Formation and local electronic structure of Ge clusters on Si(111)-7×7 surfaces

• 来源期刊: 中国物理（英文版）
• 关键词: scanning tunnelling microscopy Si(111)-7×7 surface Ge cluster
• 年，卷（期）: 2007,（9）
• 页码范围: 2661-2664
• 页数: 4页
• 语种: 英文

摘要

We report the formation and local electronic structure of Ge clusters on the Si(111)-7×7 surface studied by using variable temperature scanning tunnelling microscopy (VT-STM) and low-temperature scanning tunnelling spectroscopy (STS). Atom-resolved STM images reveal that the Ge atoms are prone to forming clusters with 1.0 nm in diameter for coverage up to 0.12 ML. Such Ge clusters preferentially nucleate at the centre of the faulted-half unit cells, leading to the 'dark sites' of Si centre adatoms from the surrounding three unfaulted-half unit cells in filled-state images. Biasdependent STM images show the charge transfer from the neighbouring Si adatoms to Ge clusters. Low-temperature STS of the Ge clusters reveals that there is a band gap on the Ge cluster and the large voltage threshold is about 0.9 V.