Na adsorption on the Si(111)-(7x7) surface: From two-dimensional gas to nanocluster array
Na adsorption on the Si(111)-(7x7) surface: From two-dimensional gas to nanocluster array
复制标题
DOI：
10.1103/physrevlett.91.126101
复制
发表时间：
2003-09-19
影响因子：
8.6
通讯作者：
Sakurai, T
中科院分区：
文献类型：
--
作者：
Wu, KH;Fujikawa, Y;Sakurai, T
用扫描隧道显微镜(STM)系统地研究了室温下Na在Si(111)-(7x7)表面上的吸附。在0.08单分子层的临界覆盖率以下，我们发现了有趣的对比度调制，而不是局域的Na吸附，加上STM图像中的条纹噪声，伴随着单调的功函数下降。在临界覆盖率以上，Na团簇出现并形成自组装阵列。结合第一性原理理论模拟，我们得出结论：(7×7)表面上的Na原子虽然与表面结合强烈(类似于2.2 eV)，但在围绕Si其余原子的“盆地”中高度移动，在初始覆盖处形成二维气相，较高覆盖处的团簇由6个Na原子和3个Si吸附原子组成。
We have systematically investigated Na adsorption on the Si(111)-(7x7) surface at room temperature using scanning tunneling microscopy (STM). Below the critical coverage of 0.08 monolayer, we find intriguing contrast modulation instead of localized Na adsorbates, coupled with streaky noise in the STM images, which is accompanied by monotonic work function drop. Above the critical coverage, Na clusters emerge and form a self-assembled array. Combined with first-principles theoretical simulations, we conclude that the Na atoms on the (7x7) surface are, while strongly bound (similar to2.2 eV) to the surface, highly mobile in "basins" around the Si rest atoms, forming a two-dimensional gas phase at the initial coverage, and that the cluster at the higher coverage consists of six Na atoms together with three Si adatoms.