Structural and electrical properties of HfO2 films grown by atomic layer deposition on Si, Ge, GaAs and GaN

HfO2 thin films were grown by atomic layer deposition on Si, Ge, GaAs and GaN substrates, using Hf((OBu)-Bu-t)(2)(mmp)(2) and HfCl4. The results show that this combination of precursors promotes a conformal and smooth growth of HfO2 films on all substrates. As grown films in the thickness range of 10-20 nm have the same electronic density and smooth surfaces. Films 20 nm thick are polycrystalline with the monoclinic structure, whereas the crystallized fraction in the 10 nm thick layers is much lower. The HfO2/Ge interface is remarkably sharp. The dielectric constant of the HfO2 films is 15. Low density of interface states and oxide fixed charges are obtained for the films grown on Si. The optimization of the HfO2 interface with the other substrates requires more effort.