Complex quantum dots in III-As nanowires

Single quantum dots embedded in the core of freestanding semiconductor nanowires grown directly on Si offer a novel and promising scheme for the realization of on-demand sources of single photons or entangled photon pairs in quantum technology systems. The primary challenge in using the nanowire growth medium lies in reducing the compositional grading effect of the axial barrier’s constituent materials. Here, we have investigated the Ga-catalyzed vapor-liquid-solid growth mechanism and optical properties of axial GaAs quantum dots confined between two Al(x)Ga(1-x)As/Al(y)Ga(1-y)As short-period superlattices inside GaAs/InxAl(1-x)As and GaAs/Al(x)Ga(1-x)As core/shell nanowires. By increasing the interfacial abruptness between the axial barrier and quantum dot, its relevance was highlighted by significant improvements in the quantum dot emission linewidth. Using tensile strain, the tuneabilty of the quantum dot emission energy was clearly demonstrated across a wide range of wavelengths by employing lattice mismatched InxAl1-xAs shells as radial barriers, showing the potential for telecom band access.