The crystalline fraction is a critical parameter for assessing the quality of silicon quantum dots(SiQDs),and its enhancement is anticipated to improve the optoelectronic performance of these materials.How-ever,achiev...The crystalline fraction is a critical parameter for assessing the quality of silicon quantum dots(SiQDs),and its enhancement is anticipated to improve the optoelectronic performance of these materials.How-ever,achieving a high crystalline fraction in small-sized SiQDs produced through the pyrolysis of hydro-gen silsesquioxane(HSQ)polymers remains a significant challenge.In this study,we successfully synthe-sized SiQDs with a diameter of 3.24 nm and a crystalline fraction of 98.4%by optimizing the triethoxysi-lane(TES)/aqueous hydrochloric acid(HCl)volume ratio during the hydrolysis-condensation process.The SiQDs exhibited a photoluminescence(PL)center at 764.1 nm and an average PL quantum yield(PLQY)of 24.4%.Our findings demonstrate that the TES/aqueous HCl volume ratio significantly influences the pro-portion of cage structure and the cross-linking density of the network structure in HSQ polymers,which in turn governs SiQD size and crystalline fraction.A high proportion of cage structures in HSQ polymers contributes to high crystallinity.Notably,an increased cross-linking density within the network structure results in higher and more uniform diffusion barriers.This phenomenon not only hinders the diffusion of silicon atoms,which leads to smaller SiQD size,but also facilitates the achievement of high crystalline fraction due to uniform diffusion.This work presents a novel approach to achieving high crystallinity in small SiQDs,with implications for advanced applications in lighting,display technologies,medical imag-ing,and photovoltaics.展开更多
We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW...We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.展开更多
In this work,we studied the persistent photoconductivity(PPC)spectra in single HgTe/CdHgTe quantum wells with different growth parameters and different types of dark conductivity.The studies were performed in a wide r...In this work,we studied the persistent photoconductivity(PPC)spectra in single HgTe/CdHgTe quantum wells with different growth parameters and different types of dark conductivity.The studies were performed in a wide radiation quantum energy range of 0.62–3.1 eV both at T=4.2 K and at T=77 K.Common features of the PPC spectra for all structures were revealed,and their relation to the presence of a CdTe cap layer in all structures and the appropriate cadmium fraction in the CdHgTe barrier layers was shown.One of the features was associated with the presence of a deep level in the CdTe layer.In addition,the oscillatory behavior of the PPC spectra in the region from 0.8–1.1 eV to 1.2–1.5 eV was observed.It is associated with the cascade emission of longitudinal optical phonons in CdHgTe barrier.展开更多
Interfacial disorders in semiconductor quantum wells(QWs)determine material properties and device performance and have attracted great research efforts using different experimental methods.However,so far,there has bee...Interfacial disorders in semiconductor quantum wells(QWs)determine material properties and device performance and have attracted great research efforts using different experimental methods.However,so far,there has been no way to quantify the lateral length distribution of the interfacial disorders in QWs.Since photoluminescence(PL)is sensitive to exciton localization,the evolutions of PL energy and linewidth under external perpendicular magnetic fields have served as effective measurement methods for QW analysis;however,the evolution of PL intensity has not played a matching role.In this paper,we develop a theoretical model correlating the PL intensity with the interfacial disorders of type-I QWs under an external perpendicular magnetic field.We verify the model's rationality and functionality using In Ga(N)As/Ga As single QWs.In addition,we derive the Urbach energy and determine the lateral length distribution of interfacial disorders.The results show that the magnetic field-dependent PL intensity,as described by our model,serves as a valid probe for quantifying the interface flatness.The model also reveals that the mechanism of magnetic-field-induced intensity enhancement is a joint effect of interfacial disorder-induced exciton localization and the transfer of excitons from dark to bright states.These insights may benefit performance improvements of type-I QW materials and devices.展开更多
Efficient exciton transport over long distances is crucial for organic optoelectronics.Despite efforts to improve the transport properties of organic semiconductors,the limited exciton diffusion remains a significant ...Efficient exciton transport over long distances is crucial for organic optoelectronics.Despite efforts to improve the transport properties of organic semiconductors,the limited exciton diffusion remains a significant obstacle for light-harvesting applications.In this study,we observe phenomena where exciton transport is significantly enhanced by light irradiation in the organic molecular crystal of 2,2'-(2,5-bis(2,2-diphenylvinyl)-1,4-phenylene)dinaphthalene(BDVPN).The exciton transport in this material is improved,as evidenced by the increased diffusion coefficient from 10^(−3) cm^(2)·s^(−1) to over 1 cm^(2)·s^(−1) and a prolonged diffusion length from less than 50 nm to nearly 700 nm characterized by time-resolved photoluminescence microscopy(TPLM).Additionally,we confirmed the enhancement of charge transport capability under irradiation as additional evidence of improved transport properties of the material.These intriguing phenomena may be associated with the material’s twisted molecular conformation and rotatable single bonds,which facilitate light-induced structural alterations conducive to efficient transport properties.Our work provides a novel insight into developing organic semiconductors with efficient exciton transport.展开更多
In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as...In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as the detector to correct distortion and calibrate the transfer function of the control line.Both methods are straightforward to implement,robust against noise,and applicable to a wide range of qubit types.The two methods differ in correction accuracy and complexity.The first,coarse predistortion(CPD)method,partially mitigates distortion.The second,all predistortion(APD)method,measures the transfer function and significantly enhances exchange oscillation uniformity.Both methods use exchange oscillation homogeneity as the metric and are suitable for any qubit driven by a diabatic pulse.We believe these methods will enhance qubit characterization accuracy and operation quality in future applications.展开更多
By numerically solving the two-dimensional semiconductor Bloch equation,we study the high-order harmonic emission of a monolayer ZnO under the driving of co-rotating two-color circularly polarized laser pulses.By chan...By numerically solving the two-dimensional semiconductor Bloch equation,we study the high-order harmonic emission of a monolayer ZnO under the driving of co-rotating two-color circularly polarized laser pulses.By changing the relative phase between the fundamental frequency field and the second one,it is found that the harmonic intensity in the platform region can be significantly modulated.In the higher order,the harmonic intensity can be increased by about one order of magnitude.Through time-frequency analysis,it is demonstrated that the emission trajectory of monolayer ZnO can be controlled by the relative phase,and the harmonic enhancement is caused by the second quantum trajectory with the higher emission probability.In addition,near-circularly polarized harmonics can be generated in the co-rotating two-color circularly polarized fields.With the change of the relative phase,the harmonics in the platform region can be altered from left-handed near-circularly polarization to right-handed one.Our results can obtain high-intensity harmonic radiation with an adjustable ellipticity,which provides an opportunity for syntheses of circularly polarized attosecond pulses.展开更多
The third-harmonic generation(THG)coefficient for a spherical quantum dot system with inversely quadratic Hellmann plus inversely quadratic potential is investigated theoretically,considering the regulation of quantum...The third-harmonic generation(THG)coefficient for a spherical quantum dot system with inversely quadratic Hellmann plus inversely quadratic potential is investigated theoretically,considering the regulation of quantum size,confinement potential depth and the external environment.The numerical simulation results indicate that the THG coefficient can reach the order of 10~(-12)m~2V~(-2),which strongly relies on the tunable factor,with its resonant peak experiencing a redshift or blueshift.Interestingly,the effect of temperature on the THG coefficient in terms of peak location and size is consistent with the quantum dot radius but contrasts with the hydrostatic pressure.Thus,it is crucial to focus on the influence of internal and external parameters on nonlinear optical effects,and to implement the theory in practical experiments and the manufacture of optoelectronic devices.展开更多
基金the Sichuan Science and Technology Program(No.2022ZYD0110)the China National Tobacco Corporation Sichuan Company(No.SCYC202120).
文摘The crystalline fraction is a critical parameter for assessing the quality of silicon quantum dots(SiQDs),and its enhancement is anticipated to improve the optoelectronic performance of these materials.How-ever,achieving a high crystalline fraction in small-sized SiQDs produced through the pyrolysis of hydro-gen silsesquioxane(HSQ)polymers remains a significant challenge.In this study,we successfully synthe-sized SiQDs with a diameter of 3.24 nm and a crystalline fraction of 98.4%by optimizing the triethoxysi-lane(TES)/aqueous hydrochloric acid(HCl)volume ratio during the hydrolysis-condensation process.The SiQDs exhibited a photoluminescence(PL)center at 764.1 nm and an average PL quantum yield(PLQY)of 24.4%.Our findings demonstrate that the TES/aqueous HCl volume ratio significantly influences the pro-portion of cage structure and the cross-linking density of the network structure in HSQ polymers,which in turn governs SiQD size and crystalline fraction.A high proportion of cage structures in HSQ polymers contributes to high crystallinity.Notably,an increased cross-linking density within the network structure results in higher and more uniform diffusion barriers.This phenomenon not only hinders the diffusion of silicon atoms,which leads to smaller SiQD size,but also facilitates the achievement of high crystalline fraction due to uniform diffusion.This work presents a novel approach to achieving high crystallinity in small SiQDs,with implications for advanced applications in lighting,display technologies,medical imag-ing,and photovoltaics.
基金supported by the National Natural Science Foundation of China(Grant No.12105210)the Knowledge Innovation Program of Wuhan-Basi Research(Grant No.2023010201010149)。
文摘We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.
基金supported by the Russian Science Foundation (Grant No. 22-12-00298)supported by the Center of Excellence "Center of Photonics" funded by the Ministry of Science and Higher Education of the Russian Federation, Contract #075-15-2022-316the Theoretical Physics and Mathematics Advancement Foundation "BASIS" scholarship for the support.
文摘In this work,we studied the persistent photoconductivity(PPC)spectra in single HgTe/CdHgTe quantum wells with different growth parameters and different types of dark conductivity.The studies were performed in a wide radiation quantum energy range of 0.62–3.1 eV both at T=4.2 K and at T=77 K.Common features of the PPC spectra for all structures were revealed,and their relation to the presence of a CdTe cap layer in all structures and the appropriate cadmium fraction in the CdHgTe barrier layers was shown.One of the features was associated with the presence of a deep level in the CdTe layer.In addition,the oscillatory behavior of the PPC spectra in the region from 0.8–1.1 eV to 1.2–1.5 eV was observed.It is associated with the cascade emission of longitudinal optical phonons in CdHgTe barrier.
基金supported by the National Natural Science Foundation of China(Grant Nos.12227901,12393830,and 12274429)the STCSM(Grant No.22QA1410600)。
文摘Interfacial disorders in semiconductor quantum wells(QWs)determine material properties and device performance and have attracted great research efforts using different experimental methods.However,so far,there has been no way to quantify the lateral length distribution of the interfacial disorders in QWs.Since photoluminescence(PL)is sensitive to exciton localization,the evolutions of PL energy and linewidth under external perpendicular magnetic fields have served as effective measurement methods for QW analysis;however,the evolution of PL intensity has not played a matching role.In this paper,we develop a theoretical model correlating the PL intensity with the interfacial disorders of type-I QWs under an external perpendicular magnetic field.We verify the model's rationality and functionality using In Ga(N)As/Ga As single QWs.In addition,we derive the Urbach energy and determine the lateral length distribution of interfacial disorders.The results show that the magnetic field-dependent PL intensity,as described by our model,serves as a valid probe for quantifying the interface flatness.The model also reveals that the mechanism of magnetic-field-induced intensity enhancement is a joint effect of interfacial disorder-induced exciton localization and the transfer of excitons from dark to bright states.These insights may benefit performance improvements of type-I QW materials and devices.
基金the National Natural Science Foundation of China(No.62075115,62335013,22275065,52073116)the National Key R&D Program of China(No.2022YFB4600400)the Natural Science Foundation of Jilin Province(20240101003JJ)for their financial support.
文摘Efficient exciton transport over long distances is crucial for organic optoelectronics.Despite efforts to improve the transport properties of organic semiconductors,the limited exciton diffusion remains a significant obstacle for light-harvesting applications.In this study,we observe phenomena where exciton transport is significantly enhanced by light irradiation in the organic molecular crystal of 2,2'-(2,5-bis(2,2-diphenylvinyl)-1,4-phenylene)dinaphthalene(BDVPN).The exciton transport in this material is improved,as evidenced by the increased diffusion coefficient from 10^(−3) cm^(2)·s^(−1) to over 1 cm^(2)·s^(−1) and a prolonged diffusion length from less than 50 nm to nearly 700 nm characterized by time-resolved photoluminescence microscopy(TPLM).Additionally,we confirmed the enhancement of charge transport capability under irradiation as additional evidence of improved transport properties of the material.These intriguing phenomena may be associated with the material’s twisted molecular conformation and rotatable single bonds,which facilitate light-induced structural alterations conducive to efficient transport properties.Our work provides a novel insight into developing organic semiconductors with efficient exciton transport.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074368,92165207,12474490,12034018,and 92265113)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302300)+1 种基金the USTC Tang Scholarshippartially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication。
文摘In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as the detector to correct distortion and calibrate the transfer function of the control line.Both methods are straightforward to implement,robust against noise,and applicable to a wide range of qubit types.The two methods differ in correction accuracy and complexity.The first,coarse predistortion(CPD)method,partially mitigates distortion.The second,all predistortion(APD)method,measures the transfer function and significantly enhances exchange oscillation uniformity.Both methods use exchange oscillation homogeneity as the metric and are suitable for any qubit driven by a diabatic pulse.We believe these methods will enhance qubit characterization accuracy and operation quality in future applications.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(Grant Nos.Y23A040001 and LY21F050001)the National Key Research and Development Program of China(Grant No.2019YFA0307700),the National Natural Science Foundation of China(Grant Nos.12074145,11774219,11975012,12374029,12304378,and 12204214)+2 种基金the Jilin Provincial Research Foundation for Basic Research,China(Grant No.20220101003JC)the Foundation of Education Department of Liaoning Province,China(Grant No.LJKMZ20221435)the National College Students Innovation and Entrepreneurship Training Program(Grant No.202310350062).
文摘By numerically solving the two-dimensional semiconductor Bloch equation,we study the high-order harmonic emission of a monolayer ZnO under the driving of co-rotating two-color circularly polarized laser pulses.By changing the relative phase between the fundamental frequency field and the second one,it is found that the harmonic intensity in the platform region can be significantly modulated.In the higher order,the harmonic intensity can be increased by about one order of magnitude.Through time-frequency analysis,it is demonstrated that the emission trajectory of monolayer ZnO can be controlled by the relative phase,and the harmonic enhancement is caused by the second quantum trajectory with the higher emission probability.In addition,near-circularly polarized harmonics can be generated in the co-rotating two-color circularly polarized fields.With the change of the relative phase,the harmonics in the platform region can be altered from left-handed near-circularly polarization to right-handed one.Our results can obtain high-intensity harmonic radiation with an adjustable ellipticity,which provides an opportunity for syntheses of circularly polarized attosecond pulses.
基金National Natural Science Foundation of China(Grant Nos.11674312,52174161,51702003,12174161 and 61775087)Anhui University of Science and Technology(Grant No.2023CX2141)。
文摘The third-harmonic generation(THG)coefficient for a spherical quantum dot system with inversely quadratic Hellmann plus inversely quadratic potential is investigated theoretically,considering the regulation of quantum size,confinement potential depth and the external environment.The numerical simulation results indicate that the THG coefficient can reach the order of 10~(-12)m~2V~(-2),which strongly relies on the tunable factor,with its resonant peak experiencing a redshift or blueshift.Interestingly,the effect of temperature on the THG coefficient in terms of peak location and size is consistent with the quantum dot radius but contrasts with the hydrostatic pressure.Thus,it is crucial to focus on the influence of internal and external parameters on nonlinear optical effects,and to implement the theory in practical experiments and the manufacture of optoelectronic devices.
