Strain relaxation comparison of GaInP and AlInAs metamorphic buffers grown on GaAs substrates

Compositionally step-graded Al1-xInxAs (x = 0-0.31) and Ga1-xInxP (x = 0.48-0.78) metamorphic buffers were grown on GaAs substrates by metal-organic chemical vapor deposition to fulfill the lattice transition from GaAs to In0.30Ga0.70As.With the same buffer structure, thickness, and misfit grade rate, InGaAs layers on AlInAs buffer displayed a much better surface morphology and lower density threading dislocations than that on GaInP buffer. The reciprocal space mappings of the samples displayed that the AlInAs buffer relax the strain quickly, while the GaInP buffer remained partially strained through the layers and sufficient relaxation was achieved after the InGaAs layer growth. The different strain relaxation mechanisms were mainly attributed to the high growth temperature of AlInAs, which facilitate dislocation nucleation and glide, especially α dislocations. For GaInP buffers, the quality can be improved profoundly by reducing the misfit grade rate. This work provides a helpful guide for the design and growth of lattice mismatched semiconductor devices.