Microwave rectification device based on centrosymmetric material and preparation method thereof

Abstract

The invention discloses a microwave rectification device based on a centrosymmetric material and a preparation method thereof, the microwave rectification device based on the centrosymmetric material comprises an iridium oxide layer, the iridium oxide layer comprises XIrO3, and X = Sr or Ca. The iridium oxide layer achieves nonlinear rectification in a centrosymmetric material system, the responsivity can be linearly regulated and controlled through an in-plane electric field, wide-band performance consistency regulation and control are achieved, the impedance matching difficulty is reduced, and the considerable rectification responsivity is still shown at 37 GHz; the application temperature range of the microwave rectification device covers the industrial-grade application temperature range, the microwave rectification device is compatible with the current semiconductor process, and large-area epitaxial growth can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of microwave rectification, and more specifically, to a microwave rectification device based on centrosymmetric materials and a preparation method thereof. Background Art

[0002] Currently, in wireless technologies and portable devices, radio frequency applications are present in all aspects of our daily lives. There is an increasing demand for energy harvesting and detection in the high-frequency band and the nano-watt level for micro-devices that convert ambient energy into electricity. How to achieve high-frequency and nano-watt level radio frequency rectification in miniaturized and micro-sized applications remains a challenge. In addition, higher-frequency rectification and detection also have great application prospects in fields such as medicine, satellite communication, UAV video transmission, meteorology, and climatology.

[0003] Generally speaking, the rectification detection of wireless microwaves converts the original alternating current into direct current in a certain way. The realization of traditional rectification devices is often based on the unidirectional conductivity of diodes.

[0004] To achieve more efficient rectification detection of alternating electric fields requires more complex rectification circuits and subsequent filtering, which increases the complexity of the device while limiting the further miniaturization of the device size, and also increases the complexity for the realization of subsequent multi-band impedance matching and other process technologies. Moreover, due to the relatively high threshold voltage required for the operation of diodes, the performance of rectification detection at low power is limited. At the same time, due to the limitation of the diode switching time, the operation at GHz depends on more complex device designs.

[0005] In 2016, Fu Liang et al. proposed (Patents: US11,837873B2) to use the intrinsic electrical properties of non-centrosymmetric inversion-symmetric materials to replace semiconductor junctions, which can also achieve microwave rectification, opening up new ideas for the development of a new generation of high-frequency rectifiers. Its physical mechanism is that in non-centrosymmetric inversion-symmetric materials, there is a significant second-order nonlinear conductivity. Due to the nonlinear Hall effect, when an alternating electric field with a frequency of f is applied to the material, a second-harmonic voltage with a frequency of 2f and a rectified voltage with a frequency of 0 will be generated in the transverse direction. And the rectified voltage characteristic of this zero frequency naturally overcomes the limitations of the threshold voltage and response time, and has great application prospects in the "THz application gap, 0.1-10THz" of current diode rectifier applications. However, to achieve this effect, it is necessary to use materials in a non-centrosymmetric inversion-symmetric system, such as monolayer graphene. Therefore, for such devices, realizing integrated applications at room temperature still poses challenges. One is to ensure the single-crystal quality at large sizes, and the second is that dual-gate voltage regulation is required for use at room temperature to adjust the carrier concentration to achieve the rectification effect, which undoubtedly increases the complexity of device integration. Third, the two-dimensional materials with significant room-temperature rectification effects reported currently have poor compatibility with current semiconductor processes. In addition, from the perspective of material selection, two-dimensional materials with specific centrosymmetric-breaking structures are required to achieve this, which limits the selectivity of alternative materials. Moreover, to achieve performance consistency in a wide frequency range, it is often necessary to be compatible with the overall impedance matching in the electrical circuit, and the complexity of using dual-gate voltage regulation increases exponentially.

[0006] Therefore, for the rectification detection of wireless microwaves, there is an urgent need to find new and simpler material systems and implementation methods that are more compatible with semiconductor processes.

[0007] Therefore, the existing technology needs to be improved. Summary of the Invention

[0008] The purpose of this application is to provide a microwave rectifier device based on centrosymmetric materials and its preparation method, aiming to solve the technical problem of how to provide a microwave rectifier device made of centrosymmetric materials to achieve microwave rectification in the existing technology.

[0009] To achieve the above purpose, the technical solution adopted in this application is:

[0010] In the first aspect, this application provides a microwave rectifier device based on centrosymmetric materials, which includes:

[0011] An iridium oxide layer, where the iridium oxide layer includes XIrO3, where X = Sr or Ca.

[0012] In an implementation manner, it further includes: a substrate for growing the iridium oxide layer, where the substrate includes a single-crystal SrTiO3 substrate.

[0013] In one embodiment, the thickness of the iridium oxide layer is 16 - 22 nm.

[0014] Second, based on the microwave rectifying device based on centrosymmetric materials provided in the above embodiments, the present application provides a preparation method of a microwave rectifying device based on centrosymmetric materials, wherein the preparation method includes the following steps:

[0015] (1) Provide a substrate, and grow an XIrO3 layer on the substrate to obtain an iridium oxide thin film material;

[0016] (2) Pattern the XIrO3 layer of the iridium oxide thin film material to form an independent cross-shaped XIrO3 layer on the substrate;

[0017] (3) Pattern the cross-shaped XIrO3 layer to expose the electrode positions;

[0018] (4) Grow metal electrodes at the electrode positions;

[0019] (5) Perform a lift-off process on the cross-shaped XIrO3 layer with metal electrodes to remove the photoresist on the cross-shaped XIrO3 layer and obtain a microwave detection device.

[0020] In one embodiment, the step of providing a substrate and growing an XIrO3 layer on the substrate to obtain an iridium oxide thin film material includes:

[0021] Prepare a target;

[0022] Deposit the XIrO3 layer on the substrate by pulsed laser deposition method using the target, and perform the first annealing and cooling to obtain an iridium oxide thin film material, wherein X = Sr or Ca.

[0023] In one embodiment, the step of depositing the XIrO3 layer on the substrate by pulsed laser deposition method using the target and performing the first annealing and cooling to obtain an iridium oxide thin film material includes:

[0024] Deposit the XIrO3 layer on the substrate by pulsed laser deposition method at a deposition temperature of 600 - 700 °C and a deposition oxygen pressure of 0.06 - 0.14 mbar, and then perform annealing and cooling at 0.1 - 0.5 bar for 20 - 40 min;

[0025] Wherein, the laser energy of the laser deposition method is 0.8 - 1.6 J / cm 2 ;

[0026] The substrate includes a single crystal SrTiO3 substrate.

[0027] In one embodiment, before the step of depositing the XIrO3 layer on the substrate by pulsed laser deposition of the target material and performing the first annealing and cooling to obtain the iridium oxide thin film material, the following steps are further included:

[0028] Ultrasonically process the substrate: ultrasonically process the substrate in a first solvent for a first time, then in a second solvent for a second time, and then in a third solvent for a third time;

[0029] Wherein, the first solvent includes acetone, and the first time is 5 - 10 min; the second solvent includes isopropyl alcohol, and the second time is 5 - 10 min; the third solvent includes deionized water, and the third time is 3 - 8 min.

[0030] In one embodiment, after the step of depositing the XIrO3 layer on the substrate by pulsed laser deposition of the target material and performing the first annealing and cooling to obtain the iridium oxide thin film material, the following steps are further included:

[0031] Perform a second annealing and cooling on the iridium oxide thin film material: perform a second annealing on the iridium oxide thin film material at 600 - 700 °C and 0.1 - 0.5 bar for 20 - 40 min, and then deposit a protective layer on the XIrO3 layer by pulsed laser deposition at a deposition temperature of 650 - 750 °C and a deposition oxygen pressure of 0.16 - 0.2 mbar, so that the protective layer protects the iridium oxide layer;

[0032] Wherein, the laser energy of the pulsed laser deposition method is 1.0 - 1.8 J / cm 2 .

[0033] In one embodiment, the step of preparing the target material includes:

[0034] Weigh and proportion the SrCO3 powder and the IrO2 powder, and use a planetary ball mill to fully grind and mix the SrCO3 powder and the IrO2 powder;

[0035] Sinter the SrCO3 powder and the IrO2 powder by a spark plasma sintering method to form an SrIrO3 target.

[0036] In one embodiment, the step of preparing the target material includes:

[0037] Weigh and proportion the CaCO3 powder and the IrO2 powder, and use a planetary ball mill to fully grind and mix the CaCO3 powder and the IrO2 powder;

[0038] Sinter the CaCO3 powder and the IrO2 powder by a spark plasma sintering method to form a CaIrO3 target.

[0039] The beneficial effects of a thin film material, a microwave rectifier device, and a preparation method and application thereof provided by the present application are at least:

[0040] The present application discloses a microwave rectifier device based on centrosymmetric materials and a preparation method thereof, wherein the microwave rectifier device based on centrosymmetric materials includes an iridium oxide layer, and the iridium oxide layer includes XIrO3, wherein X=Sr or Ca. In the present application, the iridium oxide layer realizes nonlinear rectification in a centrosymmetric material system, can linearly control the responsiveness through an in-plane electric field, realizes consistent control of wide-band performance, reduces the difficulty of impedance matching, and still exhibits considerable rectification responsiveness at 37GHz; can exhibit rectification response at 300 nanowatts, and the operating temperature range of the microwave rectifier device covers the industrial-grade operating temperature range, is compatible with current semiconductor processes, and can be epitaxially grown over a large area. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 A schematic diagram of the structure of a microwave rectifier device provided in an embodiment of the present application;

[0043] Figure 2 The microwave rectifier device provided in the embodiment of the present application shows a relationship between the rectifier voltage and the RF power under different DC electric field induction;

[0044] Figure 3 The microwave rectifier device provided in the embodiment of the present application shows a relationship between the rectifier voltage and the RF power at different RF frequencies under the induction of the same DC electric field strength;

[0045] Figure 4 The microwave rectifier device provided in the embodiment of the present application can show consistency in rectified voltage with radio frequency power at different frequencies under the induction of different DC electric field strengths;

[0046] Figure 5 The relationship between the rectifier voltage and the RF power at different temperatures of the microwave rectifier device provided in the embodiment of the present application;

[0047] Figure 6 The microwave rectifier device provided in the embodiment of the present application has a rectifier voltage response at different temperatures. DETAILED DESCRIPTION

[0048] In order to make the technical problems, technical solutions, and beneficial effects to be solved by this application more clearly understood, the following further details this application in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0049] It should be noted that when a component is referred to as "fixed to" or "disposed on" another component, it can be directly or indirectly located on that other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to that other component. The orientations or positions indicated by the terms "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positions shown in the accompanying drawings, and are only for the convenience of description and cannot be construed as a limitation to the technical solution of this application. The terms "first" and "second" are only used for the purpose of convenient description and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of technical features. The meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0050] Embodiment 1:

[0051] Please refer to Figure 1 , this embodiment provides a microwave rectifier device based on centrosymmetric materials, which includes: an iridium oxide layer, and the iridium oxide layer includes XIrO3, where X = Sr or Ca.

[0052] Specifically, the microwave rectifier device based on centrosymmetric materials further includes: a substrate for growing the iridium oxide layer, and the substrate includes a single-crystal SrTiO3 substrate.

[0053] In this embodiment, the advantage of using XIrO3 for the iridium oxide layer is that the resistance can be regulated by the thickness and growth conditions to better match the impedance designed for the device, and ultimately achieve the purpose of broadband microwave rectification with a nanowatt-level response that can be regulated by the electric field.

[0054] The thickness of the iridium oxide layer is 16 - 22 nm.

[0055] For example, the thickness of the iridium oxide can be 16 nm, or 18 nm, or 20 nm, or 22 nm. In this embodiment, if the thickness of the iridium oxide is too thick, lattice stress relaxation will occur and an ideal perovskite lattice cannot be formed; if the thickness of the iridium oxide is too thin, the film will be discontinuous.

[0056] In this embodiment, the substrate includes a single-crystal SrTiO3 substrate, that is, the substrate is made of a single-crystal SrTiO3 substrate, and the lattice parameter matching degree between the single-crystal SrTiO3 substrate and the Dirac knot line energy band structure material is relatively high.

[0057] For the sake of easy understanding, this application first gives a brief introduction to the Hall effect.

[0058] The Hall effect was first discovered by Edwin Hall in 1879 and is a classical phenomenon in physics. When a current Jx passes through a conductor or semiconductor in a magnetic field environment, the charge carriers in the material are deflected under the influence of the Lorentz force Fz caused by the magnetic field By, resulting in the accumulation of a transverse electric field Ee - namely the Hall effect. With the continuous in-depth research and the continuous improvement of high-precision measurement techniques, based on the research of the Hall effect in the traditional linear response range, the research on the Hall effect has been extended to the non-linear response range. Different from other Hall effects, a characteristic feature of this non-linear Hall effect is that in the absence of an external magnetic field, the detected Hall voltage can exhibit a dependence on a high power of the current. This more complex non-linear relationship further enriches the physical connotation of the electron transport theory and also provides a new perspective for understanding the electron behavior in materials. It is precisely because the Hall voltage and the driving current can be in a square relationship that in high-frequency circuits, frequency doubling terms and rectification terms can appear, providing a new mechanism for new rectifying devices.

[0059] Inti Sodemann and Liang Fu proposed in 2015 that under time-reversal symmetry, a quantum non-linear Hall effect can occur. They believe that in some non-centrosymmetric materials, when the system is driven by an alternating electric field, the inhomogeneous distribution of the Berry curvature will lead to the generation of a transverse voltage, which is proportional to the square of the driving current, thus exhibiting the characteristics of the non-linear Hall effect. Different from the first-order linear response, the non-linear Hall response coefficient is a second-order pseudotensor, and its form is determined by the point group symmetry, reflecting the relationship with the square or higher-order terms of the current. In a time-reversal invariant system, the Berry curvature is an odd function in momentum space Ω(k) = -Ω(-k). Therefore, since the Kramers pairs at k and -k are equally occupied, the weighted integral of the Berry curvature by the equilibrium Fermi distribution function is zero, and the first-order linear response disappears. The second-order response is also determined by the weighted integral of the Berry curvature, however, its weighting function is the first derivative of the non-equilibrium distribution function with respect to the electric field. Since the non-equilibrium carrier distribution is asymmetric under the k and -k transformation, the weighted integral of the Berry curvature by it may be a finite value, thus leading to a net anomalous velocity and further generating a transverse current. In short, a non-zero Berry curvature integral (i.e., Berry curvature dipole moment) can lead to the generation of the non-linear Hall effect. But space inversion symmetry must be broken, so it can generally be observed in non-centrosymmetric material systems.

[0060] However, the inventor of the present invention has found through research that not only can the Berry curvature dipole moment generate non-linear response, but also the Berry connection polarizability The Berry connection will be affected under the action of an electric field Generate corrections to the Berry curvature This way of breaking the material symmetry requirements by means of an electric field can realize an additional contribution term to the anomalous velocity of electrons, and then realize the nonlinear Hall effect and rectification effect in some centrosymmetric material systems that originally do not have the nonlinear Hall effect.

[0061] Material selection mechanism:

[0062] Strontium iridate, a 5d transition metal oxide, has a pbnm space group and belongs to a centrosymmetric structure.

[0063] Transition Metal Oxide (TMO for short) is a class of compounds composed of transition metal elements and oxygen elements. Due to the partial filling of electrons in the d orbitals of transition metals, these compounds exhibit diverse oxidation states and complex electronic structures, thus showing a series of rich physical and chemical properties. These properties include magnetism, conductivity, and catalytic activity, etc., making TMO play an important role in materials science and condensed matter physics. In particular, as the atomic number increases, the radius of the 5d orbital continues to increase. Compared with the 3d and 4d orbitals, the interaction between electrons in the 5d orbital weakens. However, a larger atomic number also means a stronger Spin Orbit Coupling (SOC). This strong SOC will cause the energy band to split. Due to the interaction between these energy scales, outstanding magnetoelectric properties and rich orbital-related physical properties are excited in TMO materials. In the range from weak to medium correlation strength, non-trivial band topology characteristics lead to the emergence of a series of phase states related to topological insulators, such as Weyl semimetals, axion insulators, Mott insulators, etc.

[0064] Among 5d transition metal oxides, a particularly noteworthy class is iridates with the Ruddlesden-Popper (RP) phase. In this type of compound, Ir 4+ The 5d electrons of the ions are t under the influence of spin-orbit coupling and crystal field 2g The energy level splits into a high-energy Jeff = 1 / 2 state and a low-energy Jeff = 3 / 2 state. Further increasing the electron correlation strength U divides Jeff = 1 / 2 into the upper Hubbard band and the lower Hubbard band, forming a special half-filled energy band. This Jeff = 1 / 2 state is a highly entangled quantum state, providing a unique experimental platform for studying quantum spin liquids, novel physical effects of strong correlation and SOC, and new quantum materials. This type of RP material is composed of alternating stacks of SrO and IrO2 layers, and its chemical formula is usually expressed as Srn+1 Ir n O 3n+1 , where n represents the number of layers. As the number of layers increases, significant changes occur in the electronic structure and magnetic interactions. SrIrO3 (n = ∞), although it also has the Jeff = 1 / 2 state generated by strong spin-orbit coupling, due to the transformation of its structure from a two-dimensional layered structure to a three-dimensional ABO3-type structure, it more exhibits the characteristics of a metallic state. Among them, perovskite-type SrIrO3, as a three-dimensional topological nodal semimetal, its Dirac nodal line energy band structure provides a large Berry curvature, which is also an important prerequisite for realizing the nonlinear Hall effect.

[0065] Please refer to Figure 1 , Figure 1 shows a schematic structural diagram of the microwave rectifying device of the present invention. The microwave rectifying device is made of the thin film material in Example 1 to achieve electrically tunable wireless rectification. Among them, the microwave rectifying device includes: a substrate, an XIrO3 layer, a protective layer, and electrodes. The XIrO3 layer is disposed on the substrate, and the XIrO3 layer is arranged in a cross-shaped pattern. The protective layer is disposed on the surface of the XIrO3 layer. The protective layer can be a SrTiO3 layer. The electrodes are located at the ends of the XIrO3 layer, that is, the cross-shaped XIrO3 layer. One direction is used as the direction for receiving microwaves, and the other direction is used as the direction for detecting the rectified voltage. Microwaves are irradiated along one direction, and a DC electric field is applied in the vertical direction, and a rectified voltage linearly increasing with the microwave power can be observed.

[0066] Among them, the reference numeral 100 in the figure is the substrate, 200 is the iridium oxide layer, 300 is the protective layer, 400 is the electrode, (001) is the crystal orientation of the (001) plane of the substrate, and (110) is the crystal orientation of the (110) plane of the iridium oxide layer. Specifically, the substrate can be a single-crystal SrTiO3 substrate, and the iridium oxide layer is XIrO3, where X = Sr or Ca, and the protective layer can be a SrTiO3 layer. For example, an iridium oxide layer with a crystal orientation of (110) plane can be formed on a single-crystal SrTiO3 substrate with a crystal orientation of (001) plane.

[0067] Please refer to Figure 2 , Figure 2 shows the V / W characteristic relationship diagram of the microwave rectifying device of the present invention. The microwave rectifying device shows the variation relationship of the rectified voltage with the radio frequency power under different DC electric field inductions under the irradiation of 1 GHz microwaves at room temperature. As can be seen from Figure 2 , when the DC electric field is zero, the microwave rectifying device does not show a rectifying response. When a DC electric field is applied, the microwave rectifying device can show a significant rectifying voltage response, and it increases with the increase of the DC electric field strength. This is the key to realizing the consistency regulation of multi-band performance.

[0068] Please refer to Figure 3 , under the induction of the same DC electric field intensity, the variation relationship of the rectified voltage with the RF power is shown at different RF frequencies. From Figure 3 , it can be seen that at multiple different frequencies, the microwave rectifier device exhibits a rectification effect. The frequency band covers multiple bands such as WIFI, satellite communication, radar, and UAV communication, showing a wide range of applications.

[0069] Please refer to Figure 4 , at room temperature, under the induction of different DC electric field intensities, the rectified voltage of the microwave rectifier device can show consistency with the RF power at different frequencies. From Figure 4 , it can be seen that in view of the linearly adjustable voltage responsivity of the electric field, the consistency adjustment of the rectified voltage responsivity in a wide frequency band can be realized, greatly reducing the complexity of the overall design of the microwave rectifier device.

[0070] Please refer to Figure 5 , the variation relationship of the rectified voltage with the RF power of the microwave rectifier device at different temperatures, where a microwave electric field is applied to the iridium oxide layer with a crystal orientation along the (001) plane, and a DC electric field is applied to the iridium oxide layer with a crystal orientation along the (110) plane for induction, and the rectified voltage is measured in this direction.

[0071] Please refer to Figure 6 , the rectified voltage responsivity of the microwave rectifier device at different temperatures. From Figure 5 and Figure 6 , it can be seen that the microwave rectifier device fully meets the requirements for industrial use (-40 - 85 °C) and can be extended to a wider temperature range.

[0072] Example 2:

[0073] Based on the microwave rectifier device based on centrosymmetric materials in the above embodiments, this embodiment provides a preparation method for an iridium oxide thin film material. Among them, the preparation method for the iridium oxide thin film material includes the following steps:

[0074] S100. Prepare the target.

[0075] S200. Deposit the XIrO3 layer on the substrate by pulsed laser deposition using the target, and perform the first annealing and cooling to obtain the iridium oxide thin film material, where X = Sr or Ca.

[0076] In this embodiment, the thickness of the iridium oxide layer can be controlled by adjusting the deposition time, and the regulation of the film resistance can be realized. The method provided in this embodiment is simple and feasible, can be industrially promoted, and has certain application value in the field of microwave detection. In this embodiment, the purpose of the first annealing and cooling is to fill possible oxygen vacancies.

[0077] Specifically, step S200 includes:

[0078] S210. Deposit the XIrO3 layer on the substrate by pulsed laser deposition at a deposition temperature of 600 - 700 °C and a deposition oxygen pressure of 0.06 - 0.14 mbar, and then perform annealing and cooling at 0.1 - 0.5 bar for 20 - 40 min;

[0079] Among them, the laser energy of the laser deposition method is 0.8 - 1.6 J / cm 2 .

[0080] The substrate includes a single-crystal SrTiO3 substrate, and the lattice parameter matching degree between the single-crystal SrTiO3 substrate and the epitaxial thin film material is relatively high, and the lattice parameter mismatch rate is small.

[0081] In this embodiment, the deposition temperature of the XIrO3 layer is 600 - 700 °C. For example, the deposition temperature can be 600 °C, or 610 °C, or 620 °C, or 630 °C, or 640 °C, or 650 °C, or 660 °C, or 670 °C, or 680 °C, or 690 °C, or 700 °C, etc. In this embodiment, if the deposition temperature of the XIrO3 layer is too high, the precipitation of Ir elements will occur; if the deposition temperature of the XIrO3 layer is too low, the crystallinity of the thin film will be poor.

[0082] In this embodiment, the deposition oxygen pressure of the XIrO3 layer is 0.06 - 0.14 mbar. For example, the deposition oxygen pressure of the XIrO3 layer can be 0.06 mbar, or 0.08 mbar, or 0.1 mbar, or 0.12 mbar, or 0.14 mbar, etc.

[0083] In this embodiment, after depositing the XIrO3 layer, the first annealing and cooling is performed, and the annealing temperature is 600 - 700 °C. For example, the annealing temperature can be 600 °C, or 610 °C, or 620 °C, or 630 °C, or 640 °C, or 650 °C, or 660 °C, or 670 °C, or 680 °C, or 690 °C, or 700 °C, etc.

[0084] The annealing time is 0.15 - 0.35 h. For example, the annealing time can be 0.15 h, or 0.20 h, or 0.25 h, or 0.30 h, or 0.35 h, etc.

[0085] Specifically, step S100 may include:

[0086] S111. Weigh and mix the SrCO3 powder and the IrO2 powder in proportion, and use planetary ball milling to fully grind and mix the SrCO3 powder and the IrO2 powder;

[0087] S112. Sinter SrCO3 powder and IrO2 powder by spark plasma sintering method to form SrIrO3 target.

[0088] In this embodiment, the target for depositing the XIrO3 layer can be SrIrO3 obtained by sintering SrCO3 and IrO2. Specifically, the target for the XIrO3 layer is obtained by weighing and proportioning SrCO3 and IrO2 powders with a purity higher than 99.99% according to a ratio, fully grinding and mixing them evenly by planetary ball milling, and then sintering them by spark plasma sintering method.

[0089] Specifically, step S100 may include:

[0090] S121. Weigh and proportion CaCO3 powder and IrO2 powder according to a ratio, and fully grind and mix CaCO3 powder and IrO2 powder by planetary ball milling;

[0091] S122. Sinter CaCO3 powder and IrO2 powder by spark plasma sintering method to form CaIrO3 target.

[0092] In this embodiment, the target for the XIrO3 layer can be CaIrO3 obtained by sintering CaCO3 and IrO2. Specifically, the target for the XIrO3 layer is obtained by weighing and proportioning CaCO3 and IrO2 powders with a purity higher than 99.99% according to a ratio, fully grinding and mixing them evenly by planetary ball milling, and then sintering them by spark plasma sintering method.

[0093] Before step S200, it also includes:

[0094] S300. Perform ultrasonic treatment on the substrate: Ultrasonic the substrate in the first solvent for the first time, then ultrasonic it in the second solvent for the second time, and then ultrasonic it in the third solvent for the third time;

[0095] Wherein, the first solvent includes acetone and the first time is 5 - 10 min; the second solvent includes isopropanol and the second time is 5 - 10 min; the third solvent includes deionized water and the third time is 3 - 8 min.

[0096] For example, the first time can be 5 min, or 6 min, 7 min, 8 min, 9 min or 10 min, etc.

[0097] For example, the substrate can be a single crystal SrTiO3 substrate. The single crystal SrTiO3 substrate can be pretreated before use, that is, perform ultrasonic treatment on the single crystal SrTiO3 substrate: Ultrasonic it in acetone and isopropanol for 5 - 10 min in sequence, and then ultrasonic it in deionized water for 3 - 8 min, and repeat the above ultrasonic treatment process 2 - 3 times.

[0098] After step S200, the following steps are further included:

[0099] S400. Perform a second annealing and cooling on the iridium oxide thin film material: Anneal the iridium oxide thin film material at 600 - 700 °C and 0.1 - 0.5 bar for 20 - 40 min for the second time, and then deposit a protective layer on the XIrO3 layer by pulsed laser deposition method at a deposition temperature of 650 - 750 °C and a deposition oxygen pressure of 0.16 - 0.2 mbar, so that the protective layer protects the iridium oxide layer.

[0100] Among them, the laser energy of the pulsed laser deposition method is 1.0 - 1.8 J / cm2.

[0101] For example, in this embodiment, pulsed laser technology can be used to epitaxially grow the XIrO3 layer and the SrTiO3 thin film (protective layer) on the (001) crystal plane of a single crystal SrTiO3 substrate. The laser energy of the pulsed laser is 1.2 J / cm 3 , and the pulse frequency is 2 Hz. The oxygen partial pressure for growth can be 0.1 mbar, and the growth temperature can be 700 °C. After growing the iridium oxide layer, an annealing treatment is carried out. The annealing temperature is 700 °C, and the annealing oxygen partial pressure is 300 mbar.

[0102] The iridium oxide thin film material in this embodiment can be used for microwave collection and detection. Among them, the detection range of the microwave rectifying device made of this iridium oxide thin film material is 0.1 MHz - 40 GHz, and the minimum detection power is 300 nW, having great application advantages of wide-frequency linear electric field adjustable consistency.

[0103] In this embodiment, the beneficial effects of the iridium oxide thin film material are at least as follows:

[0104] 1. Broaden the requirements for material selection in current wireless rectification based on the nonlinear Hall effect, and wireless rectification can also be achieved on centrosymmetric materials.

[0105] 2. Have a significant voltage responsivity at GHz.

[0106] 3. Reduce the complexity of gate voltage regulation and achieve multi-band consistency regulation of voltage responsivity.

[0107] 4. Achieve microwave rectification at the nano-watt level.

[0108] 5. Meet at least the industrial use range (-40 - 85 °C).

[0109] 6. Be compatible with current semiconductor processes such as CMOS, can be grown in large areas, and are suitable for the preparation of multi-size micro-nano devices.

[0110] Embodiment 3:

[0111] Based on the iridium oxide thin film material in the above embodiments, this embodiment provides a method for preparing a microwave rectifier device. The method for preparing the microwave rectifier device includes the following steps:

[0112] (1) Provide a substrate and grow an XIrO3 layer on the substrate to obtain an iridium oxide thin film material;

[0113] (2) Pattern the XIrO3 layer of the iridium oxide thin film material to form independent cross-shaped XIrO3 layers on the substrate;

[0114] (3) Pattern the cross-shaped XIrO3 layer to expose the electrode positions;

[0115] (4) Grow metal electrodes at the electrode positions;

[0116] (5) Perform a lift-off process on the cross-shaped XIrO3 layer with metal electrodes to remove the photoresist on the cross-shaped XIrO3 layer and obtain a microwave detection device.

[0117] In this embodiment, in step (1), the iridium oxide thin film material can be obtained by referring to the method of Embodiment 2; then, a cross-shaped electrode pattern can be exposed by photolithography, and dry etching can be used to retain the required material. Ti / Au electrodes can be deposited at each end part using pulsed laser. One direction is used as the microwave receiving direction, and the other direction is used as the rectified voltage detection direction. When microwaves are irradiated in one direction and a DC electric field is applied in the vertical direction, a rectified voltage that linearly increases with the microwave power can be observed.

[0118] Specifically, the method for preparing the microwave rectifier device may include:

[0119] S1. Spin-coat photoresist on the iridium oxide thin film material for the first photolithography preparation. Spin-coat ultraviolet photoresist on the iridium oxide thin film material at a spinning speed of 2000 - 4000 r / min for 40 - 60 s. Bake the iridium oxide thin film with the spin-coated photoresist at a baking temperature of 120°C for 4 - 6 min. The purpose of baking is to completely volatilize the solvent in the photoresist and prepare for the next ultraviolet exposure.

[0120] S2. Perform ultraviolet photolithography on the iridium oxide thin film material. After step S1, perform ultraviolet photolithography to transfer the cross-shaped pattern onto the photoresist, and use a developer to dissolve the unexposed area to form a cross pattern covered with photoresist.

[0121] S3. Place the iridium oxide film with a photoresist-covered cross pattern in a vacuum chamber. Use an Ar ion dry etching process with a process time of 6 - 10 min and a power of 160 - 200 W. Place the etched film in acetone to remove the photoresist, obtaining an iridium oxide film with only the pattern remaining.

[0122] S4. Repeat step S1 to spin-coat the photoresist on the iridium oxide film for the preparation of the second lithography.

[0123] S5. Then perform a second ultraviolet exposure on the iridium oxide film. Repeat step S2 to expose the XIrO3 layer in the end region of the cross-shaped pattern, obtaining the region for electrode growth. Place the exposed film in a vacuum chamber to grow the metal electrode.

[0124] Preferably, for electrode growth, use a pulsed laser deposition system with an in-situ etching function. Use the in-situ etching process to remove the protective film on the surface of the film in the region for electrode growth, and then immediately perform electrode growth.

[0125] Preferably, the electrode material is preferably Ti / Au, and the electrode thickness is 50 - 100 nm.

[0126] S6. Perform a lift-off process on the iridium oxide film with the grown metal electrode.

[0127] The grown metal electrode covers the entire sample surface. Since the metal electrode in the photoresist-protected area grows on the photoresist surface, while the metal electrode in the exposed area grows on the sample surface, place the iridium oxide film obtained in step S5 in a solution and soak it for 0.5 - 2 h. After the photoresist is completely dissolved, perform ultrasonic treatment on the iridium oxide film with the metal electrode to obtain a microwave detection device.

[0128] Preferably, the method for performing ultrasonic treatment on the iridium oxide film with the metal electrode includes: performing ultrasonic treatment on the iridium oxide film with the metal electrode in a first solvent for a first time, then performing ultrasonic treatment in a second solvent for a second time, and then drying it with nitrogen.

[0129] Preferably, the first solvent includes acetone.

[0130] Preferably, the second solvent includes isopropyl alcohol.

[0131] Preferably, the first time is 1 - 2 min.

[0132] Preferably, the second time is 1 - 2 min.

[0133] In summary, the present application discloses a microwave rectifier device based on a centrosymmetric material and a preparation method thereof, wherein the microwave rectifier device based on a centrosymmetric material includes an iridium oxide layer, and the iridium oxide layer includes XIrO3, wherein X=Sr or Ca. In the present application, the iridium oxide layer realizes nonlinear rectification in a centrosymmetric material system, and can achieve wide-band performance consistency regulation by linearly regulating the responsivity through an in-plane electric field, reduce the difficulty of impedance matching, and still show considerable rectification responsivity at 37 GHz; rectification response can be shown at 300 nanowatts, and the operating temperature range of the microwave rectifier device covers the industrial-grade operating temperature range, is compatible with current semiconductor processes, and can be epitaxially grown over a large area.

[0134] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A microwave rectifier device based on a centrosymmetric material, characterized in that: include: The iridium oxide layer comprises XIrO3, wherein X=Sr or Ca.

2. The microwave rectifier device based on centrosymmetric material according to claim 1, characterized in that: Also includes: A substrate is used to grow the iridium oxide layer, wherein the substrate comprises a single crystal SrTiO3 substrate.

3. The microwave rectifier device based on centrosymmetric material according to claim 1, characterized in that: The thickness of the iridium oxide layer is 16-22 nm.

4. A method for preparing a microwave rectifier device based on a centrosymmetric material, characterized in that: The preparation method comprises the following steps: (1) providing a substrate, and growing a XIrO3 layer on the substrate to obtain an iridium oxide thin film material; (2) patterning the XIrO3 layer of the iridium oxide thin film material to form an independent cross-shaped XIrO3 layer on the substrate; (3) performing patterning on the cross-shaped XIrO3 layer so that the cross-shaped XIrO3 layer exposes the electrode position; (4) growing a metal electrode at the electrode position; (5) Performing a lift-off process on the cross-shaped XIrO3 layer with the metal electrode to remove the photoresist on the cross-shaped XIrO3 layer to obtain a microwave detection device.

5. The method for preparing a microwave rectifier device based on a centrosymmetric material according to claim 4, characterized in that: The step of providing a substrate and growing a XIrO3 layer on the substrate to obtain an iridium oxide thin film material comprises: preparing target materials; The target material is used to deposit an XIrO3 layer on a substrate by a pulsed laser deposition method, and a first annealing and cooling is performed to obtain an iridium oxide thin film material, wherein X=Sr or Ca.

6. The method for preparing a microwave rectifier device based on a centrosymmetric material according to claim 5, characterized in that: The step of depositing an XIrO3 layer on a substrate by using a pulsed laser deposition method on a target material and performing a first annealing and cooling to obtain an iridium oxide thin film material comprises: The XIrO3 layer is deposited on the substrate by pulsed laser deposition at a deposition temperature of 600-700°C and a deposition oxygen pressure of 0.06-0.14 mbar, followed by annealing and cooling at 0.1-0.5 bar for 20-40 minutes; The laser energy of the laser deposition method is 0.8-1.6 J / cm 2 ; The substrate comprises a single crystal SrTiO3 substrate.

7. The method for preparing a microwave rectifier device based on a centrosymmetric material according to claim 5, characterized in that: The step of depositing a XIrO3 layer on a substrate by a pulsed laser deposition method and performing a first annealing and cooling to obtain an iridium oxide thin film material also includes: Ultrasonic treatment of the substrate: ultrasonic treatment of the substrate in a first solvent for a first time, then ultrasonic treatment of the substrate in a second solvent for a second time, then ultrasonic treatment of the substrate in a third solvent for a third time; Wherein, the first solvent includes acetone, and the first time is 5-10 minutes; the second solvent includes isopropanol, and the second time is 5-10 minutes; the third solvent includes deionized water, and the third time is 3-8 minutes.

8. The method for preparing a microwave rectifier device based on a centrosymmetric material according to claim 5, characterized in that: After the step of depositing the XIrO3 layer on the substrate by pulse laser deposition of the target material and performing the first annealing and cooling to obtain the iridium oxide thin film material, the method further comprises: Performing a second annealing cooling on the iridium oxide thin film material: performing a second annealing on the iridium oxide thin film material at 600-700° C. and 0.1-0.5 bar for 20-40 min, and then using a pulsed laser deposition method to deposit a protective layer on the XIrO3 layer at a deposition temperature of 650-750° C. and a deposition oxygen pressure of 0.16-0.2 mbar, so that the protective layer protects the iridium oxide layer; The laser energy of the pulsed laser deposition method is 1.0-1.8 J / cm 2 .

9. The method for preparing a microwave rectifier device based on a centrosymmetric material according to claim 5, characterized in that: The step of preparing the target material comprises: Weigh SrCO3 powder and IrO2 powder according to a certain proportion, and grind and mix the SrCO3 powder and IrO2 powder by a planetary ball mill; The SrCO3 powder and the IrO2 powder are sintered by spark plasma sintering to form a SrIrO3 target.

10. The method for preparing a microwave rectifier device based on a centrosymmetric material according to claim 5, characterized in that: The step of preparing the target material comprises: Weigh CaCO3 powder and IrO2 powder according to a certain proportion, and grind and mix the CaCO3 powder and IrO2 powder by a planetary ball mill; The CaCO3 powder and IrO2 powder are sintered by spark plasma sintering to form a CaIrO3 target.

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