Formation of Nanometer Silicon Dots with Germanium Core by Highly-Selective Low-Pressure Chemical Vapor Deposition

概要

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Spherical Si nanocrystallites with a Ge core on ultrathin SiO2 have been prepared by controlling the selective growth conditions of low-pressure chemical vapor deposition (LPCVD) using alternately pure SiH4 and 5% GeH4 diluted with He. Cross-sectional transmission electron microscopy (TEM) images show spherical Si nanocrystallites with a Ge core in contrast with hemispherical Si dots on SiO2, implying a high structural strain at the interface between the cladding Si and Ge core. Atomic force microscopy (AFM) observations and X-ray photoelectron spectroscopy (XPS) measurements confirm the highly selective growth of Ge on the pregrown Si dots and the subsequent complete coverage by Si selective growth on Ge/Si dots. Raman-scattering spectra of multiply stacked structures of dots with a Ge core show that the compositional mixing occurs partly at the Si-clad/Ge-core interface during the samples preparation. Additionally, Raman spectra have also shown that the compositional intermixing becomes significant at 850°C and the SiO2 reduction by interdiffused Ge atoms is promoted at 900°C.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2003-06-15