This paper presents high quality YBa_(2)Cu_(3)O_(7-δ)(YBCO)thin films on LaAlO_(3)substrate for microwave devices prepared by pulsed laser deposition(PLD).The double-sided YBCO films cover a large area and have been ...This paper presents high quality YBa_(2)Cu_(3)O_(7-δ)(YBCO)thin films on LaAlO_(3)substrate for microwave devices prepared by pulsed laser deposition(PLD).The double-sided YBCO films cover a large area and have been optimized for key parameters relevant to microwave device applications,such as surface morphology and surface resistance(R_(s)).This was achieved by improving the target quality and increasing the oxygen pressure during deposition,respectively.To evaluate the suitability of the YBCO films for microwave devices,a pair of microwave filters based on microstrip fabricated on films from this work and a commercial company were compared.The results show that the YBCO films in this work could completely meet the requirements for microwave devices.展开更多
Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoerciviti...Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoercivities of the MnBi/Bi film are 1.5 T and 2.35 T at room temperature and at 373K, respectively, showing a positive temperature coefficient. Microstructural investigations show that the textured MnBi film results from the orientated growth induced by the textured Bi under-layer.展开更多
Aim: The study was to fabricate FA nanopowder/Co-Cr-Mo dental alloy nanocomposite using pulsed laser deposition (PLD), and to evaluate bioactivity properties on simulated body fluid. Methods: In this work, the FA nano...Aim: The study was to fabricate FA nanopowder/Co-Cr-Mo dental alloy nanocomposite using pulsed laser deposition (PLD), and to evaluate bioactivity properties on simulated body fluid. Methods: In this work, the FA nanopowder was prepared by mixing calcium hydroxide (Ca(OH)2), phosphorouspent oxide (P2O5) and calcium fluoride (CaF2) in a planetary high energy ball mill using zirconium vial. Fluorapatite (FA) nanopowder was processed in the form of pellet for pulsed laser deposition process. The Co-Cr-Mo alloy was coated with FA nanopowder which was approximately 35 - 65 nm at various laser energy, pressure and time. The X-ray diffraction (XRD) was used to analyze phase, crystallinity and size distribution of Co-Cr-Mo/FA nanocomposite. The surface analysis was by scanning electron microscopy (SEM), Atomic Force microscopy (AFM) and Energy dispersive spectroscopy (EDS). Results: From the results obtained, It was shown that FA nanopowder deposited on Co-Cr-Mo alloy was stable during 14 days of incubation on simulated body fluid. It was also observed that the FA nanopowder coated on the surface of the alloy was still intact after the deposition process, which indicated the bioactivity and biocompatibility of the material. Conclusions: The fabrication of FA nanocomposite based dental alloys (Co-Cr-Mo) using PLD was done successfully. This was confirmed by various characterization techniques, which included XRD, AFM, SEM and EDS.展开更多
The surface morphology of buffer layer yttrium-stabilized zirconia （YSZ） of YBa2CuaO7-σ （YBCO） high temperature superconducting films relies on a series of controllable experimental parameters. In this work, we f...The surface morphology of buffer layer yttrium-stabilized zirconia （YSZ） of YBa2CuaO7-σ （YBCO） high temperature superconducting films relies on a series of controllable experimental parameters. In this work, we focus on the influence of pulsed laser frequency and target crystalline type on surface morphology of YSZ films deposited by pulsed laser deposition （PLD） on rolling assisted biaxially textured substrate tapes. Usually two kinds of particles are observed in the YSZ layer： randomly distributed ones on the whole film and self-assembled ones along grain boundaries. SEM images are used to prove that particles can be partly removed when choosing dense targets of single crystalline. Lower frequency of pulsed laser also contributes to a smoother film surface. TEM images are used to view the crystalline structure of thin film. Thus we can obtain a basic understanding of how to prepare a particle-free YSZ buffer layer for YBCO in optimized conditions using PLD. The YBCO layer with nice structure and critical current density of around 5 MA/cm2 can be reached on smooth YSZ samples.展开更多
In the present study, gallium nitride thin films were grown by using pulsed laser deposition. After the growth samples were annealed at 400 and 600 ℃ in the nitrogen atmosphere. Surface morphology of the as-grown and...In the present study, gallium nitride thin films were grown by using pulsed laser deposition. After the growth samples were annealed at 400 and 600 ℃ in the nitrogen atmosphere. Surface morphology of the as-grown and annealed samples was observed by atomic force microscopy. Post-growth annealing results in an improved surface roughness of the films. Chemical analysis of the samples was performed by X-ray photoelectron spectroscopy. Stoichiometric gallium nitride thin films were obtained for the samples annealed at 600 ℃. Optical measurements of the samples were performed to measure the band gap and optical constants of the films. Effect of annealing on the band gap and optical constants of the films was studied.展开更多
The rapid development of ultralarge-scale integration demands integrated devices from ordinary 1-dimensional integrated devices to 3-dimensional devices and multi-function devices. Because of its non-volatility and ra...The rapid development of ultralarge-scale integration demands integrated devices from ordinary 1-dimensional integrated devices to 3-dimensional devices and multi-function devices. Because of its non-volatility and radiation-hardness, very large (～1000) dielectric constant and polarizability, ferroelectric thin film and its application research have recently attracted great attention in newly functional materials and integrated devices such展开更多
The development of superconductor/insulator/superconductor（SIS）tunnel junctions inthe cuprate high-temperature superconductor family has been hampered by an anisotropicstructure and a coherence length ξ as short as...The development of superconductor/insulator/superconductor（SIS）tunnel junctions inthe cuprate high-temperature superconductor family has been hampered by an anisotropicstructure and a coherence length ξ as short as 0.3 nm. However, the discovery of Ba<sub>1-x</sub>K<sub>x</sub>-BiO<sub>3</sub>（x≈0.4） superconductor which is an isotropic cubic structure and has a展开更多
ZnNiO thin films with different contents of Ni(0-10 at.%) were fabricated on quartz and Si(100) substrates by pulsed laser deposition(PLD).We measured the samples by X-ray diffraction(XRD),field-emission scanning elec...ZnNiO thin films with different contents of Ni(0-10 at.%) were fabricated on quartz and Si(100) substrates by pulsed laser deposition(PLD).We measured the samples by X-ray diffraction(XRD),field-emission scanning electron microscope(FE-SEM),X-ray photoelectron spectroscopy(XPS),ultraviolet-visible spectrometer(UV-VIS),and Hall testing.When the Ni contents were below 3 at.%,partial Zn2+ ions were replaced by the Ni2+ ions without forming any other phases,which enhanced the conductivity of the film.When the Ni contents were above 3 at.%,Ni ions were at the interstitial sites,and Ni-related clusters and defects were able to emerge in the films,resulting in a worsening of electrical and optical properties.A ferromagnetic hysteresis with a coercive force of approximately 30 Oe was observed in the ZnNiO film with a Ni content of 3 at.% at room temperature.展开更多
The application of titanium dioxide(TiO_(2))in the photovoltaic(PV)field is gaining traction as this material can be deployed in doping-free heterojunction solar cells with the role of electron selective contact.For m...The application of titanium dioxide(TiO_(2))in the photovoltaic(PV)field is gaining traction as this material can be deployed in doping-free heterojunction solar cells with the role of electron selective contact.For modeling-based optimization of such contact,knowledge of the titanium oxide defect density of states(DOS)is crucial.In this paper,we report a method to extract the defect density through nondestructive optical measures,including the contribution given by small polaron optical transitions.The presence of both related to oxygen-vacancy defects and polarons is supported by the results of optical characterizations and the evaluation of previous observations resulting in a defect band fixed at 1 eV below the conduction band edge of the oxide.Solar cells employing pulsed laser deposited-TiO_(2)electron selective contacts were fabricated and characterized.The J-V curve of these cells showed,however,an S-shape,then a detailed analysis of the reasons for such behavior was carried out.We use a model involving the series of a standard cell equivalent circuit with a Schottky junction in order to explain these atypical performances.A good matching between the experimental measurements and the adopted theoretical model was obtained.The extracted parameters are listed and analyzed to shed light on the reasons behind the low-performance cells.展开更多
Amorphous gallium nitride （a-GaN） films with thicknesses of 5 and 300 nm are deposited on n-Si （100） substrates by pulsed laser deposition （PLD）, and their field emission （FE） properties are studied. It shows ...Amorphous gallium nitride （a-GaN） films with thicknesses of 5 and 300 nm are deposited on n-Si （100） substrates by pulsed laser deposition （PLD）, and their field emission （FE） properties are studied. It shows that compared with thicker （300 nm） a-GaN film, better FE performance is obtained on ultrathin （5 nm） a-GaN film with a threshold field of 0.78 V/μm, which is the lowest value ever reported. Furthermore, the current density reaches 42 mA/cm2 when the applied field is 3.72 V/μm. These experimental results unambiguously confirm Binh＇s theoretical analysis （Binh et al. Phys Rev Lett, 2000, 85（4）： 864-867） that the FE performance would be prominently enhanced with the coating of an ultra-thin wide band-gap semiconductor film.展开更多
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2022YFA1603903 and 2021YFA0718700)the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2020B0101340002)+3 种基金the National Natural Science Foundation of China(Grant Nos.61971415,51972012,11927808,119611410,11961141008,and 12274439)the Strategic Priority Research Program(B)of Chinese Academy of Sciences(Grant No.XDB25000000)Beijing Natural Science Foundation(Grant No.Z190008)Basic Research Youth Team of Chinese Academy of Sciences(Grant No.2022YSBR-048).
文摘This paper presents high quality YBa_(2)Cu_(3)O_(7-δ)(YBCO)thin films on LaAlO_(3)substrate for microwave devices prepared by pulsed laser deposition(PLD).The double-sided YBCO films cover a large area and have been optimized for key parameters relevant to microwave device applications,such as surface morphology and surface resistance(R_(s)).This was achieved by improving the target quality and increasing the oxygen pressure during deposition,respectively.To evaluate the suitability of the YBCO films for microwave devices,a pair of microwave filters based on microstrip fabricated on films from this work and a commercial company were compared.The results show that the YBCO films in this work could completely meet the requirements for microwave devices.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51171001,51371009 and 50971003the Foundation of Key Laboratory of Neutron Physics of CAEP under Grant No 2014BB02
文摘Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoercivities of the MnBi/Bi film are 1.5 T and 2.35 T at room temperature and at 373K, respectively, showing a positive temperature coefficient. Microstructural investigations show that the textured MnBi film results from the orientated growth induced by the textured Bi under-layer.
文摘Aim: The study was to fabricate FA nanopowder/Co-Cr-Mo dental alloy nanocomposite using pulsed laser deposition (PLD), and to evaluate bioactivity properties on simulated body fluid. Methods: In this work, the FA nanopowder was prepared by mixing calcium hydroxide (Ca(OH)2), phosphorouspent oxide (P2O5) and calcium fluoride (CaF2) in a planetary high energy ball mill using zirconium vial. Fluorapatite (FA) nanopowder was processed in the form of pellet for pulsed laser deposition process. The Co-Cr-Mo alloy was coated with FA nanopowder which was approximately 35 - 65 nm at various laser energy, pressure and time. The X-ray diffraction (XRD) was used to analyze phase, crystallinity and size distribution of Co-Cr-Mo/FA nanocomposite. The surface analysis was by scanning electron microscopy (SEM), Atomic Force microscopy (AFM) and Energy dispersive spectroscopy (EDS). Results: From the results obtained, It was shown that FA nanopowder deposited on Co-Cr-Mo alloy was stable during 14 days of incubation on simulated body fluid. It was also observed that the FA nanopowder coated on the surface of the alloy was still intact after the deposition process, which indicated the bioactivity and biocompatibility of the material. Conclusions: The fabrication of FA nanocomposite based dental alloys (Co-Cr-Mo) using PLD was done successfully. This was confirmed by various characterization techniques, which included XRD, AFM, SEM and EDS.
基金Supported by the ITER Project of the Ministry of Science and Technology of China under Grant No 2011GB113004the Shanghai Commission of Science and Technology under Grant No 11DZ1100402the Youth Fund of the National Natural Science Foundation of China under Grant No 11204174
文摘The surface morphology of buffer layer yttrium-stabilized zirconia （YSZ） of YBa2CuaO7-σ （YBCO） high temperature superconducting films relies on a series of controllable experimental parameters. In this work, we focus on the influence of pulsed laser frequency and target crystalline type on surface morphology of YSZ films deposited by pulsed laser deposition （PLD） on rolling assisted biaxially textured substrate tapes. Usually two kinds of particles are observed in the YSZ layer： randomly distributed ones on the whole film and self-assembled ones along grain boundaries. SEM images are used to prove that particles can be partly removed when choosing dense targets of single crystalline. Lower frequency of pulsed laser also contributes to a smoother film surface. TEM images are used to view the crystalline structure of thin film. Thus we can obtain a basic understanding of how to prepare a particle-free YSZ buffer layer for YBCO in optimized conditions using PLD. The YBCO layer with nice structure and critical current density of around 5 MA/cm2 can be reached on smooth YSZ samples.
基金supported by Deanship of Scientific Research at King Fahd University of Petroleum and Minerals through internal research grant IN100040
文摘In the present study, gallium nitride thin films were grown by using pulsed laser deposition. After the growth samples were annealed at 400 and 600 ℃ in the nitrogen atmosphere. Surface morphology of the as-grown and annealed samples was observed by atomic force microscopy. Post-growth annealing results in an improved surface roughness of the films. Chemical analysis of the samples was performed by X-ray photoelectron spectroscopy. Stoichiometric gallium nitride thin films were obtained for the samples annealed at 600 ℃. Optical measurements of the samples were performed to measure the band gap and optical constants of the films. Effect of annealing on the band gap and optical constants of the films was studied.
基金Research performed under the auspices of the Natural Scientific Foundation of Shanghai
文摘The rapid development of ultralarge-scale integration demands integrated devices from ordinary 1-dimensional integrated devices to 3-dimensional devices and multi-function devices. Because of its non-volatility and radiation-hardness, very large (～1000) dielectric constant and polarizability, ferroelectric thin film and its application research have recently attracted great attention in newly functional materials and integrated devices such
基金Project supported by the National Center for Research and Development on Superconducting, the National Natural Science Foundation of China and the National Laboratory of Solid State Microstructure in Nanjing University.
文摘The development of superconductor/insulator/superconductor（SIS）tunnel junctions inthe cuprate high-temperature superconductor family has been hampered by an anisotropicstructure and a coherence length ξ as short as 0.3 nm. However, the discovery of Ba<sub>1-x</sub>K<sub>x</sub>-BiO<sub>3</sub>（x≈0.4） superconductor which is an isotropic cubic structure and has a
基金Project supported by the National Natural Science Foundation of China (No. 51072181)the Doctoral Fund of Ministry of Education of China (No. 20090101110044)
文摘ZnNiO thin films with different contents of Ni(0-10 at.%) were fabricated on quartz and Si(100) substrates by pulsed laser deposition(PLD).We measured the samples by X-ray diffraction(XRD),field-emission scanning electron microscope(FE-SEM),X-ray photoelectron spectroscopy(XPS),ultraviolet-visible spectrometer(UV-VIS),and Hall testing.When the Ni contents were below 3 at.%,partial Zn2+ ions were replaced by the Ni2+ ions without forming any other phases,which enhanced the conductivity of the film.When the Ni contents were above 3 at.%,Ni ions were at the interstitial sites,and Ni-related clusters and defects were able to emerge in the films,resulting in a worsening of electrical and optical properties.A ferromagnetic hysteresis with a coercive force of approximately 30 Oe was observed in the ZnNiO film with a Ni content of 3 at.% at room temperature.
文摘The application of titanium dioxide(TiO_(2))in the photovoltaic(PV)field is gaining traction as this material can be deployed in doping-free heterojunction solar cells with the role of electron selective contact.For modeling-based optimization of such contact,knowledge of the titanium oxide defect density of states(DOS)is crucial.In this paper,we report a method to extract the defect density through nondestructive optical measures,including the contribution given by small polaron optical transitions.The presence of both related to oxygen-vacancy defects and polarons is supported by the results of optical characterizations and the evaluation of previous observations resulting in a defect band fixed at 1 eV below the conduction band edge of the oxide.Solar cells employing pulsed laser deposited-TiO_(2)electron selective contacts were fabricated and characterized.The J-V curve of these cells showed,however,an S-shape,then a detailed analysis of the reasons for such behavior was carried out.We use a model involving the series of a standard cell equivalent circuit with a Schottky junction in order to explain these atypical performances.A good matching between the experimental measurements and the adopted theoretical model was obtained.The extracted parameters are listed and analyzed to shed light on the reasons behind the low-performance cells.
基金Supported by the National Natural Science Foundation of China (Grant No. 10604001)the Beijing Nora Program (Grant No. 2008B10)
文摘Amorphous gallium nitride （a-GaN） films with thicknesses of 5 and 300 nm are deposited on n-Si （100） substrates by pulsed laser deposition （PLD）, and their field emission （FE） properties are studied. It shows that compared with thicker （300 nm） a-GaN film, better FE performance is obtained on ultrathin （5 nm） a-GaN film with a threshold field of 0.78 V/μm, which is the lowest value ever reported. Furthermore, the current density reaches 42 mA/cm2 when the applied field is 3.72 V/μm. These experimental results unambiguously confirm Binh＇s theoretical analysis （Binh et al. Phys Rev Lett, 2000, 85（4）： 864-867） that the FE performance would be prominently enhanced with the coating of an ultra-thin wide band-gap semiconductor film.
