Self‐assembled InAs quantum dots on InGaAsP/InP(100) by modified droplet epitaxy in metal–organic vapor phase epitaxy around the telecom C‐band for quantum photonic applications

The growth of InAs quantum dots (QDs) by droplet epitaxy (DE) in metal–organic vapor phase epitaxy is demonstrated for the first time on an InGaAsP layer lattice matched to InP(100). The nucleation of indium droplets on InGaAsP shows a strong dependence on the deposition temperature, with an unexpectedly low density, pointing to a strongly increased surface diffusion compared to bare InP or InGaAs surfaces previously reported. Droplets and surface morphology are characterized via atomic force microscopy and scanning electron microscopy. Droplet crystallization into InAs QDs is explored, where the crystallization process follows a modified DE growth which resembles the one on InGaAs but strongly differs from bare InP. Also, no formation of quantum dashes (QDashes) is observed, as the DE growth technique used here allows for a better control of QD nucleation, decoupled from the layer/epilayer mismatch, favoring the formation of QDs over QDashes. Optical characterizations suggest a more efficient carrier capture into the QDs if these are grown on InGaAsP compared to InGaAs. Finally, bright single-dot emission at low-temperature is detected from QDs ranging from 1300 to 1600 nm, covering the technologically relevant telecom C-band.