Complex oxides films and film systems - from analysis and simulation of the deposition process towards complex micro and nanostructures

The activity 'Functional Oxide Films and Sensors' is focused on the research on complex oxides thin film systems. The preparation, analysis, pattering and processing of oxide films and multilayers represent a mayor objective of the research towards improved or novel functional oxide microwave and sensor devices.

Various preparation technologies are employed. The emphasis lies on the PVD technologies, pulsed-laser deposition (PLD) and sputter deposition. Major aspects are:

• Deposition of single, multilayer and superlattice oxides
• Simulation of complex deposition process - e.g., Monte-Carlo simulation of high-pressure deposition, the role of atomic oxygen, new deposition concepts
• Dielectric and ferroelectric films - towards new compositions (e.g.,atomic mixing) and complex multilayer systems, including various titanates, tantalates, and niobates aiming at high permittivity, tunability, temperature stability and power handling capability combined with low microwave losses
• High-Tc films - aiming at novel fluxon effects and devices
• Micro- and nano-patterning of oxide films and devices

The structural analysis of the films and film systems is based on X-ray diffraction, Rutherford Back-Scattering and/or Raman spectroscopy. Additional to standard stoichiometric and structural characterization, the internal strain of the layers, defect situation and interface properties are analyzed.

The electronic analysis of films, test structures and devices represents a mayor aspect of the activity.
The following tools are available:

• Complete electronic characterization:
  • dc up to high GHz regime
  • temperature range from He-temperature to 500oC
  • magnetic fields up to 8T
• Impedance spectroscopy
• Capacitance measurements at various frequencies

The aims of the research activity are:

• engineering of the physical properties of oxide films- methods ranging from chemical substitution to strain induced modification of electronic properties
• vortex matter in micro- and nanostructured superconducting films - towards novel fluxon devices
• oxide thin film sensor devices for bio and chemical applications

References:

E. Hollmann and R. Wördenweber
Analysis of Defects in Epitaxial Oxide Thin Films via X-Ray Diffraction Technology
Thin Solid Films 515, 3530 (2007)

E.K. Hollmann, V.A. Vol'pyas and R. Wördenweber
Monte-Carlo simulation of the particle transport during physical vapor deposition of ceramic superconductors
Physica C 425 (2005) 101-110

R. Wördenweber, E. Hollmann, M. Poltiasev, H.W. Neumüller
Low-pressure large-area magnetron sputter deposition of YBa2Cu3O7 films for industrial applications
Supercond. Sci. Technol. 16 (2003) 584-589

R. Wördenweber
Growth of high-Tc thin films (review)
Supercond. Sci. Technol. 12 (1999) R86 - R102

contact:

Insititute of Bio- and Nanosystems II
Forschungszentrum Jülich GmbH
Leo-Brandt-Strasse
D-52425 Jülich, Germany
contact