Formation of self-assembled InGaAsN/GaP quantum dots by molecular-beam epitaxy

We have grown self-assembled InGaAsN/GaP quantum dots (QDs) with an In composition of 50% via the Stranski-Krastanov growth mode of molecular-beam epitaxy, obtaining high-density InGaAsN islands of 8×1010 cm−2. When the InGaAsN islands are directly exposed to the P2 beam, we observe a quantum-well-like hetero-interface using cross-sectional transmission electron microscopy (XTEM). This result indicates that the InGaAsN island density is remarkably reduced by As/P exchange reactions. To suppress these exchange reactions, we deposit Ga corresponding to 1 monolayer on the InGaAsN islands. When the Ga deposition sequence is finished, we use XTEM to detect InGaAsN islands embedded in GaP, which indicates that As/P exchange reactions can be suppressed by Ga deposition. Subsequently, we grow a multiple-stacked InGaAsN/GaP 5QDs using the Ga deposition sequence and report their room-temperature photoluminescence spectra.