In-situ HREM Irradiation study of point defect clustering in strained Ge_xSi_(1-x)/(001)Si heterostructure

摘要

The process of point defect clustering in compressively strained Ge_xSi_(1-x)/(001)Si heterostructures is found to be very sensitive to the amount of misfit strain. At a low misfit (0.28percent) extended defects of both interstitial and vacancy type with a density of about 10~(12) cm~(-2) are created inside the strained layer only. An increase of the misfit up to 0.46percent leads to the formation of vacancy type defects inside the Ge-Si layer and defects of interstitial type are created in the Si matrix close to the interface. In material with a large misift (0.7percent) the complete transformation of the strained Ge-Si layer into Ge rich islands occurs by misfit dislocation introduction at the islands / Si-matrix interface during electron irradiation.