Papers by Keyword: Pulsed Laser Deposition (PLD)

Abstract: Silicon carbide thin films were obtained on Si (100) and (111) substrates by means of vacuum laser ablation of α-SiC ceramic target. The influence of substrate temperature on composition, structure and surface morphology of experimental samples was examined using Rutherford backscattering spectrometry (RBS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), conventional and high-resolution transmission electron microscopy (TEM/HRTEM), atomic force microscopy (AFM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) methods.

Abstract: Good crystalline of ATO thin films is necessary to improve the electrical and optical properties. In this paper, ATO thin films were fabricated using PLD method at high temperature of 550 °C, and the effect of laser energy density on the microstructure, electrical property and optical property of the ATO films is discussed. The results suggest that ATO films show good crystalline when deposited at high temperature of 550 °C. Both the electrical and optical properties have been enhanced with the increasing of laser energy density. When the laser energy density is 5.4 J/cm², the lowest resistivity of ATO thin film is obtained with the value of 6.52×10^-4 Ω·cm and the average optical transmittances is 82.0 %.

Abstract: This paper focuses on physical properties of ZnS thin films.ZnS thin films were successfully fabricated on Fluorine-Tin-Oxide(FTO) substrates(in a vacuum chamber maintained at 10-6Torr) at the substrate temperatures(Ts) of 150°Cand 200°Cby pulsed laser deposition(PLD),respectively.The structural properties of the ZnS films were analyzed with a X-ray diffraction(XRD) spectroscopy;The surface morphology of ZnS films was examined using scanning electron microscopy(SEM). With the increasing of the substrate temperature,the intensity of the (111) diffraction peak increases clearly and the surface of the ZnS films was more homogeneous and more compact.The main phase of the films deposited at 150°C and 200°C are both cubic-zinc-blende structure.The transmission spectra of the films was measured by UV-Vis spectrophotometer(UV,model a Perkin Elmer-Lambda 950),it shown that the films have the high transmittance in the spectrum of the visible light range,and the optical energy gaps were 3.48eV and 3.54eV,corresponding to the substrate temperatures of 150°C and 200°C.The results shown that the PLD technique can fabricate the better ZnS thin films.

Abstract: La_2/3Ca_1/3MnO₃:Ag_0.05(LCMO:Ag_0.05) thin films were prepared on vicinal cut LaAlO₃(LAO) substrates with various film thicknesses by pulsed laser deposition technique (PLD). XRD results show that all the samples are shown along the (00l) orientation in orthorhombic structure with Pbnm space group. While the film thickness is around 450nm, the optimum LIV effects of the epilayer thin film have been obtained. The LIV effects enhancement of the LCMO:Ag_0.05 thin films due to the photon scattering effects have been restrained and anisotropic seebeck coefficient improved.

Abstract: In this paper, the fabrication,physical and electrochemical properties of copper silicon alloy film were systematically studied and the optimized preparation conditions were obtained.When KrF excimer laser (λ=248 nm) repetition rate is 10Hz, laser energy is 260mJ,vacuum is 10-5Pa, target and substrate revolution per minute of target is 10, substrate temperature is 300°C and deposition time is 1.0h, as-deposited film from Si target and Cu substrate is obtained by pulsed laser deposition.The XRD pattern showed that as-deposited film is cubic stucture of Cu9Si, SEM images showed that as-deposited film has regular surface, particle size is about 300nm and particle size distribution is in narrow range.And the same time the electrochemical properties of as-deposited film showed good cycleability.

Abstract: Tooth enamel cannot be reconstructed once it is destroyed immoderately. Hydroxyapatite (HAp) thin sheet can potentially be used for a novel dental biomaterial to repair the enamel. Using a pulsed laser deposition (PLD) method, we have successfully created a flexible HAp sheet of less than a few micrometers in thickness. Due to its flexibility, the HAp sheet is tightly adhered on curved surfaces at the target site. In the present study, we newly developed double-layered sheets composed of HAp film coated with tricalcium phosphate (TCP) thin layer. The HAp/TCP sheet was adhered to the extracted human teeth using a calcium phosphate solution for 3 days. The adhesive strength between the HAp/TCP sheet and tooth enamel was evaluated by quasi-static tensile tests. Moreover, the interface structure between them was observed by a scanning electron microscopy. As a result of the mechanical evaluation, the adhesive strength was greater than approximately 2.5 MPa. The electron microscopic observation revealed that the sheet was partially fused with the enamel. These findings suggest the possibility that enamel defects are repaired using the HAp/TCP sheet for a short duration.

Abstract: Transparent Conducting Antimony Doped Tin Oxide (ATO) Films Have Been Prepared on Quartz Substrate by Pulsed Laser Deposition (PLD) Technology. Despite of Extensive Researches of ATO Films Prepared by other Methods, the Study of PLD Technology Is Relatively few. PLD Technology Is Distinctive to Maintain the Elemental Components between the Targets and the Obtained Thin Flms under Optimal Conditions Contributing to Precise Control of Composition and Doping Ratio of ATO Films. The Effect of Sb₂O₃ Doping on the Electrical and Optical Properties of the ATO Films Was Investigated with Various Sb₂O₃ Doping Ratio (mol%) as 2, 4, 6, 8, 10 at 500 °C in an Oxygen Pressure of 8 Pa. The Results Suggest that the Electrical Resistivity Is Firstly Decreased and then Increased with the Increase of Sb₂O₃ Doping Ratio. When the Sb₂O₃ Doping Ratio Is about 6 mol%, the Optimal Electrical Resistivity Is 3.5×10-3 Ω.cm and the Average Optical Transmittance Is 83.1%. It Is Significant to Clarify the Impact Mechanism of Sb₂O₃ Doping Ratio to Get the Best Electrical and Optical Physical Properties. it Is Supposed that the Carrier Concentration Dominates at a Low Sb₂O₃ Doing Ratio while a Scattering Effect Is Performed at a High Sb₂O₃ Doing Ratio.

Abstract: Using the (100)-Oriented MgO Thin Film as the Buffer Layer, BaTi₂O₅ Films Were Deposited on Si(100) Substrates by Pulsed Laser Deposition under Various Oxygen Partial Pressures (P_O2). the Effects of P_O2 on the Crystal Phase, Orientation and Surface Morphology of the as-Deposited Films Were Investigated. Single-Phased Bati2o5 Films Were Obtained at P_O2 = 10-15 Pa, and the Preferred Orientation Changed from (710) to (020) with Decreasing P_O2. at P_O2 = 10 Pa, the BaTi₂O₅ Films with a Higher Degree of bItalic text-Axis Orientation and a Dense Texture Were Deposited on the Mgo(100)/Si(100) Substrates. The MgO Buffers Played an Important Role as Structural Templates for the Textured Growth of BaTi₂O₅ Films on Si Substrates.

Abstract: Ferromagnetic semimetals are valuable materials for spintronic applications . Recently, several theoretical papers reported that a good candidate in this respect is zinc-blende (ZB) CrTe. We report the THEED measurements of thin CrTe layers obtained by pulsed laser deposition on (100) KCl substrate by YAG:Nd 3+ laser. Layers were grown from tablets of pressed powder Cr₂Te₃. Films have good mirror-like morphology. High resolution diffraction patterns show a number of sharp Debye rings. Careful analysis points on the complex composition of the layers consisting mainly with hexagonal and cubic CrTe. Hexagonal structure of CrTe shows an unexpected lattice constants a = 4.181Å, c = 7.324 Å), while in the literature (J. Dijkstra et al. J. Phys. Cond. Matter 1, 9141 (1989)) these constants are 3.997Å, c = 6.222 Å. Inclusions of Te as well as hexagonal Cr are not excluded. The phases of Cr₂Te₃ and Cr₃Te₄ are observed as well.

Abstract: Two types of different oxides multifunctional thin films were deposited by PLD technique on the surface of Si and MgO substrates. First of them was CoO doped with Ca content characterized by fcc (halite) structure and second one was perovskite-type LaCoO3 compound. Their microstructure, chemical/phase composition and morphology were examined by means of diverse techniques (SEM, TEM, EDS). For the surface topography observations of thin films the Atomic Force Microscopy (AFM) was applied. Nanohardness and scratch tests (adhesion measurements) were also performed for estimation of (Co,Ca)O and LaCoO3 films mechanical properties and quality. Obtained results confirm that using PLD technique it is possible to carry stoichiometric composition of different compounds from the target to single crystal substrate however the microstructure and properties of obtained thin films are highly influenced by the substrate’s material and laser ablation parameters (laser wavelength, energy density, time and target-substrate distance).