Thin crystalline Si1-xGex layers were obtained by irradiating heavily Ge implanted (10(17) atoms cm-2) [100] oriented Si substrates with a pulsed excimer (ArF) laser. The respective influences of the implantation conditions, laser energy density or number of successive laser pulses were investigated using Rutherford backscattering channeling analysis and Raman spectroscopy. In particular, it is shown that layers of good crystalline quality can be readily obtained, the width almost constant Ge concentration being controlled by the irradiation conditions. Optimizing these conditions leads to 200 nm thick alloy layers with a constant Ge content x = 0.14. These results were interpreted using a computer simulation based on the melting-resolidification process which occur during the pulsed laser irradiations.