Proposal of general rule to prepare epitaxial ceramic thin films at low temperature from the point of crystal chemistry

We have succeeded to prepare epitaxial yttria stabilized zirconia (YSZ) thin films at room temperature (27 °C) by the use of nm thick YSZ buffer layer deposited at 800 °C on Si(0 0 1) substrate. Room temperature epitaxial growth was realized on 0.8 nm thick ultra thin YSZ buffer layer, however, to achieve high crystallinity, 6.7 nm thick was needed. On the 6.7 nm thick YSZ buffered Si(0 0 1) substrate, we have tried to prepare epitaxial oxide ceramic thin films. As the result, epitaxial CeO2, In2O3, and MnZn-ferrite thin films were successfully deposited even at room temperature. The conditions of epitaxial growth at such low temperature was considered from the point of crystal chemistry. As the result, following conditions were proposed: (1) Materials with both small lattice mismatch and small electronegativity difference; or (2) Materials with small lattice mismatch and composed of single component. These proposed conditions will helpful to design epitaxial growth of oxide ceramic thin film at low temperature.