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Electrical Characterization of Integrated InAs Nano-Structures

Astromskas, Gvidas LU (2010)
Abstract
This thesis analyzes the electrical properties of InAs nano-structures, that are integrated into different materials and geometries. The thesis describes integration related issues of InAs, the epitaxial synthesis of the InAs nano-structures and summarizes experimental techniques for analysis of electrical properties of the integrated structures. InAs thin films, nanowires and membranes are investigated to determine their electrical quality.

The thin films (> 300 nm thick) are integrated onto GaAs substrates using overgrowth over the tungsten patterns. Such integration method allows varying the area of the surface pinning region within the material to measure the extent of this region in InAs. A carrier saturation is observed... (More)
This thesis analyzes the electrical properties of InAs nano-structures, that are integrated into different materials and geometries. The thesis describes integration related issues of InAs, the epitaxial synthesis of the InAs nano-structures and summarizes experimental techniques for analysis of electrical properties of the integrated structures. InAs thin films, nanowires and membranes are investigated to determine their electrical quality.

The thin films (> 300 nm thick) are integrated onto GaAs substrates using overgrowth over the tungsten patterns. Such integration method allows varying the area of the surface pinning region within the material to measure the extent of this region in InAs. A carrier saturation is observed when the tungsten density is increased which allows determining the effective length of the surface pinning region to be under 400 nm.

InAs nanowire capacitors are investigated to measure their doping density and doping profile. The capacitance of the nanowire capacitors exhibits non parabolic band behavior and a full depletion, in contrast to conventional MOS capacitors. The threshold voltage of the fully depleted nanowires is extracted to determine doping density and dopant distribution profile within a nanowire. It is shown that dopants incorporate preferentially at the nanowire surface and the surface doping concentration is higher than in the nanowire bulk. Also, capacitance transients are analyzed to show the presence of traps in the oxide.

InAs metamorphic films are integrated onto GaSb buffer layer to evaluate the relation between the quality of the buffer layer and the InAs. It is observed, that metamorphic InAs membranes (23 nm thick) are highly resistive, while thicker membranes (90 nm thick) can be measured by Hall Effect measurements. The mobility of 90 nm membranes is found be 2700 cm^2/Vs, which indicates a loss of the metamorphic lattice. It is shown that the resistivity of thin membranes is highly sensitive to surface treatment. (Less)
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author
supervisor
opponent
  • Prof. Zetterling, Carl-Mikael, KTH, Royal Institute of Technology, Department of Microelectronics and Applied Physics, Kista
organization
publishing date
type
Thesis
publication status
published
subject
keywords
DLTS, Fermi level pinning, epitaxial growth, threshold voltage, nanowire capacitance, overgrowth, Hall mobility, GaSb, InAs
pages
118 pages
publisher
Lund University (Media-Tryck)
defense location
Lecture hall B, Department of Physics, Sölvegatan 14A, Lund University Faculty of Engineering
defense date
2010-12-14 10:15
ISBN
978-91-7473-062-3
language
English
LU publication?
yes
id
f7ddc0c3-8003-4150-9210-269a10c5905b (old id 1718361)
date added to LUP
2010-11-18 11:52:54
date last changed
2016-09-19 08:45:04
@misc{f7ddc0c3-8003-4150-9210-269a10c5905b,
  abstract     = {This thesis analyzes the electrical properties of InAs nano-structures, that are integrated into different materials and geometries. The thesis describes integration related issues of InAs, the epitaxial synthesis of the InAs nano-structures and summarizes experimental techniques for analysis of electrical properties of the integrated structures. InAs thin films, nanowires and membranes are investigated to determine their electrical quality. <br/><br>
The thin films (&gt; 300 nm thick) are integrated onto GaAs substrates using overgrowth over the tungsten patterns. Such integration method allows varying the area of the surface pinning region within the material to measure the extent of this region in InAs. A carrier saturation is observed when the tungsten density is increased which allows determining the effective length of the surface pinning region to be under 400 nm. <br/><br>
InAs nanowire capacitors are investigated to measure their doping density and doping profile. The capacitance of the nanowire capacitors exhibits non parabolic band behavior and a full depletion, in contrast to conventional MOS capacitors. The threshold voltage of the fully depleted nanowires is extracted to determine doping density and dopant distribution profile within a nanowire. It is shown that dopants incorporate preferentially at the nanowire surface and the surface doping concentration is higher than in the nanowire bulk. Also, capacitance transients are analyzed to show the presence of traps in the oxide.<br/><br>
InAs metamorphic films are integrated onto GaSb buffer layer to evaluate the relation between the quality of the buffer layer and the InAs. It is observed, that metamorphic InAs membranes (23 nm thick) are highly resistive, while thicker membranes (90 nm thick) can be measured by Hall Effect measurements. The mobility of 90 nm membranes is found be 2700 cm^2/Vs, which indicates a loss of the metamorphic lattice. It is shown that the resistivity of thin membranes is highly sensitive to surface treatment.},
  author       = {Astromskas, Gvidas},
  isbn         = {978-91-7473-062-3},
  keyword      = {DLTS,Fermi level pinning,epitaxial growth,threshold voltage,nanowire capacitance,overgrowth,Hall mobility,GaSb,InAs},
  language     = {eng},
  pages        = {118},
  publisher    = {ARRAY(0xa4ed820)},
  title        = {Electrical Characterization of Integrated InAs Nano-Structures},
  year         = {2010},
}