Effect of Zr/Ti ratio on Electrical Properties of PZT Thick Films Formed by Aerosol Deposition Process.

Abstract

Pb(Zr,Ti)O3(PZT)는 우수한 유전 및 압전 특성으로 벌크와 필름의 형태로 센서,액츄에이터,트랜듀서등 다양한 분야에 적용되고 있다.PZT의 전기적 특성은 조성비(Zr/Ti비)에 따라 현저히 달라진다고 알려져 있다.에어로졸증착법은 고밀도의 세라믹 막을 제조할 수 있는 막 형성기술이다.이 기술은 1㎛ 이하의 박막뿐만 아니라 수백㎛ 이상의 치밀한 후막을 단시간에 얻을 수 있는 공정이다.이 공정은 상온에서 원료의 고체 입자를 사용하여 기판에 충돌함으로써 상온에서 막이 형성된다.본 연구에서 PZT를 에어로졸 증착법을 사용하여 상온에서 Si기판과 sapphire기판에 10㎛ 막을 증착하였다.PZT 후막의 조성변화에 따른 전기적 특성 변화를 조사하기 위하여 필름의 Zr/Ti의 비를 45/55,52/48,60/40으로 하여였다.증착 후의 막을 전기로를 사용하여 600,700,900℃에서 1시간 동안 열처리 하였다.열처리 함에 따라 상온 증착막과 비교하여 전기적 특성이 현저히 향상되었다.상경계조성인52/48PZT 필름이 가장 높은 유전상수를 나타냈다.52/48PZT 필름을 900℃에서 1시간동안 열처리 하였을때 가장 높은 전기적 특성을 나타내었는데 유전상수(ε_(r)), 잔류분극(Pr),항전계(Ec)가 1350,31.2μC/cm²,26,8kV/cm 였다.

Lead zirconate titanate (PZT) has attracted considerable attention for various application such as sencer, actuators and transducers due to its excellent ferroelectric and piezoelectric properties in both bulk and film forms. Electrical properties of PZT are well known to depend strongly on its composition, particularly on Zr/Ti ratio. Aerosol deposition process is a novel deposition technique for the fabrication of ceramic films having high density. In can produce crack-free, dense thin and thick films ranging in thickness between submicrometer and several hundreds of micrometer in a short time. It used solid particles as raw materials and formation was achieved by collision of particles onto a substrate at room temperature. In the present study, PZT thick films with thickness of 10㎛ were deposited on silicon and sapphire substrates by aerosol deposition process at room temperature. The films with Zr/Ti ratio of 45/55, 52/48 and 60/40 were fabricated in order to investigate the effect of compositional modifications on the electrical properties. After deposition, the films were annealed at 600, 700 and 900℃ for 1h in an electric furnace. The annealed films showed markedly improved electrical properties in comparison with the as-deposited films. Relative dielectric constant showed the highest value in the ratio of 52/48 PZT film near the MPB(morphotropic phase boundary) composition. The ratio of 52/48 PZT film annealed at 900℃ for 1h exhibited the best electrical properties; Relative dielectric constant(ε_(r)), remanent polarization(Pr) and coercive field(Ec) were 1350, 31.2μC/cm² and 26.8kV/cm, respectively.