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GaN/Al 0.5 Ga 0.5 N quantum dots and quantum dashes
Author(s) -
Huault Thomas,
Brault Julien,
Natali Franck,
Damilano Benjamin,
Lefebvre Denis,
Tauk Rabih,
Leroux Mathieu,
Massies Jean
Publication year - 2009
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200880614
Subject(s) - quantum dot , photoluminescence , sapphire , materials science , molecular beam epitaxy , quenching (fluorescence) , condensed matter physics , isotropy , molecular physics , optoelectronics , nanotechnology , chemistry , epitaxy , layer (electronics) , optics , laser , physics , fluorescence
GaN/Al 0.5 Ga 0.5 N nanostructures grown on c ‐plane sapphire by molecular beam epitaxy using ammonia as N source have been studied. Depending on the ammonia pressure during the two dimensional – three dimensional transition of the GaN layer, the shape of the islands is strongly modified: elongated or isotropic islands are observed, leading to the formation of quantum dashes or quantum dots, respectively. This shape transition is seen as a consequence of a change in surface energy. The change of morphology of the GaN layer is clearly evidenced by photoluminescence measurements, and a large redshift in the emission peak is observed for quantum dashes as compared to quantum dots. An electric field ∼3 MV/cm is estimated from the measurements at an excitation power ∼20 mW/cm 2 . Weak photoluminescence quenching between low and room temperature for both QDs and QDashes structures is observed, indicating a strong confinement of carriers into the nanostructures. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)