Application of Magnesium Fluoride $(\hbox{MgF}_{2})$ Thin Films for Liquid Crystal Alignment Using Ion-Beam Irradiation

This letter introduces the characteristics of the magnesium fluoride ( MgF
₂
) inorganic film deposited by an electron-beam evaporation system for liquid crystal display (LCD) applications. We first achieved homogeneous liquid crystal (LC) alignment by controlling the ion-beam (IB) irradiation energy intensity. We also showed that MgF
₂
is more transparent than spin-coated polyimide (PI) in the visible wavelength. By chemical analysis, IB irradiation selectively broke the Mg-F bonding structure because of the IB energy intensity; thus, the MgF
₂
surface was turned to an unstable MgF
_2-x
surface, resulting in homogeneous LC orientation. Moreover, the electrooptic characteristics of a homogeneously aligned twisted nematic (TN)-LCD on the MgF
₂
layer showed good performance as the TN-LCD on the polyimide, showing a strong possibility of the MgF
₂
material as an LC alignment layer.