Abstract:A detailed investigation about the dependence of microstructure and electrical properties on annealing temperature was carried out for cerium oxide(CeO₂) ultra-thin films (18 nm to 110 nm) on n-type Si(100) substrates by RF magnetron sputtering. Substrate temperature was kept constant at 400 ℃ for all samples. The as-deposited films were subsequently annealed in air ambient at 700, 800 and 900 ℃ for 1 h respectively. The crystallinity and surface morphology of the CeO₂ films were analyzed with X-ray diffractometer(XRD), scanning electron microscope(SEM), atomic force microscope(AFM) and Raman scattering measurement. Electrical properties of the Au/CeO₂/Si/Au structure were examined by high frequency capacitance—voltage (C—V) characteristics at 1 MHz and leakage current density—electric field (J—E) characteristics. A Raman peak of the CeO₂ thin films was seen at 463 cm⁻¹. From C—V data, these films exhibit dielectric constants ranging from 18 to 23, the hysteresis width (ΔV_FB) ranging from 0.015 V to 0.12 V and the density of trapped charges ranging from 1.45×10¹¹ to 3.01×10¹¹ cm⁻². A leakage current of 4.75×10⁻⁸ −9.0×10^{−7 A/cm2} at  2 MV/cm was observed. The experimental results show that the CeO₂ buffer layers are suitable for non-volatile metal- ferroelectric-insulator-semiconductor(MFIS) structure field-effect-transistors(FETs) memory applications.

Key words: CeO₂ thin film; RF magnetron sputtering; microstructure and electrical properties; MFISFETs memory applications