In Situ STM Imaging of Silicon(111) in HF under Potential Control

Abstract

In situ scanning tunneling microscopy (STM) and atomic force microscopy (AFM) were employed to examine the surface morphology of a Si(111) cathode in 1% or a mixed and solution under potential control. In the absence of , in situ STM revealed island‐like features due to the native defects at the Si substrate and the subsequent dissolution of the native layer by the etchant. Atomic resolution was possible, and a well‐ordered hexagonal array, presumably the phase, was imaged by STM after the oxide layer was removed. This long‐range ordered structure was stable in dilute for ca. 1 h before it became disordered by the evolution of . In a mixed solution of and , depending on the relative concentration of these two species, either the oxide formation or its subsequent dissolution dominated. When the former reaction was more important, the STM tip physically scratched the insulating layer. At higher relative concentrations, a long‐range ordered one‐dimensional fiber structure arranged in a sawtooth pattern was imaged, when the dissolution of occurred. These surface features are attributed to chemical etching of Si, possibly the metastable surface species.