MOLECULAR-DYNAMICS STUDY OF COHERENT ISLAND ENERGETICS, STRESSES, ANDSTRAINS IN HIGHLY STRAINED EPITAXY

The behavior of energetics, atomically resolved stress, and strain in coherent three-dimensional islands observed in highly strained semicon ductor heteroepitaxy is examined for the first time via a molecular dy namics study of a model Ge/Si system. Evidence is found for the common but hitherto unsubstantiated practice of representing the island ener gy as a sum of surfacelike and bulklike terms, down to rather small is lands, but with significantly renormalized coefficients indicating mar ked modifications of the surface and volume elastic energies commonly employed in continuum descriptions.