Atomic-scale structural evolution of Ge(100) surfaces etched by H and D

Abstract

The atomic-scale structural evolution of Ge(100) surfaces etched by H(g) and D(g) at Ts=400 K is studied using scanning tunneling microcopy (STM) and field emission-scanning electron microscopy (FE-SEM). The STM investigation reveals that etching of the Ge(100) by H(g) and D(g) proceeds initially via the production of single atom vacancies (SV), dimer vacancies (DV), and subsequently, line defects along the Ge dimer rows. It is also observed that D(g) etches the Ge(100) surface eight times faster than H(g) does. After extensive exposures of the surface to H(g), the FE-SEM images show square etch pits with V-groove shapes, indicating that H(g) etching of the Ge(100) surface proceeds anisotropically.