CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significa...CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significantly enhances the photophysical property of CdSe NPLs.Laser spectroscopy techniques reveal suppressed electronic and hole trapping at lateral surfaces,leading to a 4.2-fold increase in photoluminescence quantum yield and a shortened emission lifetime from13.5 to 4.8 ns.In addition,amplified spontaneous emission is achieved under nanosecond pulse pumping,with thresholds of0.75 to 0.16 mJ/cm^(2)for CdSe and CdSe/CdSeS NPLs,respectively.By integrating CdSe/CdSeS NPLs with high-refractiveindex SiO2scatters,coherent random lasing is realized at a threshold of 0.21 mJ/cm^(2).These findings highlight the critical role of lateral surface passivation in optimizing optical gain and pave the way for low-cost,multifunctional nanophotonic devices.展开更多
Nowadays,a stack of heavily doped polysilicon(poly-Si)and tunnel oxide(SiO_(x))is widely employed to improve the passivation performance in n-type tunnel oxide passivated contact(TOPCon)silicon solar cells.In this cas...Nowadays,a stack of heavily doped polysilicon(poly-Si)and tunnel oxide(SiO_(x))is widely employed to improve the passivation performance in n-type tunnel oxide passivated contact(TOPCon)silicon solar cells.In this case,it is critical to develop an in-line advanced fabrication process capable of producing high-quality tunnel SiO_(x).Herein,an in-line ozone-gas oxidation(OGO)process to prepare the tunnel SiO_(x) is proposed to be applied in n-type TOPCon solar cell fabrication,which has obtained better performance compared with previously reported in-line plasma-assisted N2O oxidation(PANO)process.In order to explore the underlying mechanism,the electrical properties of the OGO and PANO tunnel SiO_(x) are analyzed by deep-level transient spectroscopy technology.Notably,continuous interface states in the band gap are detected for OGO tunnel SiO_(x),with the interface state densities(D_(it))of 1.2×10^(12)–3.6×10^(12) cm^(-2) eV^(-1) distributed in Ev+(0.15–0.40)eV,which is significantly lower than PANO tunnel SiO_(x).Furthermore,X-ray photoelectron spectroscopy analysis indicate that the percentage of SiO_(2)(Si^(4+))in OGO tunnel SiO_(x) is higher than which in PANO tunnel SiO_(x).Therefore,we ascribe the lower D_(it) to the good inhibitory effects on the formation of low-valent silicon oxides during the OGO process.In a nutshell,OGO tunnel SiO_(x) has a great potential to be applied in n-type TOPCon silicon solar cell,which may be available for global photovoltaics industry.展开更多
Passivated niobium/nitrogen(Nb-N) p-n co-doped zinc oxide nanoparticles were created by a simple precipitation process with in-situ self-formed NaCl "cage" to confine the nanoparticle growth followed by the ...Passivated niobium/nitrogen(Nb-N) p-n co-doped zinc oxide nanoparticles were created by a simple precipitation process with in-situ self-formed NaCl "cage" to confine the nanoparticle growth followed by the heat treatment in a flow of ammonia gas. Enhanced optical absorbance into the visible light region was observed in the Nb/N co-doped ZnO nanoparticle photocatalyst due to the Nb/N co-doping effect.It demonstrated a largely enhanced photocatalytic performance in the disinfection of Escherichia coli bacteria under visible light illumination, which could be attributed to the passivated co-doping of NbN to suppress the photogenerated charge carrier recombination on dopants. This robust approach for passivated p-n co-doping may also be applied to other material systems for a wide range of technical applications.展开更多
Mono-crystalline silicon solar cells with a passivated emitter rear contact(PERC)configuration have attracted extensive attention from both industry and scientific communities.A record efficiency of 24.06%on p-type si...Mono-crystalline silicon solar cells with a passivated emitter rear contact(PERC)configuration have attracted extensive attention from both industry and scientific communities.A record efficiency of 24.06%on p-type silicon wafer and mass production efficiency around 22%have been demonstrated,mainly due to its superior rear side passivation.In this work,the PERC solar cells with a p-type silicon wafer were numerically studied in terms of the surface passivation,quality of silicon wafer and metal electrodes.A rational way to achieve a 24%mass-production efficiency was proposed.Free energy loss analyses were adopted to address the loss sources with respect to the limit efficiency of 29%,which provides a guideline for the design and manufacture of a high-efficiency PERC solar cell.展开更多
Surface leakage currents of A1GaN/GaN high electron mobility transistors are investigated by utilizing a circular double-gate structure to eliminate the influence of mesa leakage current. Different mechanisms are foun...Surface leakage currents of A1GaN/GaN high electron mobility transistors are investigated by utilizing a circular double-gate structure to eliminate the influence of mesa leakage current. Different mechanisms are found under various passivation conditions. The mechanism of the surface leakage current with AI2 03 passivation follows the two-dimensional variable range hopping model, while the mechanism of the surface leakage current with SiN passivation follows the Frenkel-Poole trap assisted emission. Two trap levels are found in the trap-assisted emission. One trap level has a barrier height of 0.22eV for the high electric field, and the other trap level has a barrier height of 0.12eV for the low electric field.展开更多
This paper investigates the impact of electrical degradation and current collapse on different thickness SiNx passivated AlGaN/GaN high electron mobility transistors. It finds that higher thickness SiNx passivation ca...This paper investigates the impact of electrical degradation and current collapse on different thickness SiNx passivated AlGaN/GaN high electron mobility transistors. It finds that higher thickness SiNx passivation can significantly improve the high-electric-field reliability of a device. The degradation mechanism of the SiNx passivation layer under ON-state stress has also been discussed in detail. Under the ON-state stress, the strong electric-field led to degradation of SiNx passivation located in the gate-drain region. As the thickness of SiNx passivation increases, the density of the surface state will be increased to some extent. Meanwhile, it is found that the high NH3 flow in the plasma enhanced chemical vapour deposition process could reduce the surface state and suppress the current collapse.展开更多
Based on analysis of electrochemical machining ( ECM) process and application of finite ele- ment technique ( FET) , a method of tool design is presented which can be used in ECM with passivated electrolyte. As a resu...Based on analysis of electrochemical machining ( ECM) process and application of finite ele- ment technique ( FET) , a method of tool design is presented which can be used in ECM with passivated electrolyte. As a result of specific treatment to boundary conditions, this method needs much less com- puting time and memory space. It has been shown that the theoretical results correspond well with the experimental ones .展开更多
AlGaN/GaN high electron mobility transistors （HEMTs） are fabricated by employing SiN passivation, this paper investigates the degradation due to the high-electric-field stress. After the stress, a recoverable degrad...AlGaN/GaN high electron mobility transistors （HEMTs） are fabricated by employing SiN passivation, this paper investigates the degradation due to the high-electric-field stress. After the stress, a recoverable degradation has been found, consisting of the decrease of saturation drain current IDsat, maximal transconductance gm, and the positive shift of threshold voltage VTH at high drain-source voltage VDS. The high-electric-field stress degrades the electric characteristics of AlGaN/GaN HEMTs because the high field increases the electron trapping at the surface and in AlGaN barrier layer. The SiN passivation of AlGaN/GaN HEMTs decreases the surface trapping and 2DEC depletion a little during the high-electric-field stress. After the hot carrier stress with VDS = 20 V and VGS= 0 V applied to the device for 104 sec, the SiN passivation decreases the stress-induced degradation of IDsat from 36% to 30%. Both on-state and pulse-state stresses produce comparative decrease of IDsat, which shows that although the passivation is effective in suppressing electron trapping in surface states, it does not protect the device from high-electric-field degradation in nature. So passivation in conjunction with other technological solutions like cap layer, prepassivation surface treatments, or field-plate gate to weaken high-electric-field degradation should be adopted.展开更多
In blue quantum dot light emitting diodes(QLEDs),electron injection is insufficient,which would degrade device efficiency and stability.Herein,we employ chlorine passivated ZnO nanoparticles as electron transport laye...In blue quantum dot light emitting diodes(QLEDs),electron injection is insufficient,which would degrade device efficiency and stability.Herein,we employ chlorine passivated ZnO nanoparticles as electron transport layer to facilitate electron injection into QDs effectively.Moreover,it suppresses exciton quenching at the QD/ZnO interface by blocking charge transfer channel.As a result,the maximum external quantum efficiency of blue QLED was increased from 2.55%to 4.60%,and the operation lifetime of blue QLED was nearly 4 times longer than that of the control device.Our work indicates that election injection plays an important role in blue QLED efficiency and stability.展开更多
Based on the transport theory and the polarization relaxation model,the effects of hydrogen and hydroxyl passivation on the conductivity and dielectric properties of silicon carbide nanowires(SiCNWs)with different siz...Based on the transport theory and the polarization relaxation model,the effects of hydrogen and hydroxyl passivation on the conductivity and dielectric properties of silicon carbide nanowires(SiCNWs)with different sizes are numerically simulated.The results show that the variation trend of conductivity and band gap of passivated SiCNWs are opposite to the scenario of the size effect of bare SiCNWs.Among the influencing factors of conductivity,the carrier concentration plays a leading role.In the dielectric properties,the bare SiCNWs have a strong dielectric response in the blue light region,while passivated SiCNWs show a more obvious dielectric response in the far ultraviolet-light region.In particular,hydroxyl passivation produces a strong dielectric relaxation in the microwave band,indicating that hydroxyl passivated SiCNWs have a wide range of applications in electromagnetic absorption and shielding.展开更多
The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole was investigated by salt spraying test and electrochemical methods in artificial Ringer＇s solution. The results showed that afte...The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole was investigated by salt spraying test and electrochemical methods in artificial Ringer＇s solution. The results showed that after benzotriazole passivation, the corrosion resistance of the Cu-Zn-Al shape memory alloy was improved evidently. The anodic polarization current density of the passivated alloy decreased, the mass loss reduced, the anodic passivation accelerated, the anodic active dissolution was inhibited effectively, and the surface tarnishing was reswained. Infrared reflection spectrum test showed that Cu（Ⅰ）-benzotriazole or Cu（Ⅱ）-benzotriazole complex layer was formed on the surface of the Cu-Zn-Al shape memory alloy after passivation. This layer appeared plane, well adhesion, and presented homogeneous golden metallic luster. The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole is improved for the formation of an electrochemical stable baffle layer on passivated surface. This layer separates the metal substrate from the outside corrosion medium effectively and retards the corrosion process of dezincification.展开更多
The development of tin-based devices with low toxicity is critical for the commercial viability of perovskite solar cells.However because tin halide is a stronger Lewis acid,its crystallization rate is extremely fast,...The development of tin-based devices with low toxicity is critical for the commercial viability of perovskite solar cells.However because tin halide is a stronger Lewis acid,its crystallization rate is extremely fast,resulting in the formation of numerous defects that affect the device performance of tin-based perovskite solar cells.Herein,propylamine hydrobromide(PABr)was added to the perovskite precursor solution as an additive to passivate defects and fabricate more uniform and dense perovskite films.Because propylamine cations are too large to enter the perovskite lattices,they only exist at the grain boundary to passivate surface defects and promote crystal growth in a preferred orientation.The PABr additive raises the average short-circuit current density from 19.45 to 25.47 mA·cm^(-2)by reducing carrier recombination induced by defects.Furthermore,the device’s long-term illumination stability is improved after optimization,and the hysteresis effect is negligible.The addition of PABr results in a power conversion efficiency of 9.35%.展开更多
In order to enhance the p-type doping concentration in the LBSF, boron was added into the aluminum paste and boron doped local back surface field（B-LBSF） was successfully fabricated in this work. Through boron dopin...In order to enhance the p-type doping concentration in the LBSF, boron was added into the aluminum paste and boron doped local back surface field（B-LBSF） was successfully fabricated in this work. Through boron doping in the LBSF, much higher doping concentration was observed for the B-LBSF over the Al-LBSF. Higher doping concentration in the LBSF is expected to lead to better rear passivation and lower rear contact resistance. Based on one thousand pieces of solar cells for each type, it was found that the rear passivated crystalline silicon solar cells with B-LBSF showed statistical improvement in their photovoltaic properties over those with Al-LBSF.展开更多
The interaction between Sn and passivated stainless steel was evaluated through an easy chromaticity approach.The microstructure of Fe-Sn intermetallics(IMCs)was observed,and their growth was inspected at differenf ti...The interaction between Sn and passivated stainless steel was evaluated through an easy chromaticity approach.The microstructure of Fe-Sn intermetallics(IMCs)was observed,and their growth was inspected at differenf time after the in teract io n.The oxide film on stainless steel exposed in air locally delayed IMC growth,and the chemically passivated film protected stainless steel from Fe-Sn compound formation.To investigate the interaction mechanism,the integrity of passivated films grown on stainless steel was evaluated by chromogenic inspection.The interaction extern was related to colour measurement a*.Results indicated that the measured value of a*from the inspection decreased with the increasing exposure time,and a minimum a*value was found in chemically passivated samples.The tendency of the colour measureme was consistent with the effect of passive film on IMC growth.The in terfacial reaction of passivated stainless steel with Sn was illustrated based on the integrity of the passive films.展开更多
Surface passivation methods for porous Si (PS) surfaces, i.e., depositing diamond film or diamond-like carbon (DLC) film on PS surfaces, were attempted. Two emission bands, weak blue band and strong red band existed i...Surface passivation methods for porous Si (PS) surfaces, i.e., depositing diamond film or diamond-like carbon (DLC) film on PS surfaces, were attempted. Two emission bands, weak blue band and strong red band existed in the PL spectrum of diamond film coated on PS, were discovered by the photoluminescence measurements. The luminescent mechanism and stability were discussed. The results indicated that diamond film may stabilize the PL wavelength and intensity of PS, and therefore could become a promising passivation film of porous Si. The PL properties of PS coated by DLC films, including hydrogenated diamond like carbon (DLC:H) film and nitrogen doped DLC film (DLC:N) were also studied in this paper. The DLC films may stabilize the PL of PS, but the photoluminescent intensity was obviously weaker than that of diamond film coated PS.展开更多
Surface passivation with acidic （NH4）2S solution is shown to be effective in improving the interfacial and electrical properties of HfOE/GaSb metal oxide semiconductor devices. Compared with control samples, the sam...Surface passivation with acidic （NH4）2S solution is shown to be effective in improving the interfacial and electrical properties of HfOE/GaSb metal oxide semiconductor devices. Compared with control samples, the samples treated with acidic （NH4）2S solution show great improvements in gate leakage current, frequency dispersion, border trap density, and interface trap density. These improvements are attributed to the enhancing passivation of the substrates, according to analysis from the perspective of chemical mechanism, X-ray photoelectron spectroscopy, and high-resolution cross-sectional transmission electron microscopy.展开更多
The electrochemical behavior of the medical Stainless steel 317L which is used as in vivo fixation materials has been investigated at different passivated states in several candidate-testing solutions. The potentiodyn...The electrochemical behavior of the medical Stainless steel 317L which is used as in vivo fixation materials has been investigated at different passivated states in several candidate-testing solutions. The potentiodynamic scanning polarizaion technique was employed to measure the polarizaion curves of 317L in 0.9%NaCl solution at 37℃. The results showed that the electrochemical behaviorin 0.9% NaCl solution at 37℃ and in 2% NaCl solotion at 30℃ can be better used to detect and evaluate passivated states and corrosionresistance of 317L. In addition,the pitting potential Eb can be used as a criterion and itS lower limit could be 0.85 V(SEC) for this system.展开更多
Halide perovskite single crystals(SCs)have attracted much attention for their application in high-performance x-ray detectors owing to their desirable properties,including low defect density,high mobility–lifetime pr...Halide perovskite single crystals(SCs)have attracted much attention for their application in high-performance x-ray detectors owing to their desirable properties,including low defect density,high mobility–lifetime product(μτ),and long carrier diffusion length.However,suppressing the inherent defects in perovskites and overcoming the ion migration primarily caused by these defects remains a challenge.This study proposes a facile process for dipping Cs0.05FA0.9MA0.05PbI3 SCs synthesized by a solution-based inverse temperature crystallization method into a 2-phenylethylammonium iodide(PEAI)solution to reduce the number of defects,inhibit ion migration,and increase x-ray sensitivity.Compared to conventional spin coating,this simple dipping process forms a two-dimensional PEA2PbI4 layer on all SC surfaces without further treatment,effectively passivating all surfaces of the inherently defective SCs and minimizing ion migration.As a result,the PEAI-treated perovskite SC-based x-ray detector achieves a record x-ray sensitivity of 1.3×10^(5)μC Gyair^(-1) cm^(-2) with a bias voltage of 30 V at realistic clinical dose rates of 1–5 mGy s^(-1)(peak potential of 110 kVp),which is 6 times more sensitive than an untreated SC-based detector and 3 orders of magnitude more sensitive than a commercialα-Se-based detector.Furthermore,the PEAI-treatedperovskite SC-based x-ray detector exhibits a low detection limit(73 nGy s^(-1)),improved x-ray response,and clear x-ray images by a scanning method,highlighting the effectiveness of the PEAI dipping approach for fabricating next-generation x-ray detectors.展开更多
LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)with a spinel crystal structure presents a compelling avenue towards the development of economic cobalt-free and high voltage(~5 V)lithium-ion batteries.Nevertheless,the elevated operation...LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)with a spinel crystal structure presents a compelling avenue towards the development of economic cobalt-free and high voltage(~5 V)lithium-ion batteries.Nevertheless,the elevated operational voltage of LNMO gives rise to pronounced interfacial interactions between the distorted surface lattices characterized by Jahn-Teller(J-T)distortions and the electrolyte constituents.Herein,a localized crystallized coherent LaNiO_(3) and surface passivated Li_(3)PO_(4) layer is deposited on LNMO via a one-step calcination process.As evidenced by transmission electron microscopy(TEM),time-of-flight secondary ion mass spectrometry(ToF-SIMS)and density functional theory(DFT)calculation,the epitaxial growth of LaNiO_(3) along the LNMO lattice can effectively stabilize the structure and inhibit irreversible phase transitions,and the Li_(3)PO_(4) surface coating can prevent the chemical reaction between HF and transition metals without sacrificing the electrochemical activity.In addition,the ionic conductive Li_(3)PO_(4) and atomic wetting inter-layer enables fast charge transfer transport property.Consequently,the LNMO material enabled by the lattice bonding and surface passivating features,demonstrates high performance at high current densities and good capacity retention during long-term test.The rational design of interface coherent engineering and surface coating layers of the LNMO cathode material offers a new perspective for the practical application of high-voltage lithium-ion batteries.展开更多
Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these...Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.62174079)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2404006)Science,Technology and Innovation Commission of Shenzhen Municipality(Grant No.JCYJ20220530113015035)。
文摘CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significantly enhances the photophysical property of CdSe NPLs.Laser spectroscopy techniques reveal suppressed electronic and hole trapping at lateral surfaces,leading to a 4.2-fold increase in photoluminescence quantum yield and a shortened emission lifetime from13.5 to 4.8 ns.In addition,amplified spontaneous emission is achieved under nanosecond pulse pumping,with thresholds of0.75 to 0.16 mJ/cm^(2)for CdSe and CdSe/CdSeS NPLs,respectively.By integrating CdSe/CdSeS NPLs with high-refractiveindex SiO2scatters,coherent random lasing is realized at a threshold of 0.21 mJ/cm^(2).These findings highlight the critical role of lateral surface passivation in optimizing optical gain and pave the way for low-cost,multifunctional nanophotonic devices.
基金supported by the National Natural Science Foundation of China(Nos.62025403 and U23A20354)the Natural Science Foundation of Zhejiang Province(LD22E020001)+1 种基金“Pioneer”and“Leading Goose”R&D Program of Zhejiang(2022C01215,2024C01055)the Fundamental Research Funds for the Central Universities(226-2022-00200).
文摘Nowadays,a stack of heavily doped polysilicon(poly-Si)and tunnel oxide(SiO_(x))is widely employed to improve the passivation performance in n-type tunnel oxide passivated contact(TOPCon)silicon solar cells.In this case,it is critical to develop an in-line advanced fabrication process capable of producing high-quality tunnel SiO_(x).Herein,an in-line ozone-gas oxidation(OGO)process to prepare the tunnel SiO_(x) is proposed to be applied in n-type TOPCon solar cell fabrication,which has obtained better performance compared with previously reported in-line plasma-assisted N2O oxidation(PANO)process.In order to explore the underlying mechanism,the electrical properties of the OGO and PANO tunnel SiO_(x) are analyzed by deep-level transient spectroscopy technology.Notably,continuous interface states in the band gap are detected for OGO tunnel SiO_(x),with the interface state densities(D_(it))of 1.2×10^(12)–3.6×10^(12) cm^(-2) eV^(-1) distributed in Ev+(0.15–0.40)eV,which is significantly lower than PANO tunnel SiO_(x).Furthermore,X-ray photoelectron spectroscopy analysis indicate that the percentage of SiO_(2)(Si^(4+))in OGO tunnel SiO_(x) is higher than which in PANO tunnel SiO_(x).Therefore,we ascribe the lower D_(it) to the good inhibitory effects on the formation of low-valent silicon oxides during the OGO process.In a nutshell,OGO tunnel SiO_(x) has a great potential to be applied in n-type TOPCon silicon solar cell,which may be available for global photovoltaics industry.
基金supported financially by the Basic Science Innovation Program of Shenyang National Laboratory for Materials Science (Nos.Y4N56R1161 and Y5N56F2161)the National Key Research and Development Program of China (No.2017YFB0406300)+2 种基金the Science and Technology Plan of Guangdong Province (Nos.2014B090907002 and 2017B090907004)the China Postdoctoral Science Foundation (No.2018M631461)the Science and Technology Plan of Shenzhen City (No.JCYJ20170412171554022)
文摘Passivated niobium/nitrogen(Nb-N) p-n co-doped zinc oxide nanoparticles were created by a simple precipitation process with in-situ self-formed NaCl "cage" to confine the nanoparticle growth followed by the heat treatment in a flow of ammonia gas. Enhanced optical absorbance into the visible light region was observed in the Nb/N co-doped ZnO nanoparticle photocatalyst due to the Nb/N co-doping effect.It demonstrated a largely enhanced photocatalytic performance in the disinfection of Escherichia coli bacteria under visible light illumination, which could be attributed to the passivated co-doping of NbN to suppress the photogenerated charge carrier recombination on dopants. This robust approach for passivated p-n co-doping may also be applied to other material systems for a wide range of technical applications.
基金supported by the National Natural Science Foundation of China(No.61504155)。
文摘Mono-crystalline silicon solar cells with a passivated emitter rear contact(PERC)configuration have attracted extensive attention from both industry and scientific communities.A record efficiency of 24.06%on p-type silicon wafer and mass production efficiency around 22%have been demonstrated,mainly due to its superior rear side passivation.In this work,the PERC solar cells with a p-type silicon wafer were numerically studied in terms of the surface passivation,quality of silicon wafer and metal electrodes.A rational way to achieve a 24%mass-production efficiency was proposed.Free energy loss analyses were adopted to address the loss sources with respect to the limit efficiency of 29%,which provides a guideline for the design and manufacture of a high-efficiency PERC solar cell.
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2014AA032602the National Natural Science Foundation of China under Grant Nos 61474115 and 61501421
文摘Surface leakage currents of A1GaN/GaN high electron mobility transistors are investigated by utilizing a circular double-gate structure to eliminate the influence of mesa leakage current. Different mechanisms are found under various passivation conditions. The mechanism of the surface leakage current with AI2 03 passivation follows the two-dimensional variable range hopping model, while the mechanism of the surface leakage current with SiN passivation follows the Frenkel-Poole trap assisted emission. Two trap levels are found in the trap-assisted emission. One trap level has a barrier height of 0.22eV for the high electric field, and the other trap level has a barrier height of 0.12eV for the low electric field.
基金Project supported by the State Key Program of National Natural Science Foundation of China (Grant No. 60736033)
文摘This paper investigates the impact of electrical degradation and current collapse on different thickness SiNx passivated AlGaN/GaN high electron mobility transistors. It finds that higher thickness SiNx passivation can significantly improve the high-electric-field reliability of a device. The degradation mechanism of the SiNx passivation layer under ON-state stress has also been discussed in detail. Under the ON-state stress, the strong electric-field led to degradation of SiNx passivation located in the gate-drain region. As the thickness of SiNx passivation increases, the density of the surface state will be increased to some extent. Meanwhile, it is found that the high NH3 flow in the plasma enhanced chemical vapour deposition process could reduce the surface state and suppress the current collapse.
文摘Based on analysis of electrochemical machining ( ECM) process and application of finite ele- ment technique ( FET) , a method of tool design is presented which can be used in ECM with passivated electrolyte. As a result of specific treatment to boundary conditions, this method needs much less com- puting time and memory space. It has been shown that the theoretical results correspond well with the experimental ones .
基金Project supported by the State Key Program of National Natural Science Foundation of China (Grant No 60736033)the State Key Development Program (973 Program) for Basic Research of China (Grant No 513270407)the Advanced Research Foundation of China (Grant Nos 51311050112, 51308030102 and 51308040301)
文摘AlGaN/GaN high electron mobility transistors （HEMTs） are fabricated by employing SiN passivation, this paper investigates the degradation due to the high-electric-field stress. After the stress, a recoverable degradation has been found, consisting of the decrease of saturation drain current IDsat, maximal transconductance gm, and the positive shift of threshold voltage VTH at high drain-source voltage VDS. The high-electric-field stress degrades the electric characteristics of AlGaN/GaN HEMTs because the high field increases the electron trapping at the surface and in AlGaN barrier layer. The SiN passivation of AlGaN/GaN HEMTs decreases the surface trapping and 2DEC depletion a little during the high-electric-field stress. After the hot carrier stress with VDS = 20 V and VGS= 0 V applied to the device for 104 sec, the SiN passivation decreases the stress-induced degradation of IDsat from 36% to 30%. Both on-state and pulse-state stresses produce comparative decrease of IDsat, which shows that although the passivation is effective in suppressing electron trapping in surface states, it does not protect the device from high-electric-field degradation in nature. So passivation in conjunction with other technological solutions like cap layer, prepassivation surface treatments, or field-plate gate to weaken high-electric-field degradation should be adopted.
基金Project supported by the National Key R&D Program of China(Grant Nos.2016YFB0401702 and 2017YFE0120400)the National Natural Science Foundation of China(Grant Nos.62005114,62005115,and 61875082)+5 种基金Key-Area Research and Development Program of Guangdong Province,China(Grant Nos.2019B010925001 and 2019B010924001)Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting(Grant No.2017KSYS007)Natural Science Foundation of Guangdong Province,China(Grant No.2017B030306010)Guangdong Basic and Applied Basic Research Foundation,China(Grant No.2019A1515110437)Shenzhen Peacock Team Project(Grant No.KQTD2016030111203005)High Level University Fund of Guangdong Province,China(Grant No.G02236004).
文摘In blue quantum dot light emitting diodes(QLEDs),electron injection is insufficient,which would degrade device efficiency and stability.Herein,we employ chlorine passivated ZnO nanoparticles as electron transport layer to facilitate electron injection into QDs effectively.Moreover,it suppresses exciton quenching at the QD/ZnO interface by blocking charge transfer channel.As a result,the maximum external quantum efficiency of blue QLED was increased from 2.55%to 4.60%,and the operation lifetime of blue QLED was nearly 4 times longer than that of the control device.Our work indicates that election injection plays an important role in blue QLED efficiency and stability.
基金supported by the National Natural Science Foundation of China(Grant No.11574261)the Natural Science Foundation of Hebei Province,China(Grant No.A2021203030).
文摘Based on the transport theory and the polarization relaxation model,the effects of hydrogen and hydroxyl passivation on the conductivity and dielectric properties of silicon carbide nanowires(SiCNWs)with different sizes are numerically simulated.The results show that the variation trend of conductivity and band gap of passivated SiCNWs are opposite to the scenario of the size effect of bare SiCNWs.Among the influencing factors of conductivity,the carrier concentration plays a leading role.In the dielectric properties,the bare SiCNWs have a strong dielectric response in the blue light region,while passivated SiCNWs show a more obvious dielectric response in the far ultraviolet-light region.In particular,hydroxyl passivation produces a strong dielectric relaxation in the microwave band,indicating that hydroxyl passivated SiCNWs have a wide range of applications in electromagnetic absorption and shielding.
基金The project was financially supported by the State Key Laboratory for Corrosion and Protection of China.
文摘The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole was investigated by salt spraying test and electrochemical methods in artificial Ringer＇s solution. The results showed that after benzotriazole passivation, the corrosion resistance of the Cu-Zn-Al shape memory alloy was improved evidently. The anodic polarization current density of the passivated alloy decreased, the mass loss reduced, the anodic passivation accelerated, the anodic active dissolution was inhibited effectively, and the surface tarnishing was reswained. Infrared reflection spectrum test showed that Cu（Ⅰ）-benzotriazole or Cu（Ⅱ）-benzotriazole complex layer was formed on the surface of the Cu-Zn-Al shape memory alloy after passivation. This layer appeared plane, well adhesion, and presented homogeneous golden metallic luster. The corrosion resistance of the Cu-Zn-Al shape memory alloy passivated by benzotriazole is improved for the formation of an electrochemical stable baffle layer on passivated surface. This layer separates the metal substrate from the outside corrosion medium effectively and retards the corrosion process of dezincification.
基金supported by the Talent Fund of Beijing Jiaotong University (No.2019RC058)the National Natural Science Foundation of China (Nos.62205013,62075009,62275013,and 12274020)。
文摘The development of tin-based devices with low toxicity is critical for the commercial viability of perovskite solar cells.However because tin halide is a stronger Lewis acid,its crystallization rate is extremely fast,resulting in the formation of numerous defects that affect the device performance of tin-based perovskite solar cells.Herein,propylamine hydrobromide(PABr)was added to the perovskite precursor solution as an additive to passivate defects and fabricate more uniform and dense perovskite films.Because propylamine cations are too large to enter the perovskite lattices,they only exist at the grain boundary to passivate surface defects and promote crystal growth in a preferred orientation.The PABr additive raises the average short-circuit current density from 19.45 to 25.47 mA·cm^(-2)by reducing carrier recombination induced by defects.Furthermore,the device’s long-term illumination stability is improved after optimization,and the hysteresis effect is negligible.The addition of PABr results in a power conversion efficiency of 9.35%.
基金Funded by the National Natural Science Foundation of China(61366004)the Research Fund for the Doctoral Program of Higher Education(20123601110006)the Jiangxi Provincial Department of Education(KJLD13008)
文摘In order to enhance the p-type doping concentration in the LBSF, boron was added into the aluminum paste and boron doped local back surface field（B-LBSF） was successfully fabricated in this work. Through boron doping in the LBSF, much higher doping concentration was observed for the B-LBSF over the Al-LBSF. Higher doping concentration in the LBSF is expected to lead to better rear passivation and lower rear contact resistance. Based on one thousand pieces of solar cells for each type, it was found that the rear passivated crystalline silicon solar cells with B-LBSF showed statistical improvement in their photovoltaic properties over those with Al-LBSF.
基金the National Natural Science Foundation of China(NSFC No.51571051)Science and Technology Research Fund of Liaoning Province,Department of Education(Nos.L2016008,L2017LQN026)+1 种基金Doctor Research Startup Fund of Liaoning Province(No.201601336)Scientific Research Cultivation Fund of LSHU(No.2016PY-024).
文摘The interaction between Sn and passivated stainless steel was evaluated through an easy chromaticity approach.The microstructure of Fe-Sn intermetallics(IMCs)was observed,and their growth was inspected at differenf time after the in teract io n.The oxide film on stainless steel exposed in air locally delayed IMC growth,and the chemically passivated film protected stainless steel from Fe-Sn compound formation.To investigate the interaction mechanism,the integrity of passivated films grown on stainless steel was evaluated by chromogenic inspection.The interaction extern was related to colour measurement a*.Results indicated that the measured value of a*from the inspection decreased with the increasing exposure time,and a minimum a*value was found in chemically passivated samples.The tendency of the colour measureme was consistent with the effect of passive film on IMC growth.The in terfacial reaction of passivated stainless steel with Sn was illustrated based on the integrity of the passive films.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.60277024)Rising Star Project of Shanghai(No.02QE14018)Shanghai Foundation of Applied Materials Research&Development(0307).
文摘Surface passivation methods for porous Si (PS) surfaces, i.e., depositing diamond film or diamond-like carbon (DLC) film on PS surfaces, were attempted. Two emission bands, weak blue band and strong red band existed in the PL spectrum of diamond film coated on PS, were discovered by the photoluminescence measurements. The luminescent mechanism and stability were discussed. The results indicated that diamond film may stabilize the PL wavelength and intensity of PS, and therefore could become a promising passivation film of porous Si. The PL properties of PS coated by DLC films, including hydrogenated diamond like carbon (DLC:H) film and nitrogen doped DLC film (DLC:N) were also studied in this paper. The DLC films may stabilize the PL of PS, but the photoluminescent intensity was obviously weaker than that of diamond film coated PS.
基金supported by the State Key Development Program for Basic Research of China(Grant No.2011CBA00602)the Major Project of the NationalScience and Technology of China(Grant No.2011ZX02708-002)
文摘Surface passivation with acidic （NH4）2S solution is shown to be effective in improving the interfacial and electrical properties of HfOE/GaSb metal oxide semiconductor devices. Compared with control samples, the samples treated with acidic （NH4）2S solution show great improvements in gate leakage current, frequency dispersion, border trap density, and interface trap density. These improvements are attributed to the enhancing passivation of the substrates, according to analysis from the perspective of chemical mechanism, X-ray photoelectron spectroscopy, and high-resolution cross-sectional transmission electron microscopy.
文摘The electrochemical behavior of the medical Stainless steel 317L which is used as in vivo fixation materials has been investigated at different passivated states in several candidate-testing solutions. The potentiodynamic scanning polarizaion technique was employed to measure the polarizaion curves of 317L in 0.9%NaCl solution at 37℃. The results showed that the electrochemical behaviorin 0.9% NaCl solution at 37℃ and in 2% NaCl solotion at 30℃ can be better used to detect and evaluate passivated states and corrosionresistance of 317L. In addition,the pitting potential Eb can be used as a criterion and itS lower limit could be 0.85 V(SEC) for this system.
基金Agency for Defense Development,Grant/Award Number:UI220006TDDefense Acquisition Program Administration(DAPA),Grant/Award Number:912765601Korea Institute of Energy Technology Evaluation and Planning,Grant/Award Number:RS-2023-00237035。
文摘Halide perovskite single crystals(SCs)have attracted much attention for their application in high-performance x-ray detectors owing to their desirable properties,including low defect density,high mobility–lifetime product(μτ),and long carrier diffusion length.However,suppressing the inherent defects in perovskites and overcoming the ion migration primarily caused by these defects remains a challenge.This study proposes a facile process for dipping Cs0.05FA0.9MA0.05PbI3 SCs synthesized by a solution-based inverse temperature crystallization method into a 2-phenylethylammonium iodide(PEAI)solution to reduce the number of defects,inhibit ion migration,and increase x-ray sensitivity.Compared to conventional spin coating,this simple dipping process forms a two-dimensional PEA2PbI4 layer on all SC surfaces without further treatment,effectively passivating all surfaces of the inherently defective SCs and minimizing ion migration.As a result,the PEAI-treated perovskite SC-based x-ray detector achieves a record x-ray sensitivity of 1.3×10^(5)μC Gyair^(-1) cm^(-2) with a bias voltage of 30 V at realistic clinical dose rates of 1–5 mGy s^(-1)(peak potential of 110 kVp),which is 6 times more sensitive than an untreated SC-based detector and 3 orders of magnitude more sensitive than a commercialα-Se-based detector.Furthermore,the PEAI-treatedperovskite SC-based x-ray detector exhibits a low detection limit(73 nGy s^(-1)),improved x-ray response,and clear x-ray images by a scanning method,highlighting the effectiveness of the PEAI dipping approach for fabricating next-generation x-ray detectors.
基金supported by the National Natural Science Foundation of China(Nos.22209075,12004145)the Key Science and Technology Plan Project of Ji’an City(No.20211-015311)the Natural Science Foundation of Jiangsu Province(No.BK20200800).
文摘LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)with a spinel crystal structure presents a compelling avenue towards the development of economic cobalt-free and high voltage(~5 V)lithium-ion batteries.Nevertheless,the elevated operational voltage of LNMO gives rise to pronounced interfacial interactions between the distorted surface lattices characterized by Jahn-Teller(J-T)distortions and the electrolyte constituents.Herein,a localized crystallized coherent LaNiO_(3) and surface passivated Li_(3)PO_(4) layer is deposited on LNMO via a one-step calcination process.As evidenced by transmission electron microscopy(TEM),time-of-flight secondary ion mass spectrometry(ToF-SIMS)and density functional theory(DFT)calculation,the epitaxial growth of LaNiO_(3) along the LNMO lattice can effectively stabilize the structure and inhibit irreversible phase transitions,and the Li_(3)PO_(4) surface coating can prevent the chemical reaction between HF and transition metals without sacrificing the electrochemical activity.In addition,the ionic conductive Li_(3)PO_(4) and atomic wetting inter-layer enables fast charge transfer transport property.Consequently,the LNMO material enabled by the lattice bonding and surface passivating features,demonstrates high performance at high current densities and good capacity retention during long-term test.The rational design of interface coherent engineering and surface coating layers of the LNMO cathode material offers a new perspective for the practical application of high-voltage lithium-ion batteries.
基金supported by the Fundamental Research Funds for Central Public Welfare Research Institute,No.2020CZ-5(to WS and GS)the National Natural Science Foundation of China,No.31970970(to JSR)Fundamental Research Funds for the Central Universities,No.YWF-23-YG-QB-010(to JSR)。
文摘Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.
