Abstract
The Ⅲ-Ⅴ compound semiconductors have attracted much attention as material for high speed and low power device applications. InSb is one of the best Ⅲ-Ⅴ compound semiconductor with high electron mobility, small band gap, and high electron saturation velocity. Ge has high hole mobility. Therefore, Ⅲ-Ⅴ FinFET that combines Ⅲ-Ⅴ compound semiconductors with Ge substrates has high potential for applications in high speed and low power devices. This research aims to grow the InSb film on the Ge(111) surface by molecular beam epitaxy (MBE). The X-ray photoelectron spectroscopy and scanning tunneling microscopy have been utilized to explore the interface and atomic structure of the grown InSb films. The atomic morphology of the surface can be obtained directly in real space by using scanning tunneling microscopy, while the chemical bonding and elemental composition of the topmost few layers of the sample can be detected by X-ray photoelectron spectroscopy. Evaporating 1.0 monolayer (ML) Sb on Ge(111) by MBE followed by 500 ℃ annealing results in the 1.0 ML Sb-terminated Ge(111)-(2 × 1) surface. Subsequently depositing In atoms on the Sb/Ge(111)-(2 × 1) was performed at room temperature and followed by 400℃ post-annealing. The honeycomb-like structure of InSb/Ge(111)-(2 × 2) is observed on parts of the surface. The apparent height of InSb is 2.6 Å above the Sb/Ge(111)-(2 × 1) domains. After few cycles of In deposition and post annealing, InSb domains are grown on the Ge substrate. The atomic model of InSb/Ge(111)-(2 × 2) is also established to explain the process of growth. Several groups have reported the growth mode of Ⅲ-Ⅴ compound on the group Ⅳ substrate. In contrast, the growth of InSb films on Ge substrate is less investigated. We employed a new method to grow InSb on Ge(111) and observed the interface formation in detail. Our research sheds light to the practical applications of the future technology development.