Optical study of extended-molecular-layer flat islands in lattice-matched ${\mathrm{In}}_{0.53}$${\mathrm{Ga}}_{0.47}$As/InP and ${\mathrm{In}}_{0.53}$${\mathrm{Ga}}_{0.47}$As/${\mathrm{In}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Ga}}_{\mathit{x}}$${\mathrm{As}}_{\mathit{y}}$${\mathrm{P}}_{1\mathrm{-}\mathit{y}}$ quantum wells grown by low-pressure metal-organic vapor-phase epitaxy with different interruption cycles

Growth of lattice-matched ${\mathrm{In}}_{0.53}$ ${\mathrm{Ga}}_{0.47}$As/InP and ${\mathrm{In}}_{0.53}$ ${\mathrm{Ga}}_{0.47}$As/${\mathrm{In}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Ga}}_{\mathit{x}}$ ${\mathrm{As}}_{\mathit{y}}$ ${\mathrm{P}}_{1\mathrm{-}\mathit{y}}$ quantum wells (QW’s) by low-pressure metal-organic vapor-phase epitaxy with specific growth-interruption cycles leads to three simultaneous effects in the photoluminescence (PL) spectra: (I) energy shifts of all PL lines, (II) line broadenings, and (III) splitting of individual QW lines into multiplets associated with the formation of extended molecular-layer (ML) flat islands. Samples were grown with four or six single QW’s exhibiting overlapping PL multiplets with up to twelve ‘‘coherent’’ lines in sequence and ML thickness differences of their parent islands. It is shown, by temperature-controlled PL and PL-decay-time measurements, that these flat islands behave as independent QW’s at low temperatures, thus giving evidence of their large extensions.