Application of Magnesium Fluoride (\hbox) Thin Films for Liquid Crystal Alignment Using Ion-Beam Irradiation

• Published in: IEEE electron device letters 2013-02, Vol.34 (2), p.283-285
• Main Authors: KIM, Iee-Gon, PARK, Hong-Gyu, HAN, Jae-Jun, HAN, Jeong-Min, SEO, Dae-Shik
• Format: Article
• Language: English
• Subjects: Applied sciences; Display; Electronics; Electrooptic (EO) characteristics; Exact sciences and technology; ion-beam (IB) irradiation; liquid crystal (LC); Liquid crystals; magnesium fluoride (\hbox{MgF}_{2}); Optical surface waves; Optoelectronic devices; Polyimides; Radiation effects; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Surface waves; Threshold voltage; Time factors
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2012.2230608

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.