Influence of substrate temperature on the electrical behaviour of zinc stannate thin films deposited by electron beam evaporation technique

Abstract

A series of zinc stannate (Zn2Sn04) thin films were prepared at four different substrate temperatures; namely, room-temperature (25 °C), 50 °C, 100 °C and 200 °C. Direct-current resistivity measurements were performed on these samples in the temperature range from room temperature (-290 K) up to about 500 K. A phase transition (of positive temperature coefficient (PTC) of resistance) was observed in the thin film grown at room temperature at about 385 K. Other investigated samples showed a semiconducting behaviour of three distinct conduction mechanisms extending from intrinsic to thermal freeze-out conduction. The width of the band gap Eg was found to depend on the substrate temperature and was discussed in terms of a formation of a band tailing. Thermal freeze-out was dominant at the lower temperature region. © Société Italiana di Fisica.