Pseudomorphic and relaxed SiGe/Si(001) layer synthesis by gas immersion laser doping (GILD)

We report on the synthesis of SiGe layers on silicon by using a pulsed laser processing technique (Gas Immersion Laser Doping) where GeCl₄ gas molecules are adsorbed on the surface and further incorporated into the Si top layer by a pulsed laser induced melt/regrowth process. In-situ real-time measurements of the transient reflectivity of a laser diode reveal that SiGe is formed. Structural characterization of the SiGe layers by X-ray diffraction evidences that pseudomorphic SiGe layers are obtained. Moreover, we demonstrate that Ge concentration saturates at about 16% in the strained layers and that a relaxation process occurs when samples are exposed to 4000 laser pulses or more (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)