Pulsed-laser deposition (PLD) and laser-induced breakdown spectroscopy (LIBS) techniques are reviewed and new
results on PLD and LIBS of functional oxide materials are reported. Nano-composite high-Tc superconducting (HTS)
films with enhanced critical current density are produced by laser ablation of novel ceramic targets. The transport
properties of HTS thin films are modified by light-ion irradiation. Nano-patterning of HTS films is achieved by masked
ion beam irradiation. Optically transparent epitaxial ZnO layers are grown by PLD and acoustic resonances in the GHz
range are excited by piezoelectric actuation. LIBS is employed to analyze impurity trace elements in industrial oxide
powder. For quantitative analysis of major and minor elements the calibration-free LIBS method is refined. This CFLIBS
method is employed to the analysis of multi-element materials and very good match with nominal concentration of
oxides is achieved (relative error less than 20 %).
The use of laser-induced breakdown spectroscopy (LIBS) for the sorting of polymers containing heavy metal impurity is
investigated. Our main attention is directed towards the detection of cadmium and lead in real-life waste materials and
certified reference polymer materials. UV (193 nm ArF) and IR (1064 nm Nd:YAG) laser radiation is employed for
ablation and plasma generation in air. The LIBS spectra are measured in the UV / VIS range by using an Echelle
spectrometer equipped with an ICCD camera. Spectra are compared for the different lasers. Sorted polymer materials are
investigated by reference analysis.
Pulsed-laser deposition (PLD) is an excellent technique to grow thin films and multi-layers of complex oxide materials.
We present our recent results on deposition, characterization and nano-patterning of novel oxide high-temperature
superconductors (HTS) and piezoelectric materials. HTS thin films of improved superconducting properties are
fabricated from ceramic targets consisting of Y2Ba4CuMOy (M = metal) nano-particles embedded in YBa2Cu3O7
(YBCO) matrix. The nano-composite ceramics are UV-laser ablated and the optical plasma emission is monitored by
laser - induced breakdown spectroscopy. The HTS films reveal superconducting critical current densities that depend on
target composition and are strongly enhanced as compared to phase pure YBCO films. Application of HTS layers in
future nano-electronic devices requires novel techniques for nano-patterning. Masked ion-beam structuring enables the
nano-patterning of YBCO thin films in a direct and single-step process. Gallium orthophosphate (GaPO4) thin films and
piezoelectric ZnO multi-layers are reported also. GaPO4 is an outstanding piezoelectric material with very high
transition temperature (~ 970 °C). Epitaxial GaPO4 films are fabricated on quartz substrates by PLD and thermal post-annealing.
Long-term annealing at high temperature does not degrade the GaPO4 films. Multi-layers of Al and Li doped
ZnO are pulsed-laser deposited on various substrates and investigated for applications in thin film sensors.
Advanced thin film materials with giant dielectric permittivities up to ≈ 10000 were produced by pulsed-laser deposition. Composite targets of barium titanate (BaTiO3) and polytetrafluorethylene (PTFE) were ablated with 248 nm KrF-laser radiation in Ar atmosphere. The synthesized films have a complex microstructure and contain product species which are formed during the pulsed-laser ablation / deposition process. The dielectric permittivities of films exhibit pronounced dispersion for frequencies higher than 10 kHz. Strong dependencies of the film permittivity on target composition, layer thickness, ambient gas pressure and relative humidity are revealed. The large dielectric permittivity of these film materials may be attributed to space-charge polarization phenomena. Films deposited from the same targets in oxygen atmosphere have much lower dielectric permittivity (ετ'≈ 30).
Pulsed-laser deposition is a unique technique that has been employed for thin film growth of a broad variety of materials. We report on the deposition and characterization of advanced piezoelectric thin films and ceramic/polymer composite layers. Pulsed-laser ablation and micro-patterning of piezoelectric GaPO4 is presented.
The modifications of microstructure and of physical properties induced by the use of an additional radiofrequency beam discharge during the pulsed laser deposition (PLD) process has been investigated for different classes of materials. The materials concerned are piezoelectric oxides (ZnO), gate dielectric oxides (ZrO2), ferroelectric oxides (BaTiO3), ferroelectric relaxors (Pb1-xLax)(Zr0.65Ti0.33)O3 (PLZT) with variable La contents, respectively. Using a special configuration of the radio frequency discharge, a beam of excited and/or ionized oxygen species was produced and directed towards the substrate. RF plasma excited species identified in the spectra and impinging the substrate surface are very reactive at the surface with metals ions, neutral and sub-oxides which arrive from the laser plasma, with respect to discharge-off conditions. Thus, the RF plasma contribution is very important between the laser pulses, especially in the early after-pulse stages, when the surface of the fresh deposited film is not completely stabilized. A parametric study has been performed to evidence the corroborative effects induced by RF beam and other parameters as laser wavelength (265 nm, 355 nm, 530 nm and 1060 nm), laser fluence (2 - 25 J/cm2), oxygen pressure (0.2 - 0.8 mbar), substrate temperaeture (RT-650°C) on the composition and crystallinity and on dielectric and ferroelectric properties.
Pulsed-laser deposition is a unique technique that has been employed for thin film growth of a broad variety of materials. Tuning of deposition parameters allows to produce advanced thin films with optimized materials properties. We report on the deposition and characterization of various kinds of high-temperature superconducting thin films and of ceramic/polymer composite layers.
Pulsed-laser deposition (PLD) is a unique technique that has been employed for thin film growth of a broad variety of materials. In this contribution, PLD of high-temperature superconducting films of YBA2Cu3O7-(delta ), Bi2Sr2CaCu2O8+(delta ) and (Hg,Re)Ba2CaCu2O6+(delta ) is reported. Emphasis is put on the optimization of deposition parameters and the growth of so-called tilted films on vicinal cut substrates. Such films offer the unique possibility to measure in-plane and out-of- plane transport properties which is especially important for materials not available as single crystals. Experiments on photodoping and on vortex string channeling are presented. The electrical properties and the microstructure of the vicinal films are investigated with respect to the tilt angle and the film thickness.