Optical characteristics of hexagonal and cubic GaN self-assembled quantum dots

Yong Hoon Cho; B. J. Kown; Julien Barjon; J. Brault; B. Daudin; Henri Mariette; Le Si Dang

doi:10.1117/12.526103

16 June 2004 Optical characteristics of hexagonal and cubic GaN self-assembled quantum dots

Yong Hoon Cho, B. J. Kown, Julien Barjon, J. Brault, B. Daudin, Henri Mariette, Le Si Dang

Proceedings Volume 5352, Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII; (2004) https://doi.org/10.1117/12.526103
Event: Integrated Optoelectronic Devices 2004, 2004, San Jose, CA, United States

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.

Citation Download Citation

Yong Hoon Cho, B. J. Kown, Julien Barjon, J. Brault, B. Daudin, Henri Mariette, and Le Si Dang "Optical characteristics of hexagonal and cubic GaN self-assembled quantum dots", Proc. SPIE 5352, Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII, (16 June 2004); https://doi.org/10.1117/12.526103

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