Room temperature growth of ultra porous hot-wire deposited tantalum pentoxide
Giorgos Papadimitropoulos1*, Maria Vasilopoulou1, Nikos Vourdas1, Dimitris N. Kouvatsos1, Kostas Giannakopoulos1, Stella Kennou2, Dimitris Davazoglou1
1Institute of Nanoscience and Nanotechnology, NCSR Demokritos POB 60228, Agia Paraskevi, Attiki, 153 10, Greece
2Department of Chemical Engineering, University of Patras, Patra, 26500, Greece
Publication Date (Web): Jan 14, 2019
Copyright © 2018 VBRI Press
Tantalum pentoxide films were deposited on Si substrates at room temperature, by heating metallic filaments at temperatures below 600 oC, at a pressure of 1 Torr in O2 environment. This deposition method can be applied for all metallic oxides having higher vapor pressure than the corresponding metal. These (hwTa2O5) films were composed by amorphous material (as revealed by XRD measurements) and were found to be highly transparent within the range 350-1000 nm. Spectroscopic ellipsometry measurements have shown that the real part of the refractive index (n) of hwTa2O5 films depends on the deposition time and has a value below 1.5. As shown by scanning electron microscopy (TEM) measurements, these grains were composed by others with dimensions near 5 nm and with voids between them. The above microscopy measurements explain the high porosity of hwTa2O5 films. Moreover, hwTa2O5 films were also characterized by XPS and UPS measurements and the stoichiometric composition of the deposited films was determined.
Thin film, hot-wire deposition, tantalum pentoxide, room temperature growth.