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Title
Inverted Nanocones: An approach to increase light collection efficiency and radiative rates for GaAs quantum dots / submitted by Stefan Gruber
AuthorGruber, Stefan
CensorRastelli, Armando
PublishedLinz, 2018
Descriptionxi, 62 Seiten : Illustrationen
Institutional NoteUniversität Linz, Masterarbeit, 2018
LanguageEnglish
Document typeMaster Thesis
Keywords (GND)Nanostrukturiertes Material / Kegelschnecke <Gattung> / Licht / Strahlung / Galliumarsenid / Quantenpunkt
URNurn:nbn:at:at-ubl:1-20393 Persistent Identifier (URN)
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 The work is publicly available
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Inverted Nanocones: An approach to increase light collection efficiency and radiative rates for GaAs quantum dots [5.04 mb]
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Abstract (English)

Single photons play an important role in the lively field of quantum information science and technology. Consequently, much effort is being invested worldwide in the search for sources capable of emitting deterministic streams of indistinguishable single and entangled photons at high rates. Semiconductor-based quantum dots are among the most promising candidates to fulfill this demand, as they allow control over their emission properties and show the potential to build devices, small enough for the everyday use. Bare quantum dots however, perform badly in terms of light throughput, as most emitted photons fall victim to total internal reflection and never leave the host matrix. Consequently, this thesis presents a novel photonic structure, that is meant to improve collection efficiency over a broad range of wavelengths as well as enhance spontaneous emission rates via the Purcell effect. Using various wet-etching- and lithography techniques, a quantum dot is placed in a truncated cone-shaped structure surrounded by highly reflective walls, which are meant to focus emission and improve collection efficiency. Another important feature of this concept is the compatibility with our piezo-electric actuators, that allow us to fine-tune the emission properties of a quantum dot. Photo-luminescence measurements show that the structures bring a clear improvement in terms of collection efficiency, as the measured intensity at saturation is enhanced by more than an order of magnitude with respect to an unprocessed dot. Furthermore, a noticeable red-shift, as well as an increase in fine-structure-splitting are observable.

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