrate;

[0016] A sacrificial layer is prepared on the substrate;

[0017] The sacrificial layer is attached to the electrode structure, and the attached structure is heated to detach the electrode structure from the second substrate.

[0018] The substrate with the electrode structure is aligned and bonded to the first substrate with the graphene layer, so that the source and drain are in contact with the two ends of the graphene layer, respectively. The bonded structure is then heated, and the substrate with the sacrificial layer is peeled off from the electrode structure.

[0019] In one embodiment, in the step of attaching the sacrificial layer to the electrode structure and heating the attached structure to detach the electrode structure from the second substrate, the attached structure is heated to 40°C~50°C.

[0020] In one embodiment, in the step of aligning and bonding the substrate with the electrode structure to the first substrate with the graphene layer, such that the source and drain are in contact with the two ends of the graphene layer respectively, and heating the bonded structure to peel the substrate with the sacrificial layer from the electrode structure, the bonded structure is heated to 60°C to 100°C.

[0021] In one embodiment, the substrate includes a glass slide and a polydimethylsiloxane film adhered to the glass slide; and / or,

[0022] The sacrificial layer is a polypropylene carbonate film.

[0023] In one embodiment, the first substrate includes an intrinsic silicon layer and a silicon oxide layer located on the intrinsic silicon layer, wherein the resistivity of the intrinsic silicon layer is greater than or equal to 20000 Ω·cm; and / or,

[0024] The second substrate is a silicon substrate.

[0025] 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 are disposed opposite to each other, and when the electrode structure is transferred from the second substrate to the first substrate by a transfer process, the first side and the second side are in contact with the graphene layer respectively.

[0026] 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.

[0027] Another embodiment of the present invention provides the following technical solution:

[0028] A terahertz detector, which is prepared according to the above-described preparation method.

[0029] Another embodiment of the present invention provides the following technical solution:

[0030] A terahertz communication system includes a terahertz detector, a transimpedance amplifier, an oscilloscope, and a digital signal processor. The terahertz detector is prepared according to the above-described preparation method or is a terahertz detector described above. The transimpedance amplifier is used to amplify the electrical signal output by the terahertz detector. The oscilloscope is used to capture the electrical signal amplified by the transimpedance amplifier. The digital signal processor is used to demodulate the electrical signal captured by the oscilloscope.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention utilizes low-energy van der Waals metal integration technology to fabricate terahertz detectors in situ, effectively avoiding the impact of electrode structure fabrication on the graphene layer, maintaining its excellent intrinsic performance, and obtaining a high-performance terahertz detector.

[0033] This invention integrates a terahertz detector fabricated in situ based on low-energy van der Waals metal integration technology into a terahertz communication system, thereby obtaining a high-performance terahertz communication system and greatly improving the compactness of the terahertz communication system. Attached Figure Description

[0034] 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.

[0035] Figure 1This is a schematic flowchart of the terahertz detector fabrication method in Embodiment 1 of the present invention;

[0036] Figures 2a-2e This is a process flow diagram of the terahertz detector fabrication method in Embodiment 1 of the present invention;

[0037] Figure 3 This is an optical microscope characterization image of the terahertz detector in Embodiment 1 of the present invention;

[0038] Figure 4 This is a graph showing the dependence of the field effect factor of the terahertz detector on the gate voltage in Embodiment 1 of the present invention.

[0039] Figure 5 This is a graph showing the dependence of the terahertz photocurrent on the gate voltage of the terahertz detector in Embodiment 1 of the present invention.

[0040] Figure 6 The photocurrent response spectra of the terahertz detector in Embodiment 1 of the present invention in the W-band and J-band are shown.

[0041] Figure 7 The graph shows the dependence of the photocurrent responsivity of the terahertz detector in Embodiment 1 of the present invention on the bias voltage at 0.1THz and 0.22THz.

[0042] Figure 8 The graph shows the dependence of the noise equivalent power of the terahertz detector at 0.1THz and 0.22THz on the bias voltage in Embodiment 1 of the present invention.

[0043] Figure 9 This is a graph showing the dependence of the photocurrent responsivity of the terahertz detector at 2.55 THz on the bias voltage in Embodiment 1 of the present invention.

[0044] Figure 10 This is a graph showing the dependence of the noise equivalent power of the terahertz detector at 2.55 THz on the bias voltage in Embodiment 1 of the present invention.

[0045] Figure 11 This is a test diagram of the wireless communication transmission rate of the terahertz communication system in Embodiment 1 of the present invention.

[0046] Explanation of key figure labels:

[0047] 11-First substrate, 12-Graphene layer, 20-Second substrate, 30-Electrode structure, 301-Source, 302-Drain. Detailed Implementation

[0048] To enable those skilled in the art to better understand the technical solutions in this disclosure, the following will clearly and completely describe the technical solutions in the embodiments of this disclosure in conjunction with the accompanying drawings in the embodiments of this disclosure. Obviously, the described embodiments are only a part of the embodiments of this disclosure, rather than all of the embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this disclosure.

[0049] The present invention discloses a preparation method of a terahertz detector, including the following steps:

[0050] Provide a first substrate;

[0051] Prepare a graphene layer on the first substrate;

[0052] Provide a second substrate;

[0053] Prepare an electrode structure on the second substrate, and the electrode structure includes a source electrode and a drain electrode;

[0054] Transfer the electrode structure from the second substrate to the first substrate through a transfer process, so that the source electrode and the drain electrode are electrically connected to both ends of the graphene layer respectively.

[0055] The present invention also discloses a terahertz detector, which is prepared according to the above preparation method.

[0056] The present invention also discloses a terahertz communication system, including a terahertz detector, a transimpedance amplifier, an oscilloscope and a digital signal processor. The terahertz detector is the one prepared according to the above preparation method or the above terahertz detector. The transimpedance amplifier is used to amplify the electrical signal output by the terahertz detector. The oscilloscope is used to capture the electrical signal amplified by the transimpedance amplifier. The digital signal processor is used to demodulate the electrical signal captured by the oscilloscope.

[0057] The following further illustrates the present invention with specific examples.

[0058] Example 1:

[0059] As shown in Figure 1 The preparation method of the terahertz detector in this embodiment includes the following steps:

[0060] S1. As shown in Figure 2a Provide a first substrate 11.

[0061] Specifically, the first substrate 11 in this embodiment includes an intrinsic silicon layer and a silicon oxide layer located on the intrinsic silicon layer. The resistivity of the intrinsic silicon layer is 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.

[0062] Furthermore, this step also includes ultrasonically cleaning the first substrate sequentially with acetone, isopropanol and deionized water, and blowing the first substrate clean with a nitrogen gun to remove impurities and adhering substances from the surface of the first substrate.

[0063] S2, Combination Figure 2b As shown, a graphene layer 12 is prepared on the first substrate 11.

[0064] Specifically, in this embodiment, a single layer or single-layer graphene layer is picked up from a highly oriented graphite sheet by mechanical peeling and transferred to a first substrate.

[0065] S3, Combination Figure 2c As shown, a second substrate 20 is provided.

[0066] Specifically, in this embodiment, the second substrate 20 is a silicon substrate.

[0067] S4, Combination Figure 2d As shown, an electrode structure 30 is fabricated on the second substrate 20. The electrode structure 30 includes a source electrode 301 and a drain electrode 302.

[0068] The source and drain electrodes are both made of gold, with a thickness of 70nm.

[0069] Specifically, in this embodiment, a patterned photoresist layer is first formed on the second substrate using a laser direct writing process, and then a metal layer is deposited on the second substrate and the photoresist layer using an electron beam evaporation process. Afterward, the photoresist layer and the metal layer thereon are removed using a lift-off process, and an electrode structure including a source and a drain is fabricated on the second substrate.

[0070] S5, Combination Figure 2e As shown, the electrode structure 30 is transferred from the second substrate 20 to the first substrate 11 through a transfer process, so that the source electrode 301 and the drain electrode 302 are electrically connected to the two ends of the graphene layer 12, respectively.

[0071] Specifically, this step includes:

[0072] 1. Provide a substrate.

[0073] Specifically, the substrate includes a glass slide and a polydimethylsiloxane (PDMS) film adhered to the glass slide.

[0074] 2. Prepare a sacrificial layer on the substrate.

[0075] The sacrificial layer is a polypropylene carbonate (PC) film.

[0076] Specifically, a polypropylene carbonate film is spin-coated on a substrate, and the substrate coated with the polypropylene carbonate film is heated at 120 °C for 2 minutes.

[0077] 3. Paste the sacrificial layer on the electrode structure and heat the pasted structure to separate the electrode structure from the second substrate.

[0078] Specifically, after the polypropylene carbonate film is bonded to the electrode structure, the pasted structure is heated and its temperature is maintained at 40 °C to 50 °C. After bubbles appear in the electrode structure and it separates from the second substrate, the substrate is slowly lifted to make the electrode structure fall off the second substrate.

[0079] 4. Align and bond the substrate holding the electrode structure with the first substrate prepared with a graphene layer so that the source electrode and the drain electrode are respectively in contact with both ends of the graphene layer, and heat the bonded structure to peel off the substrate prepared with the sacrificial layer from the electrode structure.

[0080] Specifically, slowly align and bond the substrate holding the electrode structure with the first substrate prepared with a graphene layer. After ensuring that the source electrode and the drain electrode are respectively in contact with both ends of the graphene layer, heat the bonded structure and maintain its temperature at 60 °C to 100 °C. When it is observed that the polypropylene carbonate film dissolves, peel off the substrate together with the sacrificial layer from the electrode structure.

[0081] In this embodiment, the electrode structure is transferred to the first substrate by the in-situ low-energy van der Waals metal integration technology, maintaining the excellent intrinsic properties of the graphene layer, and its carrier mobility can reach 19000 cm 2 / V·s.

[0082] Combined with Figure 3 As shown, in this embodiment, the source electrode and the drain electrode form an antenna structure. The source electrode includes a first side and a second side arranged oppositely, and the drain electrode includes a third side and a fourth side arranged oppositely. The first side and the third side are arranged oppositely, and after the electrode structure is transferred from the second substrate to the first substrate by the transfer process, the first side and the second side are respectively in contact with the graphene layer. By constructing the source electrode and the drain electrode into a sub-wavelength planar metal antenna structure, stronger terahertz optical field coupling can be obtained, which is beneficial to realizing highly sensitive terahertz detection.

[0083] Specifically, the width of the source electrode first increases and then remains unchanged from the first side to the second side, and the width of the drain electrode first increases and then remains unchanged from the third side to the fourth side. In addition, the electrode structure in this embodiment further includes a first extended electrode and a second extended electrode respectively connected to the source electrode and the drain electrode, so as to facilitate electrical connection with other devices when it is integrated into a terahertz communication system.

[0084] Refer to Figure 4 and Figure 5 As shown, the field effect factor of the terahertz detector and the dependence of the terahertz photocurrent on the gate voltage in this embodiment were studied. The results show that with the change of the gate voltage, the change trends of the field effect factor and the terahertz photocurrent are basically the same, but slightly different in the negative gate voltage region, indicating that the terahertz response of the terahertz detector in this embodiment is jointly dominated by the plasma wave mechanism and the photothermal-electric mechanism.

[0085] In addition, the response performance of the terahertz detector in this embodiment at the W band, J band, and high-frequency 2.55 THz frequency position was systematically characterized and evaluated.

[0086] Refer Figure 6 And in combination with Figure 7 and Figure 8 As shown, the terahertz detector responds at multiple frequency points in the W band and J band, and has optimal responses at 0.1 THz and 0.22 THz. The current responsivity can reach 1.45 A / W and 0.67 A / W respectively with the increase of the bias voltage, and the noise equivalent power can reach 6.6 pW / Hz 1 / 2 and 22 pW / Hz 1 / 2 .

[0087] Refer Figure 9 and Figure 10 As shown, due to the high carrier mobility of the graphene layer and the optimized high-frequency antenna structure in this embodiment, the application of the terahertz detector from the low-frequency band to the high-frequency terahertz is extended, and a sensitive response at the 2.55 THz frequency position is obtained. The current responsivity reaches 6.6 mA / W, and the noise equivalent power reaches 1.18 nW / Hz 1 / 2 .

[0088] The terahertz communication system integrated with the above terahertz detector in this embodiment includes a terahertz detector, a transimpedance amplifier, an oscilloscope, and a digital signal processor. The transimpedance amplifier is used to amplify the electrical signal output by the terahertz detector, the oscilloscope is used to capture the electrical signal amplified by the transimpedance amplifier, and the digital signal processor is used to demodulate the electrical signal captured by the oscilloscope.

[0089] Specifically, in this embodiment, a single-carrier photodiode (UTC-PD) is used at the signal transmitting end to generate a terahertz signal with communication content by beat frequency, and the performance of the terahertz communication system is tested. The terahertz detector is used as the front-end receiver, and directly converts the received spatially radiated terahertz signal into a fundamental frequency electrical signal, which is amplified by the transimpedance amplifier and captured by the oscilloscope, and finally demodulated by the backend digital signal processing to obtain the communication information.

[0090] Refer Figure 11As shown, this embodiment utilizes Quadrature Phase Shift Keying (QPSK) digital modulation technology to characterize the communication transmission rate of the terahertz communication system. Generally, the acceptable bit error rate (BER) threshold for communication is 2^10. -2 Based on this, the wireless data transmission rate of the terahertz communication system in this embodiment, measured under QPSK modulation, can reach 220Mbps (>110MHz bandwidth), indicating that the terahertz communication system in this embodiment has excellent wireless communication performance.

[0091] In this embodiment, a high-performance terahertz detector fabricated in situ using low-energy van der Waals metal integration technology is integrated into the terahertz communication system, eliminating the traditional bulky mixer link, local oscillator, and quasi-optical components, thus improving the system's compactness.

[0092] As can be seen from the above technical solution, the present invention has the following beneficial effects:

[0093] This invention utilizes low-energy van der Waals metal integration technology to fabricate terahertz detectors in situ, effectively avoiding the impact of electrode structure fabrication on the graphene layer, maintaining its excellent intrinsic performance, and obtaining a high-performance terahertz detector.

[0094] This invention integrates a terahertz detector fabricated in situ based on low-energy van der Waals metal integration technology into a terahertz communication system, thereby obtaining a high-performance terahertz communication system and greatly improving the compactness of the terahertz communication system.

[0095] 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.

[0096] 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 method for fabricating a terahertz detector, characterized in that, The preparation method includes the following steps: Provide a first substrate; A graphene layer is prepared on a first substrate; Provide a second substrate; An electrode structure is fabricated on a second substrate, the electrode structure comprising a source and a drain. The electrode structure is transferred from the second substrate to the first substrate using a transfer process, so that the source and drain are electrically connected to the two ends of the graphene layer, respectively.

2. The method for fabricating a terahertz detector according to claim 1, characterized in that, The step of transferring the electrode structure onto the first substrate via a transfer process, so that the source and drain are electrically connected to the two ends of the graphene layer, respectively, includes: Provide substrate; A sacrificial layer is prepared on the substrate; The sacrificial layer is attached to the electrode structure, and the attached structure is heated to detach the electrode structure from the second substrate. The substrate with the electrode structure is aligned and bonded to the first substrate with the graphene layer, so that the source and drain are in contact with the two ends of the graphene layer, respectively. The bonded structure is then heated, and the substrate with the sacrificial layer is peeled off from the electrode structure.

3. The method for fabricating a terahertz detector according to claim 2, characterized in that, In the step of attaching the sacrificial layer to the electrode structure and heating the attached structure to detach the electrode structure from the second substrate, the attached structure is heated to 40°C~50°C.

4. The method for fabricating a terahertz detector according to claim 2, characterized in that, In the step of aligning and bonding the substrate with the electrode structure to the first substrate with the graphene layer, so that the source and drain are in contact with the two ends of the graphene layer respectively, and heating the bonded structure to peel the substrate with the sacrificial layer from the electrode structure, the bonded structure is heated to 60°C~100°C.

5. The method for fabricating a terahertz detector according to claim 2, characterized in that, The substrate includes a glass slide and a polydimethylsiloxane film adhered to the glass slide; and / or, The sacrificial layer is a polypropylene carbonate film.

6. The method for fabricating a terahertz detector according to claim 1, characterized in that, The first substrate includes an intrinsic silicon layer and a silicon oxide layer on the intrinsic silicon layer, wherein the resistivity of the intrinsic silicon layer is greater than or equal to 20000 Ω·cm; and / or, The second substrate is a silicon substrate.

7. The method for fabricating a 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 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 are disposed opposite to each other, and when the electrode structure is transferred from the second substrate to the first substrate by a transfer process, the first side and the second side are in contact with the graphene layer respectively.

8. The method for fabricating a terahertz detector according to claim 7, 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.

9. A terahertz detector, characterized in that, The terahertz detector is prepared by the preparation method according to any one of claims 1 to 8.

10. A terahertz communication system, characterized in that, The terahertz communication system includes a terahertz detector, a transimpedance amplifier, an oscilloscope, and a digital signal processor. The terahertz detector is prepared by the method according to any one of claims 1 to 8 or the terahertz detector according to claim 9. The transimpedance amplifier is used to amplify the electrical signal output by the terahertz detector. The oscilloscope is used to capture the electrical signal amplified by the transimpedance amplifier. The digital signal processor is used to demodulate the electrical signal captured by the oscilloscope.

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