Effect of substrate temperature on the texture and structure of polycrystalline Si0.7Ge0.3 films deposited on SiO2 by molecular beam deposition

Abstract

The evolution of microstructure and texture of molecular beam deposited Si0.7Ge0.3 films on SiO2 at the deposition temperature range of 400-700 degrees C was investigated by X-ray diffraction and transmission electron microscopy. At deposition temperatures between 400 and below 500 degrees C, the films were directly deposited as a mixed-phase on SiO2 and have a inversely cone-shaped structure. In this temperature range deposited as a mixed-phase, the grain size increases as the temperature increases, so that the grains not only grow up by deposition, but also laterally grow by the solid phase crystallization, furthermore, the texture is changed from a {110} texture to mixed {311} and {110} textures. At 500 degrees C, the film was deposited as only a crystalline phase and has a columnar structure with a strong (110) texture. In the temperature range of 500-700 degrees C, as the temperature increases, the {311} and {111} textures develop whereas the {110} texture reduces. The film deposited at 700 degrees C has a random orientation and structure. (C) 1999 Elsevier Science S.A. All rights reserved.