Photoluminescence of self organised InAs/GaAs quantum dots grown on (N11)B surfaces

Abstract

InAs self-assembled quantum dots (SADs) are grown on (N11)B GaAs by molecular beam epitaxy using the Stranski–Krastanow growth mode. Four GaAs substrate orientations, namely (211)B, (311)B, (411)B and (511)B have been analyzed. For each substrate we prepared three different InAs coverages (1.8, 2.3 and 2.8 monolayers) for each orientation. All the samples show photoluminescence at 2 K of evident SAD origin, with broad peaks in the range 1.0 to 1.4 eV. The luminescence efficiency of the (N11)B samples is comparable to the one from (100) reference samples and the integrated intensity is not appreciably quenched up to 70 K. For each surface orientation the SADs' size is growing, as expected, with the increasing coverage. On the other hand, at a given coverage, an enhancement of the localisation energy of the SAD states belonging to the high index respect to the (100) surface samples is observed. This effect is generally more pronounced for surface orientations with high N.