36 results about "Dirac point" patented technology

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 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 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 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 a topological insulator heterogeneous composite film with a high spin polarized electron transport channel, and the topological insulator heterogeneous composite film comprises a 6H-SiC (0001) or SrTiO3 substrate and topological insulator 6QLBi2Se3 and ordinary semiconductor 3QLSb2S3 which are in order grown on the substrate by a molecular beam epitaxy technology in an ultra high vacuum system. Through coverage of the surface of topological insulator Bi2Se3 with the Sb2S3, the electrical properties of the composite film are significantly improved compared with that of a pure Bi2Se3 film; the Dirac point is changed from 0.1eV less than valence-band maximum to 0.09eV higher than valence-band maximum, Fermi velocity is improved from 1.15 eV. Angstrom to 1.61eV. Angstrom, spin polarization rate is also increased from 0.65 to 0.91; at the same time, the width of the spin polarized electron transport channel is improved from about 1nm to 3nm, and can be further expanded according to the needs by increasing of the Sb2S3 covering layer thickness; and the Sb2S3 covering layer can reduce influence on the spin polarized electron flow transport channel due to surface contamination such as oxidation and the like.