The study of Ag adsorbed on Ge(1 1 1) 2×1 surfaces using first-principles calculations

The surface structures and electronic properties of two proposed Ge(1 1 1) 2×1 reconstruction surfaces and the Ge(1 1 1) 2×1–Ag chemisorption systems at 0.5 and 1.0 ML (monolayer) coverage are studied using first-principles calculations. The adsorption energy, work function, energy band, and density of states are calculated to distinguish the two models from each other. The calculated structures and electronic properties of the clean surface agree well with previous experimental and theoretical results. In the case of 0.5 ML coverage, the systems show metallic properties. There is a great contrast between the two optimized structures. Their electronic properties are also different. The 1 ML coverage systems show semiconductor-like properties. The electronic properties are quite similar for the two models, although their optimized geometries present slight differences.