This paper describes the fabrication and electrical characteristics of Ti/4H-SiC Schottky barrier diodes （SBDs）. The ideality factor n = 1.08 and effective Schottky barrier heightφ= 1.05eV of the SBDs were measured...This paper describes the fabrication and electrical characteristics of Ti/4H-SiC Schottky barrier diodes （SBDs）. The ideality factor n = 1.08 and effective Schottky barrier heightφ= 1.05eV of the SBDs were measured with the method of forward current density-voltage （J-V）. A low reverse leakage current below 5.96 ×10^-3A/cm^2 at a bias voltage of - 1. 1kV was obtained. By using B^＋ implantation,an amorphous layer as the edge termination was formed. We used the PECVD SiO2 as the field plate dielectric. The SBDs have an on-state current density of 430A/cm^2 at a forward voltage drop of about 4V. The specific on-resistance Ro, was found to be 6. 77mΩ2 · cm^2 .展开更多
Ultra thin epitaxial CoSi 2 films are fabricated by solid state reaction of a deposited bilayer of Co(3nm)/Ti (1nm) on n Si(100) substrates at different temperatures.The local barrier heights of the CoSi 2/Si cont...Ultra thin epitaxial CoSi 2 films are fabricated by solid state reaction of a deposited bilayer of Co(3nm)/Ti (1nm) on n Si(100) substrates at different temperatures.The local barrier heights of the CoSi 2/Si contacts are determined by using the ballistic electron emission microscopy (BEEM) and its spectroscopy (BEES) at low temperature.For CoSi 2/Si contact annealed at 800℃,the spatial distribution of barrier heights,which have mean barrier height of 599meV and a standard deviation of 21meV,obeys the Gaussian Function.However,for a sample that is annealed at 700℃,the barrier heights of it are more inhomogenous.Its local barrier heights range from 152meV to 870meV,which implies the large inhomogeneity of the CoSi 2 film.展开更多
The effect of the interaction between nanopore and chain monomer on the translocation of a single polymer chain confined in a finite size square through an interacting nanopore to a large space has been studied by two...The effect of the interaction between nanopore and chain monomer on the translocation of a single polymer chain confined in a finite size square through an interacting nanopore to a large space has been studied by two-dimensional bond fluctuation model with Monte Carlo simulation. Results indicate that the free energy barrier before the successful translocation of the chain depends linearly on the chain length as well as the nanopore length for different pore-polymer interaction, and the attractive interaction reduces the free energy barrier, leading to the reduction of the average trapping time.展开更多
Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annea...Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.展开更多
The electrical characteristics of GaN schottky diode with and without the interracial oxides are compared in this paper. The influence of interracial oxides on the electrical characteristics of the schottky diodes has...The electrical characteristics of GaN schottky diode with and without the interracial oxides are compared in this paper. The influence of interracial oxides on the electrical characteristics of the schottky diodes has been confirmed by the I-V, C-V measures. We find the barrier height have a reduction of 0.05 eV- 0.1 eV. There is an interracial insulating oxide with the thickness of 0. 05 nm- 0. 1 nm after conventional cleaning. Either the forward or the backward currents increase. The backward punch through voltages are reduced to 50% and the capacitances have increased by 100%.展开更多
Hexagonal microtube ZnO was firstly grown on single crystal p-Si (111) substrates by hydrothermal method, and fabricated Ag/n-ZnO and Au/n-ZnO Schottky junction. Schottky effective barrier heights were calculated by I...Hexagonal microtube ZnO was firstly grown on single crystal p-Si (111) substrates by hydrothermal method, and fabricated Ag/n-ZnO and Au/n-ZnO Schottky junction. Schottky effective barrier heights were calculated by I-V measurement. It is confirmed that the presence of a large amount of surface states related possibly to lattice imperfections existed near the surface leads to the pinning of the surface Fermi level at 0.35eV below the conduction-band edge. Then the fabricated Schottky barrier junctions are evaluated for their use as UV photodetectors.展开更多
The reaction dynamics of the F＋H20/D20→HF/DF＋OH/OD are investigated on an accurate potential energy surface （PES） using a quasi-classical trajectory method. For both isotopomers, the hydrogen/deuterium abstractio...The reaction dynamics of the F＋H20/D20→HF/DF＋OH/OD are investigated on an accurate potential energy surface （PES） using a quasi-classical trajectory method. For both isotopomers, the hydrogen/deuterium abstraction reaction is dominated by a direct rebound mechanism over a very low ＂reactant-like＂ barrier, which leads to a vibrationally hot HF/DF product with an internally cold OH/OD companion. It is shown that the lowered reaction barrier on this PES, as suggested by high-level ab initio calculations, leads to a much better agreement with the experimental reaction cross section, but has little impact on the product state distributions and mode selectivity. Our results further indicate that rotational excitation of the H20 reactant leads to significant enhancement of the reactivity, suggesting a strong coupling with the reaction coordinate.展开更多
To investigate the aerodynamic effect of wind barriers on a high-speed train-bridge system,a sectional model test was conducted in a closed-circuit-type wind tunnel.Several different cases,including with and without b...To investigate the aerodynamic effect of wind barriers on a high-speed train-bridge system,a sectional model test was conducted in a closed-circuit-type wind tunnel.Several different cases,including with and without barriers,with different barrier heights and porosity rates,and with different train arrangements on the bridge were taken into consideration;in addition,the aerodynamic coefficients of the train-bridge system were measured.It is found that the side force and rolling moment coefficients of the vehicle are efficiently reduced by a single-side wind barrier,but for the bridge deck these values are increased.The height and porosity rate of the barrier are two important factors that influence the windbreak effect.Train arrangement on the bridge will considerably influence the aerodynamic properties of the train-bridge system.The side force and rolling moment coefficients of the vehicle at the windward side are larger than at the leeward side.展开更多
The electrical characteristics of graphene Schottky contacts formed on undoped GaN semiconductors were investigated. Excellent rectifying behavior with a rectification ratio of -10^7 at ±2 V and a low reverse lea...The electrical characteristics of graphene Schottky contacts formed on undoped GaN semiconductors were investigated. Excellent rectifying behavior with a rectification ratio of -10^7 at ±2 V and a low reverse leakage current of 1.0 × 10^-8 A/cm^2 at -5 V were observed. The Schottky barrier heights, as determined by the thermionic emission model Richardson plots, and barrier inhomogeneity model, were 0.90, 0.72, and 1.24 ± 0.13 eV, respectively. Despite the predicted low barrier height of -0.4 eV at the graphene-GaN interface, the formation of excellent rectifying characteristics with much larger barrier heights is attributed to the presence of a large number of surface states （1.2 x 1013 states/cm2/eV） and the internal spontaneous polarization field of GaN, resulted in a significant upward surface band bending or a bare surface barrier height as high as of 2.9 eV. Using the S parameter of 0.48 （measured from the work function dependence of Schottky barrier height） and the mean barrier height of 1.24 eV, the work function of graphene in the Au/graphene/GaN stack could be approximately estimated to be as low as 3.5 eV. The obtained results indicate that graphene is a promising candidate for use as a Schottky rectifier in GaN semiconductors with n-type conductivity.展开更多
The behaviors of barrier characteristics are analyzed for spherical-oblate systems over different configurations of colliding nuclei. For this purpose, we have extended our previous study [Phys. Rev. C 89（2014） 0546...The behaviors of barrier characteristics are analyzed for spherical-oblate systems over different configurations of colliding nuclei. For this purpose, we have extended our previous study [Phys. Rev. C 89（2014） 054607], it is devoted to optimum ＂cold＂ and ＂hot＂ configuration] to analyze the same reaction systems in various configurations.The investigation on some chosen systems reveals that the barrier height and its position can be parameterized in times of the different orientations.展开更多
There is a great interest in monolithic 4H-SiC Junction Barrier Schottky （JBS） diodes with the capability of a high forward current for industrial power applications. In this paper, we report large-area monolithic 4...There is a great interest in monolithic 4H-SiC Junction Barrier Schottky （JBS） diodes with the capability of a high forward current for industrial power applications. In this paper, we report large-area monolithic 4H-SiC JBS diodes fabricated on a 10 μm 4H-SiC epitaxial layer doped to 6×1015 cm-3. JBS diodes with an active area of 30 mm2 had a forward current of up to 330 A at a forward voltage of 5 V, which corresponds to a current density of 1100 A/cm2. A near ideal breakdown voltage of 1.6 kV was also achieved for a reverse current of up to 100 gA through the use of an optimum multiple floating guard rings （MFGR） termination, which is about 87.2% of the theoretical value. The differential specific-on resistance （RSP-ON） was meas- ured to be 3.3 mΩcm2, leading to a FOM （VB2/RSP-ON） value of 0.78 GW/cm2, which is very close to the theoretical limit of the tradeoff between the specific-on resistance and breakdown voltage for 4H-SiC unipolar devices.展开更多
文摘This paper describes the fabrication and electrical characteristics of Ti/4H-SiC Schottky barrier diodes （SBDs）. The ideality factor n = 1.08 and effective Schottky barrier heightφ= 1.05eV of the SBDs were measured with the method of forward current density-voltage （J-V）. A low reverse leakage current below 5.96 ×10^-3A/cm^2 at a bias voltage of - 1. 1kV was obtained. By using B^＋ implantation,an amorphous layer as the edge termination was formed. We used the PECVD SiO2 as the field plate dielectric. The SBDs have an on-state current density of 430A/cm^2 at a forward voltage drop of about 4V. The specific on-resistance Ro, was found to be 6. 77mΩ2 · cm^2 .
文摘Ultra thin epitaxial CoSi 2 films are fabricated by solid state reaction of a deposited bilayer of Co(3nm)/Ti (1nm) on n Si(100) substrates at different temperatures.The local barrier heights of the CoSi 2/Si contacts are determined by using the ballistic electron emission microscopy (BEEM) and its spectroscopy (BEES) at low temperature.For CoSi 2/Si contact annealed at 800℃,the spatial distribution of barrier heights,which have mean barrier height of 599meV and a standard deviation of 21meV,obeys the Gaussian Function.However,for a sample that is annealed at 700℃,the barrier heights of it are more inhomogenous.Its local barrier heights range from 152meV to 870meV,which implies the large inhomogeneity of the CoSi 2 film.
文摘The effect of the interaction between nanopore and chain monomer on the translocation of a single polymer chain confined in a finite size square through an interacting nanopore to a large space has been studied by two-dimensional bond fluctuation model with Monte Carlo simulation. Results indicate that the free energy barrier before the successful translocation of the chain depends linearly on the chain length as well as the nanopore length for different pore-polymer interaction, and the attractive interaction reduces the free energy barrier, leading to the reduction of the average trapping time.
文摘Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.
基金The National Natural Science Foundation of China(G0501030160576007)
文摘The electrical characteristics of GaN schottky diode with and without the interracial oxides are compared in this paper. The influence of interracial oxides on the electrical characteristics of the schottky diodes has been confirmed by the I-V, C-V measures. We find the barrier height have a reduction of 0.05 eV- 0.1 eV. There is an interracial insulating oxide with the thickness of 0. 05 nm- 0. 1 nm after conventional cleaning. Either the forward or the backward currents increase. The backward punch through voltages are reduced to 50% and the capacitances have increased by 100%.
基金National Natural Science Foundation of China(60390073) National"973"Project of China(51310209-4)
文摘Hexagonal microtube ZnO was firstly grown on single crystal p-Si (111) substrates by hydrothermal method, and fabricated Ag/n-ZnO and Au/n-ZnO Schottky junction. Schottky effective barrier heights were calculated by I-V measurement. It is confirmed that the presence of a large amount of surface states related possibly to lattice imperfections existed near the surface leads to the pinning of the surface Fermi level at 0.35eV below the conduction-band edge. Then the fabricated Schottky barrier junctions are evaluated for their use as UV photodetectors.
文摘The reaction dynamics of the F＋H20/D20→HF/DF＋OH/OD are investigated on an accurate potential energy surface （PES） using a quasi-classical trajectory method. For both isotopomers, the hydrogen/deuterium abstraction reaction is dominated by a direct rebound mechanism over a very low ＂reactant-like＂ barrier, which leads to a vibrationally hot HF/DF product with an internally cold OH/OD companion. It is shown that the lowered reaction barrier on this PES, as suggested by high-level ab initio calculations, leads to a much better agreement with the experimental reaction cross section, but has little impact on the product state distributions and mode selectivity. Our results further indicate that rotational excitation of the H20 reactant leads to significant enhancement of the reactivity, suggesting a strong coupling with the reaction coordinate.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2013CB036203)the National Natural Science Foundation of China(Grant No.51308034)the"111"Project(Grant No.B13002)
文摘To investigate the aerodynamic effect of wind barriers on a high-speed train-bridge system,a sectional model test was conducted in a closed-circuit-type wind tunnel.Several different cases,including with and without barriers,with different barrier heights and porosity rates,and with different train arrangements on the bridge were taken into consideration;in addition,the aerodynamic coefficients of the train-bridge system were measured.It is found that the side force and rolling moment coefficients of the vehicle are efficiently reduced by a single-side wind barrier,but for the bridge deck these values are increased.The height and porosity rate of the barrier are two important factors that influence the windbreak effect.Train arrangement on the bridge will considerably influence the aerodynamic properties of the train-bridge system.The side force and rolling moment coefficients of the vehicle at the windward side are larger than at the leeward side.
文摘The electrical characteristics of graphene Schottky contacts formed on undoped GaN semiconductors were investigated. Excellent rectifying behavior with a rectification ratio of -10^7 at ±2 V and a low reverse leakage current of 1.0 × 10^-8 A/cm^2 at -5 V were observed. The Schottky barrier heights, as determined by the thermionic emission model Richardson plots, and barrier inhomogeneity model, were 0.90, 0.72, and 1.24 ± 0.13 eV, respectively. Despite the predicted low barrier height of -0.4 eV at the graphene-GaN interface, the formation of excellent rectifying characteristics with much larger barrier heights is attributed to the presence of a large number of surface states （1.2 x 1013 states/cm2/eV） and the internal spontaneous polarization field of GaN, resulted in a significant upward surface band bending or a bare surface barrier height as high as of 2.9 eV. Using the S parameter of 0.48 （measured from the work function dependence of Schottky barrier height） and the mean barrier height of 1.24 eV, the work function of graphene in the Au/graphene/GaN stack could be approximately estimated to be as low as 3.5 eV. The obtained results indicate that graphene is a promising candidate for use as a Schottky rectifier in GaN semiconductors with n-type conductivity.
文摘The behaviors of barrier characteristics are analyzed for spherical-oblate systems over different configurations of colliding nuclei. For this purpose, we have extended our previous study [Phys. Rev. C 89（2014） 054607], it is devoted to optimum ＂cold＂ and ＂hot＂ configuration] to analyze the same reaction systems in various configurations.The investigation on some chosen systems reveals that the barrier height and its position can be parameterized in times of the different orientations.
基金supported by the National Natural Science Foundation of China(Grant Nos.61404098,61176070 and 61274079)the Natural Science Foundation of Shaanxi Province(Grant No.2013JQ8012)+2 种基金Doctoral Fund of Ministry of Education of China(Grant Nos.20110203110010 and 20130203120017)National Key Basic Research Program of China(Grant Nos.2015CB759600)Key Specific Projects of Ministry of Education of China(Grant No.625010101)
文摘There is a great interest in monolithic 4H-SiC Junction Barrier Schottky （JBS） diodes with the capability of a high forward current for industrial power applications. In this paper, we report large-area monolithic 4H-SiC JBS diodes fabricated on a 10 μm 4H-SiC epitaxial layer doped to 6×1015 cm-3. JBS diodes with an active area of 30 mm2 had a forward current of up to 330 A at a forward voltage of 5 V, which corresponds to a current density of 1100 A/cm2. A near ideal breakdown voltage of 1.6 kV was also achieved for a reverse current of up to 100 gA through the use of an optimum multiple floating guard rings （MFGR） termination, which is about 87.2% of the theoretical value. The differential specific-on resistance （RSP-ON） was meas- ured to be 3.3 mΩcm2, leading to a FOM （VB2/RSP-ON） value of 0.78 GW/cm2, which is very close to the theoretical limit of the tradeoff between the specific-on resistance and breakdown voltage for 4H-SiC unipolar devices.
