Nanostructured surfaces 

Iron-doped indium-saving indium tin oxide thin films deposited by DC sputtering method using Fe3O4 target
Petrovska S.S.1, Sergiienko R.A.2, Ilkiv B.I.1, Nakamura T.3, Ohtsuka M.3
1Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhyzhanovski Str., 3, Kyiv-03142, Ukraine.
2 Physico-Technological Institute of Metals and Alloys, Vernadsky Ave., 34/1, Kyiv-03142, Ukraine.
3 Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan.
E-mail: makoto.ohtsuka.d7@tohoku.ac.jp

Iron-doped indium-saving ITO50:Fe3O4 thin films were deposited onto glass substrates unheated and preheated at 523 K by co-sputtering of ITO50 and Fe3O4 targets at different oxygen flow rates (0-0.3 sccm) and subsequently heat treated. 
It was found that minimal value of volume resistivity was obtained for ITO50:Fe3O4 thin films deposited on preheated substrates (PHS) at oxygen flow rate of 0.2 sccm that is 14 times lower than that of ITO50:Fe3O4 thin films deposited on unheated substrates (UHS) at the same oxygen flow rate.
The transmittance of both ITO50:Fe3O4 (PHS) and ITO50:Fe3O4 (UHS) thin films was improved with increasing oxygen flow rate. Doping of indium saving ITO thin films with Fe3O4 allows increasing transmittance. Average transmittance was above 85 % in visible range for both ITO50:Fe3O4 (PHS) and ITO50:Fe3O4 (UHS) thin films.
ITO50:Fe3O4 (PHS) thin films crystallizes at lower heat-treated temperature than ITO50:Fe3O4 (UHS) thin films, however undoped ITO50 (PHS) thin films deposited at the same oxygen flow was crystallizes in as-deposited state. Doping with Fe3O4 does not change the structure of undoped ITO50 (PHS) thin films.
Arithmetical mean height (Sa) and root mean square height (Sq) of as-deposited ITO50:Fe3O4 (PHS) thin films were 0.52 nm and 0.67 nm, respectively.