Dielectric properties of dysprosium- and scandium-doped hafnium dioxide thin films

Dysprosium- and scandium-doped HfO2 films have been deposited by atomic-vapor deposition on SiO2∕Si substrates. Glancing-incidence x-ray diffraction demonstrates that Dy0.10Hf0.90Ox and Sc0.10Hf0.90Ox films show a cubic crystal structure, whereas HfO2 films are monoclinic. The dielectric permittivity increases strongly from 16 for HfO2 to 32 for Dy0.10Hf0.90Ox and Sc0.10Hf0.90Ox. This leads to a reduction of the leakage current in the tunneling regime by up to three orders of magnitude for constant effective oxide thickness. For thick films (≳6nm), it is shown that leakage occurs via the Poole-Frenkel mechanism and that doping HfO2 increases leakage for constant physical oxide thickness.