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Charge transport in III-V narrow bandgap semiconductor nanowires

Dalelkhan, Bekmurat LU (2019)
Abstract
This thesis describes charge transport in III-V narrow bandgap semiconductor nanowires. We are particularly interested in quantum transport in InSb, InAs and InP-InAs core-shell nanowires. According to the type of transport mechanism dominating in the devices, this thesis can be divided into four parts.
In the first part of this thesis, we investigated the temperature dependent transport properties of InSb nanowires using field effect transistors made of InSb nanowires grown by chemical vapor deposition. Ambipolar transport is observed in measurements in a wide range of temperatures up to 300 K. A bandgap of 220 meV is extracted from the temperature dependent measurements. Hole and electron field effect mobility are determined and... (More)
This thesis describes charge transport in III-V narrow bandgap semiconductor nanowires. We are particularly interested in quantum transport in InSb, InAs and InP-InAs core-shell nanowires. According to the type of transport mechanism dominating in the devices, this thesis can be divided into four parts.
In the first part of this thesis, we investigated the temperature dependent transport properties of InSb nanowires using field effect transistors made of InSb nanowires grown by chemical vapor deposition. Ambipolar transport is observed in measurements in a wide range of temperatures up to 300 K. A bandgap of 220 meV is extracted from the temperature dependent measurements. Hole and electron field effect mobility are determined and their temperature dependence studied. The off state current shows a strong dependence on the temperature and the channel lengths of the transistors.
In the second part of this thesis, spin relaxation and quantum interference in InSb nanowires are explored. Low-field magneto-conductance measurements are performed and a crossover from weak antilocalization to weak localization is observed. The experimental results are well explained with quasi one dimensional weak localization theory. Spin relaxation length and phase coherence length are defined. A strong spin-orbit strength of αR = 0.4 eVÅ-0.87 eVÅ is extracted.
In the third part of this thesis, electron transport in a single quantum dot is studied in the weak and strong dot coupling regimes. The single quantum dots are formed in InSb nanowires by side gates. Various transport features such as sequential tunneling, excited states, and cotunnelings are investigated. Low temperature transport properties of InP-InAs core-shell nanowires are also explored and the coulomb blockade effect is revealed from a quantum structure extending over the entire core-shell nanowire.
In the last part of this thesis, we report on electron transport through double quantum dots in InSb and InAs nanowires defined by side gates. From the measurements in the weak inter dot coupling regime, Pauli spin blockade is observed. The evolutions of states in the Pauli spin-blockade region with magnetic field is also studied.
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author
supervisor
opponent
  • Doctor Ludwig, Stefan, Paul-Drude-Institut für Festkörperelektronik, Germany
organization
publishing date
type
Thesis
publication status
published
subject
keywords
InAs, InSb, InP-InAs, narrow bandgap, spin-orbit interaction, quantum dots, Nanowires, Fysicumarkivet A:2019:Dalelkhan
pages
120 pages
publisher
Department of Physics, Lund University
defense location
Rydbergsalen, Fysicum, Sölvegatan 14, Lund University, Faculty of Engineering LTH
defense date
2019-05-17 13:15:00
ISBN
978-91-7895-100-0
978-91-7895-099-7
language
English
LU publication?
yes
id
c8122738-3ab1-4010-a33e-01263e2cf1a5
date added to LUP
2019-04-16 12:35:25
date last changed
2019-07-05 16:18:32
@phdthesis{c8122738-3ab1-4010-a33e-01263e2cf1a5,
  abstract     = {This thesis describes charge transport in III-V narrow bandgap semiconductor nanowires. We are particularly interested in quantum transport in InSb, InAs and InP-InAs core-shell nanowires. According to the type of transport mechanism dominating in the devices, this thesis can be divided into four parts.<br/>In the first part of this thesis, we investigated the temperature dependent transport properties of InSb nanowires using field effect transistors made of InSb nanowires grown by chemical vapor deposition. Ambipolar transport is observed in measurements in a wide range of temperatures up to 300 K. A bandgap of 220 meV is extracted from the temperature dependent measurements. Hole and electron field effect mobility are determined and their temperature dependence studied. The off state current shows a strong dependence on the temperature and the channel lengths of the transistors. <br/>In the second part of this thesis, spin relaxation and quantum interference in InSb nanowires are explored. Low-field magneto-conductance measurements are performed and a crossover from weak antilocalization to weak localization is observed. The experimental results are well explained with quasi one dimensional weak localization theory. Spin relaxation length and phase coherence length are defined. A strong spin-orbit strength of αR = 0.4 eVÅ-0.87 eVÅ is extracted. <br/>In the third part of this thesis, electron transport in a single quantum dot is studied in the weak and strong dot coupling regimes. The single quantum dots are formed in InSb nanowires by side gates. Various transport features such as sequential tunneling, excited states, and cotunnelings are investigated. Low temperature transport properties of InP-InAs core-shell nanowires are also explored and the coulomb blockade effect is revealed from a quantum structure extending over the  entire core-shell nanowire. <br/>In the last part of this thesis, we report on electron transport through double quantum dots in InSb and InAs nanowires defined by side gates. From the measurements in the weak inter dot coupling regime, Pauli spin blockade is observed. The evolutions of states in the Pauli spin-blockade region with magnetic field is also studied.       <br/>},
  author       = {Dalelkhan, Bekmurat},
  isbn         = {978-91-7895-100-0},
  language     = {eng},
  month        = {04},
  publisher    = {Department of Physics, Lund University},
  school       = {Lund University},
  title        = {Charge transport in III-V narrow bandgap semiconductor nanowires},
  url          = {https://lup.lub.lu.se/search/ws/files/63059296/Charge_transport_in_III_V_narrow_bandgap_semiconductor_nanowires.pdf},
  year         = {2019},
}