Structural and optical characterization of self-assembled InAs-GaAs quantum dots grown on high index surfaces

The structural and the optical properties of InAs layers grown on high index GaAs surfaces by molecular beam epitaxy are investigated in order to understand the formation and the self-organization of quantum dots (QDs) on novel index surfaces. Four different GaAs substrate orientations have been examined, namely, (111)B, (311)A, (311)B and (100). The (100) surface was used as a reference sample. STM pictures exhibit a uniform QD coverage for all the samples with the exception of (111)B, which displays a surface characterized by very large islands and where STM pictures give no evidence of QD formation. The photoluminescence (PL) spectra of GaAs (100) and 311 samples show typical QD features with PL peaks in the energy range 1.15-1.35 eV with comparable efficiency. No significant quenching of PL up to temperatures as high as 70 K was observed. These results suggest that the high index substrates are promising candidates for production of high quality self-assembled QD materials for application to photonics. (C) 1997 Elsevier Science Ltd.