Crystallization of amorphous silicon-germanium films deposited by low pressure chemical vapor deposition

Thin films of SiGe were prepared on SiO2 by low pressure chemical vapor dep osition (LPCVD) from SiH4 and GeH4. With this technique there is in situ co ntrol of incorporation of germanium in SiGe films. In the deposition condit ions, films of Si1-xGex are deposited amorphous. The parameters of crystall ization kinetics of amorphous films are studied by in situ measurements of the film conductance during annealing (around 575 degrees C). We show that increasing total deposition pressure modifies the crystallization of amorph ous SiGe films and increases the crystallization time. t(c), of the layers. The structural properties are determined by X-ray diffraction (XRD) and th e incorporation of germanium is determined by secondary ion mass spectrosco py (SIMS) and conductivity versus temperature. The quality of the layers is studied by electrical measurements. The Hall effect measurement shows that the quality of the polycrystalline SiGe films obtained after crystallizati on of amorphous layers depends on annealing temperature and total depositio n pressure, which determines the crystallization mode. (C) 2000 Published b y Elsevier Science B.V. All rights reserved.