On SrTiO3 single crystal substrate,by using the pulsed electron deposition tech-nique,the high-quality electron doped Nd1.85Ce0.15CuO4?δ superconducting film was successfully fabricated. After careful study on the R-...On SrTiO3 single crystal substrate,by using the pulsed electron deposition tech-nique,the high-quality electron doped Nd1.85Ce0.15CuO4?δ superconducting film was successfully fabricated. After careful study on the R-T curves of the obtained sam-ples deposited with different substrate temperatures,thicknesses,annealing methods and pulse frequencies,the effects of them on the superconductivity of the films were found,and the reasons were also analyzed. Additionally,by using the same model of the pulsed laser deposition technique,the relation between the target-to-substrate distance and the deposition pressure was drawn out as a quantitative one.展开更多
The deposition of hydrogenated amorphous silicon carbide (a-SiC.H) films from a mixture of silane, acetylene and hydrogen gas using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) process is repo...The deposition of hydrogenated amorphous silicon carbide (a-SiC.H) films from a mixture of silane, acetylene and hydrogen gas using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) process is reported. The variation of the deposition and film characteristics such as the deposition rate- optical bandgap, photoluminescence and the infra-red (IR) absorption as a function of the hydrogen dilution is investigated. The deposition rate increases to a maximum value of ~25 nm/min at a moderate hydrogen diIution ratio of ~20 [hydrogenflow (sccm)/acetylene+silane flow (sccm)], and decreases in response to a further increase in the hydrogen dilution. There is no strong dependence of the optical bandgap on the hydrogen dilution within the dilution range investigated (10 to 60), and the optical bandgap calculated from the E04 method varied marginally from ~2.85 eV to ~3.17 eV. The room temperaturephotoluminescence (PL) peak energy and intensity shows a prominent shift to a maximum value of ~2.17 eV corresponding to maximum PL intensity at a moderate hydrogen diIution of ~30.The PL intensity shows a strong dependence on the hydrogen dilution variation. IR absorption results show that films deposited at higher hydrogen dilution have more Si-C bonding.展开更多
a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radic...a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.展开更多
Unsteady dielectric barrier discharge(DBD) plasma aerodynamic actuation technology is employed to suppress airfoil stall separation and the technical parameters are explored with wind tunnel experiments on an NACA00...Unsteady dielectric barrier discharge(DBD) plasma aerodynamic actuation technology is employed to suppress airfoil stall separation and the technical parameters are explored with wind tunnel experiments on an NACA0015 airfoil by measuring the surface pressure distribution of the airfoil.The performance of the DBD aerodynamic actuation for airfoil stall separation suppression is evaluated under DBD voltages from 2000 V to 4000 V and the duty cycles varied in the range of 0.1 to 1.0.It is found that higher lift coefficients and lower threshold voltages are achieved under the unsteady DBD aerodynamic actuation with the duty cycles less than 0.5as compared to that of the steady plasma actuation at the same free-stream speeds and attack angles,indicating a better flow control performance.By comparing the lift coefficients and the threshold voltages,an optimum duty cycle is determined as 0.25 by which the maximum lift coefficient and the minimum threshold voltage are obtained at the same free-stream speed and attack angle.The non-uniform DBD discharge with stronger discharge in the positive half cycle due to electrons deposition on the dielectric slabs and the suppression of opposite momentum transfer due to the intermittent discharge with cutoff of the negative half cycle are responsible for the observed optimum duty cycle.展开更多
The method of numerical simulation is used to fit the relationship between the photoconductivity in films and the illumination time. The generation and process rule of kinds of different charged defect states during i...The method of numerical simulation is used to fit the relationship between the photoconductivity in films and the illumination time. The generation and process rule of kinds of different charged defect states during illumination are revealed. It is found surprisingly that the initial photoconductivity determines directly the total account of photoconductivity degradation of sample.展开更多
Thermal barrier coatings (TBCs) were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia (YSZ),...Thermal barrier coatings (TBCs) were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia (YSZ), were deposited on a cylinder of superalloy substrate by the electron beam-physical vapor deposition (EB-PVD). The failure mechanism of the TBCs was investigated with a thermo-mechanical fatigue testing system under the service condition similar to that for turbine blades. Non-destructive evaluation of the coated specimens was conducted through the impedance spectroscopy. It is found that the crack initiation mainly takes place on the top coat at the edge of the heated zones.展开更多
A new electroluminescence device is fabricated by microwave plasma chemical vapour deposition system and electron beam vapour deposition system. It is comprised of highly doped silicon/diamond/boron/nitrogen-doped dia...A new electroluminescence device is fabricated by microwave plasma chemical vapour deposition system and electron beam vapour deposition system. It is comprised of highly doped silicon/diamond/boron/nitrogen-doped diamond/indium tin oxide thin films. Effects of process parameters on morphologies and structures of the thin films are detected and analysed by scanning electron microscopy, Raman spectrometer and x-ray photoelectron spectrometer. A direct-current (DC) power supply is used to drive the electroluminescence device. The blue light emission with a luminance of 1.2 cd·m^-2 is observed from this double-doped diamond thin film electroluminescence device at an applied voltage of 105 V.展开更多
SiCx nano dots and nano wires with sizes from 60 nm to approximately 2μm were fabricated using liquid cell transmission electron microscope(TEM)technology.A SiCl_(4)in CH_(2)Cl_(2)solution was sealed between two piec...SiCx nano dots and nano wires with sizes from 60 nm to approximately 2μm were fabricated using liquid cell transmission electron microscope(TEM)technology.A SiCl_(4)in CH_(2)Cl_(2)solution was sealed between two pieces of Si_(3)N_(4)window grids in an in situ TEM liquid cell.Focused 200 keV electron beams were used to bombard the sealed precursors,which caused decomposition of the precursor materials,and deposition of the nano materials on the Si_(3)N_(4)window substrates.The size of nano dots increased with beam exposure time,following an approximately exponential relationship with the beam doses.Secondary electrons are attributed as the primary sources for the Si and C reduction.A nano device was formed from a deposited nano wire,with its electrical property characterized.展开更多
A series of a-Si:H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition (HW-MWECR-CVD), subsequently exposed under simulated illumination for three hours. This p...A series of a-Si:H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition (HW-MWECR-CVD), subsequently exposed under simulated illumination for three hours. This paper studies the microstructure change during illumination by Fourier Transformation Infrared (FTIR) spectra. There are two typical transformation tendencies of microstructure after illumination. It proposes a model of light induced structural change based on the experimental results. It is found that all samples follow the same mechanism during illumination, and intrinsic structure of samples affect the total H content.展开更多
In this work, a hetero-epitaxial Al0.49In0.51As/Ga0.47In0.53 As metamorphic high electron mobility transistor(mHEMT) grown by metal–organic chemical vapor deposition(MOCVD) on p-type silicon substrate has been succes...In this work, a hetero-epitaxial Al0.49In0.51As/Ga0.47In0.53 As metamorphic high electron mobility transistor(mHEMT) grown by metal–organic chemical vapor deposition(MOCVD) on p-type silicon substrate has been successfully demonstrated. A novel AlGaAs/Al As period multiple quantum well(MQW) composite buffer scheme is developed to effectively tune the leakage current from the buffer layer. The quantized room-temperature Hall mobility of the twodimensional electron gas(2DEG) is larger than 7800 cm2/V·s, with an average sheet carrier density of 4.6×1012cm-2.Two-stage electron beam(EB) lithography technology by a JBX-6300 e-beam lithography system is developed to realize a 0.13-μm m HEMT device on Si substrate. A maximum transconductance Gm of up to 854 mS/mm is achieved, and is comparable to that of m HEMT technology on Ga As substrate with the same dimension. The fTand fmax are 135 GHz and120 GHz, respectively.展开更多
By simply adjusting the temperature and the number of materials, rod-like ZnO with different morphology, such as ZnO nanoneedles, were synthesized by a flexible thermal evaporation method. The ZnO nanorod array has th...By simply adjusting the temperature and the number of materials, rod-like ZnO with different morphology, such as ZnO nanoneedles, were synthesized by a flexible thermal evaporation method. The ZnO nanorod array has the lowest turn-on field, the highest current density, and the highest emission efficiency due to its good contact with the substrate and relatively weak field shielding effect. Experiments show that the morphology and orientation of one-dimensional ZnO nanomaterials have a great influence on its conduction field and emission current density, and the nanoarrays also contribute to electron emission. The research results have a certain reference value for the application of ZnO nanorod arrays as cathode materials for field emission devices.展开更多
This study investigated the inductively coupled plasma etching reactor and RF coils developed by North Microelectronic Corporation. Full three dimensional simulations were made at different discharge conditions. The s...This study investigated the inductively coupled plasma etching reactor and RF coils developed by North Microelectronic Corporation. Full three dimensional simulations were made at different discharge conditions. The simulations examined and compared the distribution and non-uniformity of several plasma parameters at a fixed position upon the wafer at different pressures and coil currents. These parameters included electron density, electron temperature and power deposition. The results demonstrate that the electron density, power deposition and uniformity increase with either higher pressure or stronger coil currents, while the electron temperature decreases at this condition. Coil number increase can reduce the non-uniformity of parameters in the spatial distribution. The linear relationship between power deposition and electron density does not always exist. The comparison between simulation results and experiment results is also presented in the paper.展开更多
With the aim of producing all-solid-state electrochromic mirrors, La<sub>0.67–x</sub>Li<sub>3x</sub>TiO<sub>3 </sub>(LLTO) and the WO<sub>3</sub> were prepared by elect...With the aim of producing all-solid-state electrochromic mirrors, La<sub>0.67–x</sub>Li<sub>3x</sub>TiO<sub>3 </sub>(LLTO) and the WO<sub>3</sub> were prepared by electron beam deposition. The LLTO (with x = 0.11) powder was synthesized by thermally ball-grinding method and the Li<sup>+</sup> ionic conductivity of the LLTO ceramic targets was found to be of ca. 3.25 × 10<sup>–3</sup> S/cm. Using LLTO targets for e-beam evaporation, 300 nm-thick films with the Li<sup>+</sup> ionic conductivity of 5.50 × 10<sup>–5</sup> S/cm were deposited. Combining LLTO films with WO<sub>3</sub>/ITO and LiMn<sub>2</sub>O<sub>4</sub> layers, all-solid-state electrochromic mirrors with a laminar structure of Al/LiMn<sub>2</sub>O<sub>4</sub>/LLTO/WO<sub>3</sub>/ITO were prepared. The reversible reflectance of the mirrors was well controlled by applying polarized potentials onto the ITO electrode. The obtained results suggest useful applications for electrochromic windows working as a smart reflectance mirror that can be used for auto rear-view mirrors.展开更多
β-NiAl is a potential oxidation-resistant coating material to be operated at temperatures above 1 150 ℃. In this paper,β-NiAl coatings with 0-0.5 at% Dy are prepared by electron beam physical vapor deposition (EB-...β-NiAl is a potential oxidation-resistant coating material to be operated at temperatures above 1 150 ℃. In this paper,β-NiAl coatings with 0-0.5 at% Dy are prepared by electron beam physical vapor deposition (EB-PVD). Transient oxidation behavior of the coatings is investigated. At 1 200 ℃, only stable α-Al2O3 phase is observed on the 0.05 at% doped coating, whereas the phase transfomlation from θ-Al2O3 to α-Al2O3 occurs in the 0.5 at% Dy doped coating during 1 h oxidation. At 1 100 ℃, all the coatings reveal the transient transformation of θ-α in the early 15 min and the transformation for the 0.05 at% Dy doped coating is completed within 45 min, much earlier than that for the 0.5 at% Dy doped coating. Overdoping of Dy retards the transformation of θ-α. The undoped and overdoped coatings reveal the whisker structure of θ-Al2O3 even after 20 h oxidation at 1 100 ℃, while the 0.05 at% Dy coating reveals typical granulated structure of α-Al2O3.展开更多
Active control of turbine blade tip clearance for aircraft engine continues to be a concern in engine opera- tion, because turbine blades are subjected to wear and therefore cause an increasing tip clearance between t...Active control of turbine blade tip clearance for aircraft engine continues to be a concern in engine opera- tion, because turbine blades are subjected to wear and therefore cause an increasing tip clearance between the rotating blades and the shroud and also reduce the engine efficiency. In this work, a Ni-rich Ni3A1 coating with γ'/γ two-phase microstructure was deposited by electron beam physical vapor deposition (EB-PVD), which worked as repairing the worn blade tips of single crystal blades. Nb molten pool was used to increase the molten pool tem- perature and thus to enhance the deposition rate. The microstructures and mechanical properties can be modified by the deposition temperatures and the following heat treatments. All coatings consist of γ' and γ phases. At deposition temperature of 600 ℃, a dense microstructure can be achieved to produce a coating with grain size of 1 μm and microhardness of -HV 477. After being heated for 4 h at a temperature of 1,100 ℃, the coatings have a more uniform microstructure, and microhardness maintains at a high level of -HV 292. Effect of Hf and Zr on EB-PVD Ni3Al repair coating will be further investigated.展开更多
Yttria-stabilized zirconia(YSZ)thin nanocrystalline coatings at different substrate preheating temperatures were deposited via electron beam-physical vapour deposition(EB-PVD).Nanocrystalline ZrO_(2)-Y_(2)O_(3) was de...Yttria-stabilized zirconia(YSZ)thin nanocrystalline coatings at different substrate preheating temperatures were deposited via electron beam-physical vapour deposition(EB-PVD).Nanocrystalline ZrO_(2)-Y_(2)O_(3) was deposited on the bond coat in order to compensate for the coefficient of thermal expansion(CTE),which can be functionalized as a thermal barrier coating(TBC).The aim of this study was to evaluate mechanical properties with respect to adhesion of zirconia nanocrystalline’s top ceramic layer to the interfacial bond coat by utilizing micro and nano indentation tests.In the present paper,the structural studies were carried out using X-ray diffraction(XRD)analysis of coating content(8 mol%of Y_(2)O_(3)).The tetragonal phase of stabilized zirconia was observed.Field emission scanning electron microscopy(FESEM)and atomic force microscopy(AFM)were employed to characterize the coatings’morphology and microstructure.The mechanical behavior of ZrO_(2)-Y_(2)O_(3) thin films under point loading conditions was studied by nanoindentation using a Berkovich indenter with 130 nm tip radius.Therefore,adhesion of top coat to the interfacial underlying metallic bond coat known as MCrAlY(M=Ni,Co)was estimated according to the highest peak load tests;for a 120 mN peak load,the film manifested tolerable adhesion properties.Moreover,nanoindentation of ZrO_(2)-Y_(2)O_(3) nanostructure deposited at 1050℃substrate preheating temperature produced the highest hardness value of about 21.7 GPa.Vickers micro hardness was utilized with the aid of the Tabor equation in order to achieve deeper insight into the correlation between adhesion and deposition process parameters.展开更多
In this research, a nano-Mo2 C particle dispersion-strengthened copper alloy was prepared by a novel method, i.e., electron beam physical vapor deposition(EBPVD) which has advantages of simple technical process and ...In this research, a nano-Mo2 C particle dispersion-strengthened copper alloy was prepared by a novel method, i.e., electron beam physical vapor deposition(EBPVD) which has advantages of simple technical process and low cost compared with the conventional mechanical alloying method. And the microstructure and properties of the material were investigated. The results show that the copper matrix is composed of columnar crystals with the average width of 7 lm, and the size of Mo2 C dispersoid is1–7 nm. The ultimate tensile strength of the material is486 MPa, and the electrical conductivity is 82 % IACS. As the temperature increases from 293 to 573 K, the material becomes more brittle.展开更多
The effects of YO(1.5)doping in yttria-zirconia based thermal barrier coatings(TBCs)against CMAS interaction/infiltration are discussed.The TBCs with an YO(1.5)content ranging from 43–67 mol.%(balance Zr O2)were prod...The effects of YO(1.5)doping in yttria-zirconia based thermal barrier coatings(TBCs)against CMAS interaction/infiltration are discussed.The TBCs with an YO(1.5)content ranging from 43–67 mol.%(balance Zr O2)were produced by electron beam physical vapor deposition(EB-PVD)techniques.The results reveal a trend of higher apatite formation probability with the higher free YO(1.5)available in the yttriazirconia system.Additionally,the infiltration resistance and amount of consumed coating appears to be strongly dependent on the YO(1.5)content in the coating.The thinnest reaction layer and lowest infiltration was found for the highest produced 67 YO(1.5)coating.Complementary XRD experiments with volcanic ash/YO(1.5)powder mixtures with higher yttria contents than in the coatings(80 YO(1.5)and pure YO(1.5))also showed higher apatite formation with respect to increasing yttria content.The threshold composition to promote apatite-based reaction products was found to be around 50 YO(1.5)in zirconia which was proved in the coatings and XRD powder experiments.An YO(1.5)-ZrO2-Fe O-TiO2 bearing zirconolite-type phase was formed as a reaction product for all the coating compositions which implicates that TiO2 in the melt acts as a trigger for zirconolite formation.This phase could be detrimental for CMAS/volcanic ash infiltration resistance since it can be formed alongside with apatite which controls or limits the amount of Y^(3+)available for glass crystallization.The Fe rich garnet phase containing all the possible elements exhibited a slower nucleation compared to apatite and its growth was enhanced with slow cooling rates.The implications of phase stability and heat treatment effects on the reaction products are discussed for tests performed at 1250°C.展开更多
Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both di...Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both discrete particle and nano cluster forms. The silver particles were attached to the 50 nm-thick Si3N4 windows of the wet cell and could not move freely in the liquid. With a SIC14 liquid loaded in the wet cell, silicon nano materials were controllably grown on the wet cell windows by means of a liquid phase electron beam induced deposition (EBID) method. The deposited nano dots were nicely round-shaped, and demonstrated a power law growth dependency on beam exposure time in a log-log plot. In a NiCI2 solution/Ni system, both electrochemical deposition and dissolution of the nickel nano films were observed while applying electric biases on to the nickel electrodes in the wet cell. Instead of extensional growth on existing crystals, interestingly, it is more commonly observed that new nickel nano particles grow out in front of the existing film first and then merged into the film. The wet cell set up is demonstrated to be a versatile tool for nano liquid system research.展开更多
基金Supported by the Key Project of Zhejiang Provincial Natural Science Foundation(Grant No.Z605131)the‘100 Talents Project’of Chinese Academy of Sciences,the Creative Research Group of National Natural Science Foundation of China(Grant No.60321001)the National Natural Science Foundation of China(Grant No.60571029)
文摘On SrTiO3 single crystal substrate,by using the pulsed electron deposition tech-nique,the high-quality electron doped Nd1.85Ce0.15CuO4?δ superconducting film was successfully fabricated. After careful study on the R-T curves of the obtained sam-ples deposited with different substrate temperatures,thicknesses,annealing methods and pulse frequencies,the effects of them on the superconductivity of the films were found,and the reasons were also analyzed. Additionally,by using the same model of the pulsed laser deposition technique,the relation between the target-to-substrate distance and the deposition pressure was drawn out as a quantitative one.
文摘The deposition of hydrogenated amorphous silicon carbide (a-SiC.H) films from a mixture of silane, acetylene and hydrogen gas using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) process is reported. The variation of the deposition and film characteristics such as the deposition rate- optical bandgap, photoluminescence and the infra-red (IR) absorption as a function of the hydrogen dilution is investigated. The deposition rate increases to a maximum value of ~25 nm/min at a moderate hydrogen diIution ratio of ~20 [hydrogenflow (sccm)/acetylene+silane flow (sccm)], and decreases in response to a further increase in the hydrogen dilution. There is no strong dependence of the optical bandgap on the hydrogen dilution within the dilution range investigated (10 to 60), and the optical bandgap calculated from the E04 method varied marginally from ~2.85 eV to ~3.17 eV. The room temperaturephotoluminescence (PL) peak energy and intensity shows a prominent shift to a maximum value of ~2.17 eV corresponding to maximum PL intensity at a moderate hydrogen diIution of ~30.The PL intensity shows a strong dependence on the hydrogen dilution variation. IR absorption results show that films deposited at higher hydrogen dilution have more Si-C bonding.
文摘a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.
基金supported by National Natural Science Foundation of China(No.21276036)Liaoning Provincial Natural Science Foundation of China(No.2015020123)the Fundamental Research Funds for the Central Universities of China(No.3132015154)
文摘Unsteady dielectric barrier discharge(DBD) plasma aerodynamic actuation technology is employed to suppress airfoil stall separation and the technical parameters are explored with wind tunnel experiments on an NACA0015 airfoil by measuring the surface pressure distribution of the airfoil.The performance of the DBD aerodynamic actuation for airfoil stall separation suppression is evaluated under DBD voltages from 2000 V to 4000 V and the duty cycles varied in the range of 0.1 to 1.0.It is found that higher lift coefficients and lower threshold voltages are achieved under the unsteady DBD aerodynamic actuation with the duty cycles less than 0.5as compared to that of the steady plasma actuation at the same free-stream speeds and attack angles,indicating a better flow control performance.By comparing the lift coefficients and the threshold voltages,an optimum duty cycle is determined as 0.25 by which the maximum lift coefficient and the minimum threshold voltage are obtained at the same free-stream speed and attack angle.The non-uniform DBD discharge with stronger discharge in the positive half cycle due to electrons deposition on the dielectric slabs and the suppression of opposite momentum transfer due to the intermittent discharge with cutoff of the negative half cycle are responsible for the observed optimum duty cycle.
文摘The method of numerical simulation is used to fit the relationship between the photoconductivity in films and the illumination time. The generation and process rule of kinds of different charged defect states during illumination are revealed. It is found surprisingly that the initial photoconductivity determines directly the total account of photoconductivity degradation of sample.
基金National Natural Science Foundation of China (50571005)
文摘Thermal barrier coatings (TBCs) were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia (YSZ), were deposited on a cylinder of superalloy substrate by the electron beam-physical vapor deposition (EB-PVD). The failure mechanism of the TBCs was investigated with a thermo-mechanical fatigue testing system under the service condition similar to that for turbine blades. Non-destructive evaluation of the coated specimens was conducted through the impedance spectroscopy. It is found that the crack initiation mainly takes place on the top coat at the edge of the heated zones.
基金supported by the Shanghai Education Committee of China (Grant No.07ZZ95)the Shanghai Human Resources and Social Security Bureau (Grant No.2009023)
文摘A new electroluminescence device is fabricated by microwave plasma chemical vapour deposition system and electron beam vapour deposition system. It is comprised of highly doped silicon/diamond/boron/nitrogen-doped diamond/indium tin oxide thin films. Effects of process parameters on morphologies and structures of the thin films are detected and analysed by scanning electron microscopy, Raman spectrometer and x-ray photoelectron spectrometer. A direct-current (DC) power supply is used to drive the electroluminescence device. The blue light emission with a luminance of 1.2 cd·m^-2 is observed from this double-doped diamond thin film electroluminescence device at an applied voltage of 105 V.
基金The experiments have been carried out in part in the Frederick Seitz Materials Research Laboratory Central Facilities,University of Illinois,which are partially supported by the U.S.Department of Energy under grants DE-FG02-07ER46453 and DE-FG02-07ER46471The authors thank S.J.Dillon,Y.Liu,J.Mabon,K.-W.Noh,A.Shah,T.Shang,J.G.Wen,J.M.Zuo for the kind help.The project was supported by Shanghai Leading Academic Discipline Project(B502)+2 种基金Shanghai Key Laboratory Project(08DZ2230500)Fundamental Research Fund of ECUST,Science and Technology Commission of Shanghai Municipality Project(11nm0507000)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry.
文摘SiCx nano dots and nano wires with sizes from 60 nm to approximately 2μm were fabricated using liquid cell transmission electron microscope(TEM)technology.A SiCl_(4)in CH_(2)Cl_(2)solution was sealed between two pieces of Si_(3)N_(4)window grids in an in situ TEM liquid cell.Focused 200 keV electron beams were used to bombard the sealed precursors,which caused decomposition of the precursor materials,and deposition of the nano materials on the Si_(3)N_(4)window substrates.The size of nano dots increased with beam exposure time,following an approximately exponential relationship with the beam doses.Secondary electrons are attributed as the primary sources for the Si and C reduction.A nano device was formed from a deposited nano wire,with its electrical property characterized.
文摘A series of a-Si:H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition (HW-MWECR-CVD), subsequently exposed under simulated illumination for three hours. This paper studies the microstructure change during illumination by Fourier Transformation Infrared (FTIR) spectra. There are two typical transformation tendencies of microstructure after illumination. It proposes a model of light induced structural change based on the experimental results. It is found that all samples follow the same mechanism during illumination, and intrinsic structure of samples affect the total H content.
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.61401373)the Fundamental Research Funds for Central University,China(Grant Nos.XDJK2013B004 and 2362014XK13)the Chongqing Natural Science Foundation,China(Grant No.cstc2014jcyj A40038)
文摘In this work, a hetero-epitaxial Al0.49In0.51As/Ga0.47In0.53 As metamorphic high electron mobility transistor(mHEMT) grown by metal–organic chemical vapor deposition(MOCVD) on p-type silicon substrate has been successfully demonstrated. A novel AlGaAs/Al As period multiple quantum well(MQW) composite buffer scheme is developed to effectively tune the leakage current from the buffer layer. The quantized room-temperature Hall mobility of the twodimensional electron gas(2DEG) is larger than 7800 cm2/V·s, with an average sheet carrier density of 4.6×1012cm-2.Two-stage electron beam(EB) lithography technology by a JBX-6300 e-beam lithography system is developed to realize a 0.13-μm m HEMT device on Si substrate. A maximum transconductance Gm of up to 854 mS/mm is achieved, and is comparable to that of m HEMT technology on Ga As substrate with the same dimension. The fTand fmax are 135 GHz and120 GHz, respectively.
文摘By simply adjusting the temperature and the number of materials, rod-like ZnO with different morphology, such as ZnO nanoneedles, were synthesized by a flexible thermal evaporation method. The ZnO nanorod array has the lowest turn-on field, the highest current density, and the highest emission efficiency due to its good contact with the substrate and relatively weak field shielding effect. Experiments show that the morphology and orientation of one-dimensional ZnO nanomaterials have a great influence on its conduction field and emission current density, and the nanoarrays also contribute to electron emission. The research results have a certain reference value for the application of ZnO nanorod arrays as cathode materials for field emission devices.
基金supported by North Microelectronic Corporation (NMC).
文摘This study investigated the inductively coupled plasma etching reactor and RF coils developed by North Microelectronic Corporation. Full three dimensional simulations were made at different discharge conditions. The simulations examined and compared the distribution and non-uniformity of several plasma parameters at a fixed position upon the wafer at different pressures and coil currents. These parameters included electron density, electron temperature and power deposition. The results demonstrate that the electron density, power deposition and uniformity increase with either higher pressure or stronger coil currents, while the electron temperature decreases at this condition. Coil number increase can reduce the non-uniformity of parameters in the spatial distribution. The linear relationship between power deposition and electron density does not always exist. The comparison between simulation results and experiment results is also presented in the paper.
文摘With the aim of producing all-solid-state electrochromic mirrors, La<sub>0.67–x</sub>Li<sub>3x</sub>TiO<sub>3 </sub>(LLTO) and the WO<sub>3</sub> were prepared by electron beam deposition. The LLTO (with x = 0.11) powder was synthesized by thermally ball-grinding method and the Li<sup>+</sup> ionic conductivity of the LLTO ceramic targets was found to be of ca. 3.25 × 10<sup>–3</sup> S/cm. Using LLTO targets for e-beam evaporation, 300 nm-thick films with the Li<sup>+</sup> ionic conductivity of 5.50 × 10<sup>–5</sup> S/cm were deposited. Combining LLTO films with WO<sub>3</sub>/ITO and LiMn<sub>2</sub>O<sub>4</sub> layers, all-solid-state electrochromic mirrors with a laminar structure of Al/LiMn<sub>2</sub>O<sub>4</sub>/LLTO/WO<sub>3</sub>/ITO were prepared. The reversible reflectance of the mirrors was well controlled by applying polarized potentials onto the ITO electrode. The obtained results suggest useful applications for electrochromic windows working as a smart reflectance mirror that can be used for auto rear-view mirrors.
基金National Natural Science Foundation of China (50771009, 50731001) National Basic Research Program of China (2010CB631200) Research Fund for the Doctoral Program of Higher Education of China (20070006017)
文摘β-NiAl is a potential oxidation-resistant coating material to be operated at temperatures above 1 150 ℃. In this paper,β-NiAl coatings with 0-0.5 at% Dy are prepared by electron beam physical vapor deposition (EB-PVD). Transient oxidation behavior of the coatings is investigated. At 1 200 ℃, only stable α-Al2O3 phase is observed on the 0.05 at% doped coating, whereas the phase transfomlation from θ-Al2O3 to α-Al2O3 occurs in the 0.5 at% Dy doped coating during 1 h oxidation. At 1 100 ℃, all the coatings reveal the transient transformation of θ-α in the early 15 min and the transformation for the 0.05 at% Dy doped coating is completed within 45 min, much earlier than that for the 0.5 at% Dy doped coating. Overdoping of Dy retards the transformation of θ-α. The undoped and overdoped coatings reveal the whisker structure of θ-Al2O3 even after 20 h oxidation at 1 100 ℃, while the 0.05 at% Dy coating reveals typical granulated structure of α-Al2O3.
基金supported by the Postdoctoral Science Foundation of China(No.2013M540037)
文摘Active control of turbine blade tip clearance for aircraft engine continues to be a concern in engine opera- tion, because turbine blades are subjected to wear and therefore cause an increasing tip clearance between the rotating blades and the shroud and also reduce the engine efficiency. In this work, a Ni-rich Ni3A1 coating with γ'/γ two-phase microstructure was deposited by electron beam physical vapor deposition (EB-PVD), which worked as repairing the worn blade tips of single crystal blades. Nb molten pool was used to increase the molten pool tem- perature and thus to enhance the deposition rate. The microstructures and mechanical properties can be modified by the deposition temperatures and the following heat treatments. All coatings consist of γ' and γ phases. At deposition temperature of 600 ℃, a dense microstructure can be achieved to produce a coating with grain size of 1 μm and microhardness of -HV 477. After being heated for 4 h at a temperature of 1,100 ℃, the coatings have a more uniform microstructure, and microhardness maintains at a high level of -HV 292. Effect of Hf and Zr on EB-PVD Ni3Al repair coating will be further investigated.
文摘Yttria-stabilized zirconia(YSZ)thin nanocrystalline coatings at different substrate preheating temperatures were deposited via electron beam-physical vapour deposition(EB-PVD).Nanocrystalline ZrO_(2)-Y_(2)O_(3) was deposited on the bond coat in order to compensate for the coefficient of thermal expansion(CTE),which can be functionalized as a thermal barrier coating(TBC).The aim of this study was to evaluate mechanical properties with respect to adhesion of zirconia nanocrystalline’s top ceramic layer to the interfacial bond coat by utilizing micro and nano indentation tests.In the present paper,the structural studies were carried out using X-ray diffraction(XRD)analysis of coating content(8 mol%of Y_(2)O_(3)).The tetragonal phase of stabilized zirconia was observed.Field emission scanning electron microscopy(FESEM)and atomic force microscopy(AFM)were employed to characterize the coatings’morphology and microstructure.The mechanical behavior of ZrO_(2)-Y_(2)O_(3) thin films under point loading conditions was studied by nanoindentation using a Berkovich indenter with 130 nm tip radius.Therefore,adhesion of top coat to the interfacial underlying metallic bond coat known as MCrAlY(M=Ni,Co)was estimated according to the highest peak load tests;for a 120 mN peak load,the film manifested tolerable adhesion properties.Moreover,nanoindentation of ZrO_(2)-Y_(2)O_(3) nanostructure deposited at 1050℃substrate preheating temperature produced the highest hardness value of about 21.7 GPa.Vickers micro hardness was utilized with the aid of the Tabor equation in order to achieve deeper insight into the correlation between adhesion and deposition process parameters.
基金financially supported by the National Natural Science Foundation of China (Nos. 51104131 and 51201152)Heilongjiang Provincial Natural Science Foundation of China (No. E201247)the Open Fund of Zhejiang Provincial Top Key Discipline (No. 20110929)
文摘In this research, a nano-Mo2 C particle dispersion-strengthened copper alloy was prepared by a novel method, i.e., electron beam physical vapor deposition(EBPVD) which has advantages of simple technical process and low cost compared with the conventional mechanical alloying method. And the microstructure and properties of the material were investigated. The results show that the copper matrix is composed of columnar crystals with the average width of 7 lm, and the size of Mo2 C dispersoid is1–7 nm. The ultimate tensile strength of the material is486 MPa, and the electrical conductivity is 82 % IACS. As the temperature increases from 293 to 573 K, the material becomes more brittle.
基金The Deutsche Forschungsgemeinschaft(DFG)under grant No.Schu1372/5-1,Consejo Nacional de Ciencia y Tecnologia(CONACYT)National Science Foundation(NSF)with NSF-PREM grant No.DMR-1827745。
文摘The effects of YO(1.5)doping in yttria-zirconia based thermal barrier coatings(TBCs)against CMAS interaction/infiltration are discussed.The TBCs with an YO(1.5)content ranging from 43–67 mol.%(balance Zr O2)were produced by electron beam physical vapor deposition(EB-PVD)techniques.The results reveal a trend of higher apatite formation probability with the higher free YO(1.5)available in the yttriazirconia system.Additionally,the infiltration resistance and amount of consumed coating appears to be strongly dependent on the YO(1.5)content in the coating.The thinnest reaction layer and lowest infiltration was found for the highest produced 67 YO(1.5)coating.Complementary XRD experiments with volcanic ash/YO(1.5)powder mixtures with higher yttria contents than in the coatings(80 YO(1.5)and pure YO(1.5))also showed higher apatite formation with respect to increasing yttria content.The threshold composition to promote apatite-based reaction products was found to be around 50 YO(1.5)in zirconia which was proved in the coatings and XRD powder experiments.An YO(1.5)-ZrO2-Fe O-TiO2 bearing zirconolite-type phase was formed as a reaction product for all the coating compositions which implicates that TiO2 in the melt acts as a trigger for zirconolite formation.This phase could be detrimental for CMAS/volcanic ash infiltration resistance since it can be formed alongside with apatite which controls or limits the amount of Y^(3+)available for glass crystallization.The Fe rich garnet phase containing all the possible elements exhibited a slower nucleation compared to apatite and its growth was enhanced with slow cooling rates.The implications of phase stability and heat treatment effects on the reaction products are discussed for tests performed at 1250°C.
文摘Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both discrete particle and nano cluster forms. The silver particles were attached to the 50 nm-thick Si3N4 windows of the wet cell and could not move freely in the liquid. With a SIC14 liquid loaded in the wet cell, silicon nano materials were controllably grown on the wet cell windows by means of a liquid phase electron beam induced deposition (EBID) method. The deposited nano dots were nicely round-shaped, and demonstrated a power law growth dependency on beam exposure time in a log-log plot. In a NiCI2 solution/Ni system, both electrochemical deposition and dissolution of the nickel nano films were observed while applying electric biases on to the nickel electrodes in the wet cell. Instead of extensional growth on existing crystals, interestingly, it is more commonly observed that new nickel nano particles grow out in front of the existing film first and then merged into the film. The wet cell set up is demonstrated to be a versatile tool for nano liquid system research.