Atomic step structure on vicinal H/Si(111) surface formed by hot water immersion

We investigated the hydride structures at the step edges on Si(111) surfaces after removing surface oxide with HF solution followed by immersion in boiling water, using polarized infrared attenuated total-reflection spectroscopy. Vicinal (111) surfaces misoriented toward the [112̄] direction at angles of 0°, 2°, and 4° were used to elucidate the hydride structures at the steps. We assigned absorption peaks to monohydride chains at the step edges along the [1̄10] direction, vertical dihydride (whose three atoms form a surface vertical to [111]) at the kinks, and monohydride on the terraces. We determined that the silicon monohydride chain forms an atomically straight step edge along the [1̄10] direction with a small amount of vertical dihydride kinks after 5-min immersion in boiling water. Based on these assignments, we reexamined the water temperature and time dependence of these hydride structures and discussed the step formation mechanism.