シリコンおよびゲルマニュームナノアイランドの微細構造と局所電子状態

Abstract

To study the relation between the strain and the electronic structure in two-dimensional (2D) nanoislands of Si and Ge on the Si(111)-7×7 surface, we made the nanoislands the same size and measured with the angle resolved ultraviolet photoelectron spectroscopy (ARUPS), the scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). We also calculated the relation based on the density-functional theory. In the calculation, the dangling-bond state at the strained adatom on the nanoisland (SR state) shifts to lower energy, which has a liner dependence with the height of the adatoms. The ARUPS spectrum and the STS show characteristic peaks corresponding to the SR state, whose energy depends on the deformation of the adatom. The height of the adatom on the nanoisland estimated from the energy difference is consistent with a result of the STM measurement. The strain of adatoms can be estimated from the electronic structure.