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Proceedings Paper

Optical characteristics of hexagonal and cubic GaN self-assembled quantum dots
Author(s): Yong Hoon Cho; B. J. Kown; Julien Barjon; J. Brault; B. Daudin; Henri Mariette; Le Si Dang
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Paper Abstract

Studies on the optical properties related to built-in internal electric field and carrier localization present in the GaN self-assembled quantum dots (QDs) are essential for the physical interest in atomic-like confined system and the visible and ultraviolet light emitting applications. We have systematically studied the optical properties of hexagonal GaN (h-GaN) and cubic GaN (c-GaN) self-assembled QDs by means of photoluminescence (PL), PL excitation (PLE), cathodoluminescence (CL), and time-resolved PL experiments. The GaN self-assembled QD samples were grown in Stranski-Krastanov mode by plasma-assisted molecular beam epitaxy. The substrates for the growth of h-GaN and c-GaN were 6H-SiC and 3C-SiC, respectively. With increasing temperature, the PL intensity of GaN quantum wells was dramatically decreased while that of GaN QDs was not changed much. From the wavelength-resolved CL images, strong carrier localization in the QD confinement was clearly observed. An apparent Stokes-like shift between PLE absorption edge and PL emission from the h-GaN QDs increases with increasing detection wavelength (so, with QD size), which is attributed to the separation of wavefunction overlap due to the built-in internal field present in the QDs. From the time-resolved PL experiments, we found that the measured lifetime of the h-GaN QDs emission increased with emission wavelength (i.e., with QD size), while that of the c-GaN QDs kept almost constant. It is concluded that the h-GaN QD emissions are strongly influenced by built-in internal electric field as well as carrier localization in the QDs.

Paper Details

Date Published: 16 June 2004
PDF: 8 pages
Proc. SPIE 5352, Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII, (16 June 2004); doi: 10.1117/12.526103
Show Author Affiliations
Yong Hoon Cho, Chungbuk National Univ. (South Korea)
B. J. Kown, Chungbuk National Univ. (South Korea)
Julien Barjon, CEA/CNRS (France)
LSP, CNRS, Univ. Joseph Fourier (France)
J. Brault, CEA/CNRS (France)
LSP, CNRS, Univ. Joseph Fourier (France)
B. Daudin, CEA/CNRS (France)
LSP, CNRS, Univ. Joseph Fourier (France)
Henri Mariette, CEA/CNRS (France)
LSP, CNRS, Univ. Joseph Fourier (France)
Le Si Dang, CEA/CNRS (France)
LSP/CNRS, Univ. Joseph Fourier (France)

Published in SPIE Proceedings Vol. 5352:
Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII
Kong-Thon Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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