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Cathodoluminescence Studies of Quantum Structures and III-V nitrides

Petersson, Anders LU (1998)
Abstract
Characterization of low-dimensional semiconductor structures is a challenging task. The thesis is based on experiments, using cathodoluminescence (CL) as a tool for characterization. The high spatial resolution and the possibility of spectroscopy of small structures make CL one of the most powerful techniques for these types of investigations. QDs were fabricated of InP on GaInP and InAs on GaAs by the Stranski-Krastanow (SK) method. CL was used to determine the spatial distribution of luminescence from individual quantum dots (QDs), and from QD ensembles. The size and position of QDs, produced by SK method, can be manipulated by growth conditions and by patterns on the surface. By introducing growth interrupt before capping of dots the... (More)
Characterization of low-dimensional semiconductor structures is a challenging task. The thesis is based on experiments, using cathodoluminescence (CL) as a tool for characterization. The high spatial resolution and the possibility of spectroscopy of small structures make CL one of the most powerful techniques for these types of investigations. QDs were fabricated of InP on GaInP and InAs on GaAs by the Stranski-Krastanow (SK) method. CL was used to determine the spatial distribution of luminescence from individual quantum dots (QDs), and from QD ensembles. The size and position of QDs, produced by SK method, can be manipulated by growth conditions and by patterns on the surface. By introducing growth interrupt before capping of dots the kinetics of the QD formation could be investigated. QDs form during a long interrupt and a rough two dimensional quantum well form with no interrupt. These two extremes and intermediate stages were investigated. In particular CL was used to observe luminescence from single dots. Trenches in circular patterns made it possible to investigate how the luminescence from the QDs was effected by different crystallographic orientations of trenches. A maskless technique utilizing a focused ion-beam has been used to fabricate quantum wires (QWRs). The focused ion-beam creates shallow grooves and subsequent growth of InP will produce ridges. By growing a few monolayers of InGaAs on these ridges QWRs were formed and CL was used to determine spatial distribution, and energy variations in the luminescence from these. In III-V nitrides, GaN QDs on AlGaN epitaxial layers with low Al content, can be fabricated by a recently developed method. Both the luminescence and structural properties of QD were determined. This is the first report in literature of single dot luminescence from GaN dots. Alloy fluctuations in AlxGa1-xN epitaxial films, appearing on the micrometer scale, were investigated with a resolution not achieved by other methods. Further, growth artifacts displaying intense luminescence, were investigated. These are related to vertical structures, similar to vertical quantum wires recently reported in AlGaAs films grown on patterned substrates. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Salviati, Giancarlo, Dr., CNR-MASPEC Institute, Parco Area delle Science, University Campus, 43100 Parma
organization
publishing date
type
Thesis
publication status
published
subject
keywords
AlGaN, Fysik, Physics, GaN-AlGaN, single dot spectroscopy, InP-GaInP, Stranski Krastanow, quantum dots, quantum wires, low-dimensional structures, InAs-GaAs, III-V nitride, Cathodoluminescence, III-V semiconductors, Fysicumarkivet A:1999:Petersson
pages
120 pages
defense location
Fysiska instutitionens föreläsningssal B
defense date
1999-01-15 10:15
external identifiers
  • Other:LUFTD2/(TFFF-0053)
ISBN
91-628-3338-3
language
English
LU publication?
yes
id
721b9504-7931-4e4e-8942-cf0c2cefb693 (old id 39255)
date added to LUP
2007-10-01 09:15:33
date last changed
2016-09-19 08:45:16
@misc{721b9504-7931-4e4e-8942-cf0c2cefb693,
  abstract     = {Characterization of low-dimensional semiconductor structures is a challenging task. The thesis is based on experiments, using cathodoluminescence (CL) as a tool for characterization. The high spatial resolution and the possibility of spectroscopy of small structures make CL one of the most powerful techniques for these types of investigations. QDs were fabricated of InP on GaInP and InAs on GaAs by the Stranski-Krastanow (SK) method. CL was used to determine the spatial distribution of luminescence from individual quantum dots (QDs), and from QD ensembles. The size and position of QDs, produced by SK method, can be manipulated by growth conditions and by patterns on the surface. By introducing growth interrupt before capping of dots the kinetics of the QD formation could be investigated. QDs form during a long interrupt and a rough two dimensional quantum well form with no interrupt. These two extremes and intermediate stages were investigated. In particular CL was used to observe luminescence from single dots. Trenches in circular patterns made it possible to investigate how the luminescence from the QDs was effected by different crystallographic orientations of trenches. A maskless technique utilizing a focused ion-beam has been used to fabricate quantum wires (QWRs). The focused ion-beam creates shallow grooves and subsequent growth of InP will produce ridges. By growing a few monolayers of InGaAs on these ridges QWRs were formed and CL was used to determine spatial distribution, and energy variations in the luminescence from these. In III-V nitrides, GaN QDs on AlGaN epitaxial layers with low Al content, can be fabricated by a recently developed method. Both the luminescence and structural properties of QD were determined. This is the first report in literature of single dot luminescence from GaN dots. Alloy fluctuations in AlxGa1-xN epitaxial films, appearing on the micrometer scale, were investigated with a resolution not achieved by other methods. Further, growth artifacts displaying intense luminescence, were investigated. These are related to vertical structures, similar to vertical quantum wires recently reported in AlGaAs films grown on patterned substrates.},
  author       = {Petersson, Anders},
  isbn         = {91-628-3338-3},
  keyword      = {AlGaN,Fysik,Physics,GaN-AlGaN,single dot spectroscopy,InP-GaInP,Stranski Krastanow,quantum dots,quantum wires,low-dimensional structures,InAs-GaAs,III-V nitride,Cathodoluminescence,III-V semiconductors,Fysicumarkivet A:1999:Petersson},
  language     = {eng},
  pages        = {120},
  title        = {Cathodoluminescence Studies of Quantum Structures and III-V nitrides},
  year         = {1998},
}