Structural and electrical properties of Zn doped Mn oxide thin films grown on p-Si substrates

In the present work, Zn-Mn oxide thin films were prepared on p-Si(1 0 0) substrates for structural and electrical studies. The X-ray fluorescence (XRF) technique was used to determine the relative weight fraction ratio of Mn/Zn in the prepared samples. The X-ray diffraction (XRD) study shows that films annealed at 400 °C have amorphous structure and they were crystallised under pre-annealing at 600 °C or more. Moreover, Zn oxide cannot crystallise alone, but instead it diffuses into Mn oxide grains. A comprehensive study on electrical properties was carried on. The ac-conductance and capacitance as a function of gate voltage, frequency, and temperature were studied on samples made in form of metal/oxide film/Si MOS devices. The fixed charge and interface state densities were determined and their variation with annealing process was studied and explained. It was found that the “correlated barrier hopping” CBH model controls the frequency dependence of the conductivity, while Kramers-Kronig (KK) relations explain the frequency dependence of the relative permittivity. The parameters of CBH model were determined showing that the ac-conduction is realised by single-polaron hopping mechanism. dc-Conduction properties were also studied through the voltage and temperature dependence of the leakage dc-current density. The obtained dc-data follow a Richardson-Schottky (RS) mechanism.