HIGH-RESOLUTION X-RAY-DIFFRACTION FOR GE COMPOSITION PROFILE DETERMINATION IN SI SI1-XGEX HETEROSTRUCTURES/

An investigation of the Ge composition profile, layer thickness, and c rystalline quality of Si/Si1-xGex/Si heterojunction bipolar transistor -type structures was conducted using high resolution x-ray diffraction . Diffraction scans from (004) and (113) diffraction planes were analy zed. These experimental measurements were matched to scans that were s imulated using a dynamical diffraction model to determine the Ge profi le and layer thickness. Structural parameters were determined to 2 to 3 nm in layer thickness and +/-0.003 in Ge mole fraction with the aid of the simulations and curve fitting. The Ge profile determined from t hese measurements compared very favorably to the profile determined by secondary ion mass spectroscopy measurements. The uniqueness of the s imulated spectra and hence the Ge composition profile and use of inter ference fringes to determine thicknesses and compositions are critical ly examined as well.