Vertical alignment of liquid crystals on a fully oxidized HfO_2 surface by ion bombardment

摘要

High-performance liquid crystals (LCs) driven at a 0.9 V threshold were demonstrated on very thin HfO_2 films with vertical (homeotropic) alignment by ion bombardment. Atomic layer deposition was used to obtain LC orientation on ultrathin high-quality films of double-layer HfO_2/Al_2O_3. X-ray photoelectron spectroscopy indicated that full oxidization of HfO_2 film surfaces was induced by ion bombardment, shifting the Hf 4f spectra to lower binding energies. The increased intensities of the Hf 4f peaks after ion bombardment confirmed that nonstoichiometric HfO_x was converted to the fully oxidized HfO_2 surfaces.