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Compositionally undulating step-graded Al(Ga)In_xAs(x = 0.05–0.52) buffers with the following In P layer were grown by metal–organic chemical vapor deposition(MOCVD) on(001) GaAs with a 15°miscut. The dislocation distribution and tilts of the epilayers were examined using x-ray rocking curve and(004) reciprocal space maps(RSM) along two orthogonal 《110》 directions. The results suggested that such reverse-graded layers have different effects on α and βdislocations. A higher dislocation density was observed along the [110] direction and an epilayer tilt of-1.43°was attained in the [1-10] direction when a reverse-graded layer strategy was employed. However, for conventional step-graded samples,the dislocation density is normally higher along the [1-10] direction.
Compositionally undulating step-graded Al (Ga) In_xAs (x = 0.05-0.52) buffers with the following In P layer were grown by metal-organic chemical vapor deposition (MOCVD) on (001) GaAs with a 15 ° miscut. The dislocation distribution and tilts of the epilayers were examined using x-ray rocking curve and (004) reciprocal space maps (RSM) along two orthogonal “110” directions. The results suggest that such reverse-graded layers have different effects on α and βdislocations. A higher dislocation density was observed along the [110] direction and an epilayer tilt of-1.43 ° was attained in the [1-10] direction when a reverse-graded layer strategy was employed. However, for conventional step-graded samples, the dislocation density is normally higher along the [1-10] direction.