• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.1038-1043
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• 2012

In this work, a high tunable capacitor using a multi-layer dielectric of BZN/BST/BZN is designed and characterized for reconfigurable RF applications. By utilizing a high tunable BST ferroelectric and a low-loss BZN paraelectric thin film, a multi-layer dielectric of BZN/BST/BZN obtained a tunability of 47 % and $tan{\delta}$ of 0.005. The fabricated tunable capacitor on a quartz wafer using this multi-layer dielectric achieved a Q-factor of 10 and tunability of 60 % at 800 MHz and 15 V. Its size is $327{\times}642{\mu}m2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.860-865
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• 2006

In this paper, a novel tunable inter-digital capacitor using dielectric tunable $Bi_2O_3-ZnO-Nb_2O_5(BZN)$ pyrochlore thin films is proposed. In order to improve the tunability and reduce DC bias voltage using the fringing electric field, the electrodes of the inter-digital capacitor are embedded in the thin film. Designed results using a 2.5 D simulator show that the tunability of the proposed inter-digital capacitor improves by 10 %, compared to the conventional inter-digital capacitor. The proposed IDC, which is based on the simulation results, was fabricated, using the BZN thin film deposited by a reactive RF magnetron sputtering on the on the silicon substrate. The fabricated inter-digital capacitor shows the maximum tunability of 50 % at 5.8 GHz and 18 V DC applied.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.96-96
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• 2007

Low voltage organic TFTs (OTFTs) and ZnO based TFTs (<5V), utilizing room temperature deposited $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ (BZN) thin films were recently reported, pointing to high-k gate insulators as a promising route for realizing low voltage operating flexible electronics. $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ (BZN) thin film is one of the most promising materials for gate insulator because of its large dielectric constant (~60) at room temperature. However their tendency to suffer from relatively high leakage current at low electric field (>0.3MV/cm) hinder the application of BZN thin films for gate insulator. In order to improve leakage current characteristics of BZN thin film, we mixed 30mol% MgO with 70mol% BZN and their dielectric and electric properties were characterized. We fabricated field-effect transistors with transparent oxide semiconductor ZnO serving as the electron channel and high-k $(Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7)_{0.7}(MgO)_{0.3}$ as the gate insulator. The devices exhibited low operation voltages (<4V) due to high capacitance of the $(Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7)_{0.7}(MgO)_{0.3}$ dielectric.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.230-231
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• 2009

펄스 레이저 층착법 (이하 PLD)은 다성분계 산화물 박막 또는 다층구조의 박막 제작에 매우 유용한 기술이다. 본 실험에서는 KrF 엑시머 레이저를 이용하여 pt on Si 기판 위에 150nm 두께의 $Bi_{1.5}ZnNb_{1.5}O_7$(이하 BZN) 박막을 다양한 기판온도에서 제작하였다. XRD를 이용하여 BZN 박막의 구조적 특성을 분석하였고, 박막을 MIM 구조로 제작하여 유정적 특성을 측정하였다. 제조한 BZN 박막은 $500^{\circ}C$ 이상에서 결정질을, $500^{\circ}C$ 이하의 온도에서는 비정질 특성을 보였다. 유전 특성은 100 - 400$^{\circ}C$ 영역에서는 온도가 증가함에 따라 졸은 특성을 나타내었고, $500^{\circ}C$에서부터는 감소하였다. 증착 온도 $400^{\circ}C$에서 제작한 BZN 박막이 유전상수가 67.8, 유전 손실이 0.006으로 가장 줄은 유전특성을 나타내었다.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.720-725
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• 2013

This paper has presented that fringing-electric fields enhanced by a finger-type electrode can improve the tunability of the tunable capacitor. Its top electrodes with different area and line width are designed in types of the finger for a long conducting perimeter. The tunable varactors were fabricated on a quartz substrate employing a multi-layer dielectric of a para/ferro/para-electric thin film. Compared to the conventional capacitor, finger-type capacitors are analyzed in terms of effective capacitance and tunablility. Their effective capacitance and tunability of the varactors with the long perimeter increase 24~40 % and 7~12 %, respectively, due to enhanced fringing electric fields from 1 to 2.5 GHz.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.2
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• pp.45-49
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• 2014

In this work, a phase shifter radio-frequency integrated chip (RFIC) using a simple all-pass network is presented. As a tuning element of the phase shifter RFIC, tunable capacitors with a multi-layer dielectric of a para-/ferro-/para-electrics using a high tunable BST ferroelectric and a low-loss BZN paraelectric thin film were utilized. In order to evaluate and analyze the fabricated phase shifter RFIC, the same elements such as an inductor and capacitor integrated into it are also fabricated and tested. The designed phase shifter RFIC was fabricated on a quartz substrate in the size of $1.16{\times}1.21mm^2$. As the test results, the maximum phase difference of $350^{\circ}$ is obtained at 15 V and its tuning frequency bandwidth is 90 MHz from 2.72 to 2.81GHz.