Heteroepitaxy of Ge films on Si(100) surface

Abstract

Structural and electrical properties of epitaxial Ge films on a Si(100)-2x1 surface have been studied by means of low-energy-electron diffraction (LEED), Auger-electron spectroscopy (AES), X-ray diffraction, Raman scattering and Hall measurements. We found that a thickness of more than 1000 Å is required to grow high quality epitaxial Ge films on the Si substrate at elevated temperature. This is due to island formation at the initial stage of Ge deposition. Thus, special efforts were devoted to elucidate the role of a thin Ge buffer layer fabricated at substrate temperatures below 200 °C used to grow thinner epitaxial Ge films by suppressing island formation. It was found that the thin amorphous buffer layers remained poorly crystallized during the rapid increase in substrate temperature up to 400–500 °C, prior to subsequent Ge deposition on the buffer layer. Consequently, relatively thin single crystal Ge films grew in such a way that the underlying buffer layers accommodate the strain or misfit dislocations near the Si-Ge interface.