62 results about "Fermi level" patented technology

The invention discloses a bifunctional chiral metamaterial surface capable of switching polarization conversion and wave absorption, and belongs to the technical field of electromagnetic metamaterials. The method is used for solving the problem that most existing chiral super-structure surfaces cannot realize dynamic adjustability and quantitative controllability and cannot have dual functions of polarization conversion and wave absorption at the same time. The super-structure surface unit structure is composed of a graphene film layer, a gold-vanadium dioxide resonance layer, a silicon dielectric layer and a bottom-layer continuous gold film. Switching of two functions of polarization conversion and wave absorption is realized by changing the conductivity of vanadium dioxide; polarization conversion and dynamic regulation and control of the wave absorbing efficiency are realized by changing the Fermi level of the graphene; quantitative controllability of polarization conversion and a wave absorbing function is realized by controlling a function weighting function. Besides, the chiral super-structure surface also has the advantages of incident angle robustness, small thickness and small size, has double functions of broadband, and has potential application value in the fields of optical devices, communication equipment, biomedical sensors and the like.

The invention discloses a material classification method and device based on an ultraviolet electron spectrum, a medium and a product, and relates to the technical field of material surface science and data analysis. The method comprises the following steps: acquiring ultraviolet light electron energy spectrum data of a target material to be analyzed, and extracting a first spectrum curve from the energy spectrum data; obtaining a conductor characteristic identification result of the target material according to the first spectrum curve; under the condition of determining that the target material does not have the conductor characteristics based on the conductor characteristic identification result, extracting a second spectrum curve in a preset valence band top energy interval extending towards the negative energy direction by taking the Fermi level as a starting point from the ultraviolet light electron spectrum data, and performing multi-dimensional characteristic fusion on the second spectrum curve, generating a semiconductor characteristic identification result of the target material based on the fusion result; and determining a classification result of the target material according to the semiconductor characteristic identification result. According to the scheme, the conductive attributes of the target material can be quickly and accurately classified.

The application relates to the fields of material preparation technology and radio frequency devices, in particular to a thin film substrate structure and an acoustic filter. The thin film substrate structure comprises a supporting substrate, an interface layer, an insulating layer and a functional layer; the supporting substrate has opposite first and second surfaces, and the interface layer is located on the second surface; the insulating layer is located on the side surface of the interface layer away from the supporting substrate; the functional layer is located on the side surface of the insulating layer away from the supporting substrate; and the interface layer has at least one of a deep energy level defect and a preset band gap width. The application plays a pinning effect on the Fermi level of the device by the interface layer having at least one of a deep energy level defect and a preset band gap width. The surface local conductance effect of the supporting substrate when working at a high frequency is effectively inhibited, the generation of high-order harmonics is inhibited, and the linearity of the device is optimized.

The invention relates to the technical field of photocatalysis, in particular to an I-type p-n heterojunction photocatalyst as well as a preparation method and application thereof. According to the photocatalyst, an n-type semiconductor metal organic framework NUS-8 is used as a matrix, a p-type semiconductor CuO is loaded, and an I-type p-n heterojunction structure is constructed. The preparation method comprises the following steps: by taking NUS-8 and cupric salt as raw materials and N, N-dimethylformamide as a dispersion medium, performing coordination anchoring on Cu < 2 + > on the surface of NUS-8 under solvothermal, oxidizing to form CuO nanoparticles, and constructing a coupling interface to obtain the photocatalyst. An energy band of the material is in I-type (straddling type) arrangement, a built-in electric field is formed by Fermi level difference at an interface, directional separation and migration of photo-induced electrons and holes are effectively driven, and the catalytic activity and stability of a photocatalytic reaction are remarkably improved. The material has the advantages of simple and convenient process, stable structure, excellent photocatalytic performance and the like, and is suitable for environment and energy related fields such as photocatalytic CO2 reduction and the like.

The present invention provides a quantum device and a method for manufacturing the same that enable the injection of Cooper pairs into the edges of a two-dimensional topological insulator without the use of heterointerfaces, and the control of the Fermi level at the edges of the two-dimensional topological insulator. [Solution] The quantum device comprises a monolayer 4 of tungsten ditelluride having a 1T' type crystal structure, a first electrode 6a that provides a first potential to a first portion of the monolayer that is a part of the monolayer and separated from the outer periphery of the monolayer, and a second electrode 6b that provides a second potential to a second portion of the monolayer that is a part of the monolayer and includes a certain range of the outer periphery of the monolayer. The first electrode is positioned so that Cooper pairs generated by the application of the first potential to the first portion can penetrate a third portion that is a part of the second portion and includes the certain range. The third portion is a region in which topological superconductivity occurs when Cooper pairs penetrate.

The invention discloses a fine simulation method of a CdTe-based II-VI group compound thin film solar cell and a cell structure designed based on the method. According to the method, a physical model of a CdTe-based battery is established through numerical simulation, then the energy band structure of a carrier transport layer is systematically optimized, and the quantitative criteria that a hole transport layer needs to meet the requirements that the Fermi energy level is lower than that of an absorption layer and the hole transport layer has enough positive conduction band offset and an electron transport layer needs to have a wide band gap and moderate positive conduction band offset are determined. And for the optical layer, the optimal thickness of the antireflection layer is determined, the enhancement effect of the optical path gain of the textured structure on optical absorption is quantified, and the maximization of the light capture efficiency is realized. According to the method, through electrical-optical coupling simulation, the CdTe-based solar cell structure of which the conversion efficiency is remarkably improved can be accurately predicted and guided to be designed, the defects that a traditional experiment is high in trial and error cost and long in period are effectively overcome, and a reliable theoretical design and optimization tool is provided for research and development of a high-efficiency and low-cost CdTe-based solar cell.

A method for forming a semiconductor structure, comprising: providing a substrate, including a substrate and a fin standing on the substrate, along the extension direction of the fin, the fin includes a channel region, the channel region is used to form a stacked work function layer; forming a gate dielectric layer conformally covering the top and sidewall of the fin in the channel region; forming a first work function layer conformally covering the gate dielectric layer in the channel region; forming a filling layer on the first work function layer between adjacent fins, the filling layer exposes at least the first work function layer on the top of the fin, the Fermi level of the material of the filling layer is closer to the Fermi level of the fin than the Fermi level of the material of the stacked work function layer; forming a second work function layer covering the first work function layer and the filling layer, the second work function layer and the first work function layer are used to constitute the stacked work function layer. The second work function layer is located on the top of the first work function layer and the filling layer, which reduces the probability of generating void defects in the second work function layer and improves the uniformity of the threshold voltage of the device.

The embodiment of the present application discloses a kind of transmission type terahertz absorption structure and preparation method thereof.Transmission type terahertz absorption structure includes at least one transmission type terahertz absorption composite film layer, transmission type terahertz absorption composite film layer includes substrate and the metal grating layer, insulating layer and graphene layer that are sequentially stacked in substrate side;Wherein metal grating layer and graphene layer are electrically connected with external power supply.The technical scheme of the embodiment of the present application is based on electromagnetic wave theory and the electrical properties of graphene, by additional voltage control Fermi level of graphene, adjust the absorption of absorption structure to terahertz, make the terahertz wave that pass through the present absorption structure have different intensity information under the influence of external voltage, play the role of switch, and have the advantages of active regulation, real-time control, accurate control, suitable for terahertz spectrum imaging analysis, single-pixel imaging and spectrum measurement etc.

A semiconductor device includes a semiconductor region made of a material to which conductive impurities are added, an insulating film formed on a surface of the semiconductor region, and an electroconductive gate electrode formed on the insulating film. The gate electrode is made of a material whose Fermi level is closer to a Fermi level of the semiconductor region than a Fermi level of Si in at least a portion contiguous to the insulating film.

The invention discloses an adjustable ultra-wideband terahertz metamaterial wave absorber, and belongs to the technical field of terahertz wave absorbers. The wave absorber is composed of a plurality of same metamaterial structure units which are periodically arranged, and each metamaterial structure unit is made of three layers of composite materials, wherein the first layer is a graphene pattern layer, the second layer is a polyimide dielectric layer, and the third layer is a copper reflecting layer. Wherein the graphene pattern layer adopts a combined design of four groups of square and L-shaped structures, and the four groups of structures form a biaxial symmetry layout through geometric coupling. The structure has the characteristics of wide absorption bandwidth, high absorption rate and dynamic adjustability, can realize more than 90% of efficient absorption in the frequency band of 2.28-4.68 THz, and can adjust the Fermi level of the graphene by externally applying bias voltage to realize rapid switching between the absorption state and the reflection state. The device is suitable for various application scenes such as terahertz communication, sensing and stealth.

The invention discloses a passivation material, the structural formula of the passivation material is shown in the specification, X is independently selected from F, Cl, Br or I, and Y is independently selected from-PO3H2,-SO4H,-COOH,-OH or-SH. The passivation material and uncoordinated Pb < + > on the surface of the perovskite can form a powerful double-site coordination effect, the interface defect state density is remarkably reduced, and non-radiative recombination is inhibited. Meanwhile, the interface energy band structure is effectively regulated and controlled, the Fermi level is moved upwards, the surface n-type characteristic is enhanced, and therefore energy level alignment is optimized, the electron extraction potential barrier is reduced, and the charge transmission efficiency is improved.

The application discloses a humidity sensor and a preparation method thereof. The humidity sensor comprises an insulating substrate, an electrode layer arranged on the insulating substrate, a two-dimensional transition metal sulfide layer and a two-dimensional transition metal oxide layer. The two-dimensional transition metal oxide layer is combined on the two-dimensional transition metal sulfide layer, and the two form a composite structure. The two-dimensional transition metal oxide layer and the two-dimensional transition metal sulfide layer have a Fermi energy level difference capable of causing charge transfer, thereby forming a space charge region and a potential barrier at the interface of the composite structure. The humidity sensor has high sensitivity, stability and corrosion resistance, and the working temperature and humidity range are also improved.

The application provides a multi-polarization non-reciprocal metamaterial coherent wave absorber based on temperature control and electric control cooperation, each wave absorber unit comprising two metal layers etched with quasi-# Chinese character-shaped slots arranged in an up-down mode and a metal layer with a C-shaped slot located in the middle, and a graphene grating located between adjacent metal layers, and part positions in the two quasi-# Chinese character-shaped slots being filled with a phase change material to form a composite structure with the metal layer. The application realizes conversion of the metal-insulating state of the phase change material by controlling the temperature of the phase change material, and adjusts the Fermi level of the graphene grating by controlling the bias voltage of the graphene grating, thereby realizing x-polarization and x-polarization same-polarization reciprocal coherent wave absorption, x-polarization and y-polarization cross-polarization non-reciprocal coherent wave absorption in a frequency band, and realizing y-polarization and y-polarization same-polarization reciprocal coherent wave absorption, y-polarization and x-polarization cross-polarization non-reciprocal coherent wave absorption in another frequency band, so that the application range is effectively widened.

This disclosure provides a semiconductor quantum dot feedback control method and system based on FPGA. The method includes: S1: performing linear scanning and acquiring response data of a single-electron transistor under different bias voltages; S2: determining the operating point with the steepest transconductance by optimization and outputting the optimal bias voltage corresponding to the operating point to lock the optimal operating point of the single-electron transistor; S3: extracting the high and low level distribution characteristics of random telegraph signals by acquiring signal data of the single-electron transistor in real time; S4: dynamically adjusting the bias voltage applied to the quantum dot according to the high and low level distribution characteristics to calibrate the offset between the quantum dot energy level and the source-drain Fermi level.

The application discloses a method for sensing electric voltage pressure based on interface state density modulation, a sensor and application, and comprises the following steps: constructing an interface structure with high pressure sensitive state density, containing at least one interface state density modulation layer and one solid-state electrolyte layer in close contact with the unit; under the action of external pressure, micro deformation or effective contact area change of the interface state density modulation layer is caused by pressure, and the state density of the unit interface is directly modulated; the change of the state density causes the Fermi level of the interface of the interface state density modulation layer to move, and a temporary electrochemical potential difference is generated; the electrochemical potential difference drives the directional migration of charge carriers in the solid-state electrolyte layer, and the interface charge is redistributed, so that a continuous and pressure-varying electric signal is generated in the external circuit. The application also comprises a corresponding sensor and application, and breaks through the physical limit that the traditional sensor cannot effectively detect due to charge leakage and dynamic mechanism limitation at ultra-low frequency.

The application relates to the technical field of thermoelectric materials, in particular to a MnTe alloying-regulated AgSbTe2-based thermoelectric material and preparation and application thereof. Through the MnTe alloying strategy, local composition fluctuation and lattice distortion are induced in the AgSbTe2 matrix, sub-micron scale Ag2Te second phases and Mn-Te enrichment regions are formed, intrinsic Ag / Sb cation disorder is combined, a multi-scale phonon scattering network is constructed, the propagation of phonons with different frequencies is effectively inhibited, the lattice thermal conductivity is significantly reduced, meanwhile, through carrier concentration optimization and Fermi level regulation, the Seebeck coefficient is effectively improved while the reasonable electrical conductivity is maintained, the power factor of the material is obviously improved, and therefore, the thermoelectric performance of the MnTe solid solution sample is significantly improved.

The application discloses a terahertz micro-spectrometer based on a metasurface, and has a working frequency of 1-5 terahertz; from bottom to top, the terahertz micro-spectrometer comprises a substrate, a depletion layer, a two-dimensional material absorption layer and a metal metasurface filter; source and drain electrodes are arranged at two ends of the metal metasurface filter; by applying different voltages to the source, the drain and the gate electrode, the Fermi level of the two-dimensional material absorption layer is controlled; only one metal metasurface filter is needed to perform spectrum coding, and spectrum data of an object can be collected; after decoding by deep learning, the transmittance under different frequencies is output. The spectrometer can reconstruct the spectrum data of the object at the frequency of 1-5 terahertz, and the spectrum resolution can reach 0.00078 terahertz.

The application relates to a photovoltaic device and a preparation method thereof, and an electricity-using device and a power generation device. The photovoltaic device comprises an electron transport layer, a perovskite layer and a hole transport layer which are arranged in a stack, the perovskite layer is located between the electron transport layer and the hole transport layer; the perovskite layer comprises a perovskite material; the perovskite layer has a first surface facing the electron transport layer and a second surface facing the hole transport layer; the perovskite layer has a first region near the first surface and a second region near the second surface, the first region is located between the first surface and the second region; the Fermi level of the perovskite material in the first region is closer to the conduction band bottom, and the Fermi level of the perovskite material in the second region is closer to the valence band top; in the first region, the energy level difference (J1) between the conduction band bottom and the Fermi level of the perovskite material, and the energy level difference (J2) between the Fermi level and the valence band top satisfy J2-J1>=0.3eV. The photovoltaic device has improved device efficiency.

A light detection device (1) according to an embodiment of the present disclosure comprises: a first electrode (23); a second electrode (26) provided so as to face the first electrode (23); a photoelectric conversion film (22) provided between the first electrode (23) and the second electrode (26); a first semiconductor layer (25a) provided between the photoelectric conversion film (22) and the second electrode (26); and a second semiconductor layer (25b) provided between the first semiconductor layer (25a) and the second electrode (26). The difference between the Fermi level in the first semiconductor layer (25a) and the lower-end level of the conduction band is smaller than the difference between the Fermi level in the second semiconductor layer (25b) and the lower-end level of the conduction band.

The invention relates to a photovoltaic device and a preparation method thereof, a power utilization device and a power generation device. The photovoltaic device comprises a perovskite layer and a first electron transport layer which are arranged in a stacked mode. The perovskite layer comprises a first perovskite material; the first electron transport layer comprises a first electron transport material, and the first electron transport material comprises a carbon-based hollow cage structure; the perovskite layer comprises a first region close to the first electron transport layer; the first electron transport layer comprises a second region close to the perovskite layer; recording the potential distribution at the cross section vertical to the thickness direction in the first electron transport layer and the perovskite layer as transverse potential distribution; the Moran index MLIE2 of the transverse potential distribution at the section far away from the perovskite layer in the second region is less than or equal to 0.5; the absolute value (ECF) of the energy level difference between the conduction band bottom and the Fermi level of the first perovskite material in the first region is smaller than the absolute value (EFV) of the energy level difference between the Fermi level and the valence band top. The photovoltaic device has improved photoelectric conversion efficiency.

The invention discloses a tunable infrared multi-resonance thermal emitter system based on an MgTeMoO6-graphene microcavity structure, and the system achieves the strong coupling between MgTeMoO6 phonon polaritons and graphene plasmon polaritons, enhances the light-substance interaction in a hybrid mode, and improves the intensity and directivity of a thermal emission peak value. While the three-vibrator model is used for predicting multi-frequency resonance, dynamic, continuous and controllable wavelength tuning can be realized by means of a graphene Fermi level regulation and control mechanism; benefited from the broad-spectrum phonon response and excellent lattice characteristics of the MgTeMoO6 material, the system effectively fills the structural vacancy of the tunable thermal emitter in the far infrared band; the integral thickness of the structure is small, the layering is clear, and the structure is suitable for being integrated with an existing MEMS infrared chip platform, a thermal light source array and a sensing array system; by constructing the MgTeMoO6-graphene micro-cavity structure, mid-infrared thermal emission control of multiple resonance modes is achieved, a brand new solution and theoretical support are provided for a multi-frequency thermal light source, an infrared functional device and a dynamic thermal radiation regulation and control technology, and the MgTeMoO6-graphene micro-cavity structure has wide application prospects and practical value.

The invention discloses a multiband tunable electromagnetic induction-like transparent metamaterial and application, and belongs to the technical field of electromagnetic induction transparent metamaterials. The multiband tunable electromagnetic induction-like transparent metamaterial comprises a plurality of periodically arranged structural units, each structural unit comprises a substrate, a graphene metasurface is arranged on the upper surface of each substrate, and each graphene metasurface comprises a rectangular resonator, a first split-ring resonator and a second split-ring resonator. The second split-ring resonator is located between the first split-ring resonator and the rectangular resonator, and the bottom of the second split-ring resonator is nested in the first split-ring resonator; the rectangular resonator, the first opening resonance ring and the second opening resonance ring generate three similar electromagnetic induction transparent windows in the terahertz wave band through the near-field coupling effect. According to the multiband tunable electromagnetic induction-like transparent metamaterial and the application, three high-transmittance transparent windows are generated in a terahertz wave band, a remarkable slow light effect is achieved, and the transmission amplitude, the center frequency and the slow light effect of the transparent windows are adjusted by adjusting the Fermi level of graphene.

The invention belongs to the technical field of sodium-ion battery positive electrode materials, and relates to a low-band-gap ferric sodium pyrophosphate positive electrode material and a preparation method and application thereof. The chemical formula of the low-band-gap phosphoric acid and sodium ferric pyrophosphate positive electrode material is NaxFex-1-ny / 2My (PO4) x-2P2O7 / C, x = 3, 4 or 5, M is a doped low-electronegativity element, n is the valence state of the element M, and y is larger than or equal to 0.2 and smaller than or equal to 0.01. By adjusting the type and content of the low-electronegativity doping element, the electron state density of the Fe 3d orbit near the Fermi level is increased, and the band gap width is smaller than or equal to 1 eV. The low-electronegativity element partially replaces a bivalent Fe element, so that the band gap can be reduced to improve the electronic conductivity of the polyanion material, the electrochemical activity of the polyanion material is improved, and the specific capacity and the rate capability of the polyanion material are improved; meanwhile, lattice distortion during deep sodium removal of the polyanion material can be inhibited, and the cycling stability of the polyanion material is improved.

The invention discloses a method for realizing regulation and control of a second harmonic radiation direction, which adopts a semiconductor-graphene nonlinear composite structure, and realizes modulation of a second harmonic far-field scattering mode by regulating and controlling the Fermi level of graphene. The semiconductor-graphene nonlinear composite structure comprises anisotropic nanoparticles coated with graphene, the nanoparticles can be of a single independent structure or a dimer structure formed by a plurality of nanoparticles, and when the nanoparticles are of the dimer structure, a gap exists between every two nanoparticles. The invention provides an effective and convenient method for flexibly modulating a second harmonic nonlinear far-field scattering mode by utilizing the high tunability of the optical nonlinear characteristic of the graphene.

This invention relates to the field of silicon carbide technology and discloses a method for measuring the nitrogen concentration of a silicon carbide wafer, which involves calculating the first contact potential φ on the surface of the silicon carbide wafer. sample Then, by establishing the first contact potential φ sample The difference between the conduction band bottom energy Ec and the Fermi level energy Ef of a silicon carbide wafer is obtained by establishing the first relationship between the difference between the conduction band bottom energy Ec and the Fermi level energy Ef. The specific value of the electron concentration n at equilibrium is then obtained by establishing the second relationship between the electron concentration n at equilibrium and the nitrogen concentration N. D The third relation yields the specific value of the nitrogen concentration n in the silicon carbide wafer; this allows the nitrogen content of silicon carbide to be obtained through surface potential testing, facilitating the production process and improving testing efficiency.

The application provides a semiconductor laser element provided with an ion conjugate layer, and relates to the technical field of semiconductor photoelectric devices, and sequentially comprises a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer and an upper limiting layer from bottom to top; the ion conjugate layer is arranged between the active layer and the upper wave layer and between the active layer and the lower waveguide layer; the ion conjugate layer can improve the molar absorption coefficient and compensate the polarization field, induce local polarization, and then regulate the carrier and Fermi level, improve the small rabbit degeneracy of the laser element, reduce the absorption loss of the free carrier, promote the stimulated radiation to exceed the spontaneous radiation, improve the particle inversion of the non-equilibrium carrier in the resonant cavity of the laser element, reduce the lasing threshold, realize the room-temperature continuous oscillation, improve the slope efficiency of the laser element, reduce the valence band step of the active layer, improve the hole injection efficiency and injection uniformity, and improve the peak gain and gain uniformity of the laser element.

The application discloses a defect layer modified TiO2 nanowire array photoanode and a preparation method thereof, and belongs to the technical field of photoelectrochemistry. 2 The Ti film is deposited on the surface of the NWAs by a magnetron sputtering method, and then annealing treatment is performed under a N2 atmosphere; during the annealing, Ti can capture O atoms in the TiO2 lattice to form a TiO2 defect layer containing oxygen vacancies on the surface, which helps to obtain a lower Fermi level; when a homojunction is formed between the defect layer and the main TiO2 nanowire, the Fermi levels tend to be balanced, thereby generating a built-in electric field, promoting the migration of photo-generated carriers and enhancing the utilization of light; the defect state concentration on the surface can be regulated by further regulating the Ti film deposition time and the annealing temperature and the like, so that the prepared photoanode has better PEC performance; the application provides an effective means for regulating the photoelectrocatalytic performance of TiO2 and also provides a theoretical basis for related applications.

The application discloses a liquid crystal panel and a manufacturing method thereof and a display device, and belongs to the technical field of display. The liquid crystal panel comprises a light filtering structure, opposite first and second substrates, a liquid crystal layer and a thin film transistor between the first and second substrates. The thin film transistor comprises an active layer, and the active layer comprises a channel region. A normal projection of the light filtering structure on a plane where the first substrate is located covers a normal projection of at least part of the channel region on the plane where the first substrate is located. The light filtering structure is used for filtering light in at least one sub-wave band in a visible light wave band, and the at least one sub-wave band comprises a wave band affecting the position of a Fermi level of the active layer of the thin film transistor. The application can avoid the light irradiated to the at least part of the channel region of the active layer from affecting the position of the Fermi level of the active layer, thereby avoiding the light irradiated to the thin film transistor from affecting the switching characteristic of the thin film transistor, helping to prolong the service life of the thin film transistor, and prolonging the service life of the liquid crystal panel.

The invention relates to a terahertz metasurface plasmon excitation regulation and control technology, provides a new device for realizing a decoding device based on SPP excitation and a manufacturing method of the new device, and discloses a decoder system based on surface plasmon excitation and a device manufacturing method. The plurality of graphene strips are connected through spacing layers, the plurality of electromagnetically induced transparent EIT complementary structures are sequentially arranged according to the same spacing, and all the graphene strips corresponding to the spacing layers on the left side of a dark mold opening of the EIT complementary structures arranged in sequence form a group; and all graphene strips corresponding to the opening of the right dark mold through the spacing layer form the other group, the two groups of graphene strips are connected with the metal layer by utilizing two electrodes, and the conductivity of the graphene strips is controlled by respectively changing the Fermi levels of the two groups of graphene strips, so that the regulation and control of the SPP excitation behavior in the + / -x direction are realized. The terahertz metasurface plasmon device is mainly applied to design and manufacturing occasions of terahertz metasurface plasmon systems and devices.

The application discloses a graphene-VO2-based terahertz ultra-wideband adjustable wave absorber and belongs to the technical field of terahertz technology, comprising, from top to bottom, a phase change material layer, a first dielectric layer, a graphene layer, a second dielectric layer and a reflection layer; the phase change material layer comprises a plurality of periodically arrayed VO2 umbrella-shaped patches; each VO2 umbrella-shaped patch is a regular octagon structure composed of eight congruent isosceles triangles; there are gaps between adjacent isosceles triangles; and adjacent VO2 umbrella-shaped patches are not connected with each other. The umbrella-shaped VO2 patches arranged in an array are combined with the graphene layer to realize ultra-wideband wave absorption in a 3-10 THz wave band, and the absorption rate is kept above 90%; and by respectively controlling the conductivity of the phase change material layer and the Fermi level of the graphene layer, the wave absorber presents different working states and has the characteristics of functional diversity.