Epitaxial growth of GaAsBi on thin step-graded InGaAs buffer layers

Molecular beam epitaxy growth and analysis of GaAsBi on compositional step-graded InGaAs buffer layers are presented in this study. The developed buffer is only 240 nm thick, exhibits very low surface roughness while reaching up to 0.46% lattice-mismatch with a GaAs substrate. Reciprocal-space mappings showed that 500 nm thick GaAsBi layers with 2.7%-5.3% Bi remain pseudomorphic with the InGaAs buffer, in contrast to GaAsBi grown on GaAs that were found to incur up to 50% lattice relaxation. CuPtB-type ordering and associated polarized photoluminescence were also found in the bismide layers grown on the InGaAs buffers. Optical anisotropy of a strain-free 2.7% Bi GaAsBi was further analysed by a suite of optical techniques indicating that the valence band splitting is similar to 40 meV. This study advances synthesis techniques of thick GaAsBi layers for optoelectronic device applications.

Automated summary

Molecular beam epitaxy growth and analysis of GaAsBi on compositional step-graded InGaAs buffer layers are presented in this study. The developed buffer is only 240 nm thick, exhibits very low surface roughness while reaching up to 0.46% lattice-mismatch with a GaAs substrate. Reciprocal-space mappings showed that 500 nm thick GaAsBi layers with 2.7%-5.3% Bi remain pseudomorphic with the InGaAs buffer, in contrast to GaAsBi grown on GaAs that were found to incur up to 50% lattice relaxation. CuPtB-type ordering and associated polarized photoluminescence were also found in the bismide layers grown on the InGaAs buffers. Optical anisotropy of a strain-free 2.7% Bi GaAsBi was further analysed by a suite of optical techniques indicating that the valence band splitting is similar to 40 meV. This study advances synthesis techniques of thick GaAsBi layers for optoelectronic device applications.