First-principles study of initial oxidation process of Ge(100) surfaces

Stable structures of oxygen atoms inserted into Ge(100) surfaces are investigated by first-principles calculations based on the density functional theory. Comparing the total energies of several models, the most stable structure is realized when oxygen atoms are inserted into the backbond of a lower dimer atom and the next bond along the (100) direction. We calculate the electronic density of states to reveal the origin of the stability. The structure is stable because a dangling bond of the lower dimer atom disappeared to form a four-coordinated structure. We also reveal that the dangling bond disappears from equal-amplitude plots of wave functions. These results are due to the strong electronegativity of the oxygen atom. (C) 2016 The Japan Society of Applied Physics