Thermal roughness of the homogeneous and inhomogeneous Cu(311) surface studied by high-resolution low-energy electron diffraction.
Thermal roughness of the homogeneous and inhomogeneous Cu(311) surface studied by high-resolution low-energy electron diffraction.
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通过高分辨率低能电子衍射研究均匀和非均匀 Cu(311) 表面的热粗糙度。
DOI：
10.1103/physrevb.44.13031
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Henzler
中科院分区：
文献类型：
--
作者：
Wollschläger;Luo;Henzler
用高分辨低能电子衍射研究了温度对Cu（311）表面均匀和非均匀形貌的影响。分析在各种散射条件下的衍射电子束的斑点轮廓提供了关于作为温度的函数的表面粗糙度和不均匀性的信息。从反相条件下的可逆斑点展宽可以推断，通过提高温度可以在Cu（311）表面可逆地产生原子台阶。表面从光滑的低温相转变为粗糙的高温相的临界温度是由（00）点中心尖峰在${\mathit{T}}_{\mathit{R}}$=750 K时消失得到的。在对光斑轮廓进行详细分析的基础上，我们发现Cu（311）表面的高度-高度相关性不能用Kosterlitz粗糙化的对数行为来描述。而不是这种行为，在低温阶段的高度高度相关性指数饱和的横向距离趋于无穷大，而它的特点是由一个线性发散的高温阶段。表面偏聚的硫有两个作用：Cu（311）表面大面积变成非晶，台阶原子密度增加。即使有少量的硫，表面在室温下仍然粗糙。随着硫覆盖率的增加，由于不均匀性引起的粗糙度超过了热致表面粗糙度。
The influence of temperature on the morphology of both the homogeneous and the inhomogeneous Cu(311) surfaces is investigated by high-resolution low-energy electron diffraction. Analyzing the spot profile of the diffracted electron beam under various scattering conditions provides information about both the surface roughness and inhomogeneities as a function of temperature. From the reversible spot broadening under the out-of-phase condition, it is concluded that atomic steps may be created reversibly on the Cu(311) surface by increasing the temperature. The critical temperature, at which the surface goes from the smooth, low-temperature phase into the rough, high-temperature phase, is obtained from the vanishing of the central spike of the (00) spot at ${\mathit{T}}_{\mathit{R}}$=750 K. On the basis of a detailed analysis of the spot profile, we find that the height-height correlation of the Cu(311) surface cannot be described by the logarithmic behavior predicted for Kosterlitz-Thouless roughening. Instead of this behavior, in the low-temperature phase the height-height correlation saturates exponentially as the lateral distance goes to infinity, while it is characterized by a linear divergence for the high-temperature phase. Sulfur segregated at the surface has two effects: Large areas of the Cu(311) surface become amorphous and the step-atom density increases. The surface is still rough at room temperature even with small amounts of sulfur. With increasing sulfur coverage, the roughness due to inhomogeneities overwhelms the thermally induced surface roughness.