Infrared and Raman study of H-terminated Si(lO0) surfaces produced by etching solutions

We have investigated the H-terminated Si(100) surfaces using infrared and surface Raman spectroscopy. We discussed the silicon-hydride structures on chemically etched Si(lO0) surfaces which were produced by HF: H,O, HF, and NH,F solutions. We focused especially on the dihydride structure which was the dominant species on a 1 X 1 phase. We found two distinguishable patterns in the depolarized Raman distribution corresponding to two dihydride structures. That is, the dihydride on NH,F- and HF-treated surfaces shows almost the same depolarized distribution, but that of the HF : H,O,-treated surface is significantly shifted from others. By analyzing the depolarized Raman distributions using a thin-film model, we have discussed the possible dihydride structures. The two types of depolarized distribution suggest the existence of symmetric dihydride and canted dihydride on chemically etched Si(100) surfaces.