RF magnetron sputtering 으로 증착한 epitaxial $BaTiO_3$ 박막의 초고주파 유전 특성

Abstract

The prospects of using ferroelectrics thin films for the farbrication and development of frequency and phase agile microwave devices have increased in past few years due to improvenebts in ferroelectric thin film processing techniaues as well as innovative circuit design. In microwave devices, ferroelectric thin film is used as tuning layer through the electric field dependence of the relative dielectric constant. Typical paraelectric materials ($SrTiO_3, KTaO_3, Ba Sr_1 TiO_3$) and electrically tunable microwave devices based on these materials shows that in spite of the recent year`s extensive efforts, no considerable improvement in the microwave losses in thin paraelectric films has been achieved. Thin films, regardless of fabrication method and substrate type, have much lower dielectric permittivity than bulk single crystals, and the loss tangent at microwave frequencies (10 GHz) is of the order of 0.01 (at zero dc-bias field) at room temperature. Nevertheless, quite promising component and subsystem level devices are successfully demonstrated. Use of ceramic (bulk and thick film) ferroelectrics in tunable microwave devices, currently considered for industrial applications, offer cost reduction. In this paper, explicitly for the first time, we consider possibilities and benefits of using ferroelectrics in polar phase in electrically controllable microwave devices. Examples of using ferroelectrics in polar state (e.g., Na0 5K0 5NbO3, SrTiO3 in antiferroelectric phase) in electrically tunable devices are reported. Index Terms-Ferroelectrics, paraelectrics, tunable microwave devices. This trends demand the researches about ferroelectric material with polar phase in microwave frequency. In this study, typical ferroelectric material, $BaTiO_3$ thin films with polar phase were observed dielectric properties in microwave frequency. In this study, typical ferroelectric material, $BaTiO_3$ this films with polar phase were observed dielectirc properties in microwave