IR line width broadening at nearly ideal H-termination region on Si(1 0 0) surfaces

The dependence of the line width of the coupled monohydride symmetric stretching vibration of the H-terminated Si(1 0 0)-(2×1) surface on the exposure temperature and the hydrogen exposure has been investigated with infrared reflection absorption spectroscopy (IRRAS) using CoSi2 buried metal layer substrate. Even for nearly ideally H-terminated Si(1 0 0) surface, the line width significantly changes depending on the exposure temperature and the hydrogen exposure. The reason of the line width broadening is discussed, and it is strongly suggested that hydrogen diffusion into the subsurface of Si has a significant influence on the line width broadening. Evidence of hydrogen (deuterium) diffusion into the subsurface is investigated for the first time using an IRRAS measurement.