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Fabrication, characterization and transport properties of bismuth nanowire systems

IP.com Disclosure Number: IPCOM000128059D
Original Publication Date: 1999-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 10 page(s) / 35K

Publishing Venue

Software Patent Institute

Related People

Zhang, Zhibo: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-75: URL

Abstract

Low-dimensional systems represent one of the important frontiers in solid state physics research. In this thesis, I developed a novel fabrication process to produce bismuth nanowires with ultrafine wire diameters and excellent materials properties, and studied the electronic transport properties of this new one-dimensional system. Because of the extremely small electron effective mass of Bi, these Bi nanowires provide an excellent system to study the unique properties of a quasi one-dimensional electron gas. First, Bi nanowire arrays with various wire diameters (13 -110 nm) and high packing densities (as high as 7.1 x 10 10 wires/cm 2 ) were fabricated by pressure injection of liquid Bi into the evacuated channels of an anodic alumina template. Free-standing Bi nanowires with aspect ratios (length/diameter) as large as 1000 have been produced by dissolving the anodic alumina matrix without attacking the Bi nanowires. Various characterization techniques, such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected-area electron diffraction (SAED), and X-ray diffraction (XRD), have been employed to investigate the physical structure and crystal structure of the Bi nanowires. Our Bi nanowires are shown to be dense and continuous, with a uniform wire diameter throughout the entire length of the wire. The individual nanowires are single crystals, and the nanowires have a similar crystal orientation along the wire axis in each array. The electrical transport properties of these Bi nanowire arrays were studied over a wide range of temperatures (2 - 300 K) and magnetic fields (0 - 5.4 T). At low temperatures, we observed clear classical size effects, whereby the scattering processes for electrons are dominated by the wire boundary scattering in the undoped single-crystal Bi nanowires. Strong evidence for a quantum confinement induced semi metal-to-semiconductor transition has been observed in the temperature dependence of the zero-field resistivity, and this transition is also suggested by optical transmission spectroscopy measurements. A theoretical model based on the electronic band structure of bulk Bi, suitably modified for the 1D case, has been constructed and is able to explain the many unusual phenomena observed in this new class of quasi-1D systems. 2 Thesis Supervisor: Prof. Mildred S. Dresselhaus Title: Institute Professor of Electrical Engineering and Physics Thesis Supervisor: Prof. Jackie Y. Ying Title: St. Laurent Associate Professor of Chemical Engineering 3

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 This record is the front matter from a document that appears on a server at MIT and is used through permission from MIT. See http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-75 for copyright details and for the full document in image form.

Fabrication, Characterization and Transport Properties of Bismuth Nanowire Systems

by

Zhibo Zhang
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology February 1999
SIGNATURE OF author: [[signature omitted]]

Department of Physics

November 20, 1998
CERTIFIED BY: [[SIGNATURE OMITTED]]

Prof. Mildred S. Dresselhaus Institute Professor of Electrical Engineering and Physics Thesis Supervisor Prof. Jackie Y. Ying
St. Laurent Associate Professor of Chemical engineering Thesis Supervisor ACCEPTED BY: [[SIGNATURE OMITTED]]

Prof. Thomas J. Greytak Associate Department Head for Education ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES

Massachusetts Institute of Technology Page 1 Dec 31, 1999

Page 2 of 10

Fabrication, characterization and transport properties of bismuth nanowire systems

Fabrication, Characterization and Transport Properties of Bismuth Nanowire Systems by Zhibo Zhang

Submitted to the Department of Physics on November 20, 1998, in partial fulfillment of the requirements for the degree of Doctor of Philosophy

Abstract

Low-dimensional systems represent one of the important frontiers in solid state physics research. In this thesis, I developed a novel fabrication process to produce bismuth nanowires with ultrafine wire diameters and excellent materials properties, and studied the electronic transport properties of this new one-dimensional system. Because of the extremely small electron effective mass of Bi, these Bi nanowires provide an excellent system to study the unique properties of a quasi one-dimensional electron gas. First, Bi nanowire arrays with various wire diameters (13 -110 nm) and high packing densities (as high as 7.1 x 1010

wires/cm2) were fabricated by pressure injection of liquid Bi into the evacuated channels of an anodic alumina template. Free-standing Bi nanowires with aspect ratios (length/diameter) as large as 1000 have been produced by dissolving the anodic alumina matrix without attacking the Bi nanowires. Various characterization techniques, such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected-area electron diffraction (SAED), and X- ray diffraction (XRD), have been employed to investigate the physical structure and crystal structure of the Bi nanowires. Our Bi nanowires are shown to be dense and continuous, with a uniform wire diameter throughout the entire length of the wire. The individual nanowires are single crystals, and the nanowires have a similar crystal orientation along the wire axis in each array. The electrical transport properties of these Bi nanowire arrays were studied over a wide range of temperatures (2...