36 results about "Dirac point" patented technology

The invention discloses a single crystal graphene pn node and a preparation method thereof. The modulated and doped graphene pn node is prepared according to the method which comprises the following steps of 1, annealing a copper foil substrate; 2, growing a sub-monolayer intrinsic graphene island on the surface of a copper foil by taking methane as a carbon source; 3, cleaning a growing system by using inert gas; 4, taking acetonitrile steam as a nitrogen-containing carbon source and growing nitrogen doped graphene on the boundary of the intrinsic graphene island; 5, repeating the steps 2, to 4, for at least zero time to obtain the single-level or multi-level graphene pn node; 6, quickly reducing the temperature to stop a growing process; and 7, transferring the graphene pn node which is obtained through modulating, doping and growing onto any target substrate by using polymethyl methacrylate (PMMA) as a medium. The modulated and doped graphene pn node with high quality is obtained by regulating the carbon source in the graphene growing process. The product has very high migration rate and photon to current conversion efficiency; and a transfer characteristic curve of the product has a double-Dirac point, so that the single crystal graphene pn node can be applied to logic devices, such as a phase inverter and a frequency multiplier.

The invention discloses a two-dimensional topological photonic crystal cavity, a design method thereof, and application in a laser. The two-dimensional topological photonic crystal cavity comprises aplurality of photonic crystal supercells that have a vortex-type structure change around the cavity center of the two-dimensional topological photonic crystal cavity, and the energy band of the plurality of photonic crystal supercells has a Dirac point at the equilibrium position where the vortex-type structure changes. The two-dimensional topological photonic crystal cavity, also known as a Diracvortex cavity, has the characteristics such as large mode field area, large free spectral range, narrow beam divergence angle, degeneracy of any mode and compatibility with a variety of substrate materials, and can be applied to surface emitting semiconductor lasers to ensure that the laser can still work stably in both single transverse mode and single longitudinal mode when outputting at largearea and high energy.

The invention provides an electric in-situ buckle background method for graphene plasmon reinforcing infrared spectroscopy detection. The method comprises the following steps: 1) preparing an infrared reinforcing and detecting device for a graphene plasmon component; 2) putting a to-be-detected object onto a graphene micro-structure; 3) performing an electrical test on the graphene micro-structure: measuring an Ids-Vg transport curve of graphene and reading a voltage Vg(CNP) corresponding to a Dirac point of the graphene; 4) performing infrared signal detection by utilizing the in-situ buckle background method, comprising the following sub-steps: a) by taking the voltage Vg(CNP) as the detecting background, collecting an extinction spectrum T (CNP); and b) adjusting the voltage Vg, reinforcing sample signals at various degrees by utilizing positive and negative voltages above or below the Dirac point, collecting the extinction spectrum T (EF) again, and confirming the step length of the voltage Vg according to the natures and specific measured scopes of different dielectric layer materials.

An acoustic topological insulator structure 1 is composed of a regular hexagon flat plate 2 and regular triangular prisms 3, the regular triangular prisms 3 are periodically arranged on the regular hexagon flat plate 2 according to triangular lattices, the regular triangular prisms 3 are divided to four parts, a left upper part 7 and a right lower part 8 rotate for 30 DEG in a clockwise mode, anda left lower part 9 and a right upper part 10 rotate for 30 DEG in an anticlockwise mode. The regular triangular prisms 3 of the acoustic topological insulator left rotate for 30 DEG to 0 DEG and thenright rotate for 30 DEG, the band gaps between double-degeneration energy bands are decreased gradually, a double-degeneration Dirac point is finally formed through integration, the double-degeneration Dirac point is then opened, and becoming larger gradually along with increasing of the rotating angle is achieved. When the double-degeneration energy band of the acoustic topological insulator isopened, closed and then re-opened, insulator energy band inversion and topological phase transformation can be completed, and pseudo-rotation effects are realized. The acoustic topological insulator uses the pseudo-rotation effects to realize acoustic topological robust unidirectional transmission, and a prototype device such as an acoustic splitter 1 is designed.

A pressure sensing device having a Dirac material and a method of operating the same are provided. The pressure sensing device includes a Dirac material pattern disposed on a substrate and having a band structure in which Dirac cones meet at a Dirac point. A source electrode and a drain electrode are respectively connected to the Dirac material pattern. A spacer layer including a cavity on the Dirac material pattern is disposed on the substrate. A gate electrode overlapping the Dirac material pattern is disposed on the cavity.

The invention relates to a graphene field effect transistor array biosensor and a preparation method and a detection method thereof. The invention relates to a biosensor and a preparation method and adetection method thereof, aiming at solving the problem of relatively low accuracy in the detection process of the existing graphene field effect transistor array biosensor. The sensor comprises a silicon substrate, an oxidization layer, a first metal grid electrode, a second metal grid electrode, a gate insulating layer, a first graphene conductive channel layer, a second graphene conductive channel layer, a first group source, a leakage electrode, a second group source and a leakage electrode; the preparation method comprises the following steps: I. making a transistor structure; II. performing aldehyde treatment on the graphene surface; III. modifying a detection unit graphene surface to capture antibody molecules; and IV. closing the remaining active sites on the graphene surfaces ofa detection unit and a reference unit; the detection method comprises the following steps: soaking the sensor in a solution containing be-detected antigen, and detecting the voltage at the graphene dirac point of the detection unit and the reference unit, to obtain the absolute concentration of the to-be-detected substance solution, wherein a difference value corresponds to a standard working curve.

The invention discloses a photonic crystal resonant cavity and a photonic crystal optical fiber based on a Dirac point. The photonic crystal resonant cavity and the photonic crystal optical fiber based on the Dirac point are characterized in that the mutual effect between two-dimensional local area modes supported by the photonic crystal resonant cavity and the photonic crystal optical fiber based on the Dirac point is in long range, the local area mode intensity is attenuated in space according to the power function r-3/2 of the distance, phases of the modes are jumped between two states, the phase characteristic of a standing wave is displayed, a quality factor of the modes is linearly increased along with the area of the resonant cavity, when the absorption of the materials is not considered, the size of the resonant cavity can be increased so as to improve the quality factors of the modes without limit, and meanwhile, the modes do not only exist in the Dirac frequency and further exist in other frequencies within a certain range surrounding the Dirac frequency.

The invention discloses an underwater sub-wavelength local resonance type acoustic metamaterial which comprises a water area 1, a stainless steel cylindrical shell 2 and a stainless steel three-fork star-shaped cylinder 3. Included angles among three outer forks of the stainless steel three-fork star-shaped cylinder 3 are 120 degrees, and an inner cavity of the cylinder is evenly divided into three fan-shaped cavities 9, 10 and 11. The three fan-shaped cavities 9, 10 and 11 are air domains. The underwater sub-wavelength local resonance type acoustic metamaterial disclosed by the invention hasfour sections of extremely wide complete band gaps in a frequency band [0Hz, 60000Hz]. In a complete band gap, propagation of sound waves is completely cut off and cannot continue to propagate forwards, and the possibility that an underwater object is detected by sonar due to radiation noise of the underwater object is reduced. The underwater sub-wavelength local resonance type acoustic metamaterial is provided with a Dirac point, and the standardized frequency of the lowest-frequency Dirac point is 0.0072 and is far lower than 1. The sound waves near the Dirac point frequency can realize zero-phase-difference propagation without changing the wavefront formation of the sound waves, and the possibility that underwater obstacles are actively detected by sonar is reduced.

The invention belongs to the field of sensing, and particularly relates to a super-sensitive gas sensor based on a graphene D-shaped optical fiber. According to the invention, external voltage is applied through a gold-graphene-gold heterojunction structure to adjust the Fermi level of graphene; by applying external voltage, the Fermi level of the graphene is adjusted to a position close to a Dirac point, and when sensed gas molecules are adsorbed to the graphene, the carrier concentration of the graphene is changed, so that tiny change of the Fermi level is caused. As the Fermi level of the graphene is close to a Dirac point, a four-wave mixing signal of the graphene D-shaped optical fiber excited by input pump light is most sensitive to response of external sensing molecules, and the sensing sensitivity is optimal at the moment. According to the invention, the interaction between an input optical signal and an external sensing molecule is remarkably enhanced, the size is small, the structure is simple, the sensing sensitivity reaches a single molecule level, an all-fiber structure is adopted, the optical fiber sensing and communication network can be conveniently accessed, and rapid real-time monitoring is realized.

The invention provides a preparation method of a MoSe2 in-plane homogeneous p-n junction, and belongs to the technical field of semiconductor materials. According to the method, partial channels of aMoSe2 field-effect transistor are protected, then ultraviolet ozone treatment is carried out, and the exposed channel is under the strong oxidation effect of ultraviolet ozone, and the surface layer of MoSe2 forms MoOx with a high-work function, so that electrons are transferred from the MoSe2 with relatively low work function to MoOx, the exposed MoSe2 shows hole conduction, and the protected region is still electrically conductive, and therefore electrons and holes in the same channel are electrically conductive simultaneously, and the MoSe2 in-plane homogeneous p-n junction is obtained. Experimental results show that, the rectification characteristic and the double Dirac point of the product prepared by the method disclosed by the invention are typical characteristic of the p-n junction, so that it shows that a p-n junction is successfully prepared; and the MoSe2 in-plane homogeneous p-n junction obtained by the method has obvious response to illumination.

The invention discloses a surface treatment method of the carrier concentration of an adjustable controlled carbon-based semiconductor device. The surface treatment method comprises the following steps of forming a silicane organic membrane layer on the surface of a substrate by using a silicane coupling agent, carrying out surface adsorption-type doping on a carbon-based thin-film material attached to the surface of the silicane organic membrane layer by using the different radicals and the nucleophilic and nucleus repellent characteristics in different densities of the silicane organic membrane layer, continuously adjusting the carrier concentration of the carbon-based semiconductor device attached to the surface of the silicane organic membrane layer by adjusting different radical varieties and concentration ratios, and effectively controlling the deviation position of a Dirac point of the carbon-based semiconductor device. The surface treatment method can be used for avoiding the destructive influence on graphene thin-film materials caused by conventional methods such as displacement-type doping and injection-type doping and meanwhile solving the problem of performance degradation of graphene devices caused by polarity scattering, rough fluctuation, impurity adsorption and the like of the surface of the substrate.

The invention discloses an ideal Dirac semimetal Cu2HgSnSe4 crystal. The Cu2HgSnSe4 crystal is characterized in that the Cu2HgSnSe4 crystal belongs to a tetragonal system; the space group of the crystal is (No. 121); and a conduction band and a valence band of the Cu2HgSnSe4 crystal are asymmetric in an energy band structure diagram, only Dirac fermion exists in the conduction band, and Schrodinger fermion and the Dirac fermion coexist in the valence band. If Fermi energy is located in the conduction band, transport properties are mainly derived from the Dirac fermion. Such a system is helpfulfor people to obtain relatively clean transportation experiment data, so the novel transportation property of a topological quantum state can be explored. Meanwhile, the linear dispersion relation ofelectrons near a Dirac point is always kept within the energy range of about 400 mV, and a Dirac cone energy band structure of linear dispersion has large-range frequency nonlinear response to lightwaves. The crystal has important academic value and potential application prospect.

The invention discloses a wireless energy transmission method and a structure and belongs to the technical field of wireless energy transmission. The method comprises the following steps: providing asubstrate; forming a plurality of unit structures, periodically arranging the plurality of formed unit structures on the substrate on one layer or two layers, and forming a metasurface containing Dirac points, so as to obtain a wireless energy transmission structure; exciting the metasurface of the wireless energy transmission structure by adopting a source of which the frequency is a resonant frequency corresponding to the Dirac points, enabling the various unit structures to simultaneously perform constant phase inter-coupling through magnetic resonance, generating a stable and uniform magnetic field, and performing wireless energy transmission. According to the wireless energy transmission method disclosed by the invention, the wireless energy transmission structure containing the Diracpoints is formed, and the metasurface of the wireless energy transmission structure is excited by adopting the source of which the frequency is the resonant frequency corresponding to the Dirac points, so that the uniform and stable magnetic field is generated, the wireless energy can be transmitted at a uniform transmission power, and the transmission is long in distance and wide in range.

An electromagnetic wave detector comprises: p-type and n-type graphenes arranged side by side on an insulating layer; a first electrode and a second electrode opposing each other via the graphenes; agate electrode for applying an operation voltage to the p-type and n-type graphenes; a balance circuit connected between two second electrodes; and a detection circuit. The p-type graphene has a Diracpoint voltage higher than the operation voltage. The n-type graphene has a Dirac point voltage lower than the operation voltage. In a state in which no electromagnetic wave is incident on the graphenes, the balance circuit places the first electrode and the second electrode at the same potential. In a state in which an electromagnetic wave is incident on the p-type and n-type graphenes, the detection circuit detects an electric signal between the second electrodes, and outputs an electric signal in the state in which the electromagnetic wave is incident.

The invention discloses a magnetic atom-doped superlattice [GeTe/Sb ₂ Te ₃ ] _n Materials and corresponding control methods, wherein the material is doped with magnetic atoms; the initial superlattice [GeTe/Sb ₂ Te ₃ ] _n The structure of the material has topological insulation; after doping with magnetic atoms, the topological insulation is regulated by the magnetic atoms, and the initial superlattice [GeTe/Sb ₂ Te ₃ ] _n The time-reversal symmetry possessed by the material is broken, and the magnetic atoms and their adjacent superlattice [GeTe/Sb ₂ Te ₃ ] _n The atoms in the material produce orbital hybridization, making the doped superlattice [GeTe/Sb ₂ Te ₃ ] _n The density of states in the spin-up and spin-down directions of the material has an asymmetric effect at the same time, and induces a magnetic moment. Compared with the prior art, the present invention can effectively solve the problems that the surface state Dirac cone of the topological insulator is difficult to control and the Dirac point cannot be opened by improving the specific types of key doping elements.

The invention provides a negative refractive index waveguide fast light device based on a Dirac-like point and a design method. The negative refractive index waveguide fast light device comprises an upper cladding layer and a low cladding layer, wherein the upper cladding layer and the low cladding layer are both arranged on a silicon plate, are both composed of a plurality of triangular lattice photonic crystals and have a negative refractive index, and the negative refractive index waveguide fast light device further comprises a core layer formed by silicon as a medium disposed between the upper cladding layer and the lower cladding layer; and upper boundaries, lower boundaries, left boundaries and right boundaries of the upper cladding layer and the lower cladding layer are scattering boundary conditions, and incident light enters from one side of the core layer and exits from the other side of the core layer. According to the negative refractive index waveguide fast light device, the characteristic that a frequency near the Dirac-like point can enable the effective refractive index of the photonic crystals to be negative is utilized, by controlling the frequency of the incidentlight and the thickness of the core layer, the negative refractive index of the cladding layers is achieved, and the light has the negative group velocity and the back propagation behaviors in the core layer.