With the progression of photolithography processes,the present technology nodes have attained 3 nm and even 2 nm,necessitating a transition in the precision standards for displacement measurement and alignment methodo...With the progression of photolithography processes,the present technology nodes have attained 3 nm and even 2 nm,necessitating a transition in the precision standards for displacement measurement and alignment methodologies from the nanometer scale to the sub-nanometer scale.Metasurfaces,owing to their superior light field manipulation capabilities,exhibit significant promise in the domains of displacement measurement and positioning,and are anticipated to be applied in the advanced alignment systems of lithography machines.This paper primarily provides an overview of the contemporary alignment and precise displacement measurement technologies employed in photolithography stages,alongside the operational principles of metasurfaces in the context of precise displacement measurement and alignment.Furthermore,it explores the evolution of metasurface systems capable of achieving nano/sub-nano precision,and identifies the critical issues associated with sub-nanometer measurements using metasurfaces,as well as the principal obstacles encountered in their implementation within photolithography stages.The objective is to provide initial guidance for the advancement of photolithography technology.展开更多
By means of the transfer-matrix method, the effects of parameter modulation on the quafity of near-field imaging in one-dimensional photonic crystal consisting of alternately left-handed material and right-handed mate...By means of the transfer-matrix method, the effects of parameter modulation on the quafity of near-field imaging in one-dimensional photonic crystal consisting of alternately left-handed material and right-handed material are investigated. Based on analyses of the recovery rate and ph＇ase shift, the results show that the imaging quality is not obviously affected by the minor changes of layer thickness. In addition, by modulating the material parameters of the left-handed material, it is found that for both the real part and the imaginary part, the system is more sensitive to the permeability than the permittivity for the TE wave. For the TM wave, it is reverse. These properties are very useful to fabricate left-handed material photonic crystals in practice.展开更多
Single-negative materials based on photonic crystal with multiple defect layers are designed and the free modulation of defect modes is studied. The results show that the multi-defect structure can avoid the interfere...Single-negative materials based on photonic crystal with multiple defect layers are designed and the free modulation of defect modes is studied. The results show that the multi-defect structure can avoid the interference between the defect states. Therefore, the designed double defect modes in the zero effective-phase gap can be adjusted independently by changing the thickness of different defect layers. In addition, the two tunable defect modes have the omnidirectional characteristics. This multi-defect structure with above-mentioned two advantages has potential applications in modern optical devices such as tunable omnidirectional filters.展开更多
A polarizing beam splitter （PBS） and a non-polarizing beam splitter （NPBS） based on a photonic crystal （PC） directional coupler are demonstrated. The photonic crystal directional coupler consists of a hexagonal ...A polarizing beam splitter （PBS） and a non-polarizing beam splitter （NPBS） based on a photonic crystal （PC） directional coupler are demonstrated. The photonic crystal directional coupler consists of a hexagonal lattice of dielectric pillars in air and has a complete photonic band gap. The photonic band structure and the band gap map are calculated using the plane wave expansion （PWE） method. The splitting properties of the splitter are investigated numerically using the finite difference time domain （FDTD） method.展开更多
The feasibility of using metal optics or negative ε materials, with the aim of reducing the transversal extent of waveguided photonic fields to values much less than the vacuum wavelength, in order to achieve signifi...The feasibility of using metal optics or negative ε materials, with the aim of reducing the transversal extent of waveguided photonic fields to values much less than the vacuum wavelength, in order to achieve significantly higher densities of integration in integrated photonics circuits that is possible today is discussed. Relevant figures of merit are formulated to this end and used to achieve good performance of devices with today＇s materials and to define required improvements in materials characteristics in terms of decreased scattering rates in the Drude model. The general conclusion is that some metal based circuits are feasible with today＇s matals. Frequency selective metal devices will have Q values on the order of only 10-100, and significant improvements of scattering rates or lowering of the imaginary part of e have to be achieved to implement narrowband devices. A photonic ＂Moore＇s law＂ of integration densities is proposed and exemplified.展开更多
As a new layered semiconductor material,Bi_(2)SeO_(5) has shown potential in the field of ultraviolet electronic devices in recent years because of its unique crystal structure and wide band gap.In this paper,the crys...As a new layered semiconductor material,Bi_(2)SeO_(5) has shown potential in the field of ultraviolet electronic devices in recent years because of its unique crystal structure and wide band gap.In this paper,the crystal structure,electronic structure,and thermodynamic stability of Bi_(2)SeO_(5) are studied based on first-principles calculations.The ultraviolet luminescence property of BiSe defect is predicated from defect property,which provides theoretical basis for experimental design of high-performance Bi2SeO5 photoelectric devices.展开更多
FeSe is an Fe-based paramagnetic superconductor with the simplest structure.The competition between the Néel and stripe magnetic orders is believed to be one of the reasons for the absence of magnetic orders in F...FeSe is an Fe-based paramagnetic superconductor with the simplest structure.The competition between the Néel and stripe magnetic orders is believed to be one of the reasons for the absence of magnetic orders in FeSe.FeSe is recognized as a prototypical platform for competing magnetic interactions,including Néel,stripe,and staggered antiferromagnetic coupling.However,the correlations between these magnetic orders and how they change with varying environmental conditions require further study.Here,we calculated the magnetic order of monolayer FeSe in three diferent environments:pure one,with slight lattice distortion,and on SrTiO_(3) substrate,by frst principles calculations.We fnd that in the calculated dispersion relation E(q)between the spin spiral energy E and spin spiral vector q of the monolayer FeSe structure,the stripe magnetic order M(π/2,π/2)has the lowest energy,and there is a fat E(q)between the wave vector X(π/2,0)and Néel magnetic order 2X(π,0),which are the degenerate E(q)states.The ground state of M and the highest density of states around 2X may be the reason for the competition of two magnetic orders.The slight lattice distortion does not alter the magnetic properties of monolayer FeSe.When monolayer FeSe is attached to the SrTiO_(3)substrate,the degenerate E(q)is still retained;meanwhile,the energy of the 2X(π,0)state is closer to the M state,which may be one of the reasons for the increase of superconducting temperature in FeSe/SrTiO_(3).展开更多
Self-assembled monolayers(SAMs),owing to their amphiphilic nature,tend to aggregate,which impedes the formation of a dense and uniform SAM on the substrate.Additionally,the weak adsorption ability of SAMs on the indiu...Self-assembled monolayers(SAMs),owing to their amphiphilic nature,tend to aggregate,which impedes the formation of a dense and uniform SAM on the substrate.Additionally,the weak adsorption ability of SAMs on the indium tin oxide(ITO)surface and the desorption of hydroxyl(OH)from the ITO surface induced by polar solvents can lead to the formation of vacancies.Herein,a dimethylacridine-based SAM is incorporated into the perovskite precursor solution.This SAM can be extruded from the precursor solution and enriched on the bottom surface of the perovskite,filling the vacancies and in situ forming a mixed SAM with MeO-2PACz as a hole-selective layer(HSL).The in situ formed mixed SAM optimizes the energy level alignment between the HSL and the perovskite,facilitating hole extraction and alleviating the residual strain of the perovskite film.Consequently,the perovskite solar cells(PSCs),based on the mixed SAM,achieve a power conversion efficiency(PCE)of 25.69%and exhibit excellent operational stability.When this approach is applied to 1.78 eV bandgap PSC devices,it yields a PCE of 20.08%.This work presents a unique strategy for fabricating both high-quality perovskite films and superior buried interfaces,which is also applicable to wide-bandgap PSCs.展开更多
We investigate electron mesoscopic transport in a three-terminal setup with coupled quantum dots and a magnetic flux.By mapping the original transport problem into a non-Hermitian Hamiltonian form,we study the interpl...We investigate electron mesoscopic transport in a three-terminal setup with coupled quantum dots and a magnetic flux.By mapping the original transport problem into a non-Hermitian Hamiltonian form,we study the interplay between the coherent couplings between quantum dots,the magnetic flux,and the dissipation due to the tunnel coupling with the reservoirs.展开更多
We propose a near-field thermophotovoltaic system utilizing magnetic Weyl semimetals,which exhibit a distinct gyrotropic effect originating from their intrinsic axion field.Critically,we demonstrate that intentional b...We propose a near-field thermophotovoltaic system utilizing magnetic Weyl semimetals,which exhibit a distinct gyrotropic effect originating from their intrinsic axion field.Critically,we demonstrate that intentional band dislocation,achieved by layer-specific tuning of the chemical potential,significantly enhances the energyconversion efficiency.This effect arises from the formation of quasi-flat bands in momentum space,which broaden the spectral heat flux and amplify photon tunneling above the bandgap.At optimized chemical potential mismatches,the system achieves a 65%Carnot efficiency and a power density of 7×10^(4)W·m^(-2),surpassing symmetric configurations by 7%.The optimization of the Weyl semimetals thickness further demonstrates a clear tuning window where both the output power and energy-conversion efficiency are significantly improved.These results establish chemical-potential engineering toward high-efficiency near-field thermophotovoltaics for waste heat recovery and infrared energy applications.展开更多
A novel fiber Bragg grating (FBG) current sensor with temperature compensation has been proposed. The fiber Bragg grating is glued on the surface of an isosceles triangle cantilever beam,which has a step thickness alo...A novel fiber Bragg grating (FBG) current sensor with temperature compensation has been proposed. The fiber Bragg grating is glued on the surface of an isosceles triangle cantilever beam,which has a step thickness along the beam axis. Due to the electromagnetic force created by a solenoid and a permanent magnet mounted on the top of the beam,a step strain is applied on the fiber Bragg grating. The change of the electric current in the solenoid makes the spectrum of the fiber Bragg grating split. By monitoring the shift difference of the two split center wavelengths,which is related to the electric current in the solenoid,a current sensor with temperature compensation is obtained. The test range of 0-400 mA is achieved. The experimental results also show that the relationship between the shift difference of the two split center wavelengths of the FBG and the electric current has a linearity of 0.9937,and the sensitivity is about 2.64 nm/A; the test results are independent of the temperature,so the cross sensitive problem is solved.展开更多
Wet thermal annealing effects on the properties of TaN/HfO2/Ge metal-oxide-semiconductor （MOS） structures with and without a GeO2 passivation layer are investigated. The physical and the electrical properties are ch...Wet thermal annealing effects on the properties of TaN/HfO2/Ge metal-oxide-semiconductor （MOS） structures with and without a GeO2 passivation layer are investigated. The physical and the electrical properties are characterized by X-ray photoemission spectroscopy, high-resolution transmission electron microscopy, capacitance-voltage （C-V） and current-voltage characteristics. It is demonstrated that wet thermal annealing at relatively higher temperature such as 550 ℃ can lead to Ge incorporation in HfO2 and the partial crystallization of HfO2, which should be responsible for the serious degradation of the electrical characteristics of the TaN/HfO2/Ge MOS capacitors. However, wet thermal annealing at 400 ℃ can decrease the GeOx interlayer thickness at the HfO2/Ge interface, resulting in a significant reduction of the interface states and a smaller effective oxide thickness, along with the introduction of a positive charge in the dielectrics due to the hydrolyzable property of GeOx in the wet ambient. The pre-growth of a thin GeO2 passivation layer can effectively suppress the interface states and improve the C V characteristics for the as-prepared HfO2 gated Ge MOS capacitors, but it also dissembles the benefits of wet thermal annealing to a certain extent.展开更多
A laser-diode-pumped 1.54-μm passive Q-switched erbium doped glass laser was reported. We utilize a laser diode with wavelength of 973nm to pump a 1-mm Er/Yb co-doped phosphate glass with the erbium and ytterbium con...A laser-diode-pumped 1.54-μm passive Q-switched erbium doped glass laser was reported. We utilize a laser diode with wavelength of 973nm to pump a 1-mm Er/Yb co-doped phosphate glass with the erbium and ytterbium concentrations of 1 wt.% and 21 wt.%, respectively. A Co^2＋ ：MgAl2O4 slab crystal was used as a passive Q- switcher. Q-switched pulses with repetition frequency of 800Hz, width of 7.4ns, peak power of 2.2kW and average power of 13.3 m W were obtained when absorbed pump power was 4 75 m W. A sandwich structure of the Q- switched microchip Er/Yb glass laser was demonstrated, which shows shorter pulse width of 6.8 ns. Dependences of pulse duration and repetition frequency on pump power were also investigated.展开更多
Using fully incoherent white light emitted from an incandescent bulb （a line source） and amplitude mask, we study experimentally the interaction between two 21） white-light photovoltaic dark spatial solitons with t...Using fully incoherent white light emitted from an incandescent bulb （a line source） and amplitude mask, we study experimentally the interaction between two 21） white-light photovoltaic dark spatial solitons with three different separations （40μm, 50μm and 60μm） and arrangement directions （parallel to, perpendicular to and tilted at 45° with respect to the crystalline c axis） propagating in parallel in close proximity in seff-defocusing LiNbO3：Fe crystal. Experimental results reveal that a 21） white-light dark soliton pair only experiences attractive forces when their mutual separation is sufflciently small （〈 60 μm）, and the degree of the attraction depends on their mutual separation and their arrangement direction. When the separation is larger than 60 μm, the interaction is not evident.展开更多
We report on the growth and fabrication of deep ultraviolet （DUV） light emitting diodes （LEDs） on an AIN template which was grown on a pulsed atomic-layer epitaxial buffer layer. Threading dislocation densities i...We report on the growth and fabrication of deep ultraviolet （DUV） light emitting diodes （LEDs） on an AIN template which was grown on a pulsed atomic-layer epitaxial buffer layer. Threading dislocation densities in the AlN layer are greatly decreased with the introduction of this buffer layer. The crystalline quality of the AlGaN epilayer is further improved by using a low-temperature GaN interlayer between AlGaN and AlN. Electroluminescences of different DUV-LED devices at a wavelength of between 262 and 317nm are demonstrated. To improve the hole concentration of p-type AlGaN, Mg-doping with trimethylindium assistance approach is performed. It is found that the serial resistance of DUV-LED decreases and the performance of DUV-LED such as EL properties is improved.展开更多
In this paper we report on a continuous-wave （CW） intracavity singly resonant optical parametric oscillator （ICSRO） based on periodically poled LiNbO3 （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Consi...In this paper we report on a continuous-wave （CW） intracavity singly resonant optical parametric oscillator （ICSRO） based on periodically poled LiNbO3 （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406 nm to 1513 nm is obtained. At a PPLN grating period of 29 pm and a temperature of 413 K, a maximum signal output power of 820 mW at 1500 nm is achieved when the 808 nm pump power is 10.9 W, leading to an optical-to-optical conversion efficiency of 7.51%.展开更多
High-performance and tensile-strained germanium （Ge） p-i-n photodetector is demonstrated on Si substrate. The epi- taxial Ge layers were prepared in an ultrahigh vacuum chemical vapor deposition （UHV-CVD） system u...High-performance and tensile-strained germanium （Ge） p-i-n photodetector is demonstrated on Si substrate. The epi- taxial Ge layers were prepared in an ultrahigh vacuum chemical vapor deposition （UHV-CVD） system using low tem- perature Ge buffer technique. The devices were fabricated by in situ doping and using Si as passivation layer between Ge and metal, which can improve the ohmic contact and realize the high doping. The results show that the dark current of the photodetector with diameter of 24 lain is about 2.5 × 10.7 μA at the bias voltage of-1 V, and the optical responsivity is 0.1 A/W at wavelength of 1.55 μm. The 3 dB bandwidth （BW） of 4 GHz is obtained for the photodetector with diameter of 24 μm at reverse bias voltage of 1 V. The long diffusion time of minority carrier in n-type Ge and the large contact resistance in metal/Ge contacts both affect the performance of Ge photodetectors.展开更多
We use the label-free microsphere-assisted microscopy to image low-contrast hexagonally close-packed polystyrene nanoparticle arrays with diameters of 300 and 250 nm.When a nanoparticle array is directly placed on a g...We use the label-free microsphere-assisted microscopy to image low-contrast hexagonally close-packed polystyrene nanoparticle arrays with diameters of 300 and 250 nm.When a nanoparticle array is directly placed on a glass slide,it cannot be distinguished.If a 30-nm-thick Ag film is deposited on the surface of a nanoparticle array,the nanoparticle array with nanoparticle diameters of 300 and 250 nm can be distinguished.In addition,the Talbot effect of the 300-nm-diameter nanoparticle array is also observed.If a nanoparticle sample is assembled on a glass slide deposited with a 30-nm-thick Ag film,an array of 300-nm-diameter nanoparticles can be discerned.We propose that in microsphere-assisted microscopy imaging,the resolution can be improved by the excitation of surface plasmon polaritons(SPPs) on the sample surface or at the sample/substrate interface,and a higher near-field intensity due to the excited SPPs would benefit the resolution improvement.Our study of label-free super-resolution imaging of low-contrast objects will promote the applications of microsphere-assisted microscopy in life sciences.展开更多
Based on the diffusion approximate theory （DA）, a theoretical model about the distribution of the intensity of a narrow collimation beam illuminating on a semi-lnfinite biological tissue is developed. In order to ve...Based on the diffusion approximate theory （DA）, a theoretical model about the distribution of the intensity of a narrow collimation beam illuminating on a semi-lnfinite biological tissue is developed. In order to verify the correctness of the model, a novel method of measuring the distributions of the intensity of light in Intralipid-10% suspension at 650 nm is presented and ts of the distributions of the distance-dependent intensity of scattering light in different directions are made. The investigations show that the results from our diffusion model are in good agreement with the experimental results beyond and in the areas around the light source, and the distance-dependent intensity in the incident direction attenuates approximately in the exponential form. Furthermore, our theoretic results indicate the anisotropic characteristics of the intensity in different directions of scattering light inside the biological tissue.展开更多
The spectra of fiber Bragg grating (FBG) in inhomogeneous strain fields are distorted due to its inhomogeneity of both the periods and the effective refractive index. The couple mode theory and the Runge-Kutta method ...The spectra of fiber Bragg grating (FBG) in inhomogeneous strain fields are distorted due to its inhomogeneity of both the periods and the effective refractive index. The couple mode theory and the Runge-Kutta method can be employed for exact simulation of the spectrum of Bragg grating in such field, but the convergence speed is slow. On the other hand, although the transfer matrix method could be used with higher convergence speed, the precision is poor because of the neglect of the grads of strain change. By improving the FBG equivalent period, a novel simulation method based on a modified transfer matrix method is proposed, which has the advantage of quick-convergence as well as good accuracy.展开更多
基金supported by the National Natural Science Foundation of China(No.62222511)National Key Research and Devel-opment Program of China(No.2023YFF0613000)+1 种基金Natural Science Foundation of Zhejiang Province China(No.LR22F050006)STI 2030-Major Projects(No.2021ZD0200401).
文摘With the progression of photolithography processes,the present technology nodes have attained 3 nm and even 2 nm,necessitating a transition in the precision standards for displacement measurement and alignment methodologies from the nanometer scale to the sub-nanometer scale.Metasurfaces,owing to their superior light field manipulation capabilities,exhibit significant promise in the domains of displacement measurement and positioning,and are anticipated to be applied in the advanced alignment systems of lithography machines.This paper primarily provides an overview of the contemporary alignment and precise displacement measurement technologies employed in photolithography stages,alongside the operational principles of metasurfaces in the context of precise displacement measurement and alignment.Furthermore,it explores the evolution of metasurface systems capable of achieving nano/sub-nano precision,and identifies the critical issues associated with sub-nanometer measurements using metasurfaces,as well as the principal obstacles encountered in their implementation within photolithography stages.The objective is to provide initial guidance for the advancement of photolithography technology.
文摘By means of the transfer-matrix method, the effects of parameter modulation on the quafity of near-field imaging in one-dimensional photonic crystal consisting of alternately left-handed material and right-handed material are investigated. Based on analyses of the recovery rate and ph＇ase shift, the results show that the imaging quality is not obviously affected by the minor changes of layer thickness. In addition, by modulating the material parameters of the left-handed material, it is found that for both the real part and the imaginary part, the system is more sensitive to the permeability than the permittivity for the TE wave. For the TM wave, it is reverse. These properties are very useful to fabricate left-handed material photonic crystals in practice.
文摘Single-negative materials based on photonic crystal with multiple defect layers are designed and the free modulation of defect modes is studied. The results show that the multi-defect structure can avoid the interference between the defect states. Therefore, the designed double defect modes in the zero effective-phase gap can be adjusted independently by changing the thickness of different defect layers. In addition, the two tunable defect modes have the omnidirectional characteristics. This multi-defect structure with above-mentioned two advantages has potential applications in modern optical devices such as tunable omnidirectional filters.
基金Supported by the National Natural Science Foundation of China under Grant No 60577005, and the Specialized Research Fund for the Doctoral Programme of Higher Education of China under Grant No 158110330001.
文摘A polarizing beam splitter （PBS） and a non-polarizing beam splitter （NPBS） based on a photonic crystal （PC） directional coupler are demonstrated. The photonic crystal directional coupler consists of a hexagonal lattice of dielectric pillars in air and has a complete photonic band gap. The photonic band structure and the band gap map are calculated using the plane wave expansion （PWE） method. The splitting properties of the splitter are investigated numerically using the finite difference time domain （FDTD） method.
基金Project supported by the Swedish Foundation for Strategic Research
文摘The feasibility of using metal optics or negative ε materials, with the aim of reducing the transversal extent of waveguided photonic fields to values much less than the vacuum wavelength, in order to achieve significantly higher densities of integration in integrated photonics circuits that is possible today is discussed. Relevant figures of merit are formulated to this end and used to achieve good performance of devices with today＇s materials and to define required improvements in materials characteristics in terms of decreased scattering rates in the Drude model. The general conclusion is that some metal based circuits are feasible with today＇s matals. Frequency selective metal devices will have Q values on the order of only 10-100, and significant improvements of scattering rates or lowering of the imaginary part of e have to be achieved to implement narrowband devices. A photonic ＂Moore＇s law＂ of integration densities is proposed and exemplified.
基金supported by the National Natural Science Foundation of China under Grant No.12404093the China Postdoctoral Science Foundation under Grant No.2021M702915.
文摘As a new layered semiconductor material,Bi_(2)SeO_(5) has shown potential in the field of ultraviolet electronic devices in recent years because of its unique crystal structure and wide band gap.In this paper,the crystal structure,electronic structure,and thermodynamic stability of Bi_(2)SeO_(5) are studied based on first-principles calculations.The ultraviolet luminescence property of BiSe defect is predicated from defect property,which provides theoretical basis for experimental design of high-performance Bi2SeO5 photoelectric devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.11204131 and 11974181)。
文摘FeSe is an Fe-based paramagnetic superconductor with the simplest structure.The competition between the Néel and stripe magnetic orders is believed to be one of the reasons for the absence of magnetic orders in FeSe.FeSe is recognized as a prototypical platform for competing magnetic interactions,including Néel,stripe,and staggered antiferromagnetic coupling.However,the correlations between these magnetic orders and how they change with varying environmental conditions require further study.Here,we calculated the magnetic order of monolayer FeSe in three diferent environments:pure one,with slight lattice distortion,and on SrTiO_(3) substrate,by frst principles calculations.We fnd that in the calculated dispersion relation E(q)between the spin spiral energy E and spin spiral vector q of the monolayer FeSe structure,the stripe magnetic order M(π/2,π/2)has the lowest energy,and there is a fat E(q)between the wave vector X(π/2,0)and Néel magnetic order 2X(π,0),which are the degenerate E(q)states.The ground state of M and the highest density of states around 2X may be the reason for the competition of two magnetic orders.The slight lattice distortion does not alter the magnetic properties of monolayer FeSe.When monolayer FeSe is attached to the SrTiO_(3)substrate,the degenerate E(q)is still retained;meanwhile,the energy of the 2X(π,0)state is closer to the M state,which may be one of the reasons for the increase of superconducting temperature in FeSe/SrTiO_(3).
基金supported by the Young Cross Team Project of CAS(No.JCTD-2021-14)the National Natural Science Foundation of China(51925206)Gusu Innovation and Entrepreneur Leading Talents(ZXL2022466)。
文摘Self-assembled monolayers(SAMs),owing to their amphiphilic nature,tend to aggregate,which impedes the formation of a dense and uniform SAM on the substrate.Additionally,the weak adsorption ability of SAMs on the indium tin oxide(ITO)surface and the desorption of hydroxyl(OH)from the ITO surface induced by polar solvents can lead to the formation of vacancies.Herein,a dimethylacridine-based SAM is incorporated into the perovskite precursor solution.This SAM can be extruded from the precursor solution and enriched on the bottom surface of the perovskite,filling the vacancies and in situ forming a mixed SAM with MeO-2PACz as a hole-selective layer(HSL).The in situ formed mixed SAM optimizes the energy level alignment between the HSL and the perovskite,facilitating hole extraction and alleviating the residual strain of the perovskite film.Consequently,the perovskite solar cells(PSCs),based on the mixed SAM,achieve a power conversion efficiency(PCE)of 25.69%and exhibit excellent operational stability.When this approach is applied to 1.78 eV bandgap PSC devices,it yields a PCE of 20.08%.This work presents a unique strategy for fabricating both high-quality perovskite films and superior buried interfaces,which is also applicable to wide-bandgap PSCs.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1404400)the National Natural Science Foundation of China(Grant No.12125504 and 12305050)+2 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ25A050001)the Hundred Talents Program of the Chinese Academy of Sciencesthe Natural Science Foundation of Jiangsu Higher Education Institutions of China(Grant No.23KJB140017)。
文摘We investigate electron mesoscopic transport in a three-terminal setup with coupled quantum dots and a magnetic flux.By mapping the original transport problem into a non-Hermitian Hamiltonian form,we study the interplay between the coherent couplings between quantum dots,the magnetic flux,and the dissipation due to the tunnel coupling with the reservoirs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12125504 and 12305050)the National Key R&D Program of China(Grant No.2022YFA1404400)+2 种基金the Hundred Talents Program of the Chinese Academy of Sciences,the Natural Science Foundation of Jiangsu Higher Education Institutions of China(Grant No.23KJB140017)the Opening Project of Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology(Grant No.Ammt2023B-1)the Guangdong University of Technology SPOE Seed Foundation(Grant No.SF2024111502).
文摘We propose a near-field thermophotovoltaic system utilizing magnetic Weyl semimetals,which exhibit a distinct gyrotropic effect originating from their intrinsic axion field.Critically,we demonstrate that intentional band dislocation,achieved by layer-specific tuning of the chemical potential,significantly enhances the energyconversion efficiency.This effect arises from the formation of quasi-flat bands in momentum space,which broaden the spectral heat flux and amplify photon tunneling above the bandgap.At optimized chemical potential mismatches,the system achieves a 65%Carnot efficiency and a power density of 7×10^(4)W·m^(-2),surpassing symmetric configurations by 7%.The optimization of the Weyl semimetals thickness further demonstrates a clear tuning window where both the output power and energy-conversion efficiency are significantly improved.These results establish chemical-potential engineering toward high-efficiency near-field thermophotovoltaics for waste heat recovery and infrared energy applications.
文摘A novel fiber Bragg grating (FBG) current sensor with temperature compensation has been proposed. The fiber Bragg grating is glued on the surface of an isosceles triangle cantilever beam,which has a step thickness along the beam axis. Due to the electromagnetic force created by a solenoid and a permanent magnet mounted on the top of the beam,a step strain is applied on the fiber Bragg grating. The change of the electric current in the solenoid makes the spectrum of the fiber Bragg grating split. By monitoring the shift difference of the two split center wavelengths,which is related to the electric current in the solenoid,a current sensor with temperature compensation is obtained. The test range of 0-400 mA is achieved. The experimental results also show that the relationship between the shift difference of the two split center wavelengths of the FBG and the electric current has a linearity of 0.9937,and the sensitivity is about 2.64 nm/A; the test results are independent of the temperature,so the cross sensitive problem is solved.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61176092,61036003,and 60837001)the National Basic Research Program of China (Grant No. 2012CB933503)+1 种基金the Ph.D. Program Foundation of Ministry of Education of China (Grant No. 20110121110025)the Fundamental Research Funds for the Central Universities,China (Grant No. 2010121056)
文摘Wet thermal annealing effects on the properties of TaN/HfO2/Ge metal-oxide-semiconductor （MOS） structures with and without a GeO2 passivation layer are investigated. The physical and the electrical properties are characterized by X-ray photoemission spectroscopy, high-resolution transmission electron microscopy, capacitance-voltage （C-V） and current-voltage characteristics. It is demonstrated that wet thermal annealing at relatively higher temperature such as 550 ℃ can lead to Ge incorporation in HfO2 and the partial crystallization of HfO2, which should be responsible for the serious degradation of the electrical characteristics of the TaN/HfO2/Ge MOS capacitors. However, wet thermal annealing at 400 ℃ can decrease the GeOx interlayer thickness at the HfO2/Ge interface, resulting in a significant reduction of the interface states and a smaller effective oxide thickness, along with the introduction of a positive charge in the dielectrics due to the hydrolyzable property of GeOx in the wet ambient. The pre-growth of a thin GeO2 passivation layer can effectively suppress the interface states and improve the C V characteristics for the as-prepared HfO2 gated Ge MOS capacitors, but it also dissembles the benefits of wet thermal annealing to a certain extent.
基金Supported by the Program for the New Century Excellent Talents, Excellent Young Teachers in Universities and Scientific Research Foundation for Returned 0verseas Chinese Scholars by M0E and the Natural Science Foundation of Tianjin City 05YFGPGX05100.
文摘A laser-diode-pumped 1.54-μm passive Q-switched erbium doped glass laser was reported. We utilize a laser diode with wavelength of 973nm to pump a 1-mm Er/Yb co-doped phosphate glass with the erbium and ytterbium concentrations of 1 wt.% and 21 wt.%, respectively. A Co^2＋ ：MgAl2O4 slab crystal was used as a passive Q- switcher. Q-switched pulses with repetition frequency of 800Hz, width of 7.4ns, peak power of 2.2kW and average power of 13.3 m W were obtained when absorbed pump power was 4 75 m W. A sandwich structure of the Q- switched microchip Er/Yb glass laser was demonstrated, which shows shorter pulse width of 6.8 ns. Dependences of pulse duration and repetition frequency on pump power were also investigated.
基金Supported by the National Natured Science Foundation of China under Grant Nos 60278006, 60378013 and 10474047.
文摘Using fully incoherent white light emitted from an incandescent bulb （a line source） and amplitude mask, we study experimentally the interaction between two 21） white-light photovoltaic dark spatial solitons with three different separations （40μm, 50μm and 60μm） and arrangement directions （parallel to, perpendicular to and tilted at 45° with respect to the crystalline c axis） propagating in parallel in close proximity in seff-defocusing LiNbO3：Fe crystal. Experimental results reveal that a 21） white-light dark soliton pair only experiences attractive forces when their mutual separation is sufflciently small （〈 60 μm）, and the degree of the attraction depends on their mutual separation and their arrangement direction. When the separation is larger than 60 μm, the interaction is not evident.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10774001, 60736033, 60776041 and 60876041, and National Basic Research Program of China under Grant Nos 2006CB604908 and 2006CB921607, and the National Key Basic R＆D Plan of China under Grant Nos TG2007CB307004.
文摘We report on the growth and fabrication of deep ultraviolet （DUV） light emitting diodes （LEDs） on an AIN template which was grown on a pulsed atomic-layer epitaxial buffer layer. Threading dislocation densities in the AlN layer are greatly decreased with the introduction of this buffer layer. The crystalline quality of the AlGaN epilayer is further improved by using a low-temperature GaN interlayer between AlGaN and AlN. Electroluminescences of different DUV-LED devices at a wavelength of between 262 and 317nm are demonstrated. To improve the hole concentration of p-type AlGaN, Mg-doping with trimethylindium assistance approach is performed. It is found that the serial resistance of DUV-LED decreases and the performance of DUV-LED such as EL properties is improved.
基金Project supported partly by the National Natural Science Foundation of China (Grant Nos 60637010 and 60671036)the National Basic Research Program of China (Grant No 2007CB310403)the Tianjin Applied Fundamental Research Project, China(Grant No 07JCZDJC05900)
文摘In this paper we report on a continuous-wave （CW） intracavity singly resonant optical parametric oscillator （ICSRO） based on periodically poled LiNbO3 （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406 nm to 1513 nm is obtained. At a PPLN grating period of 29 pm and a temperature of 413 K, a maximum signal output power of 820 mW at 1500 nm is achieved when the 808 nm pump power is 10.9 W, leading to an optical-to-optical conversion efficiency of 7.51%.
基金supported by the National Natural Science Foundation of China(Nos.61474094 and 61176092)
文摘High-performance and tensile-strained germanium （Ge） p-i-n photodetector is demonstrated on Si substrate. The epi- taxial Ge layers were prepared in an ultrahigh vacuum chemical vapor deposition （UHV-CVD） system using low tem- perature Ge buffer technique. The devices were fabricated by in situ doping and using Si as passivation layer between Ge and metal, which can improve the ohmic contact and realize the high doping. The results show that the dark current of the photodetector with diameter of 24 lain is about 2.5 × 10.7 μA at the bias voltage of-1 V, and the optical responsivity is 0.1 A/W at wavelength of 1.55 μm. The 3 dB bandwidth （BW） of 4 GHz is obtained for the photodetector with diameter of 24 μm at reverse bias voltage of 1 V. The long diffusion time of minority carrier in n-type Ge and the large contact resistance in metal/Ge contacts both affect the performance of Ge photodetectors.
基金Project supported by the National Natural Science Foundation of China(Grant No.61673287)。
文摘We use the label-free microsphere-assisted microscopy to image low-contrast hexagonally close-packed polystyrene nanoparticle arrays with diameters of 300 and 250 nm.When a nanoparticle array is directly placed on a glass slide,it cannot be distinguished.If a 30-nm-thick Ag film is deposited on the surface of a nanoparticle array,the nanoparticle array with nanoparticle diameters of 300 and 250 nm can be distinguished.In addition,the Talbot effect of the 300-nm-diameter nanoparticle array is also observed.If a nanoparticle sample is assembled on a glass slide deposited with a 30-nm-thick Ag film,an array of 300-nm-diameter nanoparticles can be discerned.We propose that in microsphere-assisted microscopy imaging,the resolution can be improved by the excitation of surface plasmon polaritons(SPPs) on the sample surface or at the sample/substrate interface,and a higher near-field intensity due to the excited SPPs would benefit the resolution improvement.Our study of label-free super-resolution imaging of low-contrast objects will promote the applications of microsphere-assisted microscopy in life sciences.
基金Project supported by the National Natural Science Foundation of China （Grant No 60278007）, the Natural Science Foundation of Tianjin （Grant No 033601311） and the Natural Science Foundation of Guangdong Province （Grant No 04011427）.
文摘Based on the diffusion approximate theory （DA）, a theoretical model about the distribution of the intensity of a narrow collimation beam illuminating on a semi-lnfinite biological tissue is developed. In order to verify the correctness of the model, a novel method of measuring the distributions of the intensity of light in Intralipid-10% suspension at 650 nm is presented and ts of the distributions of the distance-dependent intensity of scattering light in different directions are made. The investigations show that the results from our diffusion model are in good agreement with the experimental results beyond and in the areas around the light source, and the distance-dependent intensity in the incident direction attenuates approximately in the exponential form. Furthermore, our theoretic results indicate the anisotropic characteristics of the intensity in different directions of scattering light inside the biological tissue.
基金This workis supported by Jiangsu Province Natural Science Fou-ndation of China under project BK2004207 the National Sci-ence Fund for Distinguished Young Scholars under project60125513 .
文摘The spectra of fiber Bragg grating (FBG) in inhomogeneous strain fields are distorted due to its inhomogeneity of both the periods and the effective refractive index. The couple mode theory and the Runge-Kutta method can be employed for exact simulation of the spectrum of Bragg grating in such field, but the convergence speed is slow. On the other hand, although the transfer matrix method could be used with higher convergence speed, the precision is poor because of the neglect of the grads of strain change. By improving the FBG equivalent period, a novel simulation method based on a modified transfer matrix method is proposed, which has the advantage of quick-convergence as well as good accuracy.
