Preparation of pulsed DC magnetron deposited Fe-doped SnO sub(2) coatings

• Published in: Physica status solidi. A, Applications and materials science Vol. 213; no. 9; pp. 2303 - 2309
• Main Authors: Kormunda, Martin, Fischer, Daniel, Hertwig, Andreas, Beck, Uwe, Sebik, Matej, Esser, Norbert
• Format: Journal Article
• Language: English
• Published: 01.09.2016
• Subjects: Coatings; Constants; Deposition; Gas mixtures; Iron; Magnetron sputtering; Oxygen; Tin dioxide
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201532882

Iron-doped SnO sub(2) coatings were deposited in a 50kHz DC-pulsed magnetron sputtering discharge. The pulses had a duration of 4 mu s in selected gas mixtures from pure argon up to 60% of oxygen at a constant total pressure of 0.2Pa. A single target of SnO sub(2) with Fe inset was used. The mass spectrometry study detected the gas-related ions Ar super(+), O sub(2) super(+) and O super(+), where the last one becomes the dominant positive ion at higher oxygen contents. Atomic oxygen ions had a higher energy as it resulted from the collision-caused dissociation on the target surface. The tin-related species were detected as Sn super(+) and SnO super(+). SnO sub(2) super(+) species were not detected. The deposition rate decreased by using gas mixtures with oxygen as well as the corresponding amount of Sn-related species in the plasma. The increase of oxygen also increased significantly the sheet resistance of the films. The XPS study showed that the iron concentration decreased by using additional oxygen. But the O/Sn ratio in the coatings was constant, contrary to the increased FeO/Fe ratio in the films. An additional analysis of the coatings by spectroscopic ellipsometry has shown a dependence of the polarizability and the permittivity on the amount of oxygen used during the deposition. In contrast, the study has found no such dependence for the absorption of the layers.