Energy distribution in Ge islands on Si(001): A spectral and site-resolved analysis versus size and morphology

By a spectral and site-resolved analysis of the energy distribution (both stress and surface originated) at the atomistic scale, calculated by classical molecular dynamics for Ge islands with different morphologies on Si(001), we show how domes actually provide the largest strain release. Moreover, we point out that the usual partition of the total energy into a volume plus a surface contribution also corresponds to two separate spectral energy regions, which are the same in any morphology. However, it turns out that the volume-scaling contribution is quite complex and that the real strain relaxation term corresponds to the lower part of the energy spectrum, not scaling as the volume for small island size.