Sprodowski Carsten, Morgenstern Karina
Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstr. 2, D-30167 Hannover, Germany.
Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, Universitätsstr. 150, D-44801 Bochum, Germany.
Nanomaterials (Basel). 2019 May 7;9(5):710. doi: 10.3390/nano9050710.
If a material grows on another material with a largely different lattice constant, which of the two adapts for an energetically favorable growth? To tackle this question, we investigate the growth of Ag on Cu(111) by variable temperature scanning tunneling microscopy. The structures grown between 120 and 170 K are remarkably different from those grown between 200 and 340 K. The low-temperature structure is rectangular-like and consists of stacked rods, 7 to 8 Ag atoms long, which form a superstructure without long-range order. This structure covers the whole surface prior to nucleation of further layers. The high-temperature structure is hexagonal and consists of misfit dislocations forming 8 × 8 to 10 × 10 superstructures. For this structure, second layer nucleation sets in far before the closure of the first monolayer. While both structures are driven by the large lattice misfit between the two materials, the growing Ag layer adapts to the Cu surface at low temperature, while the Cu surface adapts to the growing Ag layer at higher temperature.
如果一种材料在晶格常数差异很大的另一种材料上生长，那么这两种材料中的哪一种会为了能量有利的生长而进行适配呢？为了解决这个问题，我们通过变温扫描隧道显微镜研究了银在铜（111）上的生长情况。在120至170 K之间生长的结构与在200至340 K之间生长的结构显著不同。低温结构呈矩形，由堆叠的棒状结构组成，棒长7至8个银原子，形成一种没有长程有序的超结构。在进一步的层成核之前，这种结构覆盖了整个表面。高温结构是六边形的，由形成8×8至10×10超结构的失配位错组成。对于这种结构，在第一层单层闭合之前很久就开始了第二层成核。虽然这两种结构都是由两种材料之间较大的晶格失配驱动的，但生长的银层在低温下适应铜表面，而铜表面在较高温度下适应生长的银层。
