A high-sensitivity,low-noise single photon avalanche diode(SPAD)detector was presented based on a 180 nm BCD process.The proposed device utilizes a p-implant layer/high-voltage n-well(HVNW)junction to form a deep aval...A high-sensitivity,low-noise single photon avalanche diode(SPAD)detector was presented based on a 180 nm BCD process.The proposed device utilizes a p-implant layer/high-voltage n-well(HVNW)junction to form a deep avalanche multiplication region for near-infrared(NIR)sensitivity enhancement.By optimizing the device size and electric field of the guard ring,the fill factor(FF)is significantly improved,further increasing photon detection efficiency(PDE).To solve the dark noise caused by the increasing active diameter,a field polysilicon gate structure connected to the p+anode was investigated,effectively suppressing dark count noise by 76.6%.It is experimentally shown that when the active diameter increases from 5 to 10μm,the FF is significantly improved from 20.7%to 39.1%,and thus the peak PDE also rises from 13.3%to 25.8%.At an excess bias voltage of 5 V,a NIR photon detection probability(PDP)of 6.8%at 905 nm,a dark count rate(DCR)of 2.12 cps/μm^(2),an afterpulsing probability(AP)of 1.2%,and a timing jitter of 216 ps are achieved,demonstrating excellent single photon detection performance.展开更多
Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.Howe...Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.However,with the rapid development of remote imaging,sensing technologies,and long-range quantum communication with fewer topographical constraints,the demand for high-efficiency single-photon detectors integrated with avionic platforms is rapidly growing.We herein designed and manufactured the first drone-based SNSPD system with a system detection efficiency(SDE)as high as 91.8%.This drone-based system incorporates high-performance NbTiN SNSPDs,a self-developed miniature liquid helium dewar,and custom-built integrated electrical setups,making it capable of being launched in complex topographical conditions.Such a drone-based SNSPD system may open the use of SNSPDs for applications that demand high SDE in complex environments.展开更多
We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured...We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured double-layer NbN nanowire to enhance the optical absorption efficiency.A cold development technique is implemented to optimize the superconducting nanowires with sub-40-nm linewidths,thus enhancing the intrinsic detection efficiency(IDE).The fabricated SSPD shows an SDE exceeding 90% at 2μm wavelength.Moreover,the detector allows an operational working temperature of 2.2 K provided by a compact GM cryo-cooler.This detector delivers excellent performance at the 2μm wavelength,and its optimized structural design implies promising potential for extending detection toward longer infrared bands.It thus holds value for advancing high-sensitivity quantum technologies,mid-infrared optical communications,and dark matter detection research.展开更多
Correction to:Opto-Electronic Science https://www.oejournal.org/oes/article/doi/10.29026/oes.2024.230029 published online 21 March 2024.After the publication of this article1,it was brought to our attention that the i...Correction to:Opto-Electronic Science https://www.oejournal.org/oes/article/doi/10.29026/oes.2024.230029 published online 21 March 2024.After the publication of this article1,it was brought to our attention that the inset image and absorption spectrum in Fig.1(b)contained a mistake,probably leading to misunderstandings.The inset image and the absorption spectrum in Fig.1(b)were not based on the specific batch of PbS colloidal quantum dots(CQDs)used in this work.展开更多
A novel Eu^(3+)-doped fluorapatite red phosphor Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2)Eu^(3+)with pure phase was synthesized in this study.Density functional theory(DFT)calculation and diffuse reflection spectrum a...A novel Eu^(3+)-doped fluorapatite red phosphor Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2)Eu^(3+)with pure phase was synthesized in this study.Density functional theory(DFT)calculation and diffuse reflection spectrum analysis reveal its potential as a matrix for phosphors excited by ultraviolet light.Eu^(3+)has a^(7)F_(0)→^(5)L_(6)transition at 394 nm,and the prepared phosphor exhibits a high emission intensity at 614 nm,which may be attributed to the^(5)D_(0)-^(7)F_(2)energy transition at the lower symmetry site of Eu^(3+).The optimal doping concentration of the phosphor is determined to be 11 mol%,with concentration quenching attributed to the exchange interaction mechanism.The overall color purity of the phosphor is up to 99.88%,with an internal quantum efficiency as high as 91.15%.Notably,Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2):11 mol%Eu^(3+)(CYBSF:11 mol%Eu^(3+))phosphors exhibit good thermal stability,with a thermal quenching temperature(T1/2)of 552 K and the intensity of emission at 423 K still at 88.89%of that at 298 K.The activation energy of the phosphor is up to 0.30287 eV.Its comprehensive luminescence performance surpasses that of commercial red phosphor,making it suitable for near ultraviolet excited warm white light emitting diode(NUV-WLED)with a high color rendering index(Ra=82)and a correlated color temperature(CCT)of 4339 K.Moreover,the phosphor achieves latent fingerprint visualization and anti-counterfeiting ink on different material surfaces:glass,aluminum foil,plastic and paper.Overall,the fluorapatite CYBSF:11 mol%Eu^(3+)phosphor holds great potential for multimodal applications due to its high quantum efficiency and good thermal stability.展开更多
The quantum yield is an important factor to evaluate the efficiency of photoreactor. This article gives an overall calculation method of the quantum efficiency( Φ ) and the apparent quantum efficiency( Φ a) to...The quantum yield is an important factor to evaluate the efficiency of photoreactor. This article gives an overall calculation method of the quantum efficiency( Φ ) and the apparent quantum efficiency( Φ a) to the TiO 2/UV photocatalysis system. Furthermore, for the immobility system (IS), the formulation of the faction of light absorbed by the TiO 2 thin film is proposed so as to calculate the quantum efficiency by using the measured value and theoretic calculated value of transmissivity (T). For the suspension system(SS), due to the difficulty to obtain the absorption coefficient ( α ) of TiO 2 particulates, the quantum efficiency is calculated by means of the relative photonic efficiency ( ζ r) and the standard quantum yield ( Φ standard ).展开更多
The Tb3＋single-doped and Tb3＋-Yb3＋co-doped glass ceramics with the precipitation of CaF2, CaF2-SrF2 solid state solu-tion and SrF2 nanocrystals were designed and prepared by taking different amounts of CaF2 and SrF...The Tb3＋single-doped and Tb3＋-Yb3＋co-doped glass ceramics with the precipitation of CaF2, CaF2-SrF2 solid state solu-tion and SrF2 nanocrystals were designed and prepared by taking different amounts of CaF2 and SrF2 as the starting fluorides to inves-tigate the influence of the crystalline phase on the total quantum efficiency. The formation of the fluoride nanocrystals and the incor-poration of the doped rare earth ions into the fluoride nanocrystals were proved by the XRD measurement. The energy transfer from Tb3＋to Yb3＋was studied by the steady and time resolved spectra. The total internal quantum efficiencies were calculated based on the measured Tb3＋lifetime, which was about 10.5%improved in the SrF2 nanocrystals precipitated glass ceramics compared with that in the CaF2 nanocrystals precipitated glass ceramics mainly due to the lower phonon energy environment. Meanwhile, the total external quantum efficiencies were evaluated with the integrating sphere measurement system, which were 18.6%, 19.3%and 24.4%, respec-tively, for the CaF2, CaF2-SrF2 and SrF2 nanocrystals precipitated glass ceramics. Additionally, obvious difference between the calcu-lated total internal quantum efficiency and the measured total external quantum efficiency was also discussed.展开更多
The reasons for low output power of AlGalnP Light Emitting Diodes （LEDs） have been analysed. LEDs with AlGaInP material have high internal but low external quantum efficiency and much heat generated inside especiall...The reasons for low output power of AlGalnP Light Emitting Diodes （LEDs） have been analysed. LEDs with AlGaInP material have high internal but low external quantum efficiency and much heat generated inside especially at a large injected current which would reduce both the internal and external quantum efficiencies. Two kinds of LEDs with the same active region but different window layers have been fabricated. The new window layer composed of textured 0.5 μm GaP and thin Indium-Tin-Oxide film has shown that low external quantum efficiency （EQE） has serious impaction on the internal quantum efficiency （IQE）, because the carrier distribution will change with the body temperature increasing due to the heat inside, and the test results have shown the evidence of LEDs with lower output power and bigger wavelength red shift.展开更多
A new method was used to prepare erbium-doped high silica （SiO2 % 〉 96 % ） glasses by sintering nanoporous glasses. The concentration of erbium ions in high silica glasses can be considerably more than that in sili...A new method was used to prepare erbium-doped high silica （SiO2 % 〉 96 % ） glasses by sintering nanoporous glasses. The concentration of erbium ions in high silica glasses can be considerably more than that in silica glasses prepared by using conventional methods. The fluorescence of 1532 nm has an FWHM （Full Wave at Half Maximum） of 50 nm, wider than 35 nm of EDSFA （erbium-doped silica fiber amplifer）, and hence the glass possesses potential application in broadband fiber amplifiers. The Judd-Ofelt theoretical analysis reflects that the quantum efficiency of this erbium-doped glass is about 0.78, although the erbium concentration in this glass （6 × 10^3） is about twenty times higher than that in silica glass. These excellent characteristics of Er-doped high silica glass will be conducive to its usage in optical amplifiers and microchip lasers.展开更多
In this study, the efficiency droop of an InGaN light-emitting diode （LED） is reduced slgnlncanUy oy using a p-AlGaN/GaN superlattice last quantum barrier. The reduction in efficiency droop is mainly caused by the d...In this study, the efficiency droop of an InGaN light-emitting diode （LED） is reduced slgnlncanUy oy using a p-AlGaN/GaN superlattice last quantum barrier. The reduction in efficiency droop is mainly caused by the decrease of electron current leakage and the increase of hole injection efficiency, which is revealed by investigating the light currents, internal quantum efficiencies, energy band diagrams, carrier concentrations, carrier current densities, and radiative recombination efficiencies of three LED structures with the advanced physical model of semiconductor device （APSYS）.展开更多
Gallium nitride （GaN） based light-emitting diodes （LEDs） with chirped multiple quantum well （MQW） structures have been investigated experimentally and numerically in this paper. Compared to conventional LEDs wit...Gallium nitride （GaN） based light-emitting diodes （LEDs） with chirped multiple quantum well （MQW） structures have been investigated experimentally and numerically in this paper. Compared to conventional LEDs with uniform quantum wells （QWs）, LEDs with chirped MQW structures have better internal quantum efficiency （IQE） and carrier injection efficiency. The droop ratios of LEDs with chirped MQW structures show a remarkable improvement at 600 mA/mm2, reduced down from 28.6% （conventional uniform LEDs） to 23.7% （chirped MQWs-a） and 18.6% （chirped MQWs-b）, respectively. Meanwhile, the peak IQE increases from 76.9% （uniform LEDs） to 83.7% （chirped MQWs-a） and 88.6% （chirped MQWs-b）. The reservoir effect of chirped MQW structures is the significant reason as it could increase hole injection efficiency and radiative recombination. The leakage current and Auger recombination of chirped MQW structures can also be suppressed. Furthermore, the chirped MQWs-b structure with lower potential barriers can enhance the reservoir effect and obtain further improvement of the carrier injection efficiency and radiative recombination, as well as further suppressing efficiency droop.展开更多
Because of the special optical characters, the color matching of fluorescent dyes is quite complicated. In order to find the algorithm of the color matching of fluorescent dyes, some experiments and measurements of on...Because of the special optical characters, the color matching of fluorescent dyes is quite complicated. In order to find the algorithm of the color matching of fluorescent dyes, some experiments and measurements of one kind of fluorescent dye were carried out. An elementary probe into the method of color matching of fluorescent dyes has been made through the expression deduced by James S. Bonham and standard Kubelka-Munk theory. The results prove that the method has a great applicability for the color matching of fabric dyed with only one kind of fluorescent dye.展开更多
We report a novel double-shelled nanoboxes photocatalyst architecture with tailored interfaces that accelerate quantum efficiency for photocatalytic CO_(2) reduction reaction(CO_(2)RR)via Mo–S bridging bonds sites in...We report a novel double-shelled nanoboxes photocatalyst architecture with tailored interfaces that accelerate quantum efficiency for photocatalytic CO_(2) reduction reaction(CO_(2)RR)via Mo–S bridging bonds sites in S_(v)–In_(2)S_(3)@2H–MoTe_(2).The X-ray absorption near-edge structure shows that the formation of S_(v)–In_(2)S_(3)@2H–MoTe_(2) adjusts the coordination environment via interface engineering and forms Mo–S polarized sites at the interface.The interfacial dynamics and catalytic behavior are clearly revealed by ultrafast femtosecond transient absorption,time-resolved,and in situ diffuse reflectance–Infrared Fourier transform spectroscopy.A tunable electronic structure through steric interaction of Mo–S bridging bonds induces a 1.7-fold enhancement in S_(v)–In_(2)S_(3)@2H–MoTe_(2)(5)photogenerated carrier concentration relative to pristine S_(v)–In_(2)S_(3).Benefiting from lower carrier transport activation energy,an internal quantum efficiency of 94.01%at 380 nm was used for photocatalytic CO_(2)RR.This study proposes a new strategy to design photocatalyst through bridging sites to adjust the selectivity of photocatalytic CO_(2)RR.展开更多
The InGaN/GaN blue light emitting diode（LED） is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wav...The InGaN/GaN blue light emitting diode（LED） is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wave functions,radiative recombination rate,and internal quantum efficiency.The simulation results reveal that the InGaN/GaN blue light emitting diode with triangular quantum wells exhibits a higher radiative recombination rate than the conventional light emitting diode with rectangular quantum wells due to the enhanced overlap of electron and hole wave functions（above 90%） under the polarization field.Consequently,the efficiency droop is only 18% in the light emitting diode with triangular-shaped quantum wells,which is three times lower than that in a conventional LED.展开更多
Light-emitting diodes (LEDs), which convert electricity to light, are widely used in modern society,for example, in lighting, flat-panel displays, medical devices and many other situations. Ge- nerally, the efficiency...Light-emitting diodes (LEDs), which convert electricity to light, are widely used in modern society,for example, in lighting, flat-panel displays, medical devices and many other situations. Ge- nerally, the efficiency of LEDs is limited by nonradiative recombination (whereby charge carriers recombine without releasing photons) and light trapping [1]. In planar LEDs, such as organic LEDs, around 70% to 80% of the light generated from the emitters is trapped in the device [2], leaving considerable opportunity for improvements in efficiency. Many methods, including the use of diffraction gratings, low-index grids and buckling patterns, have been used to extract the light trapped in LEDs [3]. However, these methods usually involve complicated fabrication processes and can distort the light-output spectrum and directionality [3].展开更多
GaN ultraviolet(UV)p-i-n photodetectors(PDs)with a 40 nm thin p-GaN contact layer are fabricated on sapphire substrates,which exhibit enhanced quantum efficiency especially in a deep-UV wavelength range.The PDs show g...GaN ultraviolet(UV)p-i-n photodetectors(PDs)with a 40 nm thin p-GaN contact layer are fabricated on sapphire substrates,which exhibit enhanced quantum efficiency especially in a deep-UV wavelength range.The PDs show good rectification behavior and low dark current in pA level for reverse bias up to-10 V.Under zero bias,the maximum quantum efficiency of the PD at 360 nm is close to 59.4%with a UV/visible rejection ratio more than 4 orders of magnitude.Even at a short wavelength of 280 nm,the quantum efficiency of the PD is still around 47.5%,which is considerably higher than that of a control device with a thicker p-GaN contact layer.The room temperature thermal noise limited detectivity of the PD is calculated to be~4.96×10^(14) cm·Hz^(1/2)W^(-1).展开更多
It is well known that cyan-emitting phosphors play a very important role in full-spectrum white LEDs.A large number of cyan-emitting phosphors have been reported in the past few years,however,most of them can only be ...It is well known that cyan-emitting phosphors play a very important role in full-spectrum white LEDs.A large number of cyan-emitting phosphors have been reported in the past few years,however,most of them can only be effectively excited by near-ultraviolet light.There are very few cyan-emitting phosphors that can be intensively excited by blue light(440 and 470 nm).Here,a novel blue-light excitable cyan-emitting phosphor BaLu_(1.95)Ce_(0.05)Al_(2)Ga_(2)SiO_(12)with excellent performance is reported.The cyan phosphor has a cubic structure in space group Ia3^(-)d with a=1.205379(3)nm,which can be easily obtained through a solid-state reaction pathway.The emission peak of the cyan phosphor is located at 500 nm and its internal quantum efficiency is as high as 90.01%when excited at 455 nm at 25℃.The cyan phosphor exhibits superior resistance against thermal quenching of luminescence,and its intensity at 125℃is as strong as 92.14%of the intensity at room temperature.Meanwhile,it also shows an outstanding resistance against water,where its luminescence intensity is hardly changed after being immersed in pure water for 528 h.The white LED lamp prepared by employing the obtained BaLu_(1.95)-Ce_(0.05)Al_(2)Ga_(2)SiO_(12)as cyan phosphor displays remarkable optical properties with CCT=4441 K,Ra=93.7,CRI=90.4 and CIE 1931(x,y)as(x=0.3648,y=0.3752).The experimental results demonstrate that BaLu_(1.95)Ce_(0.05)Al_(2)Ga_(2)SiO_(12)is a promising cyan-emitting phosphor with great application potential in full-spectrum white LEDs.展开更多
CdSe quantum dot sensitized solar cells （QDSCs） modified with graphene quantum dots （GQDs） have been successfully achieved in this work for the first time. Satisfactorily, the optimized photovoltage （Voc） of the...CdSe quantum dot sensitized solar cells （QDSCs） modified with graphene quantum dots （GQDs） have been successfully achieved in this work for the first time. Satisfactorily, the optimized photovoltage （Voc） of the modified QDSCs was approximately 0.04 V higher than that of plain CdSe QDSCs, consequently improving the photovoltaic performance of the resulting QDSCs. Served as a novel coating on the CdSe QD sensitized photoanode, GQDs played a vital role in improving Voc due to the suppressed charge recombination which has been confirmed by electron impedance spectroscopy as well as transient photovoltage decay measure- ments. Moreover, different adsorption sequences, concentration and deposition time of GQDs have also been systematically investigated to boost the power conversion efficiency （PCE） of CdSe QDSCs. After the coating of CdSe with GQDs, the resulting champion CdSe QDSCs exhibited an improved PCE of 6.59% under AM 1.5G full one sun illumination.展开更多
Effective resource management in the Internet of Things and fog computing is essential for efficient and scalable networks.However,existing methods often fail in dynamic and high-demand environments,leading to resourc...Effective resource management in the Internet of Things and fog computing is essential for efficient and scalable networks.However,existing methods often fail in dynamic and high-demand environments,leading to resource bottlenecks and increased energy consumption.This study aims to address these limitations by proposing the Quantum Inspired Adaptive Resource Management(QIARM)model,which introduces novel algorithms inspired by quantum principles for enhanced resource allocation.QIARM employs a quantum superposition-inspired technique for multi-state resource representation and an adaptive learning component to adjust resources in real time dynamically.In addition,an energy-aware scheduling module minimizes power consumption by selecting optimal configurations based on energy metrics.The simulation was carried out in a 360-minute environment with eight distinct scenarios.This study introduces a novel quantum-inspired resource management framework that achieves up to 98%task offload success and reduces energy consumption by 20%,addressing critical challenges of scalability and efficiency in dynamic fog computing environments.展开更多
The quest for higher modulation speed and lower energy consumption has inevitably promoted the rapid development of semiconductor-based solid lighting devices in recent years. GaN-based light-emitting diodes （LEDs） ...The quest for higher modulation speed and lower energy consumption has inevitably promoted the rapid development of semiconductor-based solid lighting devices in recent years. GaN-based light-emitting diodes （LEDs） have emerged as promising candidates for achieving high efficiency and high intensity, and have received increasing attention among many researchers in this field. In this paper, we use a self-assembled array-patterned mask to fabricate InGaN/GaN multi- quantum well （MQW） LEDs with the intention of enhancing the light-emitting efficiency. By utilizing inductively coupled plasma etching with a self-assembled Ni cluster as the mask, nanopillar arrays are formed on the surface of the InGaN/GaN MQWs. We then observe the structure of the nanopillars and find that the V-defects on the surface of the conventional structure and the negative effects of threading dislocation are effectively reduced. Simultaneously, we make a comparison of the photoluminescence （PL） spectrum between the conventional structure and the nanopillar arrays, achieved under an experimental set-up with an excitation wavelength of 325 mm. The analysis demonstrates that MQW-LEDs with nanopillar arrays achieve a PL intensity 2.7 times that of conventional LEDs. In response to the PL spectrum, some reasons are proposed for the enhancement in the light-emitting efficiency as follows： 1） the improvement in crystal quality, namely the reduction in V-defects; 2） the roughened surface effect on the expansion of the critical angle and the attenuated total reflection; and 3） the enhancement of the light-extraction efficiency due to forward scattering by surface plasmon polariton modes in Ni particles deposited above the p-type GaN layer at the top of the nanopillars.展开更多
基金supported by the National Natural Science Foundation of China under Grant 62171233the Natural Science Foundation of China,Jiangsu Province under Grant BK20241891the Jiangsu Province Graduate Research and Practice Innovation Plan under Grants SJCX24_0313 and KYCX24_1169。
文摘A high-sensitivity,low-noise single photon avalanche diode(SPAD)detector was presented based on a 180 nm BCD process.The proposed device utilizes a p-implant layer/high-voltage n-well(HVNW)junction to form a deep avalanche multiplication region for near-infrared(NIR)sensitivity enhancement.By optimizing the device size and electric field of the guard ring,the fill factor(FF)is significantly improved,further increasing photon detection efficiency(PDE).To solve the dark noise caused by the increasing active diameter,a field polysilicon gate structure connected to the p+anode was investigated,effectively suppressing dark count noise by 76.6%.It is experimentally shown that when the active diameter increases from 5 to 10μm,the FF is significantly improved from 20.7%to 39.1%,and thus the peak PDE also rises from 13.3%to 25.8%.At an excess bias voltage of 5 V,a NIR photon detection probability(PDP)of 6.8%at 905 nm,a dark count rate(DCR)of 2.12 cps/μm^(2),an afterpulsing probability(AP)of 1.2%,and a timing jitter of 216 ps are achieved,demonstrating excellent single photon detection performance.
基金the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0300100)the National Key Research and Development Program of China(Grant Nos.2023YFB3809600 and 2023YFC3007801)+1 种基金the National Natural Science Foundation of China(Grant Nos.62301543 and U24A20320)the Shanghai Sailing Program(Grant No.21YF1455700).
文摘Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.However,with the rapid development of remote imaging,sensing technologies,and long-range quantum communication with fewer topographical constraints,the demand for high-efficiency single-photon detectors integrated with avionic platforms is rapidly growing.We herein designed and manufactured the first drone-based SNSPD system with a system detection efficiency(SDE)as high as 91.8%.This drone-based system incorporates high-performance NbTiN SNSPDs,a self-developed miniature liquid helium dewar,and custom-built integrated electrical setups,making it capable of being launched in complex topographical conditions.Such a drone-based SNSPD system may open the use of SNSPDs for applications that demand high SDE in complex environments.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA0520403)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+1 种基金Innovation Program for Quantum Science and Technology(Grant No.2023ZD0300100)the National Natural Science Foundation of China(Grant Nos.U24A20320 and 62401554)。
文摘We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured double-layer NbN nanowire to enhance the optical absorption efficiency.A cold development technique is implemented to optimize the superconducting nanowires with sub-40-nm linewidths,thus enhancing the intrinsic detection efficiency(IDE).The fabricated SSPD shows an SDE exceeding 90% at 2μm wavelength.Moreover,the detector allows an operational working temperature of 2.2 K provided by a compact GM cryo-cooler.This detector delivers excellent performance at the 2μm wavelength,and its optimized structural design implies promising potential for extending detection toward longer infrared bands.It thus holds value for advancing high-sensitivity quantum technologies,mid-infrared optical communications,and dark matter detection research.
文摘Correction to:Opto-Electronic Science https://www.oejournal.org/oes/article/doi/10.29026/oes.2024.230029 published online 21 March 2024.After the publication of this article1,it was brought to our attention that the inset image and absorption spectrum in Fig.1(b)contained a mistake,probably leading to misunderstandings.The inset image and the absorption spectrum in Fig.1(b)were not based on the specific batch of PbS colloidal quantum dots(CQDs)used in this work.
基金supported by the National Natural Science Foundation of China(52372013)Natural Science Foundation of Shanghai(22ZR1460600)。
文摘A novel Eu^(3+)-doped fluorapatite red phosphor Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2)Eu^(3+)with pure phase was synthesized in this study.Density functional theory(DFT)calculation and diffuse reflection spectrum analysis reveal its potential as a matrix for phosphors excited by ultraviolet light.Eu^(3+)has a^(7)F_(0)→^(5)L_(6)transition at 394 nm,and the prepared phosphor exhibits a high emission intensity at 614 nm,which may be attributed to the^(5)D_(0)-^(7)F_(2)energy transition at the lower symmetry site of Eu^(3+).The optimal doping concentration of the phosphor is determined to be 11 mol%,with concentration quenching attributed to the exchange interaction mechanism.The overall color purity of the phosphor is up to 99.88%,with an internal quantum efficiency as high as 91.15%.Notably,Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2):11 mol%Eu^(3+)(CYBSF:11 mol%Eu^(3+))phosphors exhibit good thermal stability,with a thermal quenching temperature(T1/2)of 552 K and the intensity of emission at 423 K still at 88.89%of that at 298 K.The activation energy of the phosphor is up to 0.30287 eV.Its comprehensive luminescence performance surpasses that of commercial red phosphor,making it suitable for near ultraviolet excited warm white light emitting diode(NUV-WLED)with a high color rendering index(Ra=82)and a correlated color temperature(CCT)of 4339 K.Moreover,the phosphor achieves latent fingerprint visualization and anti-counterfeiting ink on different material surfaces:glass,aluminum foil,plastic and paper.Overall,the fluorapatite CYBSF:11 mol%Eu^(3+)phosphor holds great potential for multimodal applications due to its high quantum efficiency and good thermal stability.
文摘The quantum yield is an important factor to evaluate the efficiency of photoreactor. This article gives an overall calculation method of the quantum efficiency( Φ ) and the apparent quantum efficiency( Φ a) to the TiO 2/UV photocatalysis system. Furthermore, for the immobility system (IS), the formulation of the faction of light absorbed by the TiO 2 thin film is proposed so as to calculate the quantum efficiency by using the measured value and theoretic calculated value of transmissivity (T). For the suspension system(SS), due to the difficulty to obtain the absorption coefficient ( α ) of TiO 2 particulates, the quantum efficiency is calculated by means of the relative photonic efficiency ( ζ r) and the standard quantum yield ( Φ standard ).
基金Project supported by the Basic Research Project of Shanghai Science and Technology Commission(12JC1408500)
文摘The Tb3＋single-doped and Tb3＋-Yb3＋co-doped glass ceramics with the precipitation of CaF2, CaF2-SrF2 solid state solu-tion and SrF2 nanocrystals were designed and prepared by taking different amounts of CaF2 and SrF2 as the starting fluorides to inves-tigate the influence of the crystalline phase on the total quantum efficiency. The formation of the fluoride nanocrystals and the incor-poration of the doped rare earth ions into the fluoride nanocrystals were proved by the XRD measurement. The energy transfer from Tb3＋to Yb3＋was studied by the steady and time resolved spectra. The total internal quantum efficiencies were calculated based on the measured Tb3＋lifetime, which was about 10.5%improved in the SrF2 nanocrystals precipitated glass ceramics compared with that in the CaF2 nanocrystals precipitated glass ceramics mainly due to the lower phonon energy environment. Meanwhile, the total external quantum efficiencies were evaluated with the integrating sphere measurement system, which were 18.6%, 19.3%and 24.4%, respec-tively, for the CaF2, CaF2-SrF2 and SrF2 nanocrystals precipitated glass ceramics. Additionally, obvious difference between the calcu-lated total internal quantum efficiency and the measured total external quantum efficiency was also discussed.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2006AA03A121)the National Basic Research Program of China(Grant No.2006CB604900)
文摘The reasons for low output power of AlGalnP Light Emitting Diodes （LEDs） have been analysed. LEDs with AlGaInP material have high internal but low external quantum efficiency and much heat generated inside especially at a large injected current which would reduce both the internal and external quantum efficiencies. Two kinds of LEDs with the same active region but different window layers have been fabricated. The new window layer composed of textured 0.5 μm GaP and thin Indium-Tin-Oxide film has shown that low external quantum efficiency （EQE） has serious impaction on the internal quantum efficiency （IQE）, because the carrier distribution will change with the body temperature increasing due to the heat inside, and the test results have shown the evidence of LEDs with lower output power and bigger wavelength red shift.
基金Project supported bythe National Natural Science Foundation of China (50125258 and 60377040)
文摘A new method was used to prepare erbium-doped high silica （SiO2 % 〉 96 % ） glasses by sintering nanoporous glasses. The concentration of erbium ions in high silica glasses can be considerably more than that in silica glasses prepared by using conventional methods. The fluorescence of 1532 nm has an FWHM （Full Wave at Half Maximum） of 50 nm, wider than 35 nm of EDSFA （erbium-doped silica fiber amplifer）, and hence the glass possesses potential application in broadband fiber amplifiers. The Judd-Ofelt theoretical analysis reflects that the quantum efficiency of this erbium-doped glass is about 0.78, although the erbium concentration in this glass （6 × 10^3） is about twenty times higher than that in silica glass. These excellent characteristics of Er-doped high silica glass will be conducive to its usage in optical amplifiers and microchip lasers.
基金Project supported by the National Natural Science Foundation of China(Grant No.61176043)the Special Funds for Provincial Strategic and Emerging Industries Projects of Guangdong Province,China(Grant Nos.2010A081002005,2011A081301003,and 2012A080304016)+2 种基金the First Phase of Construction of Guangdong Research Institute of Semiconductor Lighting Industrial Technology,China(Grant No.2010A081001001)the High Efficiency LED Epitaxy and Chip Structure and Key Technology for Industrialization,China(Grant No.2012A080302002)the Youth Funding of South China Normal University(Grant No.2012KJ018)
文摘In this study, the efficiency droop of an InGaN light-emitting diode （LED） is reduced slgnlncanUy oy using a p-AlGaN/GaN superlattice last quantum barrier. The reduction in efficiency droop is mainly caused by the decrease of electron current leakage and the increase of hole injection efficiency, which is revealed by investigating the light currents, internal quantum efficiencies, energy band diagrams, carrier concentrations, carrier current densities, and radiative recombination efficiencies of three LED structures with the advanced physical model of semiconductor device （APSYS）.
基金supported by the National High Technology Research and Development Program of China(Grant No.2014AA032608)the Key Laboratory for Mechanical Behavior of Material of Xi’an Jiaotong University,China(Grant No.20121201)the Fundamental Research Funds for the Central Universities,China
文摘Gallium nitride （GaN） based light-emitting diodes （LEDs） with chirped multiple quantum well （MQW） structures have been investigated experimentally and numerically in this paper. Compared to conventional LEDs with uniform quantum wells （QWs）, LEDs with chirped MQW structures have better internal quantum efficiency （IQE） and carrier injection efficiency. The droop ratios of LEDs with chirped MQW structures show a remarkable improvement at 600 mA/mm2, reduced down from 28.6% （conventional uniform LEDs） to 23.7% （chirped MQWs-a） and 18.6% （chirped MQWs-b）, respectively. Meanwhile, the peak IQE increases from 76.9% （uniform LEDs） to 83.7% （chirped MQWs-a） and 88.6% （chirped MQWs-b）. The reservoir effect of chirped MQW structures is the significant reason as it could increase hole injection efficiency and radiative recombination. The leakage current and Auger recombination of chirped MQW structures can also be suppressed. Furthermore, the chirped MQWs-b structure with lower potential barriers can enhance the reservoir effect and obtain further improvement of the carrier injection efficiency and radiative recombination, as well as further suppressing efficiency droop.
文摘Because of the special optical characters, the color matching of fluorescent dyes is quite complicated. In order to find the algorithm of the color matching of fluorescent dyes, some experiments and measurements of one kind of fluorescent dye were carried out. An elementary probe into the method of color matching of fluorescent dyes has been made through the expression deduced by James S. Bonham and standard Kubelka-Munk theory. The results prove that the method has a great applicability for the color matching of fabric dyed with only one kind of fluorescent dye.
基金the Natural Science Foundation of China(11922415,12274471)Guangdong Basic and Applied Basic Research Foundation(2022A1515011168,2019A1515011718,2019A1515011337)the Key Research and Development Program of Guangdong Province,China(2019B110209003).
文摘We report a novel double-shelled nanoboxes photocatalyst architecture with tailored interfaces that accelerate quantum efficiency for photocatalytic CO_(2) reduction reaction(CO_(2)RR)via Mo–S bridging bonds sites in S_(v)–In_(2)S_(3)@2H–MoTe_(2).The X-ray absorption near-edge structure shows that the formation of S_(v)–In_(2)S_(3)@2H–MoTe_(2) adjusts the coordination environment via interface engineering and forms Mo–S polarized sites at the interface.The interfacial dynamics and catalytic behavior are clearly revealed by ultrafast femtosecond transient absorption,time-resolved,and in situ diffuse reflectance–Infrared Fourier transform spectroscopy.A tunable electronic structure through steric interaction of Mo–S bridging bonds induces a 1.7-fold enhancement in S_(v)–In_(2)S_(3)@2H–MoTe_(2)(5)photogenerated carrier concentration relative to pristine S_(v)–In_(2)S_(3).Benefiting from lower carrier transport activation energy,an internal quantum efficiency of 94.01%at 380 nm was used for photocatalytic CO_(2)RR.This study proposes a new strategy to design photocatalyst through bridging sites to adjust the selectivity of photocatalytic CO_(2)RR.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61076013,51102003,and 60990313)the National Basic Research Program of China (Grant No. 2012CB619304)the Specialized Research Fund for the Doctoral Program of Higher Education,China (Grant No. 20100001120014)
文摘The InGaN/GaN blue light emitting diode（LED） is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wave functions,radiative recombination rate,and internal quantum efficiency.The simulation results reveal that the InGaN/GaN blue light emitting diode with triangular quantum wells exhibits a higher radiative recombination rate than the conventional light emitting diode with rectangular quantum wells due to the enhanced overlap of electron and hole wave functions（above 90%） under the polarization field.Consequently,the efficiency droop is only 18% in the light emitting diode with triangular-shaped quantum wells,which is three times lower than that in a conventional LED.
文摘Light-emitting diodes (LEDs), which convert electricity to light, are widely used in modern society,for example, in lighting, flat-panel displays, medical devices and many other situations. Ge- nerally, the efficiency of LEDs is limited by nonradiative recombination (whereby charge carriers recombine without releasing photons) and light trapping [1]. In planar LEDs, such as organic LEDs, around 70% to 80% of the light generated from the emitters is trapped in the device [2], leaving considerable opportunity for improvements in efficiency. Many methods, including the use of diffraction gratings, low-index grids and buckling patterns, have been used to extract the light trapped in LEDs [3]. However, these methods usually involve complicated fabrication processes and can distort the light-output spectrum and directionality [3].
基金Supported by the National Basic Research Program of China under Grant Nos 2010CB327504,2011CB922100 and 2011CB301900the National Natural Science Foundation of China under Grant Nos 60825401,60936004,11104130 and 60990311.
文摘GaN ultraviolet(UV)p-i-n photodetectors(PDs)with a 40 nm thin p-GaN contact layer are fabricated on sapphire substrates,which exhibit enhanced quantum efficiency especially in a deep-UV wavelength range.The PDs show good rectification behavior and low dark current in pA level for reverse bias up to-10 V.Under zero bias,the maximum quantum efficiency of the PD at 360 nm is close to 59.4%with a UV/visible rejection ratio more than 4 orders of magnitude.Even at a short wavelength of 280 nm,the quantum efficiency of the PD is still around 47.5%,which is considerably higher than that of a control device with a thicker p-GaN contact layer.The room temperature thermal noise limited detectivity of the PD is calculated to be~4.96×10^(14) cm·Hz^(1/2)W^(-1).
基金Project supported by the National Natural Science Foundation of China(11864015,51962005)the Scientific Research Foundation for Universities from the Education Bureau of Jiangxi Province of China(GJJ170490,GJJ180480)。
文摘It is well known that cyan-emitting phosphors play a very important role in full-spectrum white LEDs.A large number of cyan-emitting phosphors have been reported in the past few years,however,most of them can only be effectively excited by near-ultraviolet light.There are very few cyan-emitting phosphors that can be intensively excited by blue light(440 and 470 nm).Here,a novel blue-light excitable cyan-emitting phosphor BaLu_(1.95)Ce_(0.05)Al_(2)Ga_(2)SiO_(12)with excellent performance is reported.The cyan phosphor has a cubic structure in space group Ia3^(-)d with a=1.205379(3)nm,which can be easily obtained through a solid-state reaction pathway.The emission peak of the cyan phosphor is located at 500 nm and its internal quantum efficiency is as high as 90.01%when excited at 455 nm at 25℃.The cyan phosphor exhibits superior resistance against thermal quenching of luminescence,and its intensity at 125℃is as strong as 92.14%of the intensity at room temperature.Meanwhile,it also shows an outstanding resistance against water,where its luminescence intensity is hardly changed after being immersed in pure water for 528 h.The white LED lamp prepared by employing the obtained BaLu_(1.95)-Ce_(0.05)Al_(2)Ga_(2)SiO_(12)as cyan phosphor displays remarkable optical properties with CCT=4441 K,Ra=93.7,CRI=90.4 and CIE 1931(x,y)as(x=0.3648,y=0.3752).The experimental results demonstrate that BaLu_(1.95)Ce_(0.05)Al_(2)Ga_(2)SiO_(12)is a promising cyan-emitting phosphor with great application potential in full-spectrum white LEDs.
基金supported by the National Natural Science Foundation of China (21175043,91233102)the Fundamental Research Funds for the Central Universities for financial support
文摘CdSe quantum dot sensitized solar cells （QDSCs） modified with graphene quantum dots （GQDs） have been successfully achieved in this work for the first time. Satisfactorily, the optimized photovoltage （Voc） of the modified QDSCs was approximately 0.04 V higher than that of plain CdSe QDSCs, consequently improving the photovoltaic performance of the resulting QDSCs. Served as a novel coating on the CdSe QD sensitized photoanode, GQDs played a vital role in improving Voc due to the suppressed charge recombination which has been confirmed by electron impedance spectroscopy as well as transient photovoltage decay measure- ments. Moreover, different adsorption sequences, concentration and deposition time of GQDs have also been systematically investigated to boost the power conversion efficiency （PCE） of CdSe QDSCs. After the coating of CdSe with GQDs, the resulting champion CdSe QDSCs exhibited an improved PCE of 6.59% under AM 1.5G full one sun illumination.
基金funded by Researchers Supporting Project Number(RSPD2025R947)King Saud University,Riyadh,Saudi Arabia.
文摘Effective resource management in the Internet of Things and fog computing is essential for efficient and scalable networks.However,existing methods often fail in dynamic and high-demand environments,leading to resource bottlenecks and increased energy consumption.This study aims to address these limitations by proposing the Quantum Inspired Adaptive Resource Management(QIARM)model,which introduces novel algorithms inspired by quantum principles for enhanced resource allocation.QIARM employs a quantum superposition-inspired technique for multi-state resource representation and an adaptive learning component to adjust resources in real time dynamically.In addition,an energy-aware scheduling module minimizes power consumption by selecting optimal configurations based on energy metrics.The simulation was carried out in a 360-minute environment with eight distinct scenarios.This study introduces a novel quantum-inspired resource management framework that achieves up to 98%task offload success and reduces energy consumption by 20%,addressing critical challenges of scalability and efficiency in dynamic fog computing environments.
基金supported by the Special Funds for Major State Basic Research Project of China(Grant No.2011CB301900)the High Technology Research Program of China(Grant No.2009AA03A198)+2 种基金the National Natural Science Foundation of China(Grant Nos.60990311,60721063,60906025,60936004,60731160628,and 60820106003)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK2008019,BK2010385,BK2009255,and BK2010178)the Research Funds from Nanjing University Yangzhou Institute of Opto-electronics,China
文摘The quest for higher modulation speed and lower energy consumption has inevitably promoted the rapid development of semiconductor-based solid lighting devices in recent years. GaN-based light-emitting diodes （LEDs） have emerged as promising candidates for achieving high efficiency and high intensity, and have received increasing attention among many researchers in this field. In this paper, we use a self-assembled array-patterned mask to fabricate InGaN/GaN multi- quantum well （MQW） LEDs with the intention of enhancing the light-emitting efficiency. By utilizing inductively coupled plasma etching with a self-assembled Ni cluster as the mask, nanopillar arrays are formed on the surface of the InGaN/GaN MQWs. We then observe the structure of the nanopillars and find that the V-defects on the surface of the conventional structure and the negative effects of threading dislocation are effectively reduced. Simultaneously, we make a comparison of the photoluminescence （PL） spectrum between the conventional structure and the nanopillar arrays, achieved under an experimental set-up with an excitation wavelength of 325 mm. The analysis demonstrates that MQW-LEDs with nanopillar arrays achieve a PL intensity 2.7 times that of conventional LEDs. In response to the PL spectrum, some reasons are proposed for the enhancement in the light-emitting efficiency as follows： 1） the improvement in crystal quality, namely the reduction in V-defects; 2） the roughened surface effect on the expansion of the critical angle and the attenuated total reflection; and 3） the enhancement of the light-extraction efficiency due to forward scattering by surface plasmon polariton modes in Ni particles deposited above the p-type GaN layer at the top of the nanopillars.
