Coherent X-ray measurement of step-flow propagation during growth on polycrystalline thin film surfaces
Coherent X-ray measurement of step-flow propagation during growth on polycrystalline thin film surfaces
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DOI：
10.1038/s41467-019-10629-8
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发表时间：
2019-06-14
影响因子：
16.6
通讯作者：
Ludwig, Karl F., Jr.
中科院分区：
文献类型：
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作者：
Headrick, Randall L.;Ulbrandt, Jeffrey G.;Ludwig, Karl F., Jr.
人工生长薄膜的性质强烈地受到生长过程中的表面处理的影响。相干X射线提供了一种更好地理解这种远离平衡的过程和波动的方法。在这里，我们报告的C-60的真空沉积在石墨烯涂覆的表面上的X射线光子相关光谱研究在表面敏感的条件下的结果。通过测量晶体土丘形成后生长后期的阶边速度，观察到阶流。我们表明，步骤边缘的速度耦合到梯田的长度，并有一个变化的速度从较大的步长在结晶土丘的中心，以紧密间隔，更慢的传播步骤在其边缘。结果扩展理论的表面生长，因为该行为是一致的表面演化过程，包括表面扩散，运动的步骤边缘，并在步骤边缘的附件与显着的步骤边缘障碍。
The properties of artificially grown thin films are strongly affected by surface processes during growth. Coherent X-rays provide an approach to better understand such processes and fluctuations far from equilibrium. Here we report results for vacuum deposition of C-60 on a graphene-coated surface investigated with X-ray Photon Correlation Spectroscopy in surface-sensitive conditions. Step-flow is observed through measurement of the step-edge velocity in the late stages of growth after crystalline mounds have formed. We show that the step-edge velocity is coupled to the terrace length, and that there is a variation in the velocity from larger step spacing at the center of crystalline mounds to closely-spaced, more slowly propagating steps at their edges. The results extend theories of surface growth, since the behavior is consistent with surface evolution driven by processes that include surface diffusion, the motion of step-edges, and attachment at step edges with significant step-edge barriers.