Chu Ming-Wen, Szafraniak Izabela, Scholz Roland, Harnagea Catalin, Hesse Dietrich, Alexe Marin, Gösele Ulrich
Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Saale), Germany.
Nat Mater. 2004 Feb;3(2):87-90. doi: 10.1038/nmat1057. Epub 2004 Jan 18.
Defects exist in almost all materials and defect engineering at the atomic level is part of modern semiconductor technology. Defects and their long-range strain fields can have a negative impact on the host materials. In materials with confined dimensions, the influence of defects can be even more pronounced due to the enhanced relative volume of the 'defective' regions. Here we report the dislocation-induced polarization instability of (001)-oriented Pb(Zr(0.52)Ti(0.48))O(3) (PZT) nanoislands, with an average height of approximately 9 nm, grown on compressive perovskite substrates. Using quantitative high-resolution electron microscopy, we visualize the strain fields of edge-type misfit dislocations, extending predominantly into a PZT region with a height of approximately 4 nm and width of approximately 8 nm. The lattice within this region deviates from the regular crystal structure. Piezoresponse force microscopy indicates that such PZT nanoislands do not show ferroelectricity. Our results suggest that misfit engineering is indispensable for obtaining nanostructured ferroelectrics with stable polarization.
几乎所有材料中都存在缺陷，原子级别的缺陷工程是现代半导体技术的一部分。缺陷及其长程应变场会对主体材料产生负面影响。在尺寸受限的材料中，由于“缺陷”区域相对体积的增加，缺陷的影响可能会更加明显。在此，我们报告了在压缩钙钛矿衬底上生长的平均高度约为9nm的(001)取向Pb(Zr(0.52)Ti(0.48))O(3)（PZT）纳米岛的位错诱导极化不稳定性。利用定量高分辨率电子显微镜，我们观察到刃型失配位错的应变场，其主要延伸到高度约为4nm、宽度约为8nm的PZT区域。该区域内的晶格偏离了规则晶体结构。压电力显微镜表明，此类PZT纳米岛不显示铁电性。我们的结果表明，对于获得具有稳定极化的纳米结构铁电体而言，失配工程是必不可少的。
