This paper focused on forming of thick liquid crystal films containing fine polymers in a new design for microwave variable phase-shifters with fast response time. As the liquid crystal molecular alignment became unstable in thicker liquid crystal film which was essential to variable phase shifters, the three-dimensional network structure of the polymers was formed in a 100-µm-thick liquid crystal film to stabilized it, using photopolymerization of the monomer. Measurement of the electrooptic properties of the polymer-stabilized liquid crystal film revealed that the relaxation response time of the liquid crystal alignment with removal of driving voltage was drastically decreased by dispersing the polymer at a concentration of several %. A new variable phase-shifter, composed of a microstrip transmission line (stripe length: 193 mm), was fabricated by using the polymer-stabilized liquid crystal film as the dielectric material. When a driving voltage of 70 V_rms was applied vertically to the liquid crystal film, the device showed phase shift of 80 degrees at 20 GHz. It also exhibited phase-shift properties over a wide microwave frequency range.

*Postdoctoral fellow

Numerical analysis of microdischarge in a surface-type ac plasma display cell was performed using time-dependent, three-dimensional (3-D) fluid equations to comprehend the discharge characteristics. We investigated the breakdown dynamics in terms of the width of the address electrode and barrier ribs because these are the typical 3-D parameters of the ac plasma display panel (ac PDP). It has been clarified that the width of the address electrode is an important factor in the formation of discharge volume with wall annihilation by barrier ribs and the accumulation of wall charges on the address electrode. The obtained time dependent spatial characteristics of ac PDP discharge by the width of the address electrode and the effect of wall annihilation by barrier ribs will help us to design the optimized ac PDP cells for stable write and sustain discharges.

Since the tunneling processes of electrons were influenced by the structures at the interfaces, we should focus on the crystallographical differences of each layer in the tunneling magnetoresistance (TMR) devices. [Ni₈₁Fe₁₉/Al-O/Co₇₅Fe₂₅] films with TMR were deposited by a dual ion beam sputtering (DIBS) method, where it has an excellent controllability of film structures. We have proposed the interfacial modulation technique (IMT), in which only a couple of monolayers at the initial growth region of each depositing layer were bombarded by Kr ions. Using IMT, the crystallographic structures and interfacial conditions of the films were controlled by the energy of Kr bombardment. The effect of Kr ion bombardment on the initial growth region seemed to be effective in decreasing the film resistivity and in attaining the excellent crystallinity of Ni-Fe and Co-Fe ferromagnetic films, especially at the optimized bombarding energy of 100 eV. In addition, stoichiometric and stable Al₂O₃ insulation films could be attained by sputtering of pure Al target with O₂ concurrently flow to the substrate at flow rate of 10 SCCM using reactive DIBS and IMT. These optimized films were applicable as the ferromagnetic and the insulation layers in TMR devices, respectively.