This manuscript presents a numerical analysis of the Excimer Laser Annealing and Crystallization induced in a set of amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on crystalline (c-) Si(100), with the aim to select the adequate range of energy densities for growing SiGe alloys of definite graded compositions, that might be useful as sacrificial layers for the fabrication of Si based Micro-Electro-Mechanical Systems and Silicon-On-Nothing devices. We have been able to predict the energy threshold to get an adequate epitaxial SiGe alloy growth with a thickness ranging from 10 to 30 nm. Temperature distribution, melting depth as well as the Ge concentration gradient have been calculated and compared with experimental results. (c) 2008 Elsevier B.V. All rights reserved.