• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 309
  • 40
  • 31
  • 22
  • 14
  • 9
  • 8
  • 4
  • 4
  • 4
  • 3
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 553
  • 553
  • 553
  • 129
  • 119
  • 119
  • 88
  • 78
  • 70
  • 69
  • 68
  • 68
  • 57
  • 50
  • 50
  • 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.
91

Growth and Characterization of Epitaxial Graphene Grown by Thermal Annealing 6-H SiC(001) and Chemical Vapor Deposition

Peng, Hung-Yu 10 August 2011 (has links)
This research has discussed the graphene growth mechanism and the achievement, the main purpose is to try the best method to grow graphene which is large size, uniform, and continue. The main issue is about growth and characterizations in full text which is separated by thermal annealing 6-H SiC(001) and chemical vapor deposition on the copper foil to grow graphenen. For instances, to adjust the growth parameters and the growth methods to get graphene and to control the quality, to analysis the number of layers, to research the characterizations during growth process, and to find the better transfer method are all the important focus in this paper. The morphology of samples is studied by SEM, AFM, STM, OM and so on, further the thickness of graphene layers can be observed by AFM and STM. Due to the limit of instruments, the thickness of graphene layer (~0.35 nm) and the thickness of 6-H SiC(001) steps (~1.5 nm) are not easy to observe actually. Raman spectroscopy is the main analysis tool I have employed, it is the fast way to calculate the number of layers (G, 2D band). In addition, Raman scattering is able to know the information of electronic structure variation (2D band), to investigate the stress which is caused by substrate and to estimate the quality of graphene (D, G band). Finally, I take chemical vapor deposition to grow graphenen on the copper foil. Sample is successfully transferred onto SiO2, and the number of graphene layers is estimated to be about two and the structure is AA stacking from these data. The data also shows the graphene is large size, uniform, and continue.
92

Synthesis of Boron-Containing Carbon Nanotubes Catalyzed by Cu/£^- Al2O3

Chen, Yun-chu 07 September 2011 (has links)
Boron-doped carbon nanotubes are predicted to behave as semiconductors over a large range of diameters and chiralities and might thus constitute a suitable class of material for nanoelectronics technology. Boron-doped CNTs were reported as by-products when BC2N nanotubes were prepared by an arc-discharge method. The potential doping of CNTs with different kinds of atoms might provide a mechanism for controlling their electronic properties. We have synthesized boron-doped carbon nanotubes (CNTs) directly on copper catalyst by decomposition of B(OCH3)3 in chemical vapor deposition method. The results were characterized and analyzed by scanning electron microscopy (SEM), Raman, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), solid-state NMR and TGA.
93

Effect of nanosized buffer layer and processing parameters on epitaxial growth of ZnO on LiAlO2 by chemical vapor deposition

Lu, Chien-pin 07 September 2011 (has links)
Zinc Oxide (ZnO) has great potential for applications on ultraviolet/blue light emitting devices because of high exciton binding energy and low cost. This research use low lattice-mismatched £^-LiAlO2 (LAO) substrate to grow ZnO epitaxial films by chemical vapor deposition (CVD). The first part of the present study deals with effect of processing parameters including temperature of Zinc procuser, sample position and growth temperature on ZnO epilayer. High the precuser temperature and long distance between sample and center of CVD furnace resulted in high growth rates. When growth rate was low, (10 0) ZnO (m-ZnO) was obtained and its crystallinity and luminescence property were poor. After increasing the growth rate to a certain extent, the surface of epilayer was flat and the crystallinity was improved. A further increase of growth rate resulted in a mixture of m-ZnO and c-plane in the ZnO epilayer. Based on the first part of study, the second part was focused on examining the effect of a nanosized buffer layer on inhibiting the nucleation of c-plane ZnO. Results showed that the nucleation of c-plane ZnO was indeed inhibited at low growth temperature. Finally, the crystallinity the optical property of the epilayer were improved by introducing a thick and flat buffer layer of ~170 nm in thickness.
94

Nanolithographic control of carbon nanotube synthesis

Huitink, David Ryan 15 May 2009 (has links)
A method offering precise control over the synthesis conditions to obtain carbon nanotube (CNT) samples of a single chirality (metallic or semi-conducting) is presented. Using this nanolithographic method of catalyst deposition, the location of CNT growth is also precisely defined. This technique obviates three significant hurdles that are preventing the exploitation of CNT in micro- and nano-devices. Microelectronic applications (e.g., interconnects, CNT gates, etc.) require precisely defined locations and spatial density, as well as precisely defined chirality for the synthesized CNT. Conventional CVD synthesis techniques typically yield a mixture of CNT (semi-conducting and metallic types) that grow at random locations on a substrate in high number density, which leads to extreme difficulty in application integration. Dip Pen Nanolithography (DPN) techniques were used to deposit the catalysts at precisely defined locations on a substrate and to precisely control the catalyst composition as well as the size of the patterned catalyst. After deposition of catalysts, a low temperature Chemical Vapor Deposition (CVD) process at atmospheric pressure was used to synthesize CNT. Various types of catalysts (Ni, Co, Fe, Pd, Pt, and Rh) were deposited in the form of metal salt solutions or nano-particle solutions. Various characterization studies before and after CVD synthesis of CNT at the location of the deposited catalysts showed that the CNT were of a single chirality (metallic or semiconducting) as well as a single diameter (with a very narrow range of variability). Additionally, X-ray photoelectron spectroscopy (XPS) was used to characterize the deposited samples before and after the CVD, as was lateral force microscopy (LFM) for determination of the successful deposition of the catalyst material immediately after DPN as well as following the CVD synthesis of the samples. The diameter of the CNT determines the chirality. The diameter of the CNT measured by TEM was found to be consistent with the chirality measurements obtained from Raman Spectroscopy for the different samples. Hence, the results showed that CNT samples of a single chirality can be obtained by this technique. The results show that the chirality of the synthesized CNT can be controlled by changing the synthesis conditions (e.g., size of the catalyst patterns, composition of the catalysts, temperature of CVD, gas flow rates, etc.).
95

Experimental study for the local heat transfer on a rectangular substrate in TFT-LCD manufacturing process

Su, Chun-shuo 17 July 2006 (has links)
Chemical vapor deposition is an important thin film process for the fabrication of TFT-LCD(Thin-Film-Transistor Liquid Crystal Display), the heat transfer coefficient on the substrate is the important influence parameter in the manufacturing process. For this reason, the main object of this thesis is to set up a temperature measurement system of transient thermochromatic liquid crystals. Furthermore, an experimental is carried out in the present study to investigate the characteristics of heat transfer resulting from a low speed air jet impinging onto a rectangular substrate confined in a vertical rectangular chamber. Finally, empirical equations are proposed to correlate the effect of Reynolds number¡BSeparation distances and Ratio of outlet.
96

Plasma deposition and treatment by a low temperature cascade arc torch /

Yu, Qingsong, January 1998 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 154-161). Also available on the Internet.
97

Effect of cosputtered catalyst on growth and alignment of carbon nanotubes by plasma enhanced chemical vapor deposition /

Gunderson, Eric P. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 85-92). Also available on the World Wide Web.
98

Multivariable study on homoepitaxial growth of diamond on planar and non-planar substrates

Samudrala, Gopi Krishna. January 2009 (has links) (PDF)
Thesis (Ph. D.)--University of Alabama at Birmingham, 2009. / Title from PDF title page (viewed Jan. 28, 2010). Additional advisors: Shane A. Catledge, Joseph G. Harrison, Raymond G. Thompson, Uday K. Vaidya. Includes bibliographical references (p. 75-78).
99

Computational studies of reacting flows with applications in nanoscale materials synthesis

Cho, Joungmo, January 2009 (has links)
Thesis (Ph. D.)--University of Massachusetts Amherst, 2009. / Includes bibliographical references (p. 179-194). Print copy also available.
100

Growth and characterization of group III-nitride power transistors, power rectifiers and solar-blind detectors by metalorganic chemical vapor deposition /

Lambert, Damien Jean Henri, January 2000 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 158-170). Available also in a digital version from Dissertation Abstracts.

Page generated in 0.1761 seconds