Structural phase transitions of Si(111)-(√3x√3)R30°-Au:: Phase transitions in domain-wall configurations
Structural phase transitions of Si(111)-(√3x√3)R30°-Au:: Phase transitions in domain-wall configurations
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DOI：
10.1103/physrevb.57.10100
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发表时间：
1998-04-15
影响因子：
3.7
通讯作者：
Henzler, M
中科院分区：
文献类型：
--
作者：
Nagao, T;Hasegawa, S;Henzler, M
用低能电子衍射和扫描隧道显微镜研究了Au吸附在Si（111）-root 3和6x6表面上的畴壁行为。在室温下，在衍射中从α-根3 ×根3图案到β-根3 ×根3图案的连续变化与畴壁密度的增加和它们的特征构型变化相关，作为Au覆盖度的函数，θ = 0.76-0.96。已经发现，尖锐的根部3 X根部3尖峰持续存在，与畴壁形态无关。在室温下θ = 0.79时的无标记畴壁在753 K时转变为圆形畴壁，并最终在893 K左右完全分解消失，导致明显的3 × 3结构的大畴。当θ = 0.96以上时，当样品在600 K左右退火并缓慢冷却时，畴壁以长程有序排列，周期为6 × 6。相反，在退火后淬火冷却后，形成平均间距为6a（其中a是衬底晶格周期）的畴壁中的亚稳非晶排列，其对应于β-根3 X根3结构。
Behaviors of domain walls on the Au-adsorbed Si(111)-root 3 x root 3 and 6 x 6 surfaces have been investigated by spot-profile-analyzing low-energy electron diffraction and scanning tunneling microscopy. A continuous change from the alpha-root 3 x root 3 pattern to the beta-root 3 x root 3 pattern in diffraction at room temperature has been correlated to the increase in domain-wall density and their characteristic configuration change as a function of Au coverage Theta = 0.76-0.96. It has been found that the sharp root 3 x root 3 spikes persists irrespective of the domain-wall morphology. The zigzagging domain walls at Theta = 0.79 at room temperature are found to transform to roundish ones at 753 K, and finally decompose completely to vanish around 893 K resulting in apparent large domains of root 3 x root 3 structure. Above Theta = 0.96, the domain walls are proposed to arrange with a long-range order with 6 x 6 periodicity when the sample is annealed at around 600 K and slowly cooled. On the contrary, metastable amorphous arrangement in the domain walls with average separation of 6a (where a is the substrate lattice period) is formed after annealing followed by quench cooling, which corresponds to the beta-root 3 x root 3 structure.