東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back

Switch To: Labeled | MARC Mode | ISBD

Growth, structure, and optical chara...

Cooley, Benjamin Joseph.

Linked to FindBook

Google Book

Amazon

博客來

Growth, structure, and optical characterization of diluted magnetic semiconductor nanowires.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Growth, structure, and optical characterization of diluted magnetic semiconductor nanowires./
Author:	Cooley, Benjamin Joseph.
Description:	123 p.
Notes:	Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: 2174.
Contained By:	Dissertation Abstracts International72-04B.
Subject:	Physics, Solid State. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3442913
ISBN:	9781124488080

Growth, structure, and optical characterization of diluted magnetic semiconductor nanowires.
Cooley, Benjamin Joseph.

Growth, structure, and optical characterization of diluted magnetic semiconductor nanowires. - 123 p.

Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: 2174.

Thesis (Ph.D.)--The Pennsylvania State University, 2010.

Nanowires combining the usually disparate areas of semiconductors and magnetism are of contemporary relevance within the context of semiconductor spintronics. This is a relatively new field of research that seeks to exploit electron spin within electronic and opto-electronic semiconductor devices. While much of the effort within semiconductor spintronics has been directed toward fundamental studies and applications of 3D, 2D and 0D systems, there has been little work to date on 1D systems. The distinctive change in the electronic density of states with changing dimensionality provides a strong motivation for developing and exploring semiconductor nanowires in which one might be able to probe and control spin-dependent phenomena within a 1D or quasi-1D environment. This thesis explores the crystal growth, structural properties and magneto-optical behavior of quasi-1D semiconductor nanowires in which we incorporate magnetism through two approaches: first, by synthesizing nanowires of the diluted magnetic semiconductor (Zn,Mn)Se, wherein the d-shell electrons of substitutional Mn ions interact with the band states of the ZnSe host lattice via sp--d exchange; second, by making hybrid core-shell nanostructures wherein a metallic ferromagnetic shell (MnAs) is epitaxially deposited on a semiconductor nanowire (GaAs). After an introductory overview of past work in the field and a description of the experimental techniques relevant to the thesis, we discuss our experimental results.

ISBN: 9781124488080Subjects--Topical Terms:

1669244
Physics, Solid State.

Growth, structure, and optical characterization of diluted magnetic semiconductor nanowires.
LDR:05948nam a2200325 4500 001 1962084
005 20140730075026.5
008 150210s2010 ||||||||||||||||| ||eng d
020 $a 9781124488080
035 $a (MiAaPQ)AAI3442913
035 $a AAI3442913
040 $a MiAaPQ $c MiAaPQ
100 1 $a Cooley, Benjamin Joseph. $3 2098104
245 1 0 $a Growth, structure, and optical characterization of diluted magnetic semiconductor nanowires.
300 $a 123 p.
500 $a Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: 2174.
500 $a Adviser: Nitin Samarth.
502 $a Thesis (Ph.D.)--The Pennsylvania State University, 2010.
520 $a Nanowires combining the usually disparate areas of semiconductors and magnetism are of contemporary relevance within the context of semiconductor spintronics. This is a relatively new field of research that seeks to exploit electron spin within electronic and opto-electronic semiconductor devices. While much of the effort within semiconductor spintronics has been directed toward fundamental studies and applications of 3D, 2D and 0D systems, there has been little work to date on 1D systems. The distinctive change in the electronic density of states with changing dimensionality provides a strong motivation for developing and exploring semiconductor nanowires in which one might be able to probe and control spin-dependent phenomena within a 1D or quasi-1D environment. This thesis explores the crystal growth, structural properties and magneto-optical behavior of quasi-1D semiconductor nanowires in which we incorporate magnetism through two approaches: first, by synthesizing nanowires of the diluted magnetic semiconductor (Zn,Mn)Se, wherein the d-shell electrons of substitutional Mn ions interact with the band states of the ZnSe host lattice via sp--d exchange; second, by making hybrid core-shell nanostructures wherein a metallic ferromagnetic shell (MnAs) is epitaxially deposited on a semiconductor nanowire (GaAs). After an introductory overview of past work in the field and a description of the experimental techniques relevant to the thesis, we discuss our experimental results.
520 $a The first set of experiments focuses on ZnSe and (Zn,Mn)Se nanowires grown in a single stage. The nanowires were grown on Si and GaAs substrates with a thin layer of gold evaporated onto them, which were then annealed before growth so that the gold formed nanoscale droplets. The growth yields samples covered in random arrays of nanowires growing out an an angle to the substrate, with an undergrowth of crooked nanowires and other small structures. The long thin nanowires vary in diameter, down to &sim; 10 nm, with &sim; 15--20 nm being fairly common. Structural characterization done by transmission electron microscopy (TEM) shows that the long nanowires are largely single crystal, though often with many stacking faults, and tend to form in the wurtzite crystal structure with c-axis growth direction. Elemental analysis performed on individual nanowires using X-ray energy dispersive spectroscopy shows that Mn can be incorporated into Zn1-xMn xSe nanowires in high concentrations, up to x &sim; 0.6. Magneto-photoluminescence (magneto-PL) measurements of as-grown samples reveal substantial Zeeman shifts in the nearband edge luminescence, but only partial polarization, indicating the luminescence is originating in a nanostructured environment. Surprisingly, however, nearly all of the PL signal comes from the nanostructured undergrowth rather than the long nanowires, as shown from magneto-PL measurements of samples which were sonicated to remove the long nanowires.
520 $a The next set of experiments covers ZnSe and (Zn,Mn)Se nanowires grown using a two-stage process. The substrates are prepared in a similar manner as the in the previous samples. The first stage of growth is carried out at lower than normal substrate temperature, which results in highly tapered nanoneedles with narrow tips (&sim; 10 nm). The second stage of growth is performed under normal nanowire growth conditions, yielding narrow nanowires growing from the tips of the nanoneedles. These nanowires have far fewer defects than nanowires grown in a single stage process. Magneto-PL measurements carried out in a micro-PL system show many localized emitters and near band edge emission that shifts in a magnetic field. Sonicated samples gave similar results, indicating that the undergrowth is still responsible for much of the luminescence, even though there is much less undergrowth than in the single stage nanowires. Measurements of dispersed samples suggests that some of the luminescence may be coming from nanowires, but the sources of emission from dispersed samples could not be conclusively identified.
520 $a The last set of experiments involves core-shell nanowires created by growing epitaxial shells on GaAs nanowire cores. The GaAs cores are grown using a selfseeded technique, in which a GaAs substrate is coated with SiO 2 and then etched to open nanoscale pinholes in the SiO2. During growth, Ga atoms accumulate in the pinholes and form droplets that then serve as seed particles for VLS nanowire growth. To create the shells, the growth conditions are changed to epitaxial growth conditions. Shells of the ferromagnetic metal MnAs have been grown epitaxially on the side faces of the GaAs nanowires. The epitaxial relationship between the MnAs and GaAs depends on whether the GaAs is in the zincblende or wurtzite crystal phase. ZnSe and (Zn,Mn)Se shells have also been grown on the GaAs nanowires, providing a possible alternative method to create quasi-1D systems of (Zn,Mn)Se.
590 $a School code: 0176.
650 4 $a Physics, Solid State. $3 1669244
650 4 $a Engineering, Materials Science. $3 1017759
650 4 $a Physics, Condensed Matter. $3 1018743
690 $a 0600
690 $a 0794
690 $a 0611
710 2 $a The Pennsylvania State University. $3 699896
773 0 $t Dissertation Abstracts International $g 72-04B.
790 $a 0176
791 $a Ph.D.
792 $a 2010
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3442913