Molecular beam epitaxial GaAs films were grown onto Si substrates (001) 4 off towards <111>A and towards <111>B. They were then studied by means of transmission electron microscopy. The results indicated that, in both samples, threading dislocations in the GaAs epilayer were blocked mainly within a thin layer near to the GaAs/Si interface. This thin layer resembled an inner interface; consisting of pyramidal islands, and was flatter on the As growth surface than on the Ga growth surface. In the case of type-B samples, the dislocation density was lower, the inner interface was flatter and the number of twins was much higher than in type-A samples.

Y.Yang, H.Chen, Y.Q.Zhou, X.B.Mei, Q.Huang, J.M.Zhou, F.H.Li: Journal of Materials Science, 1996, 31[3], 829-33