Study of dc conduction mechanisms in dysprosium–manganese oxide insulator thin films grown on Si substrates

Abstract

Samples of amorphous and crystalline (Dy–Mn) oxide thin films have been prepared on Si(p) substrates. The crystal structure of the oxide film annealed under different conditions was investigated by the X-ray diffraction method (XRD). The percentage weight composition of the compound-oxide films was determined by the X-ray fluorescence (XRF) spectroscopy method. It was observed that Dy oxide and Mn oxide prevent each other to crystallize alone or making a solid solution even at 600 °C, but a compound of DyMnO 3 was formed through the solid-state reaction at T > 800 °C. Samples in form of Al/oxide/Si MOS structures were characterised by measuring their capacitance as a function of gate voltage C( V g) in order to determine the fixed and interface charge densities as well as the oxide voltage in terms of gate voltage. The total surface charge density was in the device-grade of 10 10–10 11 cm −2. The dc measurements at room temperature show that the main mechanism controlling the current flow is the Richardson–Schottky (RS) mechanism. The parameters of the RS model like the field lowering coefficients and the dynamic relative permittivity were determined. The leakage current density of the samples was studied as a function of temperature in a range of (293–380 K). It was observed that the temperature dependence of crystalline (Dy–Mn) oxide films has a property that higher temperature reduces the current, which may be important in the application in circuits that operate under extreme conditions. Thermal activation energies of electrical conduction were determined.