Domain structures induced by tensile thermal strain in epitaxial PbTiO3 films on silicon substrates
Domain structures induced by tensile thermal strain in epitaxial PbTiO3 films on silicon substrates
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DOI：
10.1063/5.0074884
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发表时间：
2022-01-21
影响因子：
3.2
通讯作者：
Funakubo, Hiroshi
中科院分区：
文献类型：
--
作者：
Sato, Tomoya;Kodera, Masanori;Funakubo, Hiroshi
在硅衬底上制备外延铁电材料是设计用于微机电系统（MEMS）的优质铁电器件的关键。研究了在Si衬底上生长具有外延SrTiO3缓冲层的PbTiO3外延薄膜的畴结构，特别是薄膜厚度的依赖关系。Si的低热膨胀系数不仅影响相对较厚的膜区，而且影响较薄的膜区（001）取向畴的体积分数。与沉积在SrTiO3衬底上的PbTiO3薄膜相比，尽管衬底引起了强烈的失配应变，但在薄至18nm的薄膜上观察到（100）取向畴。此外，（001）取向结构域的饱和体积分数小于PbTiO3在SrTiO3上的饱和体积分数。热应变在确定畴结构中起着至关重要的作用，因此，有望控制MEMS器件中有用的薄膜的电性能。
The fabrication of epitaxial ferroelectric materials on Si substrates is key to the design of superior ferroelectric devices for applications involving microelectromechanical systems (MEMS). The domain structures of epitaxial PbTiO3 films grown on Si substrates with an epitaxial SrTiO3 buffer layer were investigated, especially in terms of film thickness dependence. The low thermal expansion coefficient of Si was found to affect the volume fraction of (001)-oriented domains not only in relatively thick film regions but also in the thinner ones. Compared with the PbTiO3 films deposited on SrTiO3 substrates, (100)-oriented domains were observed in films as thin as 18nm, notwithstanding the strong misfit strain induced by the substrate. Moreover, the saturated volume fraction of the (001)-oriented domain was smaller than that of PbTiO3 on SrTiO3. Thermal strain plays a critical role in determining domain structures and is, therefore, expected to govern the electric properties of films useful in MEMS devices.