DISLOCATION NUCLEATION BARRIER IN SIGE SI STRUCTURES GRADED TO PURE GE/

High-resolution triple-axis x-ray diffraction measurements were used t o study strain relaxation in the individual layers of a SiGe/Si struct ure step-graded to pure Ge. The tilt of each layer is explained by ext ending the model previously proposed for obtaining the nucleation acti vation energy of dislocations to account for the reduced miscut of the growth surface as the sample relaxes and the variation in the materia ls properties with alloy composition. (C) 1994 American Institute of P hysics.