Stability of the Si–H bond on the hydrogen-terminated Si(1 1 1) surface studied by sum frequency generation

Stability of the Si–H bonds on the hydrogen-terminated Si(1 1 1) surface has been investigated by sum frequency generation (SFG) spectroscopy in air at room temperature. The SFG observation showed that the Si(1 1 1) surface is terminated by a monolayer of monohydride (Si–H) after etching in a concentrated ammonium fluoride (NH4F) solution. The number of Si–H bonds decreased with laser irradiation time and the abstraction rate of hydrogen atoms on Si increased with the increase of input energy of “visible” light. The Si–H bond under irradiation at 1064 nm light was more stable than that at 532 nm light with a given intensity. A small amount of water in air severely lowered the stability of Si–H bond because of a photoelectrochemical reaction under laser irradiation.