Improved quality of InP layer on GaAs substrates by using compositionally modulated step-graded AlGaInAs buffers

Improved quality of metal–organic chemical vapor deposition grown InP layer on GaAs substrate was achieved by using compositional modulated step-graded AlGaInxAs (x = 0.05–0.52) buffers. With the insertion of tensile stained AlGaInAs layers into the compressive buffers, we obtained a high crystal quality InP layer with a smooth surface and low threading dislocation confirmed by atomic force microscopy, transmission electron microscopy, photoluminescence and X-ray diffraction reciprocal space mapping. This indicated that the tensile strained AlGaInAs layers into the compressive AlGaInAs layers can change the glide direction and facilitate annihilation reactions of dislocations, and the interfaces also can prevent the vertical growth of threading dislocations propagating through the structures. The results show that the compositional modulated step-graded AlGaInxAs buffers grown on GaAs hold great promise to be virtual substrates of other metamorphic devices.