| Abstract: | Hafnium oxide thin films doped with different concentrations of yttrium are prepared on Si(100) substrates at room temperature using a reactive magnetron sputtering system.The effects of Y content on the bonding structure,crystallographic structure,and electrical properties of Y-doped HfO_2 films are investigated.The x-ray photoelectron spectrum(XPS) indicates that the core level peak positions of Hf 4 f and O 1 s shift toward lower energy due to the structure change after Y doping.The depth profiling of XPS shows that the surface of the film is completely oxidized while the oxygen deficiency emerges after the stripping depths have increased.The x-ray diffraction and high resolution transmission electron microscopy(HRTEM) analyses reveal the evolution from monoclinic HfO_2 phase towards stabilized cubic HfO_2 phase and the preferred orientation of(111) appears with increasing Y content,while pure HfO_2 shows the monoclinic phase only.The leakage current and permittivity are determined as a function of the Y content.The best combination of low leakage current of 10-7 A/cm~2 at 1 V and a highest permittivity value of 29 is achieved when the doping ratio of Y increases to 9 mol%.A correlation among Y content,phase evolution and electrical properties of Y-doped HfO_2 ultra-thin film is investigated. |
