Ferroelectricity in ultrathin yttrium-doped hafnium oxide films prepared by chemical solution deposition based on metal chlorides and alcohol

We suggest a facile way to prepare precursor solutions with metal salts and alcohol and fabricate ultrathin ferroelectric yttrium-doped hafnium oxide films on Pt(111)/TiO2/SiO2/Si substrates by chemical solution deposition and post-annealing treatment. The samples were prepared with 5.2 mol% yttrium-doping and had a thickness ranging from 3 nm to 9 nm. We also varied the post-annealing temperature from 600 °C to 800 °C. The ultrathin films were characterized by transmission electron microscopy (TEM) and Raman spectroscopy. Their local ferroelectric properties were investigated by piezoresponse force microscopy (PFM) for domain imaging and polarization switching at nanoscale.