在Cd(0001)基底上外延生长单原子层锗

Epitaxial Growth of Single Atomic Layer Germanium on Cd(0001)Substrate

利用超高真空低温扫描隧道显微镜(STM)技术和密度泛函理论(DFT)研究了锗(Ge)在Cd(0001)表面的薄膜生长行为和电子性质.研究发现室温下沉积在Cd(0001)表面上的Ge原子容易形成纳米尺度的团簇.当Cd衬底的温度降至100K左右,Ge原子形成单原子层厚的二维薄膜.高分辨的STM图表明Ge的单原子层具有1×1的赝晶结构.扫描隧道谱(STS)测量发现Ge的单原子层表现出金属性行为.DFT计算结果表明:Ge原子优先占据Cd(0001)衬底的六角密排空位,Ge与Cd(0001)衬底之间存在静电作用,Ge原子之间通过共价键相结合.

The growth behavior and electronic properties of germanium(Ge)on the Cd(0001)surface have been studied by ultra-high vacuum low-temperature scanning tunneling microscopy and density functional theory.It was found that Ge atoms deposited on the surface of Cd(0001)at room temperature readily form nanoscale clusters.The Ge atoms formed a two-dimensional film with a single atomic layer thickness as the temperature of the Cd substrate was lowered to about 100 K.The high-resolution STM map showed that the monatomic layer of Ge has a 1×1 pseudocrystalline structure.Scanning tunneling spectroscopy(STS)measurements revealed that the monoatomic layers of Ge exhibit metallic behavior.The results of the DFT calculation showed that Ge atoms preferentially occupy the hexagonal close empty position of the Cd(0001)substrate,there was an electrostatic interaction between Ge and Cd(0001)substrate,and Ge atoms were combined by a covalent bond.