Tokyo Institute of Technology, Department of Physics, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan.
Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
Sci Rep. 2017 Jun 19;7(1):3773. doi: 10.1038/s41598-017-03843-1.
The Kardar-Parisi-Zhang (KPZ) class is a paradigmatic example of universality in nonequilibrium phenomena, but clear experimental evidences of asymptotic 2D-KPZ statistics are still very rare, and far less understanding stems from its short-time behavior. We tackle such issues by analyzing surface fluctuations of CdTe films deposited on polymeric substrates, based on a huge spatio-temporal surface sampling acquired through atomic force microscopy. A pseudo-steady state (where average surface roughness and spatial correlations stay constant in time) is observed at initial times, persisting up to deposition of ~10 monolayers. This state results from a fine balance between roughening and smoothening, as supported by a phenomenological growth model. KPZ statistics arises at long times, thoroughly verified by universal exponents, spatial covariance and several distributions. Recent theoretical generalizations of the Family-Vicsek scaling and the emergence of log-normal distributions during interface growth are experimentally confirmed. These results confirm that high vacuum vapor deposition of CdTe constitutes a genuine 2D-KPZ system, and expand our knowledge about possible substrate-induced short-time behaviors.
Kardar-Parisi-Zhang（KPZ）类是不平衡现象普遍性的典范，但明确的渐近 2D-KPZ 统计数据的实验证据仍然非常罕见，并且对其短时间行为的理解则更少。我们通过分析基于原子力显微镜获得的巨大时空表面采样，来解决 CdTe 薄膜在聚合物衬底上的表面波动问题。在初始时间观察到伪稳态（其中平均表面粗糙度和空间相关性随时间保持不变），直到沉积约 10 个单层。这种状态是由粗糙化和光滑化之间的精细平衡支撑的，这得到了一个唯象的生长模型的支持。KPZ 统计数据在长时间内出现，通过通用指数、空间协方差和几个分布得到了彻底验证。界面生长过程中家族维西克标度的最新理论推广和对数正态分布的出现得到了实验证实。这些结果证实了高真空蒸镀 CdTe 构成了真正的 2D-KPZ 系统，并扩展了我们对可能的衬底诱导短时间行为的认识。
