X-ray diffraction study of strain distribution in oxidized Si nanowires

Strain distributions in oxidized Si nanowires fabricated on a (001)-oriented silicon-on-insulator wafer have been determined by analyzing intensity profiles of the diffraction, caused by the nanowire periodicity, around the 111 Bragg point. In this analysis, theoretical diffraction curves, calculated by a kinematical treatment, are fitted to experimental ones, examining positions of the central and fringe maxima and their intensity ratios. Strains in oxidized samples are shown to be negative at the bottom surface and positive at the top surface of nanowires changing with depth in a concave way. The magnitudes of the strains at the bottom surface and at the top surface increase monotonically with increasing the oxidation time. The determined strain of a sample oxidized at 850 °C for 5 h is 0.50% at the top surface and -0.11% at the bottom surface.