Crystallization of amorphous Ge_xSi_1-x films on SiO₂

Abstract

The stability of amorphous GeSi films on SiO2 is of great importance in solid phase epitaxial growth of GeSi on insulator layers for application in integrated microelectronics. One of the important parameters of this process is the incubation time for the crystallization. This incubation time t0 of amorphous GeSi films on SiO2 subtrates was studied as a function of temperature between 350 and 650 °C by means of in situ transmission electron microscopy. The amorphous GexSi1-x films, having x = 9%, 26% and 54% Ge and a thickness of 150 nm, were deposited on oxidized silicon substrates by means of molecular beam processing. The temperature dependence of the incubation time follows an Arrhenius curve with an activation energy between 2.16 and 2.88 eV. The lattice parameter of the initial GexSi1-x crystals formed in the amorphous film, measured by means of electron diffraction, has a dependence on the germanium concentration which declines from linear. In the grain growth stage of the GexSi1-x films the dendritic crystallization morphology is found to dominate. © 1992.