6 results about "Wurtzite crystal structure" patented technology

A method for searching for ferroelectric materials, such as wurtzite crystal structures, that have low coercive fields and high spontaneous polarization values ​​using first-principles calculations is provided. [Solution] The method includes a first extraction step of obtaining, from a crystal structure database, ferroelectric material candidates with non-centrosymmetric symmetry as first candidates; a calculation step of calculating the band gap value, polarization reversal barrier energy value, and spontaneous polarization value of each first candidate obtained in the first extraction step using first-principles calculations; an insulating property determination step of determining whether the calculated band gap value satisfies insulating properties; a polarization reversal determination step of determining whether the calculated polarization reversal barrier energy value is within a range in which polarization reversal is possible; a spontaneous polarization determination step of determining whether the calculated spontaneous polarization value is within a range in which ferroelectric properties are exhibited; and a second extraction step of extracting, as ferroelectric materials, first candidates for which the determination results in the insulating property determination step, polarization reversal determination step, and spontaneous polarization determination step are all acceptable.

The utility model discloses a high-performance storage device structure using AlScN ferroelectric material, comprising a substrate layer, an insulating layer, a ferroelectric layer, a polarization buffer layer and a grid layer which are arranged in sequence from bottom to top, the ferroelectric layer adopts an AlScN film, the thickness of the ferroelectric layer is 20nm, and the polarization buffer layer adopts AlN, and the thickness of the polarization buffer layer is 10nm. The utility model provides a high-performance storage device structure using an AlScN ferroelectric material, AlScN has a wurtzite crystal structure, is stable in ferroelectricity, can keep a specific electric state after an external electric field is removed, can keep stable in an environment as high as 1100 DEG C, is an ideal material for realizing non-volatile storage, and can be used as a high-performance storage device. AlScN has the lowest dielectric constant in the inorganic ferroelectric material, and is beneficial to increasing the sensing margin of the FeRAM; the AlScN thin film can grow at the temperature lower than 400 DEG C by using a magnetron sputtering technology, is compatible with a CMOS (Complementary Metal Oxide Semiconductor) manufacturing process, does not contain volatile elements, and reduces the pollution risk in the COMS (Complementary Metal Oxide Semiconductor) process.

The present invention relates to a coated cutting tool consisting of a substrate body and a coating, the substrate being cemented carbide and the coating comprising a first cubic metal nitride layer and a 10 to 500 nm thick Al 1‑v‑y‑z M v Si y X z N layer below the first cubic metal nitride layer, wherein 0 < v < 0.75, 0 < y < 0.20, 0 < z < 0.10, wherein the Al 1‑v‑y‑ z M v Si y X z N layer has a wurtzite crystal structure. 1‑v‑y‑z M v Si y X z N layer has a wurtzite crystal structure.

This invention discloses a doped aluminum nitride ferroelectric thin film, a ferroelectric device, and its fabrication method. The doped aluminum nitride ferroelectric thin film has a wurtzite crystal structure and forms an atomic layer structure with periodically modulated doping concentration along the polarization axis [0001]. This structure is composed of alternating stacks of highly doped and low-doped atomic sublayers, with a period length as small as one unit cell length. The vertical spacing between cation and anion layers in different sublayers varies, thus introducing localized polarization differences at the atomic scale. By controlling the sputtering parameters, a periodic distribution of doping elements along the film thickness direction can be achieved. Under external electric field or electron beam excitation, the thin film exhibits non-collective step-like polarization reversal dynamics, which is beneficial for reducing the polarization reversal energy barrier and improving ferroelectric switching performance. This invention also provides a ferroelectric device based on this thin film and its fabrication method, which has good process compatibility and application prospects.

The invention provides a preparation method and application of a piezoelectric sensor vibration device based on an h-BN / GaN heterojunction, and belongs to the technical field of piezoelectric sensors, a third-generation semiconductor material gallium nitride is used as a core material of a novel piezoelectric sensor, and the piezoelectric sensor vibration device based on the h-BN / GaN heterojunction is prepared by using piezoelectric characteristics determined by inherent asymmetry of a GaN wurtzite crystal structure. The problem of heat temperature failure caused by Curie temperature limitation of conventional piezoelectric materials such as piezoelectric ceramics is solved, and meanwhile, the technical problems that a traditional piezoelectric sensor is narrow in frequency response range, poor in temperature stability and slow in dynamic response are solved by utilizing the characteristics of high forbidden bandwidth, high electron mobility and high temperature resistance of GaN. On the basis of a GaN material, an h-BN / GaN heterostructure is constructed by means of hexagonal boron nitride (h-BN), the piezoelectric effect of a strain engineering and interface collaborative polarization enhancement device is utilized, the technical problem that the piezoelectric coefficient is low when GaN is singly used for preparing a piezoelectric sensor is solved, meanwhile, the two-dimensional structural characteristic of the h-BN is utilized, the flexible piezoelectric detector can be prepared in cooperation with the GaN, and the flexible piezoelectric sensor has the advantages of being simple in structure, low in cost and the like. And light-weight and thin-film device design is realized.

This invention discloses a quantum dot with oriented luminescence, comprising: a core; and a shell covering the outer surface of the core. The core includes a wurtzite crystal structure, and the shell includes both a wurtzite crystal structure and a zincblende crystal structure, such that the quantum dot's crystal structure forms a polymorphic crystal structure along the c-axis of the wurtzite crystal. The polymorphic crystal structure includes two layers of zincblende crystal structure and a wurtzite crystal structure located between the two layers of zincblende crystal structure. By forming the quantum dot with a polymorphic crystal structure along the c-axis of the wurtzite crystal, the orientation of the quantum dot's transition dipole moment is controlled, thereby controlling the orientation of the quantum dot's luminescence. This invention also discloses a quantum dot thin film prepared using the above-mentioned quantum dot. The dipole-dipole interactions between the quantum dots cause the c-axis of the wurtzite crystals of the quantum dots to be antiparallel to each other and perpendicular to the substrate, making the preferred orientation of the quantum dot thin film's transition dipole moment parallel to the substrate.