Controlling ion fluxes during reactive sputter-deposition of SnO{sub 2}:F
- Empa—Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Thin Films and Photovoltaics, Überlandstrasse 129, 8600 Dübendorf (Switzerland)
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)
Magnetron sputtering of fluorine-doped tin oxide (FTO) is a scalable deposition method for large-area transparent conducting films used in fenestration, photovoltaics, and other applications. The electrical conductivity of sputtered FTO is, however, lower than that of spray-pyrolized FTO because of the ion damage induced by high energy ions leading to a reduction of the crystal quality in sputtered FTO films. In this study, various ion species present during the reactive sputtering of a metallic tin target in a mixed Ar/O{sub 2}/CF{sub 4} atmosphere are systematically characterized by energy and mass spectrometry, and possible ways of controlling the ion fluxes are explored. Ion energy distribution functions (IEDFs) of the negative ions F{sup −} and O{sup −} exhibit large peaks at an energy corresponding to the full target voltage. Although the applied partial pressure of CF{sub 4} is about 1/30 than that of O{sub 2}, the obtained IEDFs of F{sup −} and O{sup −} have comparable peak height, which can be attributed to a higher electronegativity of F. The IEDFs of positively charged O{sup +}, O{sub 2}{sup +}, Ar{sup +}, and Sn{sup +} species have their peaks around 2–8 eV. To control ion fluxes a solenoid or permanent magnets were placed between the target and the mass spectrometer. The flux of positive ions could be varied by several orders of magnitude as a function of the applied current through the solenoid, whereas the high-energy (>100 eV) negative F{sup −} and O{sup −} ions were not notably deflected. By using permanent magnets with the B-field orthogonal to the ion trajectory, the flux of O{sup −} ions could be decreased by two orders and the exposure to the high-energy F{sup −} ions was completely suppressed.
- OSTI ID:
- 22308460
- Journal Information:
- Journal of Applied Physics, Vol. 116, Issue 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N{sub 2}
Energy distribution of negative O sup minus and OH sup minus ions emitted from YBaCuO and iron garnet targets by dc and rf magnetron sputtering
Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ARGON IONS
CARBON TETRAFLUORIDE
DEPOSITION
DISTRIBUTION FUNCTIONS
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRONEGATIVITY
ENERGY SPECTRA
FILMS
FLUORINE ADDITIONS
MAGNETRONS
MASS SPECTROMETERS
MASS SPECTROSCOPY
OXYGEN IONS
PERMANENT MAGNETS
PHOTOVOLTAIC EFFECT
SPUTTERING
TIN OXIDES