Spatial variation of available electronic excitations within individual quantum dots.
Nano Lett
; 13(2): 716-21, 2013 Feb 13.
Article
en En
| MEDLINE
| ID: mdl-23276278
ABSTRACT
Quantum dots (QDs) allow for manipulation of the position and energy levels of electrons at sub-10 nm length scales through control of material chemistry, size, and shape. It is known from optical studies that the bandgap of semiconductor QDs increases as their size decreases due to the narrowing of the quantum confinement potential. The mechanism of quantum confinement also indicates that the localized properties within individual QDs should depend on their shape in addition to their size, but direct observations of this effect have proven challenging due to the limited spatial resolution of measurement techniques at this scale and the ability to remove contributions from the surroundings. Here we present experimental evidence of spatial variations in the lowest available electron transition energy within a series of single electrically isolated QDs due to a dome-shaped geometry, measured using electron energy-loss spectroscopy in a (scanning) transmission electron microscope [(S)TEM-EELS]. We observe a consistent increase in the energy onset of electronic excitations from the lateral center of the dot toward the edges, which we attribute purely to shape. This trend is in qualitative agreement with a simple quantum simulation of the local density of states in a dome-shaped QD.
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Teoría Cuántica
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Puntos Cuánticos
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Electrones
Tipo de estudio:
Qualitative_research
Idioma:
En
Revista:
Nano Lett
Año:
2013
Tipo del documento:
Article
País de afiliación:
Estados Unidos