RAMAN-SCATTERING AND STRESS MEASUREMENTS IN SI1-XGEX LAYERS EPITAXIALLY GROWN ON SI(100) BY ION-BEAM SPUTTER DEPOSITION

Si1-xGex thin films have been grown on silicon substrates by ion-beam sputter deposition (IBSD). Film stress has been determined from the change in deflection curvature of the substrate after deposition and strain has been investigated by using Raman scattering spectroscopy. These properties have been studied as a function of different parameters: growth temperature, layer thickness, and annealing conditions. Raman and stress results are in close correspondence with regard to effects of deposition temperature. Si-rich films (0 less-than-or-equal-to x less-than-or-equal-to 0.3) were compressively strained for all deposition temperatures. A compressive to tensile stress change was observed in the Ge-rich alloys (x = 0.6) when the growth temperature reached T(g) almost-equal-to 500-degrees-C. In addition, the strain as a function of depth from the surface has been studied by changing the laser wavelength. The strain has been shown to increase from the surface to the interior of the film. The origin of the stress observed in IBSD films is discussed and we show that this stress is due to the effect of the bombardment of the growing film by energetic sputtered atoms and can be understood by using the atomic peening model.