Surface dihydrides on Ge(100): A scanning tunneling microscopy study

Abstract

We studied the atomic scale surface evolution of Ge(100) exposed at 300 K to gas-phase hydrogen atoms, H(g). Surface H(g) uptake created a 2×1:H phase, quickly reaching ∼1 monolayer H coverage. However, in contrast to the Si(100) surface, dangling bonds of the Ge(100) surface could never be completely removed by H(g) due to their regeneration by highly efficient surface H abstraction. This, together with the instability of surface dihydrides, GeH2(a), inhibited the large-scale formation of 3×1:H and 1×1:H phases. Short GeH2(a) rows, present in small metastable 3×1:H domains formed near defect sites, were etched selectively by H(g), producing line defects.