SPONTANEOUS NUCLEATION OF MISFIT DISLOCATIONS IN STRAINED EPITAXIAL LAYERS

Although existing theoretical calculations predict relatively large ac tivation energy barriers ( > 10 eV) for misfit dislocation nucleation in relatively low misfit heteroepitaxial systems, it is shown that the nucleation of misfit dislocations can occur spontaneously demonstrati ng a vanishingly small activation energy barrier. A wide range of Ge.S i1-x/Si (x < 0.5) heterostructures grown by MBE and CVD techniques are studied using optical and electron microscopical techniques in order to elucidate a novel misfit dislocation nucleation mechanism which is found to be rate-controlled solely by glide-activated processes with a ctivation energies of almost-equal-to 2 eV.