Computer Simulation of Li and Be Wetting Layers on the Si (100) Surface

Within the framework of the of density functionality theory and the pseudopotential method, the atomic and electronic structure of the two-dimensional Li–Si and Be–Si systems forming on the Si (100) surface is calculated, with a metal thickness of one to three monolayers (ML). At the first ML, the formation of ordered silicide wetting layer of Li (with atoms embedded inside the top layer Si) and Be (with atoms embedded between the top two Si layers) was detected. At 2 ML, the systems are modified: Li atoms occupy positions between the top two Si layers, and Be atoms rise at positions above the top Si layer. After that, with a coating thickness of 3 ML, in the case of Li, a continuous disordered wetting layer is formed, and in the case of Be, a wetting layer in the form of disordered chains along the length. At 1 ML, an energy gap appears in the electronic structure of the studied systems in the density of electronic states near the Fermi level, the width of which is 1.02 eV and 0.36 eV, respectively, for Li-Si and Be-Si systems. Then the gap disappears, first for the lithium system (at 2 ML), and then, for the beryllium system (at 3 ML).