Comparing InGaAs and GaAsSb Metamorphic Buffer Layers on GaAs Substrates for InAs Quantum Dots Emitting at 1.55μm

Summary

Cross-sectional transmission electron microscopy techniques are used to study two samples with different metamorphic buffer layers of InGaAs or GaAsSb, grown by molecular beam epitaxy (MBE) on GaAs (001). On top of these buffers several InGaAs/InAl(Ga)As superlattices and finally two stacks of InAs/GaAs quantum dots were deposited. Compared with the standard InGaAs buffer, the GaAsSb buffer exhibits a smoother surface and a higher degree of plastic strain relaxation. The InAs quantum dots grown on GaAsSb seem to benefit from this in that their photoluminescence intensity is much higher than from the corresponding sample grown on a standard InGaAs buffer.