A device for guiding TEM waves in a medium nanowire radio frequency transmission line

Abstract

A device for guiding TEM waves using dielectric nanowires is disclosed, relating to the fields of nanotechnology and microwave technology. The device structure includes a substrate, a zinc oxide seed layer, a ground signal electrode, a transmission signal electrode, and zinc oxide nanowires, forming a coplanar waveguide structure. The dielectric nanowires replace the signal lines in traditional coplanar waveguide structures. The TEM signal fed to one electrode is guided by the nanowires to the other signal electrode, ensuring that the electric field is along the normal direction of the nanowire surface and the magnetic field is along the tangential direction. Under the influence of the external electric field and the Lorentz force, the space charge region of the nanowire undergoes dynamic polarization, achieving internal zero field and surface electromagnetic shielding, thereby guiding the TEM wave. This coplanar waveguide structure design ensures good guidance performance at frequencies above 10 GHz.

Description

Technical Field

[0001] This invention relates to the fields of nanotechnology and microwave technology, specifically to a device for a radio frequency transmission line that uses dielectric nanowires to guide TEM waves. Background Technology

[0002] Technological advancements stem from a deeper understanding of fundamental problems. Waveguides are the basic information carriers in modern communication technologies. While metal surfaces and various dielectric interfaces can guide the directional propagation of electromagnetic waves under certain conditions, a major drawback of metallic materials at microwave frequencies is their high conductivity. This limits microwave penetration and introduces unnecessary losses. In the path to miniaturization of microwave circuits, there are two remedies: nanostructures or dielectric materials. Complete microwave penetration can be guaranteed when at least one dimension of the nanowire is smaller than the penetration depth, while dielectric ceramics possess naturally low conductor losses and can significantly reduce waveguide size due to their high dielectric constant. However, microwave transmission using single-dielectric nanowires (NW) is rarely reported, especially in the ultra-high frequency (SHF, 3-30 GHz) band, which is crucial for wireless communication, sensing technologies, and universal quantum interconnects.

[0003] The reason for this gap is that, according to Maxwell's equations, a single-conductor transmission line does not allow transverse electromagnetic (TEM) modes. However, TEM waves have no cutoff wavelength limitation, making them the optimal method for subwavelength transmission. Electromagnetic power flows through space. The guidance of electromagnetic waves involves finding a space to confine them. Since electromagnetic waves cannot exist in metals and can only exist in dielectrics, it is generally believed that electromagnetic waves have only three guidance modes:

[0004] (1) Due to the reflection of electromagnetic waves by metals, the guiding effect of metals on electromagnetic waves occurs both outside the metal itself and between metals. It is evident that nanoscale microwave transmission structures consistently possess high conductivity. For example, metal nanowire thin films (MnM) are platforms composed of numerous metal nanowire arrays and can be used to fabricate many microwave devices, such as transformers, crossbars, and interposers. Although carbon nanotubes (CNTs) are superior to metal nanowires, they still exhibit ballistic electron flow with a mean free path of several micrometers and the ability to carry high current densities. Therefore, carbon nanotubes can be used for slow-wave transmission, which is very similar to the applications of superconductors.

[0005] (2) The guiding effect of dielectric materials on electromagnetic waves occurs within the dielectric itself; therefore, microwave dielectric waveguides are not nanoscale. Under infinite boundary conditions, the operating wavelength is much smaller than the size of the dielectric material, and TEM waves can propagate within the dielectric material. Therefore, X-ray optics is often used to understand the transmission, reflection, and absorption of electromagnetic waves. When the operating wavelength is comparable to the size of the dielectric material, a common method is to confine the electromagnetic wave within the dielectric waveguide. In this case, due to the finite cutoff wavelength, the dielectric material can only guide TE or TM modes through the waveguide. Therefore, classic microwave dielectric waveguides are typically a few micrometers in size, while nanoscale dielectric waveguides usually operate in the terahertz or optical bands.

[0006] (3) Surface waves provide a third way through field localization. In this case, electromagnetic waves are not completely confined to the interior of the solid when they achieve subwavelength transmission. Surface waves can be basically divided into three types: (1) The first type is based on the interaction between electromagnetic waves and a large number of electrons in the solid. Therefore, surface plasmon polarizations (SPPs) at optical frequencies and artificial surface plasmon polarizations (SSPPs) at microwave frequencies both require metals. Although solid-state plasmas also appear in semiconductors, such as silicon in the microwave band, high conductivity is still required, and charge carriers are injected by pin diodes. (2) The second type of surface waves is based on the interaction between electromagnetic waves and lattice vibrations. Therefore, surface phonon polaritons (SPhPs) involving transverse optical phonons usually operate in the infrared to terahertz range. (3) The third type of wave belongs to elastic mechanical waves, such as surface acoustic waves (SAWs). Therefore, the frequencies reported in the literature are usually limited to a few GHz.

[0007] This invention will provide a fourth method for guiding electromagnetic waves, namely, a device for guiding TEM waves using dielectric nanowires in a radio frequency transmission line. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide a novel electromagnetic wave guiding structure, namely a device for guiding TEM waves in radio frequency transmission lines using dielectric nanowires. By utilizing the motional polarization generated by the inherent electric dipole moment of the space charge region on the surface of the self-organized nanowire under the action of an external electric field, and the simultaneous action of the Lorentz force of the magnetic field, the elastic displacement polarization of the space charge is utilized to achieve zero field inside the nanowire and electromagnetic shielding on the surface. This completely couples the electromagnetic wave to the external space of the nanowire, guiding the electromagnetic wave using the space charge region, thus realizing a dielectric nanowire-guided TEM wave radio frequency transmission line. The guiding effect is excellent at frequencies greater than 10 GHz.

[0009] By utilizing the localization of the electron wave function when the semiconductor surface states are occupied by electrons, a repulsive force is formed against the free electrons, maintaining the separation of positive and negative charges to form an electric dipole moment, thereby maintaining the existence of the surface electric field. This makes the electric field component on the nanowire surface have the same properties as a two-dimensional electrostatic field. Under the action of the Lorentz force, the magnetic field generated below the surface cancels out the magnetic field above the surface, thereby maintaining the internal zero field and completely coupling the electromagnetic wave to the outside of the NW to achieve guidance.

[0010] A device for a radio frequency transmission line guiding TEM waves using dielectric nanowires is characterized by a coplanar waveguide structure, which allows the TEM signal to be fed to electrodes and then transmitted to the nanowires. The device structure includes: a substrate, zinc oxide seed layers, a ground signal electrode, a transmission signal electrode, and zinc oxide nanowires. Two rectangular zinc oxide seed layers with a spacing (the spacing is related to the length of the nanowires and has no specific limitation, but can be adjusted according to micro / nano fabrication technology) are placed on the substrate. Transmission signal electrodes are located on the outer side and top of the two zinc oxide seed layers along their length directions, corresponding to two symmetrical transmission signal electrodes. The structure is a T-shaped polygon composed of a rectangle and an isosceles trapezoid (the wide base of the isosceles trapezoid contacts the outer side along the length of the transmission signal electrode, and the narrow base of the isosceles trapezoid connects to the short side of the rectangle to form the overall T-shaped polygonal transmission signal electrode). Cuboid ground signal electrodes are located at both ends of the zinc oxide seed layer, with gaps between them. The length of the zinc oxide seed layer is perpendicular to the length of the ground signal electrodes. The two ground signal electrodes are parallel, and the zinc oxide seed layer and the transmission signal electrode are located between them. Zinc oxide nanowires are grown between the two zinc oxide seed layers, bridging each other. These nanowires are suspended relative to the substrate, i.e., they do not contact the substrate. The zinc oxide seed layer, ground signal electrode, and transmission signal electrode are all located on the substrate.

[0011] The T-shaped transmission signal electrode is formed by the sides of a rectangle coinciding with the shorter side of one of the two parallel sides of an isosceles trapezoid. This transmission signal electrode exposes one side of the two zinc oxide seed layers, ensuring that the zinc oxide nanowires can grow laterally suspended relative to the substrate between the two seed layers. The number of nanowires is proportional to the length of the seed layer (the specific ratio depends on the micro / nano process and the hydrothermal growth conditions of the nanowires). Using the transmission electrode-seed layer-nanowire-seed layer-transmission electrode as the axis of symmetry, two identical rectangular ground signal electrodes are positioned on either side of the axis. The shorter side of the ground signal electrode is the same length as the shorter side of the transmission signal electrode (the shorter side of the rectangle), and the longer side of the ground signal electrode is the same as the overall length of the "transmission electrode-seed layer-nanowire-seed layer-transmission electrode" structure. The distance between the perpendicular bisector of the shorter side of the ground signal electrode and the perpendicular bisector of the shorter side of the transmission signal electrode depends on the specifications of the GSG probe (a three-probe RF test probe with a ground-signal-ground configuration) used during testing. Thus, the overall structure of the device is a coplanar waveguide structure of ground-signal-ground, with the middle part of the transmission signal line being replaced by a zinc oxide nanowire array instead of metal electrodes.

[0012] Preferably, the spacing between the two sublayers is 5 micrometers to 15 micrometers;

[0013] Preferably, the seed layer length is 100 micrometers to 180 micrometers;

[0014] Preferably, the distance between the short perpendicular line of the ground signal electrode and the short perpendicular line of the transmission signal electrode is 150 micrometers to 250 micrometers.

[0015] The complete propagation process of the electromagnetic wave signal involves the test instrument generating a TEM signal, which is then fed to a ground-signal-ground coplanar waveguide structure via a GSG probe. The ground signal probe of the probe corresponds to the ground signal electrode in the device structure, and the signal probe corresponds to the transmission signal electrode in the device structure. After the TEM signal is fed to the coplanar waveguide structure, it couples between the ground electrode and the signal electrode and propagates to the other end of the device structure. When the signal propagates to the nanowire portion, the nanowires act as transmission signal lines, and their number is proportional to the seed layer length. The zinc oxide nanowires are coupled to the ground signal lines on both sides. The TEM signal fed to the coplanar waveguide electrode by the GSG probe is now coupled between the nanowires and the ground signal lines. The electric field direction is the normal to the nanowire surface, and the magnetic field direction is the tangential direction of the nanowire surface. The magnitude and direction of the electric and magnetic fields are constantly changing. The charges in the space charge region of the nanowire are dynamically polarized under the action of the external electric field. Combined with the Lorentz force of the magnetic field, the space charges undergo elastic displacement polarization and generate surface current to maintain the tangential magnetic field. This achieves electromagnetic shielding on the nanowire surface and zero field inside, thereby enabling the guidance of TEM waves and realizing a radio frequency transmission line structure for guiding TEM waves using dielectric nanowires.

[0016] By utilizing the localization of the electron wave function when the semiconductor surface states are occupied by electrons, a repulsive force is formed against the free electrons, maintaining the separation of positive and negative charges to form an electric dipole moment, thereby maintaining the existence of the surface electric field. This makes the electric field component on the nanowire surface have the same properties as a two-dimensional electrostatic field. Under the action of the Lorentz force, the magnetic field generated below the surface cancels out the magnetic field above the surface, thereby maintaining the internal zero field and completely coupling the electromagnetic wave to the outside of the NW to achieve guidance.

[0017] By utilizing the kinetic polarization of the inherent electric dipole moment of the space charge region on the surface of the self-organized nanowire (NW) under the action of an external electric field, and the simultaneous action of the Lorentz force of the magnetic field, the zero field inside the NW and the electromagnetic shielding on the surface are achieved through the elastic displacement polarization of the space charge. The electromagnetic waves are completely coupled to the external space of the NW, and the electromagnetic waves are guided by the space charge region to realize the radio frequency transmission line of TEM wave guided by the dielectric nanowire with a frequency greater than 10 GHz. Attached Figure Description

[0018] Figure 1A Top view of the coplanar waveguide structure of the radio frequency transmission line of the present invention;

[0019] Figure 1B A three-dimensional view of the coplanar waveguide structure of the radio frequency transmission line of the present invention;

[0020] Figure 2 Scanning electron microscope image of the coplanar waveguide structure of the radio frequency transmission line of this invention;

[0021] Figure 3 Scanning electron microscope image of nanowire bridging in the coplanar waveguide structure of the radio frequency transmission line of this invention;

[0022] Figure 4A S11 curves measured at different nanowire lengths in Example 1 of this invention;

[0023] Figure 4B S21 curves measured at different nanowire lengths in Example 1 of this invention;

[0024] Figure 5A S11 curves measured with different numbers of nanowires in Example 1 of this invention;

[0025] Figure 5B S21 curves measured with different numbers of nanowires in Example 1 of this invention;

[0026] Figure 1A , 1B In the diagram: 1 is the substrate; 2 is the ground signal electrode; 3 is the transmission signal electrode; 4 is the zinc oxide seed layer; 5 is the zinc oxide nanowire.

[0027] Figure 5A , 5BIn the middle: the number of nanowires is proportional to the length of the seed layer. Detailed Implementation

[0028] To make the objectives and advantages of the present invention clearer, the present invention will be further described below through embodiments. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments.

[0029] Example 1:

[0030] This embodiment provides a dielectric nanowire-guided TEM wave radio frequency transmission line, the coplanar waveguide structure of which is shown below. Figure 1A and Figure 1B The image includes a top view and a perspective view; a scanning electron microscope image of the overall coplanar waveguide structure is shown below. Figure 2 The scanning electron microscope image of the nanowire bridging portion in the coplanar waveguide structure is shown below. Figure 3 .

[0031] A dielectric nanowire-guided TEM wave radio frequency transmission line utilizes the motional polarization of the inherent electric dipole moment of the space charge region on the surface of the self-organized nanowire (NW) under the action of an external electric field, and the simultaneous action of the Lorentz force of the magnetic field. Through the elastic displacement polarization of the space charge, zero field inside the NW and electromagnetic shielding on the surface are achieved, and the electromagnetic wave is completely coupled to the external space of the NW. The electromagnetic wave is guided by the space charge region, realizing a dielectric nanowire-guided TEM wave radio frequency transmission line with a frequency greater than 10 GHz.

[0032] The device structure includes: a substrate, a zinc oxide seed layer, a ground signal electrode, a transmission signal electrode, and zinc oxide nanowires; there are two parallel rectangular zinc oxide seed layers with a certain spacing on the substrate (the seed layer spacing in this embodiment is 5 micrometers and 10 micrometers). Two symmetrical transmission signal electrodes are located on the outer side and top of the two zinc oxide seed layers. The electrode shape is a polygon composed of rectangles and isosceles trapezoids (specifically, a polygon obtained by coinciding the short side of the rectangle with the short side of one of the two parallel sides of the isosceles trapezoid). The transmission signal electrodes expose one side of the pair of zinc oxide seed layers, ensuring that the zinc oxide nanowires can grow laterally suspended relative to the substrate between the two types of seed layers. The number of nanowires is proportional to the length of the seed layer (in this embodiment, the seed layer lengths are 100 micrometers and 140 micrometers). With the transmission electrode-seed layer-nanowire-seed layer-transmission electrode as the axis of symmetry, two identical rectangular ground signal electrodes are located on both sides of the axis of symmetry. The short side of the ground signal electrode is the same length as the short side of the transmission signal electrode, and the long side of the ground signal electrode is the same as the overall length of the "transmission electrode-seed layer-nanowire-seed layer-transmission electrode" structure. The spacing between the perpendicular bisector of the short side of the ground signal electrode and the perpendicular bisector of the short side of the transmission signal electrode is determined according to the specifications of the GSG probe (a three-probe RF test probe with a ground-signal-ground configuration) used during testing. Thus, the overall structure of the device is a ground-signal-ground coplanar waveguide structure, with the middle section of the transmission signal line using a zinc oxide nanowire array instead of metal electrodes.

[0033] The preparation method of the above structure includes the following steps:

[0034] Step 1: Select 500um thick BF glass as the substrate, clean the substrate and dry it.

[0035] Step 2: Pattern the substrate from Step 1 using photolithography.

[0036] Step 3: Using sputtering and ultrasonic lift-off processes, a zinc oxide seed layer is prepared on the patterned substrate from Step 2 above.

[0037] Step 4: Wash and dry the sample from Step 3 again;

[0038] Step 5: Use photolithography to perform a second patterning on the sample from Step 4 above;

[0039] Step 6: Using sputtering and ultrasonic lift-off processes, ground signal electrodes and transmission signal electrodes are fabricated on the substrate that has been patterned twice in Step 5 above.

[0040] Step 7: Using a hydrothermal method, zinc oxide nanowires are generated on the sample prepared in Step 6 above.

[0041] TEM waves, or transverse electromagnetic waves, cannot be effectively transmitted in a single-wire structure. Therefore, the coplanar waveguide structure designed in this invention plays a crucial role in the transmission of TEM waves. The coplanar waveguide electrode structure couples the TEM wave between the transmission signal electrode and the ground signal electrode. The TEM wave propagates forward from the electrode section to the zinc oxide nanowire section. Since the nanowire is suspended relative to the substrate, the magnetic field can surround the nanowire, i.e., along the tangential direction of the nanowire surface, while the electric field is along the normal direction of the nanowire surface. The simultaneous action of the electric and magnetic fields causes dynamic polarization in the space charge region on the nanowire surface, generating a polarization current. This maintains the zero field inside the nanowire and the propagation of the TEM wave along the nanowire surface, thereby realizing a radio frequency transmission line that uses dielectric nanowires to guide TEM waves.

[0042] S-parameters are important parameters in the field of microwave technology. S-parameter curves can, to a certain extent, indicate the absorption and transmission capabilities of a device. S11 is the input return loss, i.e., the reflection coefficient at port one when the two ports are matched; S21 is the forward transmission coefficient, i.e., the transmission coefficient from port one to port two when the two ports are matched. These two parameters have many representations. When expressed in dB, the values ​​are both negative. The smaller the S11 value (the lower the curve), the smaller the reflection coefficient, which means a relatively larger amount of signal is successfully incident; conversely, the larger the S21 value (the higher the curve), the larger the transmission coefficient, which means more signal is transmitted from port one to port two. Generally, -10dB is used as an observation point. When S11 is less than this value, it is considered that 90% of the electromagnetic wave signal is successfully incident; when S21 is greater than this value, it is considered that 90% of the electromagnetic wave signal is successfully transmitted. Therefore, from... Figure 4A , 4B It's easy to see that when the nanowire is shorter, the S11 curve is lower and the S21 curve is higher, indicating better transmission of electromagnetic wave signals. The longer the transmission line, the worse the transmission effect; the shorter the transmission line, the better the transmission effect—this is also easy to understand. From... Figure 5A , 5B It can be observed that when the seed layer length is longer (more nanowires), the S11 curve is very low, while the S21 curve is very high. Using the -10dB standard, the zinc oxide nanowires with a 140-micron seed layer exhibit excellent transmission performance and a very wide effective bandwidth. It is foreseeable that the greater the number of nanowires and the shorter their length, the more pronounced their guiding effect on electromagnetic waves will be.

[0043] This invention replaces the signal lines in traditional coplanar waveguide structures with dielectric nanowires. TEM signals fed to one electrode are guided to the other electrode via the nanowires, ensuring the electric field is along the normal direction of the nanowire surface and the magnetic field is along the tangential direction. Under the influence of the external electric field and Lorentz force, the space charge region of the nanowire undergoes dynamic polarization, achieving internal zero field and surface electromagnetic shielding, thereby guiding the TEM wave. This coplanar waveguide structure design ensures excellent guidance performance at frequencies above 10 GHz.

Claims

1. A device for a dielectric nanowire-guided TEM wave radio frequency transmission line, characterized in that, The device structure is a coplanar waveguide structure, comprising: a substrate, a zinc oxide seed layer, a ground signal electrode, a transmission signal electrode, and zinc oxide nanowires. Two parallel rectangular zinc oxide seed layers with a gap are located on the substrate. Transmission signal electrodes are positioned on the outer side and top of the two zinc oxide seed layers along their lengths, corresponding to two symmetrical transmission signal electrodes. The transmission signal electrodes are T-shaped polygons composed of rectangles and isosceles trapezoids, with the wide base of the isosceles trapezoid and the narrow base of the isosceles trapezoid in contact with the outer side along its length. The transmission signal electrode, connected to the short side of the rectangle, forms a T-shaped polygonal structure. A cuboid ground signal electrode is located at both ends of the zinc oxide seed layer, with a gap between it and the zinc oxide seed layer. The length direction of the zinc oxide seed layer is perpendicular to the length direction of the ground signal electrode. The two ground signal electrodes are parallel, and both the zinc oxide seed layer and the transmission signal electrode are located between them. Overlapping zinc oxide nanowires grow between the two zinc oxide seed layers, suspended relative to the substrate (i.e., not in contact with it). The zinc oxide seed layer, ground signal electrode, and transmission signal electrode are all located on the substrate.

2. The device for a dielectric nanowire-guided TEM wave radio frequency transmission line according to claim 1, characterized in that, The T-shaped transmission signal electrode is formed by the side of a rectangle coinciding with the shorter side of one of the two parallel sides of an isosceles trapezoid. This transmission signal electrode exposes one side of the two zinc oxide seed layers, ensuring that the zinc oxide nanowires can grow laterally suspended relative to the substrate between the two seed layers. The number of nanowires is proportional to the length of the seed layer. With the transmission electrode-seed layer-nanowire-seed layer-transmission electrode as the axis of symmetry, there are two identical rectangular ground signal electrodes on both sides of the axis of symmetry. The shorter side of the ground signal electrode is the same length as the shorter side of the transmission signal electrode, i.e., the shorter side of the rectangle, and the longer side of the ground signal electrode is the same as the overall length of the "transmission electrode-seed layer-nanowire-seed layer-transmission electrode" structure.

3. The device for a dielectric nanowire-guided TEM wave radio frequency transmission line according to claim 1, characterized in that, The distance between the perpendicular bisector of the short side of the ground signal electrode and the perpendicular bisector of the short side of the transmission signal electrode depends on the specifications of the GSG probe used during testing.

4. The device for a dielectric nanowire-guided TEM wave radio frequency transmission line according to claim 1, characterized in that, The spacing between the two sublayers is 5 micrometers to 15 micrometers; the seed layer length is 100 micrometers to 180 micrometers. The distance between the perpendicular bisector of the short side of the ground signal electrode and the perpendicular bisector of the short side of the transmission signal electrode is 150 micrometers to 250 micrometers.

5. The device for a dielectric nanowire-guided TEM wave radio frequency transmission line according to claim 1, characterized in that, Electromagnetic waves are fully coupled to the outside of the nanowire, enabling guidance.

6. The device for a dielectric nanowire-guided TEM wave radio frequency transmission line according to claim 1, characterized in that, A radio frequency transmission line for guiding TEM waves using dielectric nanowires, with a frequency greater than 10 GHz.

7. A device for a dielectric nanowire-guided TEM wave radio frequency transmission line according to any one of claims 1-6, characterized in that, The complete propagation process of the electromagnetic wave signal involves the test instrument generating a TEM signal, which is then fed to a ground-signal-ground coplanar waveguide structure via a GSG probe. The ground signal probe of the probe corresponds to the ground signal electrode in the device structure, and the signal probe corresponds to the transmission signal electrode in the device structure. After the TEM signal is fed to the coplanar waveguide structure, it couples between the ground electrode and the signal electrode and propagates to the other end of the device structure. When the signal propagates to the nanowire portion, the nanowires act as transmission signal lines, and their number is proportional to the seed layer length. The zinc oxide nanowires couple with the ground signal lines on both sides, and are then transmitted by the GSG probe. The TEM signal fed to the coplanar waveguide electrode is coupled between the nanowire and the ground signal line. The electric field direction is the normal direction of the nanowire surface, and the magnetic field direction is the tangential direction of the nanowire surface. The magnitude and direction of the electric and magnetic fields are constantly changing. The charges in the space charge region of the nanowire are dynamically polarized under the action of the external electric field. Combined with the Lorentz force of the magnetic field, the space charges undergo elastic displacement polarization and generate surface current to maintain the tangential magnetic field. This achieves electromagnetic shielding on the nanowire surface and zero field inside, thereby enabling the guidance of TEM waves and realizing the radio frequency transmission line structure of dielectric nanowire guiding TEM waves.

8. A method for fabricating a device for a dielectric nanowire-guided TEM wave radio frequency transmission line according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Select BF glass as the substrate, clean the substrate and dry it; Step 2: Using photolithography, the substrate from Step 1 is patterned with seed layers, with a spacing of 5 micrometers to 15 micrometers between a pair of seed layers; Step 3: Using sputtering and ultrasonic lift-off processes, a ZnO seed layer with a thickness of 80 nm to 200 nm is prepared on the patterned substrate in Step 2 above. Step 4: Wash and dry the sample from Step 3 again; Step 5: Use photolithography to pattern the electrodes on the sample from Step 4 above; Step 6: Using sputtering and ultrasonic lift-off processes, Au ground signal electrodes and transmission signal electrodes are fabricated on the substrate that has been patterned twice in Step 5 above. The electrode thickness is 150 micrometers to 600 micrometers. Step 7: Using a hydrothermal method, zinc oxide nanowires are generated on the sample prepared in Step 6 above.

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