Complex impedance spectroscopy of high-k HfO2 thin films in Al/HfO2/Si capacitor for gate oxide applications

摘要: The dielectric responses of ultrathin (~6.65 nm) HfO2 films, in the form Al/HfO2/Si capacitors were prepared by rf sputtering technique, has been studied wide frequency range as a function deposition temperatures. Deposition temperatures varied from room temperature (30 °C) to 500 °C. Thickness and interfacial surface roughness heterostructures extracted fitting specular X-ray reflectivity data. impedance analysis combined with modulus spectroscopy was performed get insight microscopic features like grain, grain boundary film–electrode interfaces their effects film properties. films exhibited maximum dispersion both real imaginary part at low range. studies showed distribution relaxation times due presence grains boundaries films. Impedance revealed that polarization caused space charges film/electrode plays an important role behavior capacitor. In order explain effectively plots contain one or two arcs more than contributions, results are interpreted using approach proposed Abrantes (Z / vs. |Z // |/f representation). loss (tan δ) curves fact there is possibility existence Schottky barrier insulator semiconductor interface, which traps distributed throughout semiconductor-insulator interface it believed be auto doping during process. ac conductivity, σ (ω), varies (ω) = Bω n n 0.06–0.71.