| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1665514 | Thin Solid Films | 2014 | 5 Pages |
•Lanthanum titanium oxide films were deposited by reactive magnetron sputtering.•A La2Ti2O7 chemical composition is proposed, with an unusual orthorhombic cell.•At 10 GHz, the dielectric losses are lower than 0.02.•No variation of the dielectric constant is observed under DC electric biasing.
Perovskite lanthanum titanium oxide thin films were deposited on (001) MgO, (001) LaAlO3 and Pt(111)/TiO2/SiO2/(001)Si substrates by RF magnetron sputtering, using a La2Ti2O7 homemade target sputtered under oxygen reactive plasma. The films deposited at 800 °C display a crystalline growth different than those reported on monoclinic ferroelectric La2Ti2O7 films. X-ray photoelectron spectroscopy analysis shows the presence of titanium as Ti4 + ions, with no trace of Ti3 +, and provides a La/Ti ratio of 1.02. The depositions being performed from a La2Ti2O7 target under oxygen rich plasma, the same composition (La2Ti2O7) is proposed for the deposited films, with an unusual orthorhombic cell and Cmc21 space group. The films have a textured growth on MgO and Pt/Si substrates, and are epitaxially grown on LaAlO3 substrate. The dielectric characterization displays stable values of the dielectric constant and of the losses in the frequency range [0.1–20] GHz. No variation of the dielectric constant has been observed when a DC electric field up to 250 kV/cm was applied, which does not match a classical ferroelectric behavior at high frequencies and room temperature for the proposed La2Ti2O7 orthorhombic phase. At 10 GHz and room temperature, the dielectric constant of the obtained La2Ti2O7 films is ε ~ 60 and the losses are low (tanδ < 0.02).
