Strain relaxation in Ga0.955In0.045As epilayers, molecular beam epitaxially grown onto (001) vertical-gradient Bridgman-type GaAs substrates, was determined by using monochromatic synchrotron X-radiation topography. Striations parallel to the [110] direction were observed in every topograph of samples which were grown by using a non-uniform temperature distribution. Such patterns were never seen in specimens which were grown with a uniform temperature across the wafer. A detailed analysis of the contrast indicated that twins were formed. These twins, which were associated with oval defects, appeared to relax the strain in the epilayer without requiring misfit dislocation formation.

Strain Relaxation in InGaAs Epilayers on GaAs by Means of Twin Formation P.Möck, K.Mizuno, B.K.Tanner, G.Lacey, C.R.Whitehouse, G.W.Smith, A.M.Keir: Japanese Journal of Applied Physics - 1, 1999, 38[6A], 3628-31