31st Annual SSRL Users' Meeting

A precise ex-situ strain measurement on silicon nanowires (NW’s) is performed using the kappa goniometer in SSRL beamline 11-3 with the wavelength of 0.0975 nm. Silicon NW’s are grown from TiSi₂ catalyst on Si substrates by chemical vapor deposition (CVD). The mean diameter of Si NW’s is 35.9 nm with standard deviation of 7.8 nm. The preferred growth orientation of the nanowires is considered to be <111> since it has been reported that Si NW’s with the diameter larger than 15 nm usually grow along their <111> orientation. The geometry of in-plane and out-of-plane scattering is defined by the direction of scattering vector and the strain values are measured along the two strongest diffracting planes, (111) and (220). The peak positions are calibrated by the bulk silicon (004) peak from the substrate. Tensile strains are observed along growth or longitudinal direction and compressive strains are obtained along radial direction although the magnitude is very small. The diffraction patterns using the normal laboratory source are compared with those from the SSRL beamline.