| AVS 55th International Symposium & Exhibition | |
| Applied Surface Science | Wednesday Sessions |
| Session AS-WeA |
| Session: | Frontiers of Analysis and Combined Materials |
| Presenter: | M. Bruns, Forschungszentrum Karlsruhe GmbH, Germany |
| Authors: | M. Bruns, Forschungszentrum Karlsruhe GmbH, Germany M. Fuchs, Forschungszentrum Karlsruhe GmbH, Germany R. Ochs, Forschungszentrum Karlsruhe GmbH, Germany S. Schlabach, Forschungszentrum Karlsruhe GmbH, Germany D.V. Szabó, Forschungszentrum Karlsruhe GmbH, Germany T. Grehl, ION-TOF GmbH, Germany S. Kayser, ION-TOF GmbH, Germany M. Fartmann, Tascon GmbH, Germany |
| Correspondent: | Click to Email |
Sputtered SnO2 thin films are well established as gas sensing layers in analytical micro systems such as the Karlsruhe micro nose (KAMINA). To improve the performance towards higher sensitivity a very promising approach is to replace the sputtered thin films with films made of SnO2 nanoparticles. This can easily be achieved by the Karlsruhe microwave plasma process (KMPP), a versatile precursor based gas-phase plasma process suited to synthesize nanoscaled particles with diameters less than 5 nm.1 Regarding long-term stability, such SnO2 nanoparticles can be coated in-situ with a protective ultra-thin SiO2 shell in a downstream step and then directly deposited onto the respective micro devices. These core/shell nanoparticles are expected to prevent the gas sensitive core from growing and agglomeration, respectively, while preserving electrical contact. The prerequisite is to achieve an inhomogeneous SiO2 shell enabling direct contact between adjacent SnO2 nanoparticles, i.e. simply acting as a spacer.
This contribution focuses on the characterization of nanoparticle thin films with a thickness of 200 nm made of core/shell SnO2/ SiO2 nanoparticles by means of X-ray photoelectron spectroscopy (XPS). The main points of interest in this context are chemical binding states and information on the shell thickness in a non-destructive manner. For this purpose, the SiO2 shell thickness systematically was increased while keeping the SnO2 core size constant. In case of the desired inhomogeneous ultra-thin SiO2 shells low energy ion scattering (LEIS) solely is a suitable means to distinguish between Sn and Si within the outermost monolayer of the spherical particles to prove the attainability of open-pored coatings. In addition, transmission electron microscopy (TEM), X-ray diffraction (XRD), and He-Pycnometry were used to achieve a comprehensive characterization.
1B. Schumacher, R Ochs, H. Troesse, S. Schlabach, M. Bruns, D. V. Szabó, J. Haußelt, Plasma Process. Polym. 4 (2007) 865.