Preparation of Ferroelectric Superlattice Using Phot-excited Process and Their applications to Functional Deviccs

光激发铁电超晶格的制备及其在功能器件中的应用

基本信息

批准号：
06452217
负责人：
SHIOSAKI Tadashi
金额：
$ 3.33万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

PbTiO_3, Pb (Zr, Ti) O_3 (PZT) and (Pb, La) (Zr, Ti) O_3 (PLZT) thin films were prepared by MOCVD in order to realize the Pb-based ferroelectric superlattice structure. For the evaluation of the crystallinity and epitaxial relationship of the ultrathin films, the energy dispersive typed total reflection X-ray diffraction (TRXD) method was used for the first time. The growth mechanism of pbTiO_3 and PZT thin films at the initial growth stage was also investigated using an atomic force microscope (AFM).Using TRXD,in-plane orientation, epitaxial relationship and lattice spacing of PbTiO_3 and PZT thin films (3 nm - 100 nm in thickness) grown on Pt/MgO were evaluated. From these measurements, it was found that the in-plane orinetations of PbTiO_3 and PZT were strongly dependent on that of Pt on MgO.Lattice spacing of PZT (100) in in-plane at an azimutal angle of 0ﾟ was 0.399nm. It was also found that PZT on Pt/MgO was compressed in the in-plane and tensed in the vertical direction by the internal stress derived from the inner strains such as lattice mismatch, differnce in the thermal expansion coefficient and the volume change with the ferroelectric phase transition. AFM observations of initial growth stage of PbTiO_3 showed that the islands grew gradually in a lateral dimension until finally they covered the entire substrate surface. From AFM observatins, it was found that the main growth mechanism initial growth stages (-100 nm in thickness) was two-dimensional growth.From our experiments, it was found that the TRXD method and AFM are very useful to evaluate the structural nature of ultrathin ferroelectric films. In particular, the energy dipersive type TRXD method is very promising to evaluate ferroelectric superlattice structure because highly precise in-situ measurement with high reliability can be carried out.

PBTIO_3，PB（ZR，TI）O_3（PZT）和（PB，LA）（Zr，Ti）O_3（plzt）薄膜由MOCVD制备，以实现基于PB的铁电级别超级晶格结构。为了评估超薄薄膜的结晶度和外延关系，首次使用了能量分散的总反射X射线衍射（TRXD）方法。还使用原子力显微镜（AFM）研究了初始生长阶段的PBTIO_3和PZT薄膜的生长机制。使用TRXD，平面内向，外延关系和PBTIO_3和PZT薄膜的晶格间距（3 nm -100 nm -inm -ym -100 nm）在厚度上进行了评估。从这些测量值中可以发现，PBTIO_3和PZT的面板内部非常依赖于MGO上的Pt。在平面内的PZT（100）在平面内的平面内占0 ﾟ的平面间距为0.399nm。还发现，PT/MGO上的PZT在平面内被压缩，并通过从晶格不匹配等内部菌株（热膨胀系数的差异）衍生而成的内部应力，在垂直方向上张紧，热膨胀系数的差异以及体积随铁电相变的变化而变化。对PBTIO_3初始生长阶段的AFM观察表明，这些岛屿逐渐生长在横向尺寸上，直到最终覆盖了整个底物表面。从AFM观察者那里，发现主要的生长机理初始生长阶段（厚度为-100 nm）是二维生长。从我们的实验中，发现TRXD方法和AFM对于评估超级超薄铁电膜的结构性非常有用。特别是，能量纺纱型TRXD方法非常有希望评估铁电超晶格结构，因为可以进行高可靠性的高度精确的原位测量。