Search

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 Y 2 Ba 4 CuMO y (M = metal) nano-particles embedded in YBa 2 CU 3 O 7 (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 (GaPO 4 ) thin films and piezoelectric ZnO multi-layers are reported also. GaPO 4 is an outstanding piezoelectric material with very high transition temperature (∼ 970 °C). Epitaxial GaPO 4 films are fabricated on quartz substrates by PLD and thermal post-annealing. Long-term annealing at high temperature does not degrade the GaPO 4 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 r ’ 10000 were produced by pulsed-laser deposition. Composite targets of barium titanate (BaTiO 3 ) 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 ( r ’ 30). Keywords: Pulsed-laser deposition, PTFE polymer, ceramic / polymer composites, giant dielectric permittivity, space-charge / interfacial polarization

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.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.