Comparison of Si(111) surfaces prepared using aqueous solutions of NH4F versus HF

Abstract

Vacuum scanning tunneling microscopy has been used to investigate the hydrogen-terminated Si(111) surfaces obtained upon dissolution of the native oxide in HF and NH4F solutions. Whereas etching in aqueous HF acid produces an atomically rough surface, comparable treatment in NH4F results in atomically flat surfaces. These atomically flat surfaces are extremely well ordered and exhibit terraces which extend thousands of angstroms.