Structural Dynamics in Thermal Treatment of Amorphous Indium Oxide Films

Thermal treatment of amorphous indium oxide (In_xO) films is used in various basic studies as a means of tuning the disorder perceived by the electronic system. In this process, the resistance of a given sample decreases, whereas its amorphous structure and chemical composition is preserved. The main effect of the process is an increase in the system density, which, in turn, leads to improved interatomic overlap manifested as improved conductivity. A similar effect has been observed in studies of other amorphous systems that were subjected to pressure. Herein, the Raman spectra of amorphous In_xO change in response to thermal treatment in a similar way as in pressure experiments performed on other disordered and amorphous systems. A study of how thermal treatment changes the system dynamics is presented by monitoring the resistance versus time of In_xO films following various stages of thermal treatment. The time dependence of the sample resistance fits the stretched exponential law with parameters that change systematically with repeated thermal treatment cycles. The implications of these results to slow dynamics phenomena that are governed by the Kohlrausch's law are discussed.