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Novel Transport Characterizations in Layered Two-Dimensional Materials and Bulk Chalcogenides.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Novel Transport Characterizations in Layered Two-Dimensional Materials and Bulk Chalcogenides./
Author:	Peng, Lintao.
Description:	1 online resource (182 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 79-08(E), Section: B.
Contained By:	Dissertation Abstracts International79-08B(E).
Subject:	Applied physics. -
Online resource:	click for full text (PQDT)
ISBN:	9780355824841

Novel Transport Characterizations in Layered Two-Dimensional Materials and Bulk Chalcogenides.
Peng, Lintao.

Novel Transport Characterizations in Layered Two-Dimensional Materials and Bulk Chalcogenides. - 1 online resource (182 pages)

Source: Dissertation Abstracts International, Volume: 79-08(E), Section: B.

Thesis (Ph.D.)--Northwestern University, 2018.

Includes bibliographical references

The isolation of graphene by the simple Scotch-tape method led to the discovery of many novel two-dimensional (2D) materials. Since then, many new material growth and characterization techniques were proposed and many new phenomena were observed in layered 2D materials. Black phosphorous (BP) and topological insulator(TI) Bi2Se3 are examples of them. Besides the layered TIs and semiconducting transition metal dichalcogenides, many other bulk chalcogenides are of particular interest like the misfit layer chalcogenides (MLCs), phase change chalcogenides (PCCs), and many more. In this research, novel electrical transport techniques will be discussed to study the properties of 2D BP, Bi2Se3, and two bulk chalcogenides: the MLC Bi-Cr-Se and the PCC K2Sb8Se 13.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780355824841Subjects--Topical Terms:

1181953
Applied physics.
Index Terms--Genre/Form:

554714
Electronic books.

Novel Transport Characterizations in Layered Two-Dimensional Materials and Bulk Chalcogenides.
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245 1 0 $a Novel Transport Characterizations in Layered Two-Dimensional Materials and Bulk Chalcogenides.
264 0 $c 2018
300 $a 1 online resource (182 pages)
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500 $a Source: Dissertation Abstracts International, Volume: 79-08(E), Section: B.
500 $a Adviser: Matthew Grayson.
502 $a Thesis (Ph.D.)--Northwestern University, 2018.
504 $a Includes bibliographical references
520 $a The isolation of graphene by the simple Scotch-tape method led to the discovery of many novel two-dimensional (2D) materials. Since then, many new material growth and characterization techniques were proposed and many new phenomena were observed in layered 2D materials. Black phosphorous (BP) and topological insulator(TI) Bi2Se3 are examples of them. Besides the layered TIs and semiconducting transition metal dichalcogenides, many other bulk chalcogenides are of particular interest like the misfit layer chalcogenides (MLCs), phase change chalcogenides (PCCs), and many more. In this research, novel electrical transport techniques will be discussed to study the properties of 2D BP, Bi2Se3, and two bulk chalcogenides: the MLC Bi-Cr-Se and the PCC K2Sb8Se 13.
520 $a The central focus of this research is the semiconducting 2D black phosphorous which has moderate tunable band-gap and high mobility. It is also a 2D material with in-plane anisotropy caused by the puckered planar structure along the armchair direction. Previous study employed both optical techniques and a multiple-step etch fabrication process to quantify the anisotropic electrical tensor of such 2D materials. Here, the crystal orientation of an exfoliated BP flake is determined by purely electrical means. A sequence of three resistance measurements on an arbitrarily shaped flake with five contacts determines the three independent components of the anisotropic in-plane resistivity tensor, thereby revealing the crystal axes. The resistivity anisotropy ratio decreases linearly with increasing temperature T and carrier-density reaching a maximum ratio of 3.0 at low temperatures and densities, while mobility indicates impurity scattering at low T and acoustic phonon scattering at high T.
520 $a Then the disorder-induced switching hysteresis common to 2D materials has been quantitatively addressed in this research using BP as an example. The widely observed hysteresis in the gate-dependent conductivity of many 2D materials was primarily attributed to the substrate and/or the surface adsorbates which has not been well quantified. By measuring the switching transient conductivity of BP field-effect transistor devices with step-like gate-bias change, the hysteresis-related heavy-tail transients in both pristine and highly disordered BP were modeled to within the dispersive diffusion frame. Along with the proposed continuous time random walk model, the characteristic energy of the trap tail which causes the slow relaxation and therefore the hysteresis, can be extracted from the temperature dependent behaviors.
520 $a Due to the sensitivity of 2D materials to their physical and chemical environment, these materials function well as surface sensors and field effect transistor channels. Two of the most important parameters to characterize eventual device applications are the density and mobility in the presence of an interface disorder potential. A disorder-scaling method is introduced here to analyze gate-dependent conductivity as a function of changing disorder potential strength. It can extract relative changes in carrier density and mobility while the disorder potential is increased and decreased in strength revealing the underlying doping mechanism. This method was demonstrated with support from accurate Hall measurements on multilayer BP as well as its application on monolayer Bi2Se3 to study the surface adsorption/desorption process.
520 $a Aside from 2D chalcogenides, our interests have extended to 3D chalcogenides of more complex structures. One is the semiconducting MLCs Bi-Cr-Se. The electrical properties of both bulk and thin flake devices were measured. A non-Gaussian resistance noise was observed in the exfoliated device indicating a possible way to characterize 2D magnetic dynamics with quasi-1D transport properties. A newly identified three-phase chalcogenide compound K2Sb 8Se13 was also investigated. The electrical properties of all three phases and their respective transitions were measured which is essential for potential novel applications in electronics.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Applied physics. $3 1181953
650 4 $a Materials science. $3 557839
650 4 $a Condensed matter physics. $3 1148471
655 7 $a Electronic books. $2 local $3 554714
690 $a 0215
690 $a 0794
690 $a 0611
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a Northwestern University. $b Applied Physics. $3 1190169
773 0 $t Dissertation Abstracts International $g 79-08B(E).
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10749459 $z click for full text (PQDT)