Strain relaxation processes in strained-Si layer on SiGe-on-insulator substrates

Misfit defects in strained Si layers on SiGe-on-insulator (SGOI) substrates were studied by transmission electron microscopy. With increasing the strained layer thickness, stacking faults, extending from the Si surface to the strained-Si/SiGe interface, with 90° Shockley partial dislocations at the interfaces were found to be increasingly formed in the strained Si layers. This fact indicates that the cumulative tensile strain in strained Si layers on SGOI substrates causes generation and glide on {111} planes of the 90° partial dislocations, leading to the relaxation of the strained Si layers. A density of Shockley partial dislocations at the Si/SiGe interface was found to depend on surface cleaning of SiGe layers prier to the epitaxial growth of strained Si layers. An interfacial nucleation of Shockley partial dislocations is discussed.