Characterization of strained Si wafer surface by density functional theory analysis

Using first-principles total energy calculations within density functional theory (DFT), we investigated the surface properties, especially focusing upon the surface reactivity, of strained Si layer deposited onto SiGe underlayer, in comparison with normal (non-strained) Si surface. We used a cluster model as the surface of the strained Si and normal Si, and results of our calculation indicate that, when the Si possessed strained condition, the total energy is destabilized and the value of the gap between HOMO and LUMO became smaller than that of normal Si. In addition, we estimated the reactivity of the strained Si and normal Si surfaces with trace metal ion species in solution. As a result of the adsorption energy calculation of Cu²⁺, Ni²⁺ and Fe²⁺ to Si (1 0 0) surface, it was suggested that the adsorption energy of the metal ion species to the strained Si surface is more stable than that of the normal Si.