The effect of inserting compressively or tensely strained layers into compositionally graded SiGe buffers on strain relaxation and threading dislocation density was investigated. The samples having compressively strained layers exhibited lower threading dislocation density and more enhanced relaxation than those having tensely strained layers. In addition, dislocations were accumulated at the top part of the tensely strained layers within the graded buffers, while no accumulation was found at the compressively strained layers. These results might be due to the effect of strain from the thin inserted layers on the dislocation interactions in the compressively strained graded buffers.

Thin Strained Layers Inserted in Compositionally Graded SiGe Buffers and Their Effects on Strain Relaxation and Dislocations. J.S.Park, M.Curtin, J.Bai, S.Bengtson, M.Carroll, A.Lochtefeld: Journal of Applied Physics, 2007, 101[5], 053501