Efficient Emission from InAlGaAs Single Quantum Dots with Low Lattice Misfit and AlGaAs Indirect Bandgap Barrier

T. Słupiński, K.P. Korona, J. Papierska and J. Borysiuk Faculty of Physics, University of Warsaw, L. Pasteura 5, 02-093 Warsaw, Poland

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We report on molecular beam epitaxy growth and properties of rarely studied quaternary In0.4(Al0.75Ga0.25)0.6As self-assembled quantum dots, which show strong and efficient emission of red light from single quantum dots. The increased yield is, among others, due to efficient energy transfer from indirect band-gap Al0.75Ga0.25As barriers. To maximize photon energy emitted from quantum dots, low In composition, xIn=0.4 was applied, which also lowered the lattice misfit close to the limit of 2D/3D transition in the Stranski-Krastanov growth mode. Time-resolved micro-photoluminescence shows emission at 650-750 nm. Well-resolved single quantum dot photoluminescence lines (decay time of ≈ 1-2 ns) are observed despite a high concentration ≈ 3×1011 cm-2 of quantum dots. We discuss this observation assuming newly a role of carriers or excitons diffusion/tunneling between quantum dots at high surface concentration of dots and a possible role of lattice disorder inside the dot on the exciton lifetime.

DOI: 10.12693/APhysPolA.130.1229 PACS numbers: 78.55.Cr, 73.22.-f, 78.47.jd