Strong Carrier Localization in GaInN/GaN Quantum Dots Grown by Molecular Beam Epitaxy

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Abstract
GaInN/GaN quantum dots (QDs) are grown by molecular beam epitaxy making use of the Stranski-Krastanov growth regime. In situ scanning tunneling microscopy (STM) evidences the formation of three-dimensional GaInN islands. An island density as high as 1012 cm-2 is deduced from STM images. It is shown that the room-temperature photoluminescence (PL) of GaInN/GaN QDs can be tuned from 3 eV to 2.5 eV by increasing the GaInN thickness from 10 to 30 Å. Photothermal deflection spectroscopy is carried out to measure the absorption of GaInN/GaN QDs. For dots emitting at 2.63 eV, a Stokes shift of 250 meV is found between the maximum PL energy and the absorption edge indicating very strong carrier localization.