Date of Award

1-1-2020

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Nanoscale Science and Engineering

Program

Nanoscale Engineering

Content Description

1 online resource (vii, 121 pages) : color illustrations.

Dissertation/Thesis Chair

Serge Oktyabrsky

Committee Members

Hassaram Bakhru, Alain Diebold, Nathaniel Cady, Pavel Murat

Keywords

III-V Semiconductors, Molecular Beam Epitaxy, Quantum Dots, Scintillator, Waveguide, Quantum dots, Scintillation counters, Photoluminescence, Gallium arsenide

Subject Categories

Nanoscience and Nanotechnology

Abstract

Scintillation and optical properties of an integrated InAs/GaAs Quantum Dot (QD) Scintillation Detector were investigated to improve efficiency and reduce the decay time of luminescence. The photoluminescent properties of InAs QDs embedded in a GaAs matrix were studied as-grown by molecular beam epitaxy (MBE) on GaAs substrates, and on foreign substrates fabricated as thick (10-25 μm) waveguides. The luminescent efficiency of QDs as-grown on GaAs substrates were examined using photoluminescence (PL) measurements at room temperature and the thermal quenching of PL was analyzed by comparing the integrated PL intensities at 77K-400K. PL measurements were used to optimize QD AlAs capping, QD density (by varying spacing between QD layers), p-type modulation doping between QD layers, and the relative red-shift in QD luminescence from the GaAs band-edge. Room temperature PL revealed improved efficiency using QDs with >350 meV redshifted PL from the addition of a ~2 monolayer (ML) AlAs capping layer on top of the QDs and increased QD layer spacing (~800 nm). PL across a wide range of temperatures showed reduced PL thermal quenching with three distributed p-type modulation doping layers as compared to a single modulation doping layer.

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