Optical properties of individual site-controlled Ge quantum dots

We report photoluminescence (PL) experiments on individual SiGe quantum dots (QDs) that were epitaxially grown in a site-controlled fashion on pre-patterned Si(001) substrates. We demonstrate that the PL line-widths of single QDs decrease with excitation power to about 16 meV, a value that is much n...

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Bibliographic Details
Published in:Applied physics letters 2015-06, Vol.106 (25)
Main Authors: Grydlik, Martyna, Brehm, Moritz, Tayagaki, Takeshi, Langer, Gregor, Schmidt, Oliver G., Schäffler, Friedrich
Format: Article
Language:English
Subjects:
Applied physics
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Epitaxial growth
EPITAXY
EXCITATION
GERMANIUM SILICIDES
LAYERS
LINE WIDTHS
MEV RANGE 10-100
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
POTENTIALS
QUANTUM DOTS
SIGNALS
Silicon germanides
Silicon substrates
SUBSTRATES
TRAPS
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Summary:We report photoluminescence (PL) experiments on individual SiGe quantum dots (QDs) that were epitaxially grown in a site-controlled fashion on pre-patterned Si(001) substrates. We demonstrate that the PL line-widths of single QDs decrease with excitation power to about 16 meV, a value that is much narrower than any of the previously reported PL signals in the SiGe/Si heterosystem. At low temperatures, the PL-intensity becomes limited by a 25 meV high potential-barrier between the QDs and the surrounding Ge wetting layer (WL). This barrier impedes QD filling from the WL which collects and traps most of the optically excited holes in this type-II heterosystem.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4923188