Mechanisms of dc-current transfer in tris(acetylacetonato)iron(III) films

Thin tris(acetylacetonato)iron(III) films were prepared by sublimation in vacuum on p-Si substrates for electrical investigation. The prepared films were characterized by X-ray diffraction (XRD) which shows the material to exhibit polycrystalline orthorhombic structure. Thin films of the complex were prepared as a gate-insulator for metal/insulator/Si (MIS) device. The capacitance-gate voltage, C(V_g) characteristics of the constructed MIS device were measured, from which the relative permittivity and the density of the charges in the sample were extracted. The dc-electrical conduction in the complex film was studied at room temperature and in the temperature range of (293–353 K). It was found that the data follow a Poole–Frenkel (PF) mechanism for low voltages and a trap-charge-limited space-charge-limited conductivity (TSCLC) mechanism for higher voltages. The switching observed between the two mechanisms was explained. The characteristic parameters both mechanisms were also determined. It was concluded that the dc-conduction can be described by hopping between structural defects that form trap levels in localized states near the bottom of the mobility band. Therefore, the density of structural defects in the film, which are controllable by the method of preparation, is critical in determining the mechanism of current transfer.