A direct tunneling model through gate dielectric s in CMOS devices in the frame of WKB approximation is reported.In the model,an im proved one-band effective mass approximation is used for the hole quantization, wher...A direct tunneling model through gate dielectric s in CMOS devices in the frame of WKB approximation is reported.In the model,an im proved one-band effective mass approximation is used for the hole quantization, where valence band mixing is taken into account.By comparing to the experiments, the model is demonstrated to be applicable to both electron and hole tunneling c urrents in CMOS devices.The effect of the dispersion in oxide energy gap on the tunneling current is also studied.This model can be further extended to study th e direct tunneling current in future high-k materials.展开更多
[Objective]The experiment aimed to explore a new way for observing surface structure of Nostoc sphaeroides Kutzing. [Method] The scanning electron microscope was used to observe the epidermal ultrastructure of wild an...[Objective]The experiment aimed to explore a new way for observing surface structure of Nostoc sphaeroides Kutzing. [Method] The scanning electron microscope was used to observe the epidermal ultrastructure of wild and cultured Nostoc sphaeroides Kutzing. [ Result] The epidermis of wild and cultured Nostoc sphaeroides Kutzing showed mixture structure of fibril colloid which was reticular arranged. The difference between wild and cultured Nostoc sphaeroides Kutzing was that the outer epidermis of cultured Nostoc sphaeroides Kutzing had trichome distribution but the wild Nostoc sphaeroides Kutzing did not has such distribution. The obsevation results of under smaller than 10 μm by scanning electron microscope was touched thick and showed many folds and distortions. [ Conclusion] The scanning electron microscope was an effective way to study development of Nostoc sphaeroides Kutzing colony and it was worth popularizing.展开更多
The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel.The effects of average current density on the surface morphology,microstructure,aver...The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel.The effects of average current density on the surface morphology,microstructure,average grain size and microhardness of nickel coatings were investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD)and microhardness measurement.In addition,the corrosion resistances of coating and substrate were compared.It is revealed that the nickel coatings prepared by pulse jet electrodeposition exhibit a fine-grained structure with a smooth surface and a high density,although some pores and defects are still present in coatings.With the increase of average current density,the average grain size of nickel coatings is reduced at first and then increased.The coating with the optimum compactness,the smallest average grain size(13.7 nm)and the highest microhardness are obtained at current density of 39.8 A/dm2.The corrosion resistance is obviously increased for the coatings prepared by pulse jet electrodeposition;however,the corrosion rate is increased after a certain period due to the penetration of the corrosive media.展开更多
A novel kind of waterborne epoxy coating pigmented by nano-sized aluminium powders on high strength steel was formulated. Several coatings with different pigment volume content (PVC) were prepared. The coating morphol...A novel kind of waterborne epoxy coating pigmented by nano-sized aluminium powders on high strength steel was formulated. Several coatings with different pigment volume content (PVC) were prepared. The coating morphology was observed using scanning electron microscopy (SEM), and the electrochemical properties were investigated by electrochemical impedance spectroscopy (EIS). Immersion test and neutral salt spray test were also conducted to investigate the corrosion resistance of the coating. It is demonstrated that the critical pigment volume content (CPVC) value is between 30% and 40%. The coating with PVC of 30% exhibits good corrosion resistance in 3.5% (mass fraction) NaCl solution.展开更多
Modeling vapor pressure is crucial for studying the moisture reliability of microelectronics, as high vapor pressure can cause device failures in environments with high temperature and humidity. To minimize the impact...Modeling vapor pressure is crucial for studying the moisture reliability of microelectronics, as high vapor pressure can cause device failures in environments with high temperature and humidity. To minimize the impact of vapor pressure, a super-hydrophobic(SH) coating can be applied on the exterior surface of devices in order to prevent moisture penetration. The underlying mechanism of SH coating for enhancing device reliability, however, is still not fully understood. In this paper, we present several existing theories for predicting vapor pressure within microelectronic materials. In addition, we discuss the mechanism and effectiveness of SH coating in preventing water vapor from entering a device, based on experimental results. Two theoretical models, a micro-mechanics-based whole-field vapor pressure model and a convection-diffusion model, are described for predicting vapor pressure. Both methods have been successfully used to explain experimental results on uncoated samples. However, when a device was coated with an SH nanocomposite, weight gain was still observed, likely due to vapor penetration through the SH surface. This phenomenon may cast doubt on the effectiveness of SH coatings in microelectronic devices. Based on current theories and the available experimental results, we conclude that it is necessary to develop a new theory to understand how water vapor penetrates through SH coatings and impacts the materials underneath. Such a theory could greatly improve microelectronics reliability.展开更多
VAlN coating is of particular interest for dry cutting applications owing to its low-friction and excellent abrasiveness.Nano-multilayer structure is designed to tailor the properties of VAlN coating.In this work,a se...VAlN coating is of particular interest for dry cutting applications owing to its low-friction and excellent abrasiveness.Nano-multilayer structure is designed to tailor the properties of VAlN coating.In this work,a series of VAlN/Si_(3)N_(4) nano-multilayer coatings with varied Si_(3)N_(4) layer thicknesses were prepared by reactive sputtering method.The microstructure and mechanical properties of the coatings were both investigated.It is revealed that Si_(3)N_(4) with a shallow thickness(~0.4 nm)was crystallized and grown coherently with VAlN,showing a remarkable increase in hardness compared to VAlN monolayer coating.The hardness of coherently VAlN/Si_(3)N_(4) nano-multilayer coatings reached to 48.7 GPa.With further increase of Si_(3)N_(4) layer thickness,the coherent growth of nano-multilayers was terminated,showing amorphous structure formed in nano-multilayers and the hardness was declined.On the other hand,when Si_(3)N_(4) layer thickness was 0.4 nm,the friction coefficient of VAlN/Si_(3)N_(4) nano-multilayer coating was almost equal to that of VAlN monolayer coating,which was attributed to the crystallization of Si_(3)N_(4) and the produced coherent interfaces between VAlN and Si_(3)N_(4) for the hardening effect of nano-multilayer coatings.Upon further increase of Si_(3)N_(4) layer thickness,pronounced improvement of friction coefficient in VAlN/Si_(3)N_(4) nano-multilayer coating was observed.展开更多
基金Project supported by the Reform and Development of Local Colleges and Universities of the Central Government of China(323210001)Project supported by the Harbin Talents of China(2015RAQXJ036)。
文摘A direct tunneling model through gate dielectric s in CMOS devices in the frame of WKB approximation is reported.In the model,an im proved one-band effective mass approximation is used for the hole quantization, where valence band mixing is taken into account.By comparing to the experiments, the model is demonstrated to be applicable to both electron and hole tunneling c urrents in CMOS devices.The effect of the dispersion in oxide energy gap on the tunneling current is also studied.This model can be further extended to study th e direct tunneling current in future high-k materials.
文摘[Objective]The experiment aimed to explore a new way for observing surface structure of Nostoc sphaeroides Kutzing. [Method] The scanning electron microscope was used to observe the epidermal ultrastructure of wild and cultured Nostoc sphaeroides Kutzing. [ Result] The epidermis of wild and cultured Nostoc sphaeroides Kutzing showed mixture structure of fibril colloid which was reticular arranged. The difference between wild and cultured Nostoc sphaeroides Kutzing was that the outer epidermis of cultured Nostoc sphaeroides Kutzing had trichome distribution but the wild Nostoc sphaeroides Kutzing did not has such distribution. The obsevation results of under smaller than 10 μm by scanning electron microscope was touched thick and showed many folds and distortions. [ Conclusion] The scanning electron microscope was an effective way to study development of Nostoc sphaeroides Kutzing colony and it was worth popularizing.
基金Project(50175053) supported by the National Natural Science Foundation of China
文摘The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel.The effects of average current density on the surface morphology,microstructure,average grain size and microhardness of nickel coatings were investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD)and microhardness measurement.In addition,the corrosion resistances of coating and substrate were compared.It is revealed that the nickel coatings prepared by pulse jet electrodeposition exhibit a fine-grained structure with a smooth surface and a high density,although some pores and defects are still present in coatings.With the increase of average current density,the average grain size of nickel coatings is reduced at first and then increased.The coating with the optimum compactness,the smallest average grain size(13.7 nm)and the highest microhardness are obtained at current density of 39.8 A/dm2.The corrosion resistance is obviously increased for the coatings prepared by pulse jet electrodeposition;however,the corrosion rate is increased after a certain period due to the penetration of the corrosive media.
基金Project(51001007) supported by the National Natural Science Foundation of ChinaProject(2011ZE51057) supported by the Aero Science Foundation of China
文摘A novel kind of waterborne epoxy coating pigmented by nano-sized aluminium powders on high strength steel was formulated. Several coatings with different pigment volume content (PVC) were prepared. The coating morphology was observed using scanning electron microscopy (SEM), and the electrochemical properties were investigated by electrochemical impedance spectroscopy (EIS). Immersion test and neutral salt spray test were also conducted to investigate the corrosion resistance of the coating. It is demonstrated that the critical pigment volume content (CPVC) value is between 30% and 40%. The coating with PVC of 30% exhibits good corrosion resistance in 3.5% (mass fraction) NaCl solution.
基金the support of the National High-Tech Research and Development Program of China (863 Program) (2015AA03A101)
文摘Modeling vapor pressure is crucial for studying the moisture reliability of microelectronics, as high vapor pressure can cause device failures in environments with high temperature and humidity. To minimize the impact of vapor pressure, a super-hydrophobic(SH) coating can be applied on the exterior surface of devices in order to prevent moisture penetration. The underlying mechanism of SH coating for enhancing device reliability, however, is still not fully understood. In this paper, we present several existing theories for predicting vapor pressure within microelectronic materials. In addition, we discuss the mechanism and effectiveness of SH coating in preventing water vapor from entering a device, based on experimental results. Two theoretical models, a micro-mechanics-based whole-field vapor pressure model and a convection-diffusion model, are described for predicting vapor pressure. Both methods have been successfully used to explain experimental results on uncoated samples. However, when a device was coated with an SH nanocomposite, weight gain was still observed, likely due to vapor penetration through the SH surface. This phenomenon may cast doubt on the effectiveness of SH coatings in microelectronic devices. Based on current theories and the available experimental results, we conclude that it is necessary to develop a new theory to understand how water vapor penetrates through SH coatings and impacts the materials underneath. Such a theory could greatly improve microelectronics reliability.
基金Project(51201187)supported by the National Natural Science Foundation of China。
文摘VAlN coating is of particular interest for dry cutting applications owing to its low-friction and excellent abrasiveness.Nano-multilayer structure is designed to tailor the properties of VAlN coating.In this work,a series of VAlN/Si_(3)N_(4) nano-multilayer coatings with varied Si_(3)N_(4) layer thicknesses were prepared by reactive sputtering method.The microstructure and mechanical properties of the coatings were both investigated.It is revealed that Si_(3)N_(4) with a shallow thickness(~0.4 nm)was crystallized and grown coherently with VAlN,showing a remarkable increase in hardness compared to VAlN monolayer coating.The hardness of coherently VAlN/Si_(3)N_(4) nano-multilayer coatings reached to 48.7 GPa.With further increase of Si_(3)N_(4) layer thickness,the coherent growth of nano-multilayers was terminated,showing amorphous structure formed in nano-multilayers and the hardness was declined.On the other hand,when Si_(3)N_(4) layer thickness was 0.4 nm,the friction coefficient of VAlN/Si_(3)N_(4) nano-multilayer coating was almost equal to that of VAlN monolayer coating,which was attributed to the crystallization of Si_(3)N_(4) and the produced coherent interfaces between VAlN and Si_(3)N_(4) for the hardening effect of nano-multilayer coatings.Upon further increase of Si_(3)N_(4) layer thickness,pronounced improvement of friction coefficient in VAlN/Si_(3)N_(4) nano-multilayer coating was observed.
