PbTe(111)薄膜的分子束外延生长及其表面结构特性

摘要

采用分子束外延(MBE)方法在BaF2(111)衬底上直接外延生长了PbTe薄膜.反射高能电子衍射(RHEED)实时监控的衍射图样揭示了PbTe在BaF2(111)表面由三维生长向二维生长的变化过程.转动对称性的研究结合第一性原理密度泛函理论(DFT)的计算揭示了在富Pb及衬底温度(Lsub)为350℃的生长条件下,得到的PbTe(111)薄膜具有稳定的(2x1)重构表面.PbTe(111)-(2×1)表面覆盖Te膜后,通过300℃的退火处理,重构表面可完全复原,这为大气环境下PbTe薄膜表面结构的保护提供了有效的方法.%PbTe thin films were epitaxially grown on BaF2(111) substrate using molecular beam epitaxy (MBE).In situ characterization by reflection high energy electron diffraction (RHEED) revealed a transition of the growth mode from 3D to 2D.Rotational symmetry studies combined with first principles density functional theory (DFT) calculations revealed that under Pb-rich and 350 ℃ substrate temperature (Tsub) growth conditions,stable (2 x 1) reconstructions appear on the PbTe(111) surface.When the surface of PbTe(111)-(2 x 1) was covered with Te,the stable (2 x 1) reconstructions could be retrieved under 300 ℃ annealing.This provides an effective method for the protection of PbTe film surfaces from the atmospheric environment.