The effect of graded interfaces in step-graded buffer structures on crystal relaxation efficiency is investigated by transmission electron microscopy and double crystal X-ray diffraction. A higher recombination rate leading to higher edge dislocation densities and a strong diminution of the tilt, is evidenced when graded interfaces are used. The latter feature is a consequence of the poor stability of dislocation multiplication sources in graded interfaces. The lower strain energy release of dislocation segments and a diminution of the pinning points in graded interfaces reduce the lifetime of dislocations sources, producing a better distribution of Burgers vector in the misfit dislocations array.

This work was made possible through grants from the Spanish Interministerial Commission for Science and Technology CICYT (MEC), the European ESPRIT Program (BLES, no. 6854), and the Andalusian Government (group 6020).

5 páginas, 5 figuras, 1 tabla.-- Comunicación presentada al 3º International Workshop on Expert Evaluation and Control of Compound Semiconductor Materials and Technologies.

Peer reviewed