122 results about "Spontaneous polarization" patented technology

The present disclosure provides a semiconductor green laser. The semiconductor green laser, from bottom to top, comprising a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper limiting layer. The active layer is a quantum well composed of well layers and barrier layers. Each of the well layers includes any one of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN, and GaN, or any combination thereof. Each of the barrier layers includes any one of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN, and GaN, or any combination thereof. An electron effective mass of each of the well layers is less than an electron effective mass of each of the barrier layers. A spontaneous polarization coefficient of each of the well layers is less than a spontaneous polarization coefficient of each of the barrier layers.

Semiconductor light-emitting devices are provided, which includes a substrate, a Negative-type semiconductor, a quantum well, an electron-blocking layer, and a Positive-type semiconductor arranged in a sequential stack. The quantum well includes a first quantum well, a second quantum well, and a third quantum well. Optical parameters of the first quantum well, the second quantum well, and the third quantum well are distributed in a gradient in at least one direction. The quantum well includes a periodic structure consisting of a well layer and a barrier layer. A coefficient of thermal expansion of the well layer is smaller than or equal to that of the barrier layer. An elastic coefficient of the well layer is smaller than or equal to that of the barrier layer. A lattice constant of the well layer is greater than or equal to that of the barrier layer. A coefficient of spontaneous polarization of the well layer is smaller than or equal to that of spontaneous polarization of the barrier layer.

An electromagnetic wave detector includes a first ferroelectric layer, a two-dimensional material layer, a first electrode pair, and a second electrode pair. The first electrode pair includes a first electrode and a second electrode. The second electrode pair includes a third electrode and a fourth electrode. The first electrode pair and the second electrode pair are electrically connected to the two-dimensional material layer. The third electrode and the fourth electrode are disposed to face each other in a first direction perpendicular to a polarization direction of spontaneous polarization of the first ferroelectric layer. The first electrode and the second electrode are disposed to face each other in a second direction different from the first direction.

The invention belongs to the technical field of lithium ion solid-state batteries, and relates to a composite polymer electrolyte membrane as well as a preparation method and application thereof. The preparation method of the composite polymer electrolyte membrane comprises the following steps: generating a precursor salt containing Ba and Ti on the surface of an inorganic solid electrolyte through a wet chemical method, and forming a compact barium titanate coating layer on the surface of the electrolyte in a high-temperature calcination process to obtain the barium titanate surface modified inorganic solid electrolyte; uniformly dissolving a high-molecular polymer material, the barium titanate surface modified inorganic solid electrolyte and a lithium salt in a solvent, heating and stirring to prepare a uniform solution; and drying to form a membrane to obtain the polymer composite electrolyte membrane. Barium titanate has a special piezoelectric property and can be spontaneously polarized in a crystal structure to generate a polarization field, and the polarization field can sensitively sense the nonuniformity of lithium ion transmission dynamics and interact with the nonuniformity to balance the transmission process of lithium ions in the solid electrolyte, so that the bottleneck problem of ion migration in the traditional electrolyte is solved.

In a semiconductor element including a silicon carbide heterostructure, the resistance component generated due to spontaneous polarization at the hetero-matched interface is suppressed, thereby reducing the specific on-resistance of the semiconductor element. A hetero-matched interface (S X ) and 1 × 10 19 cm -3 The tunnel doped region (D T By providing the layer, a carrier transport mechanism by tunneling is realized, and the specific on-resistance of the semiconductor element is kept low.

The invention discloses a two-dimensional material photoelectric detector based on a ferroelectric pyroelectric effect. The two-dimensional material photoelectric detector comprises a ferroelectric functional layer; the double-layer electrode is positioned above the ferroelectric functional layer; the two-dimensional material thin film is arranged above the double-layer electrode and is in contact with the ferroelectric functional layer; the spontaneous polarization direction of the ferroelectric is perpendicular to the thickness direction of the two-dimensional material film; the double-layer electrode comprises an upper metal layer and a lower metal layer, and the lower metal layer is in contact with the ferroelectric functional layer and is used for enhancing the binding force between the upper metal layer and the ferroelectric functional layer; the upper metal layer has a conductive function; the two-dimensional material film is a photosensitive area of the detector and is used for receiving irradiation of a light source.

The invention discloses a method for screening strontium potassium niobate ceramics with high spontaneous polarization intensity, which comprises the following steps: introducing oxygen vacancy, A-site cation (K + and Sr < 2 + >) vacancy and B-site cation (Nb15 + and Nb25 +) vacancy structures by considering that K < + >, Sr < 2 + > and a small amount of Nb5 < + > are easy to volatilize when KSN is sintered at a high temperature and along with the generation of oxygen vacancy, and calculating the oxygen vacancy according to a first principle calculation thought; the strontium potassium niobate ceramic with high spontaneous polarization intensity is screened according to the spontaneous polarization intensity of strontium potassium niobate existing in A-site cation vacancy (K < + > vacancy and Sr < 2 + > vacancy) and oxygen vacancy and B-site cation vacancy (Nb5 < + > vacancy) and oxygen vacancy; a first principle method is adopted for theoretical calculation, the strontium potassium niobate material component with high spontaneous polarization intensity is theoretically screened out, on-demand design is achieved, the research and development period is shortened, theoretical guidance is provided for actual experiments, and the experiment time and cost are saved.

Embodiments of the present description provide a semiconductor green laser. The semiconductor green laser successively comprises, from bottom to top, a substrate (100), a lower confinement layer (101), a lower waveguide layer (102), an active layer (103), an upper waveguide layer (104), and an upper confinement layer (105). The active layer (103) is a quantum well consisting of a well layer and a barrier layer, the period of the quantum well is z, and z is greater than or equal to 1 and less than or equal to 3; the well layer comprises any one or any combination of aluminum indium gallium nitride (AlInGaN), aluminum indium nitrogen (AlInN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitrogen (InGaN), and gallium nitride (GaN), the thickness of the well layer is p, and p is greater than or equal to 5 angstroms and less than or equal to 100 angstroms; the barrier layer comprises any one or any combination of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN, and GaN, the thickness of the barrier layer is q, and q is greater than or equal to 10 angstroms and less than or equal to 200 angstroms; and the electron effective mass of the well layer is smaller than that of the barrier layer, the spontaneous polarization coefficient of the well layer is smaller than that of the barrier layer, and the band gap of the well layer is smaller than that of the barrier layer.

The invention discloses a high-performance lead-free piezoelectric catalytic material and a preparation method and application thereof, and belongs to the field of catalytic materials and pollution abatement, the preparation method of the lead-free piezoelectric catalytic material comprises the following steps: weighing K2CO3, Na2CO3, Nb2O5, Fe2O3 and Co2O3, mixing, performing ultrasonic dispersion treatment, and then performing grinding and presintering treatment to obtain precursor powder; grinding the precursor powder again, and then tabletting to obtain a green body; the green body is subjected to sintering treatment and grinding treatment in sequence, and ceramic powder is obtained; the ceramic powder is placed in pure water for ultrasonic treatment, then drying treatment is conducted, and the lead-free piezoelectric catalytic material is obtained. The potassium-sodium niobate-based lead-free piezoelectric catalytic material prepared through the processes of compact sintering, grinding, pure water ultrasonic treatment and the like has extremely high spontaneous polarization, has a very obvious effect on piezoelectric catalytic degradation of rhodamine B, and has the advantages of being environmentally friendly, efficient, high in catalytic activity, safe, stable, capable of reacting at normal temperature and the like.

A piezoelectric actuator comprises a stack of a plurality of piezoelectric films, a piezoelectric element having electrodes disposed between the piezoelectric films and at both end surfaces, and a drive circuit. Each of the plurality of piezoelectric films has asymmetric polarization-voltage hysteresis characteristics with two different absolute values of coercive voltage. The drive circuit applies a unipolar voltage waveform that generates an electric field in the same direction as the direction of spontaneous polarization in at least one layer from among the plurality of piezoelectric films and generates an electric field in the direction opposite to the direction of spontaneous polarization in the other piezoelectric films. A minimum voltage value V1 having a minimum absolute value in the unipolar voltage waveform is set such that the ratio of the slope T0 at 0 [V] to the slope T1 at the minimum voltage value V1 [V] in a hysteresis curve indicating bipolar polarization-hysteresis characteristics in another piezoelectric film satisfies |T0 / T1| ≥ 1.5.

The invention provides a photoelectric memory and a preparation method and a modulation method thereof, and belongs to the technical field of photoelectric memories. The photoelectric memory comprises a substrate; the polarization layer is located on the first surface of the substrate, and the polarization layer is made of a material with a spontaneous polarization effect; the photosensitive layer is located on the polarization layer or located between the substrate and the polarization layer, and the photosensitive layer is suitable for generating a photo-induced electron-hole pair in response to an optical signal incident to the photosensitive layer; wherein the polarization layer forms a built-in electric field in the photosensitive layer based on a spontaneous polarization effect, the built-in electric field is suitable for separating photo-generated electron-hole pairs, and the photoelectric memory realizes optical signal writing and nonvolatile storage based on a capture effect of a defect state of the photosensitive layer on photo-generated holes. The photoelectric memory provided by the invention has the advantages of good retention characteristic, high switch ratio and polymorphic storage capability.

The present invention discloses a semiconductor laser comprising: a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper confinement layer, arranged in order from bottom to top; the active layer comprising a well layer and a barrier layer; the electron effective mass of the well layer of the active layer being smaller than the electron effective mass of the barrier layer, the spontaneous polarization coefficient of the well layer of the active layer being smaller than the spontaneous polarization coefficient of the barrier layer, and the bandgap width of the well layer of the active layer being smaller than the bandgap width of the barrier layer. The present invention can suppress InN phase separation, segregation, and composition fluctuation in high-In content semiconductor lasers, effectively improve the crystal quality and interface quality of the active layer, effectively enhance the electron-hole recombination efficiency of the active layer, and effectively reduce defects and non-radiative recombination centers, thereby effectively improving the slope efficiency of green lasers.

A ferroelectric liquid crystal (FLC) material for the deformed helix FLC (DHFLC) electro-optical mode devices and shows optimum electro-optical properties including high tilt angle (>38°), and short helix pitch (<120 nm), and spontaneous polarization (>100 nC / cm2) comprising at least two components, wherein at least one FLC component is a chiral compound of Formula (I):particularly:wherein W1 and W2 are chiral groups with polar substituent at chiral centre, A and B are independently N atom or CH groups providing that at least one of A or B is N atom. Other various groups are as defined herein.

To provide a liquid crystal composition and a liquid crystal display element, capable of preventing the occurrence of alignment defects.SOLUTION: The present invention provides a liquid crystal composition having spontaneous polarization, wherein a Ps variation ratio, representing a value calculated by dividing the spontaneous polarization value at 70°C by the spontaneous polarization value at 25°C, is 0.60 or more, and wherein the sum total of the content (wt.%) of compounds having three or more cyclic structures is greater than the sum total of the content (wt.%) of compounds having two or fewer cyclic structures. The present invention also provides a liquid crystal display element having the liquid crystal composition sealed therein.SELECTED DRAWING: Figure 8(b)

According to the semiconductor device and the power equipment provided by the invention, the 3C-SiC current-carrying layer is epitaxially grown on the carbon surface (000-1) of the 4H-SiC channel layer, due to spontaneous polarization of the 4H-SiC channel layer, 2DEG can be induced at the interface of the 3C-SiC current-carrying layer and the 4H-SiC channel layer, and very high 2DEG density can be realized. Theoretical calculation shows that the 2DEG surface density at the interface can reach 1.28 * 10 < 13 > / cm < 2 >. Based on the physical property, a power device structure using 2DEG as a control channel is designed, a 2DEG channel region formed based on a 3C-SiC and 4H-SiC heterogeneous interface and a schottky gate electrode on the 3C-SiC surface are realized, and a depletion type unipolar power device based on electron conduction is realized. The specific on-resistance of the device is effectively reduced through the high mobility of 2DEG formed by using a 3C-SiC and 4H-SiC heterogeneous interface.

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 present invention provides a semiconductor laser device provided with a quantum-confined Stark modulation layer, which sequentially includes a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper confinement layer from bottom to top; quantum-confined Stark modulation layers are provided between the active layer and the upper waveguide layer and between the active layer and the lower waveguide layer; the quantum-confined Stark modulation layer utilizes the current-induced ferroelectric phase transition polarization effect to cause magnetostriction and ferrovalley coupling effects to regulate the strain field and polarization direction reversal under current injection conditions in the laser, modulate the piezoelectric polarization and spontaneous polarization fields of the laser, reduce the quantum-confined Stark effect, lower the valence band offset of the laser device, improve the uniformity of hole injection and laser gain uniformity, increase the overlap probability of the electron-hole wave functions in the active layer of the laser, enhance the stimulated emission of the laser device, reduce the excitation threshold of the laser device, enhance the confinement factor, and improve the peak gain of the laser device.

The utility model belongs to the technical field of LED epitaxial structures, and particularly discloses a wavelength-adjustable LED epitaxial structure, which comprises a patterned substrate, a buffer layer grown on the patterned substrate, a 3D + GR layer grown on the buffer layer, an N layer grown on the GR layer, and a polarization improvement layer grown between the GR layer and the N layer or between the buffer layer and the 3D layer. And the polarization improvement layer sequentially comprises an AlN1 layer, a ferroelectric material layer and an AlN2 layer. According to the utility model, a ferroelectric material layer (BaTiO, PbZrTiO3 and the like) is inserted into an N-type semiconductor, and spontaneous polarization can be generated under the action of an external electric field or stress by utilizing an important characteristic, namely polarization reversibility, of a ferroelectric material. When the ferroelectric material is plated below the N layer (electronic conducting layer), the polarization direction of the ferroelectric material can be regulated and controlled through an external electric field or stress. By adjusting the polarization direction and intensity, the fine adjustment of PN junction energy level distribution can be realized, so that the wavelength can be indirectly and quickly adjusted.

The utility model relates to a semiconductor laser element with a gradient polarization layer, which sequentially comprises a substrate, a lower coating layer, a lower wave layer, an active layer, an upper waveguide layer, an electron blocking layer and an upper coating layer from bottom to top, and is characterized in that the gradient polarization layer is arranged between the substrate and the lower coating layer. The piezoelectric polarization coefficient distribution, the spontaneous polarization coefficient distribution, the Philips ionization degree distribution, the elastic coefficient distribution, the covalent bond energy distribution, the polarization optical phonon energy distribution, the transverse sound velocity distribution, the saturated electron drift rate distribution and the like of the gradient polarization layer have special curve distribution; therefore, the semiconductor laser element has the advantages of reducing the polarization effect, reducing the hole migration barrier, reducing the electron leakage and the like.

The invention discloses a room-temperature ferroelectric material with an extremely low coercive field, a large spontaneous polarization value and a high Curie temperature and a preparation method and application thereof, the room-temperature ferroelectric material is a zero-dimensional organic-inorganic hybrid perovskite crystal material, has the following chemical formula (C2H8N) 4PbBr6, has the spontaneous polarization value of 2.3 [mu] C / cm < 2 > and the coercive field of 0.11 kV / cm, and has the Curie temperature of greater than 400 K, and the room-temperature ferroelectric material is a ferroelectric material with an extremely low coercive field, a large spontaneous polarization value and a high Curie temperature. Wide application prospects are realized in low-loss nonvolatile memories, sensors, capacitors, optical modulators, electromagnetic nondestructive testing and battery technologies.

The invention relates to the technical field of accelerators, and particularly discloses a pyroelectric electrostatic analyzer which comprises a vacuum cavity, a first pyroelectric crystal, a second pyroelectric crystal and a temperature controller. The first pyroelectric crystal and the second pyroelectric crystal are arranged in the vacuum cavity; a gap is formed between the first pyroelectric crystal and the second pyroelectric crystal to form a channel; the spontaneous polarization vectors of the first pyroelectric crystal and the second pyroelectric crystal are parallel to each other, and the directions of the spontaneous polarization vectors are consistent; the temperature controller is used for controlling the temperature of the first pyroelectric crystal and the second pyroelectric crystal, so that the polarity of a ferroelectric domain in the pyroelectric crystal with temperature change is changed to generate pyroelectric high voltage, and electric field force is provided for charged particles entering the channel, so that the charged particles meeting the condition can pass through the channel; according to the pyroelectric electrostatic analyzer, a large-size high-voltage power supply and numerous complex high-voltage components are removed, and the pyroelectric electrostatic analyzer has great advantages in the aspects of cost, size and use safety.

To provide a resonant tunneling diode and a terahertz oscillator capable of further performance improvement. The resonant tunneling diode includes: a multi-quantum well structure that is composed of a group-III nitride semiconductor; a first electrode that is connected to one of sides of the multi-quantum well structure; and a second electrode that is connected to the other side of the multi-quantum well structure. The multi-quantum well structure includes a first barrier layer, a first quantum well layer, a second barrier layer, a second quantum well layer, and a third barrier layer, which are arranged in order from the first electrode toward the second electrode. The first barrier layer, the second barrier layer, and the third barrier layer have a thickness through which a carrier can pass by a tunneling effect. The first quantum well layer and the second quantum well layer each have a potential gradient by spontaneous polarization or a sum of spontaneous polarization and piezoelectric polarization, and have mutually different thicknesses. The first quantum well layer and the second quantum well layer have compositions with different magnitudes of potential energy.

The embodiments of the present invention provide a method for improving the performance of optical devices, semiconductor optical devices and electronic equipment, and relate to the field of semiconductor optoelectronic technology. The present invention determines the spontaneous polarization intensity of the first compound, the bending parameter of the second compound and the piezoelectric polarization intensity of the material surface where the quantum well is located based on the quantum well's own parameters by constructing a correspondence between the external electric field intensity of the quantum well and the total polarization intensity of the material surface where the quantum well is located. Then, the total spontaneous polarization intensity of the material surface where the quantum well is located is determined based on the piezoelectric polarization intensity and the total polarization intensity. Finally, the material components of the quantum well are determined based on the total spontaneous polarization intensity, the spontaneous polarization intensity of the first compound and the bending parameter of the second compound, so that the polarization electrostatic field intensity of the quantum well is opposite in direction to the external electric field intensity and has the same value. The present invention has the advantage of improving the quantum efficiency and luminous efficiency of AlGaN-based semiconductor ultraviolet devices.

The invention provides a pyroelectric effect enhanced gallium oxide infrared detector and a preparation method thereof. The pyroelectric effect enhanced gallium oxide infrared detector sequentially comprises a substrate, a first metal electrode layer, a gallium oxide thin film and a second metal electrode layer from bottom to top, wherein the gallium oxide thin film is in an epsilon crystal phase, and the crystal phase is 1t; 001gt, 001gt; the crystal orientation is a spontaneous polarization direction; the first metal electrode layer and the gallium oxide thin film are arranged on the substrate; 001gt, 001gt; the crystal face forms ohmic contact; the second metal electrode layer is connected with the 1t of the gallium oxide thin film; 00gt to 1gt; and the crystal face forms Schottky contact. When the temperature of the device changes due to the influence of infrared radiation, the intrinsic pyroelectric effect resulting from the change of the spontaneous polarization intensity of gallium oxide and the junction type pyroelectric effect resulting from the temperature sensitivity of a Schottky junction space charge region are superposed, pyroelectric currents in the same direction are generated in an external circuit, signal superposition is realized, and the temperature sensitivity of the device is improved. Therefore, the overall pyroelectric response of the device is obviously improved; and the pyroelectric response of the epsilon-phase gallium oxide film in infrared detection application is improved.

The application provides a manufacturing method of a low-ohmic contact gallium oxide power transistor and a device. 3 The UID layer is then grown on the Fe-doped beta-Ga2O3 substrate by using an epitaxial device, a lightly-doped channel layer is then grown on the UID layer, and then a Si-doped GaN layer is grown by using the epitaxial device; since the spontaneous polarization effect of GaN and the doping are relatively easy, a heavily-doped GaN layer can be easily obtained, the GaN layer is annealed in an oxygen atmosphere at high temperature to form a heavily-doped Ga2O3 cap layer, so that the lattice mismatch between the two is reduced, and the cap layer serves as an ohmic contact layer, then a Ti / Au metal stack is deposited on the cap layer to form a good ohmic contact, so that the on-resistance of the device is reduced, and then the gate is manufactured and electrodes are led out to form the low-ohmic contact gallium oxide power transistor.

To provide an actuator that can suppress a decrease in the increment of the displacement of a diaphragm even when an increased voltage is applied between a first electrode and a second electrode.SOLUTION: An actuator includes a vibration plate, a first electrode provided above the vibration plate, a piezoelectric layer provided above the first electrode and including a complex oxide having a perovskite structure, and a second electrode provided above the piezoelectric layer, and the remanent polarization of the piezoelectric layer is 0.535 times or less of a spontaneous polarization of the piezoelectric layer.SELECTED DRAWING: Figure 2

The application discloses a screening method and device of piezoelectric anisotropic perovskite material, and high-throughput calculation and screening are performed on tetragonal phase ABO3 perovskite oxide material through first principle calculation, the correlation between piezoelectricity and lattice tetragonality, polarization displacement, spontaneous polarization and elastic constant is pointed out, and the method can be used for screening and guiding design of high-performance piezoelectric material. The application gives a three-dimensional representation of piezoelectric coefficient, re-evaluates the piezoelectric coefficient ratio |d 33 / d 31 | which is widely used at present, and points out the deficiency in representing piezoelectric anisotropy, and can be extended to anisotropy of other piezoelectric materials.

The application relates to the technical field of LEDs, in particular to a GaN-based epitaxial structure growth method for improving anti-static capability, which comprises the following steps: S3: sequentially growing a 10-30 nm Si-doped N-AlGaN layer and a 5-15 nm GaN layer; when the Si-doped N-AlGaN layer is grown, the reaction cavity temperature is set to 900-1200 DEG C, and the pressure is 100 Torr-300 Torr, wherein the Si doping concentration is 10 18 ‑10 19 atom / cm 3 ; when the GaN layer is grown, the reaction cavity temperature is set to 900-1200 DEG C, and the pressure is 100 Torr-300 Torr; S4: the step S3 is repeated for 8-10 times; the application has the beneficial effect that the structure formed by the steps S3 and S4 is a stress release layer, the stress release layer forms an n-type AlGaN / GaN alternating superlattice layer by using high-energy Al, and the short-period superlattice technology route can effectively improve the carrier transport performance, so that when a heterojunction is formed between GaN and AlGaN, spontaneous polarization is generated, and the anti-static performance of the LED epitaxial structure is greatly improved.

This invention discloses a method for establishing a phase-field model of a polycrystalline phase relaxor ferroelectric, the method comprising the following steps: 1. Determining the free energy of the polycrystalline phase relaxor ferroelectric; 2. Determining the order parameter of the polycrystalline phase relaxor ferroelectric as spontaneous polarization. P i 3. Represent free energy as spontaneous polarization P i The invention employs several methods: 1) introducing ferroelectric-ferroelectric phase boundaries and random local electric fields; 2) solving the Ginzburg-Landau partial differential equations to obtain the spatial evolution of spontaneous polarization, thereby determining the domain structure of polycrystalline relaxed ferroelectrics and ultimately establishing a phase-field model for polycrystalline relaxed ferroelectrics. Based on a model ferroelectric system, this invention, by considering ferroelectric-ferroelectric phase boundaries and random local electric fields, reproduces the unique domain structure characteristics of polycrystalline relaxed ferroelectrics with the coexistence of multiple nanometer-sized ferroelectric phases, establishes a phase-field model for polycrystalline relaxed ferroelectrics, and improves the theoretical model of polycrystalline relaxed ferroelectrics, which is beneficial for guiding the design of novel high-performance ferroelectric materials.

Provided is a semiconductor light-emitting element. The semiconductor light-emitting element comprises: a substrate, an electron-type semiconductor, quantum wells, an electron-blocking layer and a hole-type semiconductor, which are sequentially stacked, wherein respective optical parameters of a first quantum well, a second quantum well and a third quantum well among the quantum wells are distributed in a gradient manner in at least one direction; each quantum well comprises a periodic structure composed of a well layer and a barrier layer; a thermal expansion coefficient of the well layer is less than or equal to a thermal expansion coefficient of the barrier layer; an elastic coefficient of the well layer is less than or equal to an elastic coefficient of the barrier layer; a lattice constant of the well layer is greater than or equal to a lattice constant of the barrier layer; and a spontaneous polarization coefficient of the well layer is less than or equal to a spontaneous polarization coefficient of the barrier layer. By designing optical parameters of quantum wells to be distributed in a gradient manner in at least one direction, the reflection and refraction of light can be improved, and the light emission angle of emergent light is increased, thereby improving light extraction efficiency. Moreover, by designing parameter differences of the quantum wells, the thermal mismatch and lattice mismatch of the quantum wells can be reduced.