A method of electroless silver deposition on silver activated p-type silicon（111） wafer was proposed. The silver seed layer was deposited firstly on the wafer in the solution of 0.005 mol/L AgNO3 ＋0.06 mol/L HE The...A method of electroless silver deposition on silver activated p-type silicon（111） wafer was proposed. The silver seed layer was deposited firstly on the wafer in the solution of 0.005 mol/L AgNO3 ＋0.06 mol/L HE Then the silver film was electrolessly deposited on the seed layer in the electroless bath of AgNO3＋NH3＋acetic acid＋NH2NH2 （pH 10.2）. The morphology of the seed layer and the silver films prepared under the condition of the different bath composition was compared by atomic force microscopy. The reflectance of the silver films with different thickness was characterized by Fourier transform infrared spectrometry. The experimental results indicate that the seed layer possesses excellent catalytic activity toward electroless silver deposition and rotating of the silicon wafer during the electroless silver deposition could lead to formation of the smoother silver film.展开更多
For large diarneter silicon single crystal, the solid-liquid growth interface is necessary to be a coneaveshape with a certain radius range. If the change of the radius of growth interface is not in this limited range...For large diarneter silicon single crystal, the solid-liquid growth interface is necessary to be a coneaveshape with a certain radius range. If the change of the radius of growth interface is not in this limited range,the growth of DF (dislocation free) sinsle crystal is very difficult. The growth of FZ-Si single crystal was stud-ied. It is found that the growth speed ( 2. 5～2. 7 mm/min) as well as the rotation speed (3. 5 r/min) for theΦ100 mm crystal can be smaller . comparing with the Φ76. 2 mm crystal with the same coil. In order to satisfythe demand of large diameter crystal . the size of coil should be large enough, and the shape should satisfy theneed of the growth interface of crystal. With the increasing of diameter , the heating power , the anode voltageand the strength of electric field within the coil should be increased, and Ar pressure in surrounding circum-stance should also be higher , from 1. 96 × 1 0￣4 Pa to 4. 90 × 10￣4 Pa.According to the above growth factors, three rods of Φ100 mm FZ-Si single crystal were grown success-fully , the weights are 8～10 kg. When the diameter of crystal cone is increased to a limited size, “remeltingarca” will occur in the surface of the crystal , which cause a failure of growing DF crystal , this reason may bethat the recrystalliztion direction has been chansed , as it does.展开更多
Hydrogenated amorphous silicon oxide(a-SiOx:H) is an attractive passivation material to suppress epitaxial growth and reduce the parasitic absorption loss in silicon heterojunction(SHJ) solar cells. In this paper, a-S...Hydrogenated amorphous silicon oxide(a-SiOx:H) is an attractive passivation material to suppress epitaxial growth and reduce the parasitic absorption loss in silicon heterojunction(SHJ) solar cells. In this paper, a-SiOx:H layers on different orientated c-Si substrates are fabricated. An optimal effective lifetime(τ(eff)) of 4743 μs and corresponding implied opencircuit voltage(iV(oc)) of 724 mV are obtained on〈100〉-orientated c-Si wafers. While τ(eff) of 2429 μs and iV_(oc) of 699 mV are achieved on 111-orientated substrate. The FTIR and XPS results indicate that the a-SiOx:H network consists of SiOx(Si-rich), Si–OH, Si–O–SiHx, SiO2 ≡ Si–Si, and O3 ≡ Si–Si. A passivation evolution mechanism is proposed to explain the different passivation results on different c-Si wafers. By modulating the a-SiOx:H layer, the planar silicon heterojunction solar cell can achieve an efficiency of 18.15%.展开更多
The energy deposition for low-energy electron beam on Si-SiO2 models was calculated by Monte-Carlo method. Making use of electron paramagnetic resonance (EPR) technique, an investigation of the effect of dopant type a...The energy deposition for low-energy electron beam on Si-SiO2 models was calculated by Monte-Carlo method. Making use of electron paramagnetic resonance (EPR) technique, an investigation of the effect of dopant type and concentration on EPR signal variations was carried out by using p-type and n-type silicon(111) wafers with concentration of 1×1015 cm 3 and 1×1017 cm 3, and the changes of intensity of defect paramagnetic centers before and after irradiation of electrons were compared. The chemical states of Si-SiO2 structure were determined by X-ray photoelectrons spectroscopy(XPS). The results clearly indicate that the effects of dopant variations (type and concentration) are of obvious difference. Compared with p-type silicon, n-type silicon, especially with higher dopant concentration, tends to produce defect at the interface under low-energy electron irradiation with certain flux, which arises from the hole trapped on a nonbridging oxygen atom bonded to P. It is represented in the form of distinct changes of POHC intensity and P2P spectrum. According to the theoretical and experimental data, the relationship among electron energy deposition, chemical states of element Si at SiO2 -Si(111) interface, and radiation effect were analyzed and discussed.展开更多
1. Introduction Thermal oxidation of silicon monocrystalis a very important process in fabricationof metal--oxide--semiconductor (MOS) devices.In recent years it has received great atten-tion. Various proposals for ox...1. Introduction Thermal oxidation of silicon monocrystalis a very important process in fabricationof metal--oxide--semiconductor (MOS) devices.In recent years it has received great atten-tion. Various proposals for oxidation modeshave been made by different groups.Now most of the authors working in thisfield hold the view that the oxidation rateof silicon obeys a typical parabolic rule,that is, the oxidation reaction is controlledby diffusion. The experimental data inRef. can be taken and a kinetic curve展开更多
The effect of driving frequency on the structure of silicon grown on Ag（111） film is investigated, which was prepared by using the very-high-frequency（VHF）（40.68 MHz and 60 MHz） magnetron sputtering. The energy ...The effect of driving frequency on the structure of silicon grown on Ag（111） film is investigated, which was prepared by using the very-high-frequency（VHF）（40.68 MHz and 60 MHz） magnetron sputtering. The energy and flux density of the ions impinging on the substrate are also analyzed. It is found that for the 60-MHz VHF magnetron sputtering, the surface of silicon on Ag（111） film exhibits a small cone structure, similar to that of Ag（111） film substrate, indicating a better microstructure continuity. However, for the 40.68-MHz VHF magnetron sputtering, the surface of silicon on Ag（111） film shows a hybrid structure of hollowed-cones and hollowed-particles, which is completely different from that of Ag（111）film. The change of silicon structure is closely related to the differences in the ion energy and flux density controlled by the driving frequency of sputtering.展开更多
Silicon(Si)has emerged as a potent anode material for lithium-ion batteries(LIBs),but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation,leading to material...Silicon(Si)has emerged as a potent anode material for lithium-ion batteries(LIBs),but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation,leading to material pulverization and capacity degradation.Recent research on nanostructured Si aims to mitigate volume expansion and enhance electrochemical performance,yet still grapples with issues like pulverization,unstable solid electrolyte interface(SEI)growth,and interparticle resistance.This review delves into innovative strategies for optimizing Si anodes’electrochemical performance via structural engineering,focusing on the synthesis of Si/C composites,engineering multidimensional nanostructures,and applying non-carbonaceous coatings.Forming a stable SEI is vital to prevent electrolyte decomposition and enhance Li^(+)transport,thereby stabilizing the Si anode interface and boosting cycling Coulombic efficiency.We also examine groundbreaking advancements such as self-healing polymers and advanced prelithiation methods to improve initial Coulombic efficiency and combat capacity loss.Our review uniquely provides a detailed examination of these strategies in real-world applications,moving beyond theoretical discussions.It offers a critical analysis of these approaches in terms of performance enhancement,scalability,and commercial feasibility.In conclusion,this review presents a comprehensive view and a forward-looking perspective on designing robust,high-performance Si-based anodes the next generation of LIBs.展开更多
The homoepitaxial growth of multilayer Si thin film on Si(111) surfaces was simulated by Monte Carlo (MC) method with realistic growth model and physical parameters. Special emphasis was placed on revealing the influe...The homoepitaxial growth of multilayer Si thin film on Si(111) surfaces was simulated by Monte Carlo (MC) method with realistic growth model and physical parameters. Special emphasis was placed on revealing the influence of the Ehrlich-Schwoebel (ES) barrier on the growth modes and morphologies. It is evident that there exists the ES barrier during multilayer Si thin film growth on Si (111) surface, which is deduced from the incomplete layer-by-layer growth process in the realistic experiments. The ES barrier EB=0.1～0.125 eV is estimated from the three-dimensional (3D) MC simulation and compared with the experimental results.展开更多
AIM:To evaluate the efficacy and safety of silicone oil(SO)as a corneal lubricant to improve visualization during vitrectomy.METHODS:Patients who underwent vitreoretinal surgery were divided into two groups.Group 1 wa...AIM:To evaluate the efficacy and safety of silicone oil(SO)as a corneal lubricant to improve visualization during vitrectomy.METHODS:Patients who underwent vitreoretinal surgery were divided into two groups.Group 1 was operated on with initial SO(Oxane 5700)as a corneal lubricant.Group 2 was operated on with initial lactated ringer’s solution(LRS)and then replaced with SO as required.Fundus clarity was scored during the surgery.Fluorescein staining was performed to determine the damage to corneal epithelium.RESULTS:Totally 114 eyes of 114 patients were included.Single SO use maintained a clear cornea and provided excellent visualization of surgical image.In group 1,the fundus clarity was grade 3 in 41/45 eyes and grade 2 in 4/45 eyes.In group 2,corneal edema frequently occurred after initial LRS use.The fundus clarity was grade 3 in 19/69 eyes,2 in 37/69 eyes and 1 in 13/69 eyes(P<0.05).SO was applied in 29 eyes of initial LRS use with subsequent corneal edema,which eliminated the corneal edema in 26 eyes.Corneal fluorescein staining score in group 1 was 0 in 28 eyes,1 in 11 eyes and 2 in 6 eyes,and 40,20 and 9,respectively,in group 2(all P>0.05).CONCLUSION:The use of SO as a corneal lubricant is effective and safe for preserving and improving corneal clarity and providing clear surgical field during vitrectomy.展开更多
Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and frag...Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.展开更多
In this paper, different steps of work and experiments that are done in order to implant nitrogen ion in silicon with the energy of 25 keV, density of 24 μA/cm2 and doses of 5 × 1013 atom/cm2, 1?× 1014 atom...In this paper, different steps of work and experiments that are done in order to implant nitrogen ion in silicon with the energy of 25 keV, density of 24 μA/cm2 and doses of 5 × 1013 atom/cm2, 1?× 1014 atom/cm2 and 1?× 1015 atom/ cm2 (according to the calculation and applying time at planting) at room temperature (in the lack of heat phase) and without annealing will be presented. The XRD analysis is done before and after planting to observe changes in the lattice and the possibility of forming a crystalline phase of silicon nitride in this case. Also, the study of changes in the lattice arrangement and AFM analysis is done to observe the topography of the surface. Besides, the investigation on surface roughness and changes caused by ion implantation on the surface and spectrophotometry analysis before and after planting due to the study of changes in optical properties are done.展开更多
As a typical two-dimensional(2D) coating material, graphene has been utilized to effectively reduce secondary electron emission from the surface. Nevertheless, the microscopic mechanism and the dominant factor of seco...As a typical two-dimensional(2D) coating material, graphene has been utilized to effectively reduce secondary electron emission from the surface. Nevertheless, the microscopic mechanism and the dominant factor of secondary electron emission suppression remain controversial. Since traditional models rely on the data of experimental bulk properties which are scarcely appropriate to the 2D coating situation, this paper presents the first-principles-based numerical calculations of the electron interaction and emission process for monolayer and multilayer graphene on silicon(111) substrate. By using the anisotropic energy loss for the coating graphene, the electron transport process can be described more realistically. The real physical electron interactions, including the elastic scattering of electron-nucleus, inelastic scattering of the electron-extranuclear electron, and electron-phonon effect, are considered and calculated by using the Monte Carlo method. The energy level transition theory-based first-principles method and the full Penn algorithm are used to calculate the energy loss function during the inelastic scattering. Variations of the energy loss function and interface electron density differences for 1 to 4 layer graphene coating Go Si are calculated, and their inner electron distributions and secondary electron emissions are analyzed. Simulation results demonstrate that the dominant factor of the inhibiting of secondary electron yield(SEY) of Go Si is to induce the deeper electrons in the internal scattering process. In contrast, a low surface potential barrier due to the positive deviation of electron density difference at monolayer Go Si interface in turn weakens the suppression of secondary electron emission of the graphene layer. Only when the graphene layer number is 3, does the contribution of surface work function to the secondary electron emission suppression appear to be slightly positive.展开更多
SiC films were prepared by heating polystyrene/Si（111） in normal pressure argon atmosphere at different temperatures. The films were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectr...SiC films were prepared by heating polystyrene/Si（111） in normal pressure argon atmosphere at different temperatures. The films were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared absorption measurements. The thicknesses of SiC films were calculated from FTIR spectra. The growth kinetics of the growth process of SiC films were investigated as well. The thicknesses of the SiC films grown for 1 h with increasing growth temperatures have different trends in the three temperature ranges： increasing slowly （1200-1250 ℃）, increasing quickly （1250- 12.70 ℃）, and decreasing （1270-1300 ℃）. The apparent activation energies of the growth process of SiC films in the three ranges were calculated to be 122.5,522.5, and -127.5 J/mol respectively. Mechanisms of the different growth processes were discussed. The relation between film thicknesses and growth temperatures indicated that the growth process was a 2D mechanism in the first range and 3D mechanism in the second range. In the third range, the thicknesses of SiC films were decreased by the volatility of Si and C atoms.展开更多
Silicon(Si)is widely used as a lithium‐ion‐battery anode owing to its high capacity and abundant crustal reserves.However,large volume change upon cycling and poor conductivity of Si cause rapid capacity decay and p...Silicon(Si)is widely used as a lithium‐ion‐battery anode owing to its high capacity and abundant crustal reserves.However,large volume change upon cycling and poor conductivity of Si cause rapid capacity decay and poor fast‐charging capability limiting its commercial applications.Here,we propose a multilevel carbon architecture with vertical graphene sheets(VGSs)grown on surfaces of subnanoscopically and homogeneously dispersed Si–C composite nanospheres,which are subsequently embedded into a carbon matrix(C/VGSs@Si–C).Subnanoscopic C in the Si–C nanospheres,VGSs,and carbon matrix form a three‐dimensional conductive and robust network,which significantly improves the conductivity and suppresses the volume expansion of Si,thereby boosting charge transport and improving electrode stability.The VGSs with vast exposed edges considerably increase the contact area with the carbon matrix and supply directional transport channels through the entire material,which boosts charge transport.The carbon matrix encapsulates VGSs@Si–C to decrease the specific surface area and increase tap density,thus yielding high first Coulombic efficiency and electrode compaction density.Consequently,C/VGSs@Si–C delivers excellent Li‐ion storage performances under industrial electrode conditions.In particular,the full cells show high energy densities of 603.5 Wh kg^(−1)and 1685.5 Wh L^(−1)at 0.1 C and maintain 80.7%of the energy density at 3 C.展开更多
Monolithic textured perovskite/silicon tandem solar cells(TSCs)are expected to achieve maximum light capture at the lowest cost,potentially exhibiting the best power conversion efficiency.However,it is challenging to ...Monolithic textured perovskite/silicon tandem solar cells(TSCs)are expected to achieve maximum light capture at the lowest cost,potentially exhibiting the best power conversion efficiency.However,it is challenging to fabricate high-quality perovskite films and preferred crystal orientation on commercially textured silicon substrates with micrometersize pyramids.Here,we introduced a bulky organic molecule(4-fluorobenzylamine hydroiodide(F-PMAI))as a perovskite additive.It is found that F-PMAI can retard the crystallization process of perovskite film through hydrogen bond interaction between F^(−)and FA^(+)and reduce(111)facet surface energy due to enhanced adsorption energy of F-PMAI on the(111)facet.Besides,the bulky molecular is extruded to the bottom and top of perovskite film after crystal growth,which can passivate interface defects through strong interaction between F-PMA+and undercoordinated Pb^(2+)/I^(−).As a result,the additive facilitates the formation of large perovskite grains and(111)preferred orientation with a reduced trap-state density,thereby promoting charge carrier transportation,and enhancing device performance and stability.The perovskite/silicon TSCs achieved a champion efficiency of 30.05%based on a silicon thin film tunneling junction.In addition,the devices exhibit excellent longterm thermal and light stability without encapsulation.This work provides an effective strategy for achieving efficient and stable TSCs.展开更多
Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few decades.In particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than t...Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few decades.In particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than the diffraction limit,making it a useful method for efficient nanomanufacturing.However,compared with the low-spatial-frequency LIPSS(LSFL),the structure size of the HSFL is smaller,and it is more easily submerged.Therefore,the formation mechanism of HSFL is complex and has always been a research hotspot in this field.In this study,regular LSFL with a period of 760 nm was fabricated in advance on a silicon surface with two-beam interference using an 800 nm,50 fs femtosecond laser.The ultrafast dynamics of HSFL formation on the silicon surface of prefabricated LSFL under single femtosecond laser pulse irradiation were observed and analyzed for the first time using collinear pump-probe imaging method.In general,the evolution of the surface structure undergoes five sequential stages:the LSFL begins to split,becomes uniform HSFL,degenerates into an irregular LSFL,undergoes secondary splitting into a weakly uniform HSFL,and evolves into an irregular LSFL or is submerged.The results indicate that the local enhancement of the submerged nanocavity,or the nanoplasma,in the prefabricated LSFL ridge led to the splitting of the LSFL,and the thermodynamic effect drove the homogenization of the splitting LSFL,which evolved into HSFL.展开更多
文摘A method of electroless silver deposition on silver activated p-type silicon（111） wafer was proposed. The silver seed layer was deposited firstly on the wafer in the solution of 0.005 mol/L AgNO3 ＋0.06 mol/L HE Then the silver film was electrolessly deposited on the seed layer in the electroless bath of AgNO3＋NH3＋acetic acid＋NH2NH2 （pH 10.2）. The morphology of the seed layer and the silver films prepared under the condition of the different bath composition was compared by atomic force microscopy. The reflectance of the silver films with different thickness was characterized by Fourier transform infrared spectrometry. The experimental results indicate that the seed layer possesses excellent catalytic activity toward electroless silver deposition and rotating of the silicon wafer during the electroless silver deposition could lead to formation of the smoother silver film.
文摘For large diarneter silicon single crystal, the solid-liquid growth interface is necessary to be a coneaveshape with a certain radius range. If the change of the radius of growth interface is not in this limited range,the growth of DF (dislocation free) sinsle crystal is very difficult. The growth of FZ-Si single crystal was stud-ied. It is found that the growth speed ( 2. 5～2. 7 mm/min) as well as the rotation speed (3. 5 r/min) for theΦ100 mm crystal can be smaller . comparing with the Φ76. 2 mm crystal with the same coil. In order to satisfythe demand of large diameter crystal . the size of coil should be large enough, and the shape should satisfy theneed of the growth interface of crystal. With the increasing of diameter , the heating power , the anode voltageand the strength of electric field within the coil should be increased, and Ar pressure in surrounding circum-stance should also be higher , from 1. 96 × 1 0￣4 Pa to 4. 90 × 10￣4 Pa.According to the above growth factors, three rods of Φ100 mm FZ-Si single crystal were grown success-fully , the weights are 8～10 kg. When the diameter of crystal cone is increased to a limited size, “remeltingarca” will occur in the surface of the crystal , which cause a failure of growing DF crystal , this reason may bethat the recrystalliztion direction has been chansed , as it does.
基金Project supported by the National Key Research and Deveopment Program of China(Grant No.2018YFB1500402)the National Natural Science Foundation of China(Grant Nos.61674084 and 61874167)+5 种基金the Fundamental Research Funds for Central Universities,Chinathe Natural Science Foundation of Tianjin City,China(Grant No.17JCYBJC41400)the Open Fund of the Key Laboratory of Optical Information Science&Technology of Ministry of Education of China(Grant No.2017KFKT014)the 111 Project,China(Grant No.B16027)the International Cooperation Base,China(Grant No.2016D01025)Tianjin International Joint Research and Development Center,China。
文摘Hydrogenated amorphous silicon oxide(a-SiOx:H) is an attractive passivation material to suppress epitaxial growth and reduce the parasitic absorption loss in silicon heterojunction(SHJ) solar cells. In this paper, a-SiOx:H layers on different orientated c-Si substrates are fabricated. An optimal effective lifetime(τ(eff)) of 4743 μs and corresponding implied opencircuit voltage(iV(oc)) of 724 mV are obtained on〈100〉-orientated c-Si wafers. While τ(eff) of 2429 μs and iV_(oc) of 699 mV are achieved on 111-orientated substrate. The FTIR and XPS results indicate that the a-SiOx:H network consists of SiOx(Si-rich), Si–OH, Si–O–SiHx, SiO2 ≡ Si–Si, and O3 ≡ Si–Si. A passivation evolution mechanism is proposed to explain the different passivation results on different c-Si wafers. By modulating the a-SiOx:H layer, the planar silicon heterojunction solar cell can achieve an efficiency of 18.15%.
基金supported by Major Foundation for Development of Science and Technology of China Academy of Engineering Physics (No. 2007A02001)
文摘The energy deposition for low-energy electron beam on Si-SiO2 models was calculated by Monte-Carlo method. Making use of electron paramagnetic resonance (EPR) technique, an investigation of the effect of dopant type and concentration on EPR signal variations was carried out by using p-type and n-type silicon(111) wafers with concentration of 1×1015 cm 3 and 1×1017 cm 3, and the changes of intensity of defect paramagnetic centers before and after irradiation of electrons were compared. The chemical states of Si-SiO2 structure were determined by X-ray photoelectrons spectroscopy(XPS). The results clearly indicate that the effects of dopant variations (type and concentration) are of obvious difference. Compared with p-type silicon, n-type silicon, especially with higher dopant concentration, tends to produce defect at the interface under low-energy electron irradiation with certain flux, which arises from the hole trapped on a nonbridging oxygen atom bonded to P. It is represented in the form of distinct changes of POHC intensity and P2P spectrum. According to the theoretical and experimental data, the relationship among electron energy deposition, chemical states of element Si at SiO2 -Si(111) interface, and radiation effect were analyzed and discussed.
文摘1. Introduction Thermal oxidation of silicon monocrystalis a very important process in fabricationof metal--oxide--semiconductor (MOS) devices.In recent years it has received great atten-tion. Various proposals for oxidation modeshave been made by different groups.Now most of the authors working in thisfield hold the view that the oxidation rateof silicon obeys a typical parabolic rule,that is, the oxidation reaction is controlledby diffusion. The experimental data inRef. can be taken and a kinetic curve
基金supported by the National Natural Science Foundation of China(Grant Nos.11675118 and 11275136)
文摘The effect of driving frequency on the structure of silicon grown on Ag（111） film is investigated, which was prepared by using the very-high-frequency（VHF）（40.68 MHz and 60 MHz） magnetron sputtering. The energy and flux density of the ions impinging on the substrate are also analyzed. It is found that for the 60-MHz VHF magnetron sputtering, the surface of silicon on Ag（111） film exhibits a small cone structure, similar to that of Ag（111） film substrate, indicating a better microstructure continuity. However, for the 40.68-MHz VHF magnetron sputtering, the surface of silicon on Ag（111） film shows a hybrid structure of hollowed-cones and hollowed-particles, which is completely different from that of Ag（111）film. The change of silicon structure is closely related to the differences in the ion energy and flux density controlled by the driving frequency of sputtering.
基金financially supported by the Jiangsu Distinguished Professors Project(No.1711510024)the funding for Scientific Research Startup of Jiangsu University(Nos.4111510015,19JDG044)+3 种基金the Jiangsu Provincial Program for High-Level Innovative and Entrepreneurial Talents Introductionthe National Natural Science Foundation of China(No.22008091)Natural Science Foundation of Guangdong Province(2023A1515010894)the Open Project of Luzhou Key Laboratory of Fine Chemical Application Technology(HYJH-2302-A).
文摘Silicon(Si)has emerged as a potent anode material for lithium-ion batteries(LIBs),but faces challenges like low electrical conductivity and significant volume changes during lithiation/delithiation,leading to material pulverization and capacity degradation.Recent research on nanostructured Si aims to mitigate volume expansion and enhance electrochemical performance,yet still grapples with issues like pulverization,unstable solid electrolyte interface(SEI)growth,and interparticle resistance.This review delves into innovative strategies for optimizing Si anodes’electrochemical performance via structural engineering,focusing on the synthesis of Si/C composites,engineering multidimensional nanostructures,and applying non-carbonaceous coatings.Forming a stable SEI is vital to prevent electrolyte decomposition and enhance Li^(+)transport,thereby stabilizing the Si anode interface and boosting cycling Coulombic efficiency.We also examine groundbreaking advancements such as self-healing polymers and advanced prelithiation methods to improve initial Coulombic efficiency and combat capacity loss.Our review uniquely provides a detailed examination of these strategies in real-world applications,moving beyond theoretical discussions.It offers a critical analysis of these approaches in terms of performance enhancement,scalability,and commercial feasibility.In conclusion,this review presents a comprehensive view and a forward-looking perspective on designing robust,high-performance Si-based anodes the next generation of LIBs.
基金Project supported by the Natural Science Foundation for Young Scientists of Zhejiang Province (RC02069)
文摘The homoepitaxial growth of multilayer Si thin film on Si(111) surfaces was simulated by Monte Carlo (MC) method with realistic growth model and physical parameters. Special emphasis was placed on revealing the influence of the Ehrlich-Schwoebel (ES) barrier on the growth modes and morphologies. It is evident that there exists the ES barrier during multilayer Si thin film growth on Si (111) surface, which is deduced from the incomplete layer-by-layer growth process in the realistic experiments. The ES barrier EB=0.1～0.125 eV is estimated from the three-dimensional (3D) MC simulation and compared with the experimental results.
基金Supported by the Shanghai Key Clinical Specialty,Shanghai Eye Disease Research Center(No.2022ZZ01003)the Science and Technology Commission of Shanghai(No.20DZ2270800).
文摘AIM:To evaluate the efficacy and safety of silicone oil(SO)as a corneal lubricant to improve visualization during vitrectomy.METHODS:Patients who underwent vitreoretinal surgery were divided into two groups.Group 1 was operated on with initial SO(Oxane 5700)as a corneal lubricant.Group 2 was operated on with initial lactated ringer’s solution(LRS)and then replaced with SO as required.Fundus clarity was scored during the surgery.Fluorescein staining was performed to determine the damage to corneal epithelium.RESULTS:Totally 114 eyes of 114 patients were included.Single SO use maintained a clear cornea and provided excellent visualization of surgical image.In group 1,the fundus clarity was grade 3 in 41/45 eyes and grade 2 in 4/45 eyes.In group 2,corneal edema frequently occurred after initial LRS use.The fundus clarity was grade 3 in 19/69 eyes,2 in 37/69 eyes and 1 in 13/69 eyes(P<0.05).SO was applied in 29 eyes of initial LRS use with subsequent corneal edema,which eliminated the corneal edema in 26 eyes.Corneal fluorescein staining score in group 1 was 0 in 28 eyes,1 in 11 eyes and 2 in 6 eyes,and 40,20 and 9,respectively,in group 2(all P>0.05).CONCLUSION:The use of SO as a corneal lubricant is effective and safe for preserving and improving corneal clarity and providing clear surgical field during vitrectomy.
基金This project was financially supported by the National Natural Science Foundation of China(31601244 and 31971843)the Guangdong Provincial Key Field Research and Development Plan Project,China(2019B020221003)the Modern Agricultural Industrial Technology System of Guangdong Province,China(2020KJ105).
文摘Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.
文摘In this paper, different steps of work and experiments that are done in order to implant nitrogen ion in silicon with the energy of 25 keV, density of 24 μA/cm2 and doses of 5 × 1013 atom/cm2, 1?× 1014 atom/cm2 and 1?× 1015 atom/ cm2 (according to the calculation and applying time at planting) at room temperature (in the lack of heat phase) and without annealing will be presented. The XRD analysis is done before and after planting to observe changes in the lattice and the possibility of forming a crystalline phase of silicon nitride in this case. Also, the study of changes in the lattice arrangement and AFM analysis is done to observe the topography of the surface. Besides, the investigation on surface roughness and changes caused by ion implantation on the surface and spectrophotometry analysis before and after planting due to the study of changes in optical properties are done.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61901360 and 12175176)the Natural Science Foundation of Shaanxi Province, China (Grant No. 2020JQ-644)the Scientific Research Projects of the Shaanxi Education Department, China (Grant No. 20JK0808)。
文摘As a typical two-dimensional(2D) coating material, graphene has been utilized to effectively reduce secondary electron emission from the surface. Nevertheless, the microscopic mechanism and the dominant factor of secondary electron emission suppression remain controversial. Since traditional models rely on the data of experimental bulk properties which are scarcely appropriate to the 2D coating situation, this paper presents the first-principles-based numerical calculations of the electron interaction and emission process for monolayer and multilayer graphene on silicon(111) substrate. By using the anisotropic energy loss for the coating graphene, the electron transport process can be described more realistically. The real physical electron interactions, including the elastic scattering of electron-nucleus, inelastic scattering of the electron-extranuclear electron, and electron-phonon effect, are considered and calculated by using the Monte Carlo method. The energy level transition theory-based first-principles method and the full Penn algorithm are used to calculate the energy loss function during the inelastic scattering. Variations of the energy loss function and interface electron density differences for 1 to 4 layer graphene coating Go Si are calculated, and their inner electron distributions and secondary electron emissions are analyzed. Simulation results demonstrate that the dominant factor of the inhibiting of secondary electron yield(SEY) of Go Si is to induce the deeper electrons in the internal scattering process. In contrast, a low surface potential barrier due to the positive deviation of electron density difference at monolayer Go Si interface in turn weakens the suppression of secondary electron emission of the graphene layer. Only when the graphene layer number is 3, does the contribution of surface work function to the secondary electron emission suppression appear to be slightly positive.
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.50672095）.
文摘SiC films were prepared by heating polystyrene/Si（111） in normal pressure argon atmosphere at different temperatures. The films were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared absorption measurements. The thicknesses of SiC films were calculated from FTIR spectra. The growth kinetics of the growth process of SiC films were investigated as well. The thicknesses of the SiC films grown for 1 h with increasing growth temperatures have different trends in the three temperature ranges： increasing slowly （1200-1250 ℃）, increasing quickly （1250- 12.70 ℃）, and decreasing （1270-1300 ℃）. The apparent activation energies of the growth process of SiC films in the three ranges were calculated to be 122.5,522.5, and -127.5 J/mol respectively. Mechanisms of the different growth processes were discussed. The relation between film thicknesses and growth temperatures indicated that the growth process was a 2D mechanism in the first range and 3D mechanism in the second range. In the third range, the thicknesses of SiC films were decreased by the volatility of Si and C atoms.
基金Guangdong Basic and Applied Basic Research Foundation,Grant/Award Number:2020A1515110762Research Grants Council of the Hong Kong Special Administrative Region,China,Grant/Award Number:R6005‐20Shenzhen Key Laboratory of Advanced Energy Storage,Grant/Award Number:ZDSYS20220401141000001。
文摘Silicon(Si)is widely used as a lithium‐ion‐battery anode owing to its high capacity and abundant crustal reserves.However,large volume change upon cycling and poor conductivity of Si cause rapid capacity decay and poor fast‐charging capability limiting its commercial applications.Here,we propose a multilevel carbon architecture with vertical graphene sheets(VGSs)grown on surfaces of subnanoscopically and homogeneously dispersed Si–C composite nanospheres,which are subsequently embedded into a carbon matrix(C/VGSs@Si–C).Subnanoscopic C in the Si–C nanospheres,VGSs,and carbon matrix form a three‐dimensional conductive and robust network,which significantly improves the conductivity and suppresses the volume expansion of Si,thereby boosting charge transport and improving electrode stability.The VGSs with vast exposed edges considerably increase the contact area with the carbon matrix and supply directional transport channels through the entire material,which boosts charge transport.The carbon matrix encapsulates VGSs@Si–C to decrease the specific surface area and increase tap density,thus yielding high first Coulombic efficiency and electrode compaction density.Consequently,C/VGSs@Si–C delivers excellent Li‐ion storage performances under industrial electrode conditions.In particular,the full cells show high energy densities of 603.5 Wh kg^(−1)and 1685.5 Wh L^(−1)at 0.1 C and maintain 80.7%of the energy density at 3 C.
基金the financial support of National Key Research and Development Program of China(Grant No.2023YFB4202503)the Joint Funds of the National Natural Science Foundation of China(Grant No.U21A2072)+7 种基金Natural Science Foundation of China(Grant No.62274099)Natural Science Foundation of Tianjin(No.20JCQNJC02070)China Postdoctoral Science Foundation(No.2020T130317)the Overseas Expertise Introduction Project for Discipline Innovation of Higher Education of China(Grant No.B16027)Tianjin Science and Technology Project(Grant No.18ZXJMTG00220)Key R&D Program of Hebei Province(No.19214301D)provided by the Haihe Laboratory of Sustainable Chemical Transformationsthe Fundamental Research Funds for the Central Universities,Nankai University.
文摘Monolithic textured perovskite/silicon tandem solar cells(TSCs)are expected to achieve maximum light capture at the lowest cost,potentially exhibiting the best power conversion efficiency.However,it is challenging to fabricate high-quality perovskite films and preferred crystal orientation on commercially textured silicon substrates with micrometersize pyramids.Here,we introduced a bulky organic molecule(4-fluorobenzylamine hydroiodide(F-PMAI))as a perovskite additive.It is found that F-PMAI can retard the crystallization process of perovskite film through hydrogen bond interaction between F^(−)and FA^(+)and reduce(111)facet surface energy due to enhanced adsorption energy of F-PMAI on the(111)facet.Besides,the bulky molecular is extruded to the bottom and top of perovskite film after crystal growth,which can passivate interface defects through strong interaction between F-PMA+and undercoordinated Pb^(2+)/I^(−).As a result,the additive facilitates the formation of large perovskite grains and(111)preferred orientation with a reduced trap-state density,thereby promoting charge carrier transportation,and enhancing device performance and stability.The perovskite/silicon TSCs achieved a champion efficiency of 30.05%based on a silicon thin film tunneling junction.In addition,the devices exhibit excellent longterm thermal and light stability without encapsulation.This work provides an effective strategy for achieving efficient and stable TSCs.
基金supports from the National Natural Science Foundation of China(12074123,12174108)the Foundation of‘Manufacturing beyond limits’of Shanghai‘Talent Program'of Henan Academy of Sciences.
文摘Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few decades.In particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than the diffraction limit,making it a useful method for efficient nanomanufacturing.However,compared with the low-spatial-frequency LIPSS(LSFL),the structure size of the HSFL is smaller,and it is more easily submerged.Therefore,the formation mechanism of HSFL is complex and has always been a research hotspot in this field.In this study,regular LSFL with a period of 760 nm was fabricated in advance on a silicon surface with two-beam interference using an 800 nm,50 fs femtosecond laser.The ultrafast dynamics of HSFL formation on the silicon surface of prefabricated LSFL under single femtosecond laser pulse irradiation were observed and analyzed for the first time using collinear pump-probe imaging method.In general,the evolution of the surface structure undergoes five sequential stages:the LSFL begins to split,becomes uniform HSFL,degenerates into an irregular LSFL,undergoes secondary splitting into a weakly uniform HSFL,and evolves into an irregular LSFL or is submerged.The results indicate that the local enhancement of the submerged nanocavity,or the nanoplasma,in the prefabricated LSFL ridge led to the splitting of the LSFL,and the thermodynamic effect drove the homogenization of the splitting LSFL,which evolved into HSFL.
