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

Abstract

Thin films of SiGe were prepared on SiO 2 by low pressure chemical vapor deposition (LPCVD) from SiH 4 and GeH 4. With this technique there is in situ control of incorporation of germanium in SiGe films. In the deposition conditions, films of Si 1− x Ge x are deposited amorphous. The parameters of crystallization kinetics of amorphous films are studied by in situ measurements of the film conductance during annealing (around 575°C). We show that increasing total deposition pressure modifies the crystallization of amorphous SiGe films and increases the crystallization time, t c, of the layers. The structural properties are determined by X-ray diffraction (XRD) and the incorporation of germanium is determined by secondary ion mass spectroscopy (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 crystallization of amorphous layers depends on annealing temperature and total deposition pressure, which determines the crystallization mode.