62 results about "Piezoelectric polarization" patented technology

The invention provides a surface-emitting gallium nitride VCSEL laser chip and an epitaxial defect suppression preparation method thereof, and relates to the technical field of laser chips, the surface-emitting gallium nitride VCSEL laser chip comprises a substrate, a low-temperature nucleating layer, a high-temperature recovery layer, a stress regulation type nano mask composite defect blocking layer, an n-type nitride DBR reflector, an active region, a polarization enhanced tunnel junction and the like, the defect blocking layer adopts an in-situ silicon nitride nano-porous mask layer to be matched with an aluminum gallium nitride / gallium nitride stress compensation superlattice layer, through pulse type lateral epitaxial overgrowth annihilation penetrating dislocation, and the n-type nitride DBR reflector adopts an AlInN / GaN lattice matching material system to be combined with a hydrogen etching interruption modification technology, so that thick film growth with zero cracks and high reflectivity is realized; a polarization enhanced tunneling junction is used at the top to replace ITO, and the hole tunneling probability is enhanced by piezoelectric polarization in InGaN, so that efficient current injection with low working voltage and no absorption loss is realized, the dislocation density and the device voltage are remarkably reduced, and the yield of an epitaxial wafer and the photoelectric conversion efficiency are improved.

The invention discloses an AlGaInP red light LED chip structure with a polarization-induced tunnel junction and a preparation method thereof. The chip structure sequentially comprises a GaAs substrate, an n-type GaAs buffer layer, an n-type etching barrier layer, an n-type GaAs ohmic contact layer, an n-type limiting layer, a non-doped InGaP / quantum well structure, a p-type spacer layer, a p-type AlGaInP polarization-induced doping layer, an insertion layer and an n-type ohmic contact layer from bottom to top. Wherein the p-type AlGaInP polarization induction doping layer introduces a piezoelectric polarization electric field through an Al component gradual change design, high-density two-dimensional hole gas is formed through induction, and the high-Al component insertion layer and the n-type ohmic contact layer form a tunnel junction; according to the invention, the problems of low p-type doping efficiency and high resistivity of the AlGaInP material with high Al component are fundamentally solved, the epitaxial structure and the chip process are simplified, the series resistance of the chip is reduced, the luminous efficiency is improved, the yield is improved, and the method has remarkable technical and commercial values.

The invention provides a semiconductor laser element with a spin polarization sub-layer. The semiconductor laser element comprises a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper limiting layer which are sequentially arranged from bottom to top. According to the semiconductor laser element, the spin polarization sub-layers of a multi-layer structure are arranged between the upper limiting layer and the upper waveguide layer in the semiconductor laser element, and the electron mobility distribution characteristic and the piezoelectric polarization coefficient distribution characteristic of each spin polarization sub-layer are limited. Specific electron mobility distribution and piezoelectric polarization coefficient distribution of the spin polarization sub-layer form an asymmetric discrete potential barrier, lattice distortion structure polarization is modulated, charge dipole momentum net accumulation is increased, the piezoelectric polarization effect of the active layer is regulated and controlled, the quantum restriction effect is suppressed, energy band inclination of the active layer is reduced, and hole injection band order is reduced. The overlapping probability of the electron hole wave function is improved, and the internal quantum efficiency is improved.

The invention belongs to the technical field of semiconductor photoelectrons, and provides a gallium nitride-based red light emitting diode and a preparation method thereof. The epitaxial structure of the gallium nitride-based red light emitting diode sequentially comprises a sapphire substrate, a low-temperature GaN nucleating layer, a high-temperature non-doped GaN buffer layer, an n-type GaN layer, a composite stress release layer, an In < x > Ga < 1-x > N / In < y > Ga < 1-y > N multi-quantum well light emitting layer, a low-temperature p-type protective layer, a p-Aly < 1 > Ga < 1-y > N electron barrier layer, a high-temperature p-type GaN layer and a p-type InGaN contact layer from bottom to top. The V-shaped layer and the Inx1Ga1-x1N / GaN superlattice structure layer are introduced between the n-type GaN layer and the In < x > Ga < 1-x > N / In < y > Ga < 1-y > N multi-quantum well light-emitting layer to perform stress release, so that the influence of a piezoelectric polarization field on the spatial distribution of an electron hole wave function is reduced, and the radiation recombination light-emitting efficiency of an active region is improved.

The invention discloses a p-type GaN field effect transistor based on multichannel two-dimensional hole gas and a preparation method of the p-type GaN field effect transistor. The field effect transistor comprises a substrate, a buffer layer and a channel layer, wherein the buffer layer and the channel layer are sequentially arranged on one side of the substrate in a stacked mode. The plurality of channel sub-layers comprise a p-GaN layer, a p-Inx1Ga (1-x1N) layer, a p-Inx2Ga (1-x2N) layer,..., a p-InxnGa (1-xnN) layer which are sequentially stacked on one side, far away from the substrate, of the buffer layer, and the thickness of the channel sub-layers is 10-500 nm; wherein x1, x2,..., xn are component proportions of the indium element in each channel sub-layer, and n is a positive integer greater than or equal to 2; and x < 1lt > is greater than or equal to 0.05. X2lt; x2lt; ... xn < = 1. According to the field effect transistor, through controlling the indium component gradient of each channel sub-layer, remarkable spontaneous polarization charges and piezoelectric polarization charges are generated at the heterojunction interface, so that high-density two-dimensional hole gas is induced to be generated, and the current density of the field effect transistor is improved.

This invention discloses an interlayer confined piezoelectric composite film of graphene oxide, its electric field-driven preparation method, and its application. The preparation method includes: preparing a graphene oxide dispersion using the Hummers method and filtering it to form a graphene oxide film; placing the graphene oxide film in an electric-driven device, introducing different precursor solutions on both sides of the film, and driving the precursor components to migrate into the interlayer confined space of the graphene oxide under the action of an applied electric field; under the synergistic effect of electric field driving and interlayer confinement, the precursors entering the interlayer react and crystallize in situ to form a piezoelectric functional phase. The prepared composite film can generate piezoelectric polarization under mechanical stimulation conditions and can be used for ion selective adsorption / separation, especially suitable for the selective adsorption / separation of uranium and vanadium ions in high-salt water systems. This invention achieves a synergistic improvement in interfacial charge regulation and ion selectivity regulation by constructing a piezoelectric functional phase in situ within the interlayer confined space of graphene oxide.

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 invention discloses a preparation method of a Z-type heterojunction composite catalyst capable of inducing photon-generated carrier transfer by piezoelectric polarization, multiferroic BiFeO3 and favorable visible light response CdS nanosheets are utilized to construct a Z-type heterostructure with an active electron transmission characteristic, so that the light absorption capacity and an energy band structure are optimized; due to the combination of the BiFeO3 particles and the ultrathin CdS, not only is the agglomeration of the CdS nanosheets inhibited, but also the specific surface area of a reaction system is favorably increased. According to the invention, multiferroic BiFeO3 and a favorable visible light response CdS nanosheet are utilized to construct a Z-type heterostructure with an active electron transmission characteristic. The construction of the active electron transmission system promotes the separation and transmission of current carriers, and provides a new strategy for improving the photocatalytic hydrogen production reaction activity.

The invention discloses defective NH2-Ni-MOF as well as a preparation method and application thereof, and belongs to the field of piezoelectric electro-catalytic hydrogen production. The method comprises the following steps: firstly, synthesizing a precursor NH2-Ni-MOF through a solvothermal method, putting the NH2-Ni-MOF material and a grinding ball into a ball mill together by a seller, and grinding to obtain defective NH2-Ni-MOF; and the grinding ball is a mixture of five large balls with the diameter of 10 mm and fifteen small balls with the diameter of 5 mm. The D3-NH2-Ni-MOF prepared by mixing and grinding the grinding balls in a specific proportion realizes the synergistic effect of high-energy impact and high-frequency grinding, and successfully introduces lattice defects with the maximum concentration. The defect structure can effectively promote separation and migration of photon-generated carriers and enhance the piezoelectric polarization effect of the material under the ultrasonic action, so that the piezoelectric synergistic photocatalytic performance is remarkably improved. Under the combined action of sun illumination and ultrasonic vibration, the D3-NH2-Ni-MOF catalyst is dispersed in a methanol aqueous solution, and efficient and stable water decomposition hydrogen production activity can be achieved.

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 application provides a gallium nitride-based semiconductor blue laser, which comprises, from bottom to top, a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper limiting layer, wherein a topological interface state layer is arranged between the upper waveguide layer and the upper limiting layer, and the topological interface state layer has breakdown field strength distribution characteristics and electron affinity energy distribution characteristics. Through the specific breakdown field strength distribution and electron affinity energy distribution of the topological interface state layer, a new body boundary energy band is formed, a strong spin center is formed at the interface, the coupling between adjacent interface states and the spin-splitting asymmetry of the electron band structure are enhanced, the spin-orbit torque effect is enhanced, the piezoelectric polarization and the thermal stress mismatch of the laser element are relieved, the valence band step is reduced, the uniformity of the valence band step is improved, the uniformity of the carrier injection into the active layer is improved, and the gain uniformity is improved.

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 relates to the technical field of electrocatalytic materials, in particular to a SnSe piezoelectric catalyst and a preparation method and application thereof. The preparation method comprises the following steps: dispersing selenium powder in deionized water, adding NaBH4 powder to obtain a selenium source precursor solution, dispersing sodium ascorbate in deionized water, adding anhydrous SnCl2 powder to obtain a tin source precursor solution, and adding the selenium source precursor solution into the tin source precursor solution to obtain a mixed solution; the pH value of the mixed solution is adjusted to 2-7, then the mixed solution is subjected to a hydrothermal reaction, and the SnSe piezoelectric catalyst is obtained through filtering and drying in sequence. In a one-step hydrothermal system, through coordinated regulation and control of pH and hydrothermal temperature, coordinated regulation of the SnSe material in the aspects of nucleation, growth, valence evolution and defect structure is realized, a novel piezoelectric catalytic material with a mixed valence structure and nanorod morphology is successfully constructed, the piezoelectric polarization capability, the carrier separation efficiency and the ROS generation capability of the material are remarkably enhanced, and the preparation method is simple and easy to implement. And excellent organic pollutant degradation performance is obtained.

The invention discloses a modified MoSe2 piezoelectric catalyst and a preparation method and application thereof.The catalyst is characterized in that Mo < 2 + > in MoSe2 nanosheets is partially replaced by Fe < 2 + >, a structure in which the MoSe2 nanosheets and FeSe2 nanosheets are randomly layered and stacked is formed, and the structure is in a nanoflower shape; the preparation method comprises the following steps: uniformly dispersing MoSe2 powder in water, then adding ferric salt and hydrazine hydrate, fully mixing, and then carrying out hydrothermal reaction to obtain the modified MoSe2 piezoelectric catalyst. FeSe2 is introduced into MoSe2, so that the catalytic activity of MoSe2 is improved, and the nanoflower-shaped structure not only is beneficial to induction of piezoelectric polarization, but also can expose more edge active sites, so that the piezoelectric catalytic activation efficiency of peroxydisulfate is improved.

The application relates to the technical field of piezoelectric photocatalytic materials, in particular to a Na,Sm-CaBi2Nb2O9 / O V -BiOBr piezoelectric photocatalytic material, a preparation method and application thereof. The method comprises the following steps: firstly, preparing Na,Sm-CaBi2Nb2O9 by a molten salt method and dispersing the Na,Sm-CaBi2Nb2O9 in a mannitol solution; then, adding PVP and Bi(NO3)3.5H2O in sequence; and finally, adding a saturated NaBr solution drop by drop and performing hydrothermal treatment; through accurate control of a hydrothermal temperature and a reaction time, a Na,Sm-CaBi2Nb2O9 / O 2+ -BiOBr S-type heterojunction piezoelectric photocatalyst which is rich in oxygen vacancies and has a shared (Bi2O2) V interface is finally obtained. The catalyst realizes the transfer of carrier recombination centers through the electron capture effect of oxygen vacancies, optimizes the local dipole state distribution and the interface non-centrosymmetry, effectively controls the carrier recombination path, significantly enhances the piezoelectric polarization strength, successfully inhibits the self-reduction behavior of the interface Bi 3+ , and greatly improves the piezoelectric photocatalytic activity. The application effectively solves the problems of high crystal face mismatch degree, insufficient stability and low piezoelectric photocatalytic activity of traditional bismuth-based heterojunction materials by constructing structure-matched heterojunction materials, and opens up a new way for the application of layered bismuth-based perovskite materials in the field of piezoelectric photocatalytic water splitting.

The embodiment of the invention provides a core-shell type catalyst as well as a preparation method and application thereof, and the core-shell type catalyst comprises an inner core comprising I-doped BiOI; and the film layer comprises BiOI and is arranged on the surface of the inner core. The heterojunction of a core-shell structure formed by BiOI-coated I-doped BiOI not only can efficiently remove algae under illumination, but also can promote piezoelectric activation of persulfate without illumination, so that all-weather algae removal is realized; moreover, due to closer interface contact and larger contact area of the heterojunction in the core-shell structure, not only can the transfer and separation of photogenerated charges be improved, but also the stability can be ensured, tight protection is provided for active sites to resist severe environmental conditions, and the inactivation speed of the catalyst is effectively slowed down; meanwhile, due to the fact that BiOI has good piezoelectric performance, a heterojunction interface built-in electric field and a piezoelectric polarization electric field generated by the core-shell type catalyst can remarkably reduce carrier interface recombination so as to enhance charge separation efficiency, and photocatalytic reaction activity is remarkably improved.

The application discloses a kind of ultraviolet micro light emitting diode based on piezoelectro-optoelectronics and preparation method, the ultraviolet micro light emitting diode includes: substrate layer structure, including: AlN layer, formed on substrate;AlGaN superlattice layer is formed on AlN layer;And N type AlGaN layer, formed on AlGaN superlattice layer;And a plurality of interval arranged microwire structures, each microwire structure includes: AlGaN multi-quantum well microwire layer, formed on N type AlGaN layer;P type AlGaN microwire layer, formed on AlGaN multi-quantum well microwire layer;And P type GaN microwire layer, formed on P type AlGaN microwire layer;Wherein, by applying stress, so that substrate protrudes to the direction of a plurality of interval arranged microwire structures and forms arc structure, in turn, so that layer structure and microwire structure produce bending strain, introduce piezoelectric polarization field.The application as well as the ultraviolet light source micro light emitting diode of piezoelectro-optoelectronics modulation improves the overall light emitting characteristic of ultraviolet micro size light emitting diode.

This invention discloses a light-emitting diode (LED) epitaxial wafer and its fabrication method. The LED epitaxial wafer includes a substrate and, sequentially stacked on the substrate, a buffer layer, an undoped GaN layer, an N-type GaN layer, a composite insertion layer, a multiple quantum well layer, an electron blocking layer, and a P-type GaN layer. The composite insertion layer includes, sequentially stacked on the N-type GaN layer, a BN layer, a BInN layer, and a weakly P-type nitride layer. The LED fabricated by this invention can improve the crystal quality of the multiple quantum well layer and alleviate the piezoelectric polarization of the multiple quantum well layer, thereby improving the luminous efficiency of the LED epitaxial wafer.

This invention proposes a semiconductor laser device with a spin-polarized sublayer, comprising, from bottom to top, a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper confinement layer. This invention establishes a multi-layered spin-polarized sublayer structure between the upper confinement layer and the upper waveguide layer in the semiconductor laser device, and defines the electron mobility distribution and piezoelectric polarization coefficient distribution characteristics of each spin-polarized sublayer. The specific electron mobility distribution and piezoelectric polarization coefficient distribution of the spin-polarized sublayer form an asymmetric discrete potential barrier, modulating the polarization of the lattice distortion structure, increasing the net accumulation of charge dipole momentum, controlling the piezoelectric polarization effect of the active layer, suppressing the quantum confinement Stark effect, reducing the band tilt of the active layer, reducing the hole injection band order, increasing the overlap probability of electron-hole wave functions, and improving the internal quantum efficiency.

The present application relates to a kind of barrier layer structures with asymmetric insertion layer, including barrier layer, barrier layer is used to form source, gate and drain, insertion layer is embedded in barrier layer inside, insertion layer forms first insertion section between source to gate, forms second insertion section between gate to drain, the thickness of first insertion section is less than the thickness of second insertion section;A kind of power device, including barrier layer structure with asymmetric insertion layer.In the present application, the spontaneous polarization, piezoelectric polarization effect of asymmetric insertion layer is much stronger than barrier layer, the insertion layer of gate, drain side is thicker, resulting in local barrier being higher, electric field peak spontaneously migrates from gate edge to drain side and gradually reduces, the distribution of peak electric field is optimized, and the overall performance of device is improved;The breakdown voltage of the present application is effectively improved, peak electric field is significantly reduced, Ron is not degraded basically, current collapse effect is significantly inhibited, meet the design requirements of high-voltage GaN HEMT.

The present invention relates to a volume acoustic component (10) comprising a first electrode (120) and a second electrode (122), and a piezoelectric element (100) comprising a first piezoelectric layer (101) and a second piezoelectric layer (103), which are arranged one above the other and between the first electrode (120) and the second electrode (122). The piezoelectric element (100) comprises at least one intermediate layer (102) arranged between the first piezoelectric layer (101) and the second piezoelectric layer (103). The piezoelectric layers (101, 102, 103) of the piezoelectric element (100) alternately have a negative or positive piezoelectric polarization. The piezoelectric layers (102) with negative polarization have a first alloying degree and the piezoelectric layers (101, 103) with positive polarization have a second alloying degree which differs from the first alloying degree.

The invention provides a tumor marker dual detection device and a preparation method and application thereof.The tumor marker dual detection device comprises a first supporting layer, a substrate, a second supporting layer, a channel layer, a barrier layer, an insulating layer, a first through hole, a nano hole, a groove and a second through hole which are arranged from bottom to top, a modification layer is arranged in the groove and used for modifying reactants, and the first through hole and the second through hole are formed in the substrate. And a metal layer is arranged in the second through hole. Piezoelectric polarization and self-polarization effects in a heterostructure are formed by the channel layer and the barrier layer, transverse two-dimensional electron gas is generated, an induced electric field is generated by specific recognition of reactants and tumor markers of the modification layer, local two-dimensional electron gas concentration is affected, and specific change of transverse current is caused. In addition, specific binding of the reactants and tumor markers within the nanopore results in persistent volume occupancy, resulting in a longitudinal current reduction. And by combining double criteria of transverse current and longitudinal current change, early screening and detection of cancers are realized, and the application value is high.

The invention provides a PVDF (Polyvinylidene Fluoride) nanofiltration membrane based on piezoelectric response and double charge layer collaborative construction as well as a preparation method and application thereof, and relates to the technical field of nanofiltration membranes. The method comprises the following steps: (1) reacting PVDF powder with an organic alkali solution to obtain modified PVDF; (2) carrying out ultrasonic dispersion on the modified PVDF, a pore-foaming agent, a plasticizer and a polar solvent to obtain a membrane casting solution; (3) forming the membrane casting solution into a PVDF base membrane by adopting a non-solvent phase inversion method; and (4) sequentially soaking the base membrane in a hydrophilic monomer solution and an oil-phase monomer solution, and carrying out piezoelectric polarization or thermally induced polarization treatment on the membrane body to obtain the double-charge PVDF nanofiltration membrane. The double-charge nanofiltration membrane prepared by the invention has the properties of high flux, low driving pressure, pollution resistance and the like, is suitable for the fields of high-concentration saline water treatment, brackish water desalination, antibiotic removal and the like, and has a wide application prospect.

The present invention discloses a method for measuring the flexoelectric coefficient of a separable piezoelectric two-dimensional material, comprising: testing N samples with different distance values ​​respectively, where the distance value is the distance from the thickness bisector of the two-dimensional material to the thickness bisector of the sample along the thickness direction of the base plate in one sample; since the distance value affects the strain state and piezoelectric polarization of the two-dimensional material, the flexoelectric contribution and the piezoelectric contribution are separated according to the total polarization difference of multiple samples, thereby accurately measuring the flexoelectric coefficient of the two-dimensional material.

The present invention provides a method for preparing a PVDF β - crystal strong piezoelectric ultrafiltration membrane, which comprises the following steps: adding an organic base to PVDF powder to obtain modified PVDF, adding the modified PVDF, carboxylated graphene oxide powder, catalyst, plasticizer, and pore - forming agent into a DMAC solution respectively, ultrasonically mixing them evenly, then performing phase inversion, and finally successively undergoing activation and strong - pressure polarization to obtain a PVDF β - crystal piezoelectric ultrafiltration membrane. The preparation method of the present invention can improve the uniformity, stability, and hydrophilicity of the membrane, greatly enhance the anti - fouling ability, and effectively combine the low - resistance water passage and the greatly improved desalination ability of water molecules. The obtained PVDF β - crystal piezoelectric ultrafiltration membrane has the advantages of low energy consumption, high - efficiency removal of humic acid under high concentration and low pollution conditions, and high desalination efficiency.

The application provides a surface-emitting gallium nitride VCSEL laser chip and an epitaxial defect suppression preparation method thereof, relates to the technical field of laser chips, and comprises a substrate, a low-temperature nucleation layer, a high-temperature recovery layer, a stress regulation type nano mask composite defect blocking layer, an n-type nitride DBR reflector, an active region and a polarization enhancement type tunnel junction and the like. The defect blocking layer adopts an in-situ silicon nitride nano porous mask layer in cooperation with an aluminum gallium nitride / gallium nitride stress compensation superlattice layer, penetrative dislocations are annihilated through pulse type lateral epitaxial overgrowth, the n-type nitride DBR reflector adopts an AlInN / GaN lattice matching material system combined with a hydrogen etching interruption modification technology, zero crack and high reflectivity thick film growth are realized, the top uses a polarization enhancement type tunnel junction to replace ITO, the hole tunneling probability is enhanced by using the piezoelectric polarization in InGaN, low working voltage, absorption loss-free high-efficiency current injection are realized, the dislocation density and the device voltage are significantly reduced, and the epitaxial wafer yield and the photoelectric conversion efficiency are improved.

The application discloses a gallium nitride-based bipolar junction transistor and a preparation method thereof, and relates to the technical field of semiconductors; a two-dimensional electron gas layer is generated on the side close to a GaN channel layer at the interface between an AlGaN barrier layer and the GaN channel layer through piezoelectric polarization and spontaneous polarization effects; a groove for depositing and growing a P-type semiconductor layer is formed by etching from the middle of the top surface of an insulating layer to the bottom surface of the GaN channel layer; two grooves for depositing and growing an emitter and a collector are formed by etching from the top surface of an emitter insulating layer away from the end of the P-type semiconductor layer and the top surface of a collector insulating layer away from the end of the P-type semiconductor layer to the top surface of an emitter AlGaN barrier layer; a base is deposited and grown on the top surface of the P-type semiconductor layer; and the application can greatly improve the mobility of electrons in the emitter and the collector, and improve the large-current output capability, power density and high-frequency application capability of the device.

The present invention discloses a piezoelectric-photocatalytic water decomposition hydrogen production Cu-P / CdS catalyst with a distorted [CdS4] structure and its preparation method and application, belonging to the field of catalyst and hydrogen energy technology. The present invention provides a water decomposition hydrogen production Cu-P / CdS catalyst, the preparation method of which includes: dispersing a cadmium source and a sulfur source in water, heating to 130-150°C for reaction, and preparing CdS; CdS is dispersed in a copper source aqueous solution and dried to obtain a powder; the powder is mixed with a phosphorus source and calcined to obtain a piezoelectric-photocatalyst. The present invention suppresses electron-hole recombination by embedding an electron-withdrawing group Cu-P on the surface of non-centrosymmetric CdS, forming a [0001] direction piezoelectric polarization, causing [CdS4] to be distorted and forming an electronic dipole moment, providing electron-hole migration and separation driving force, greatly improving hydrogen production activity and stability, and without the need for loading precious metals, reducing production costs.

The invention provides a semiconductor laser element provided with a piezoelectric polarization regulation and control layer, which comprises a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper limiting layer which are sequentially arranged from bottom to top, and is characterized in that the piezoelectric polarization regulation and control layer is arranged between the lower limiting layer and the lower waveguide layer; the piezoelectric polarization regulation and control layer has a deformation potential distribution characteristic and a piezoelectric polarization coefficient distribution characteristic. According to the invention, the laser can be induced to generate piezoelectric polarization regulation and control under the action of an electric field of current injection, spontaneous polarization and piezoelectric polarization of the active layer are reconciled, the quantum confinement Stark effect is reduced, the valence band order of a laser element is reduced, the injection efficiency and transport of holes are improved, and ultrafast transport of carriers is realized. And stimulated radiation and electric lasing gain of the laser element are improved.