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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Indium Nitride: An Investigation of Growth, Electronic Structure and Doping

Anderson, Phillip Alistair January 2006 (has links)
The growth, electronic structure and doping of the semiconductor InN has been explored and analysed. InN thin films were grown by plasma assisted molecular beam epitaxy. The significance of the relative fluxes, substrate temperature and buffer layers was explored and related to the electrical and structural properties of the films. An exploration of the effect of active nitrogen species on InN films found that excited molecular nitrogen was preferred for growth over atomic and ionic species. An optimised recipe for InN was developed incorporating all explored parameters. The bandgap of InN was explored using the techniques of optical absorption, photoluminescence and photoconductivity. All three techniques identified a feature near 0.67 eV as the only dominant and reproducible optical feature measurable from InN thin films. No evidence for any optical features above 1 eV was discovered. The effect of the Burstein-Moss effect is discussed and the debate over the relative impact of the effect is related to problems with precisely measuring electron concentrations. Photoluminescence from mixed phase InN films containing significant zincblende content is presented, with tentative evidence presented for a zincblende band gap near 0.61 eV. Native defects within InN were studied by near edge X-ray absorption fine structure spectroscopy. Nitrogen related defects were found to be unlikely candidates for the high as-grown n-type conductivity. The most likely candidate remains nitrogen vacancies. Ion implantation was shown to cause substantial damage to the InN lattice, which could not be fully repaired through annealing. The limitation on annealing temperatures may limit the use of implantation as a processing tool for InN. Mg was shown to exhibit great promise as a potential p-type dopant. Photoluminescence from Mg doped films was found to quench at high Mg concentrations, consistent with a depletion region near the surface. The potential dilute magnetic semiconductor In1-xCrxN was explored. All of the In1-xCrxN films were found to be ferromagnetic at room temperature and exhibited saturated magnetic moments of up to 0.7 emu/g. An interesting correlation between background electron concentration and remnant moment is presented and the consequences of theoretical exchange models discussed. The bandgap of chromium nitride was also investigated and found to be an indirect gap of 0.7 eV.
52

GSMBE growth on V-groove patterned substrates for InP-based quantum wires /

Wang, Jun. January 1997 (has links)
Thesis (Ph.D) -- McMaster University, 1997. / Includes bibliographical references (leaves 130-139). Also available via World Wide Web.
53

Molecular-beam epitaxial growth of low-dark-current avalanche photodiodes

Hurst, Jeffrey Byron, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
54

Structure and dynamics of interfaces in the epitaxial growth and erosion on (110) and (100) crystal surfaces

Levandovsky, Artem. January 2004 (has links)
Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vii, 129 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.
55

Characterization of as-grown and annealed narrow band gap nitrides grown by molecular beam epitaxy /

Reifsnider, Jason Miles, January 2003 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references (leaves 124-133). Also available in an electronic version.
56

Molecular beam epitaxy of quantum dots for high speed photodetectors /

Baklenov, Oleg, January 1999 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 125-132). Available also in a digital version from Dissertation Abstracts.
57

Ordered ZnSe nanowire arrays grown on GaAs (111) substrate by molecular beam epitaxy /

Liu, Na. January 2005 (has links)
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 69-70). Also available in electronic version.
58

Studies of the initial stage of silicon carbide growth on silicon

Ziemer, Katherine S. January 2001 (has links)
Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xvi, 217, 2 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 198-207).
59

MBE Growth and Instrumentation

Tarigopula, Sriteja 05 1900 (has links)
This thesis mainly aims at application of principles of engineering technology in the field of molecular beam epitaxy (MBE). MBE is a versatile technique for growing epitaxial thin films of semiconductors and metals by impinging molecular beams of atoms onto a heated substrate under ultra-high vacuum (UHV) conditions. Here, a LabVIEW® (laboratory virtual instrument engineering workbench) software (National Instruments Corp., http://www.ni.com/legal/termsofuse/unitedstates/usH) program is developed that would form the basis of a real-time control system that would transform MBE into a true-production technology. Growth conditions can be monitored in real-time with the help of reflection high energy electron diffraction (RHEED) technique. The period of one RHEED oscillation corresponds exactly to the growth of one monolayer of atoms of the semiconductor material. The PCI-1409 frame grabber card supplied by National Instruments is used in conjunction with the LabVIEW software to capture the RHEED images and capture the intensity of RHEED oscillations. The intensity values are written to a text file and plotted in the form of a graph. A fast Fourier transform of these oscillations gives the growth rate of the epi-wafer being grown. All the data being captured by the LabVIEW program can be saved to file forming a growth pedigree for future use. Unattended automation can be achieved by designing a control system that monitors the growth in real-time and compares it with the data recorded from the LabVIEW program from the previous growth and adjusts the growth parameters automatically thereby growing accurate device structures.
60

Novel Semi-Conductor Material Systems: Molecular Beam Epitaxial Growth and Characterization

Elmarhoumi, Nader M. 12 1900 (has links)
Semi-conductor industry relies heavily on silicon (Si). However, Si is not a direct-band gap semi-conductor. Consequently, Si does not possess great versatility for multi-functional applications in comparison with the direct band-gap III-V semi-conductors such as GaAs. To bridge this gap, what is ideally required is a semi-conductor material system that is based on silicon, but has significantly greater versatility. While sparsely studied, the semi-conducting silicides material systems offer great potential. Thus, I focused on the growth and structural characterization of ruthenium silicide and osmium silicide material systems. I also characterized iron silicon germanide films using extended x-ray absorption fine structure (EXAFS) to reveal phase, semi-conducting behavior, and to calculate nearest neighbor distances. The choice of these silicides material systems was due to their theoretically predicted and/or experimentally reported direct band gaps. However, the challenge was the existence of more than one stable phase/stoichiometric ratio of these materials. In order to possess the greatest control over the growth process, molecular beam epitaxy (MBE) has been employed. Structural and film quality comparisons of as-grown versus annealed films of ruthenium silicide are presented. Structural characterization and film quality of MBE grown ruthenium silicide and osmium silicide films via in situ and ex situ techniques have been done using reflection high energy electron diffraction, scanning tunneling microscopy, atomic force microscopy, cross-sectional scanning electron microscopy, x-ray photoelectron spectroscopy, and micro Raman spectroscopy. This is the first attempt, to the best of our knowledge, to grow osmium silicide thin films on Si(100) via the template method and compare it with the regular MBE growth method. The pros and cons of using the MBE template method for osmium silicide growth are discussed, as well as the structural differences of the as-grown versus annealed films. Future perspectives include further studies on other semi-conducting silicides material systems in terms of growth optimization and characterization.

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