Ce诱导Si(111)表面重构和相变机制的研究  

Cerium-Induced Surface Reconstructions and Phase Transition on Si(111)

作　　者：王畅 王学森[2] 肖文德 WANG Chang;WANG Xuesen;XIAO Wende(School of Physics,Beijing Institute of Technology,Beijing 100081,China;Department of Physics,National University of Singapore,Singapore 117542)

机构地区：[1]北京理工大学物理学院,北京100081 [2]新加坡国立大学物理系,新加坡117542

出　　处：《真空科学与技术学报》2022年第4期256-259,共4页Chinese Journal of Vacuum Science and Technology

基　　金：国家自然科学基金项目(11734003,21773008);北京市自然科学基金项目(Z190006)。

摘　　要：利用扫描隧道显微镜,研究了在Si(111)表面沉积Ce原子后在不同温度下退火得到的多种重构。在Ce覆盖度为1/3 ML和样品退火温度500℃下,得到√3×√3-R30°结构。提高样品退火温度至850℃,得到2×3重构。随着样品退火温度升至950℃,样品表面出现2×3、17×6、11×6和5×2等多种重构共存。进一步提高样品退火温度至1150℃,得到单一的5×2相。根据电子计数规则理论,提出了由蜂窝链和Seiwatz链构成的2×3、5×2和(2n+1)×6中间相的结构模型。其中,5×2重构中蜂窝链的Si原子占比最大,Ce原子覆盖度最低,结构最稳定。不同相的转变是由于Seiwatz链和蜂窝链的形成导致了体系能量的降低。本文研究对理解稀土金属诱导Si(111)表面重构的物理机制和转变过程具有重要意义。Various Cerium-induced reconstructions on Si(111)and their phase transitions were investigated by scanning tunneling microscopy.A √3×√3-R30°reconstruction was observed on the sample at the Ce cover⁃age of 1/3 ML and with sample annealing at 500℃.This surface structure evolved into a 2×3 reconstruction after sample annealing at 850℃.With the annealing temperature rising to 950℃,we observed the coexistence of several reconstructions,including 2×3,17×6,11×6 and 5×2.The pure 5×2 phase was obtained by further increasing the annealing temperature to 1150℃.The structural models of the 2×3,5×2 and(2n+1)×6 phases composed of honey⁃comb chains and Seiwatz chains were proposed according to the electron counting rule.The atomic proportion of Si atoms consisting of the honeycomb chains in the 5×2 reconstruction is the largest among the observed reconstruc⁃tions.As the honeycomb chains are more stable than the Seiwatz chains,the 5×2 reconstruction is the energetically most favorable structure.The phase transition from the √3×√3-R30°reconstruction to the 2×3 reconstruction is driven by the formation of the Seiwatz chains,while the structural evolution to the 5×2 reconstruction is driven by the formation of the honeycomb chains.Our study is of great significance for understanding the physical mechanism and phase transition of rare earth metals-induced reconstructions on the Si(111)surfaces.

关 键 词：铈 Si(111)-7×7 扫描隧道显微镜 表面重构 

分 类 号：O469[理学—凝聚态物理] TN3[理学—电子物理学]