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Development of Key Technologies for White Lighting Based on Light-Emitting Diodes (LEDs)

Description: This program was organized to focus on materials development issues critical to the acceleration of solid-state lighting, and was split into three major thrust areas: (1) study of dislocation density reduction for GaN grown on sapphire using 'cantilever epitaxy', and the impact of dislocation density on the performance of state-of-the-art high-power LEDs; (2) the evaluation of in situ techniques for monitoring gas phase chemistry and the properties of GaN-based layers during metal-organic vapor… more
Date: March 31, 2004
Creator: Goetz, Werner; Imler, Bill; Kim, James; Kobayashi, Junko; Kim, Andrew; Krames, Mike et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Fundamental Mechanisms of Interface Roughness

Description: Publication quality results were obtained for several experiments and materials systems including: (i) Patterning and smoothening of sapphire surfaces by energetic Ar+ ions. Grazing Incidence Small Angle X-ray Scattering (GISAXS) experiments were performed in the system at the National Synchrotron Light Source (NSLS) X21 beamline. Ar+ ions in the energy range from 300 eV to 1000 eV were used to produce ripples on the surfaces of single-crystal sapphire. It was found that the ripple wavelength v… more
Date: January 6, 2009
Creator: Headrick, Randall L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A cell nanoinjector based on carbon nanotubes

Description: Technologies for introducing molecules into living cells are vital for probing the physical properties and biochemical interactions that govern the cell's behavior. Here we report the development of a nanoscale cell injection system-termed the nanoinjector-that uses carbon nanotubes to deliver cargo into cells. A single multi-walled carbon nanotube attached to an atomic force microscope tip was functionalized with cargo via a disulfide-based linker. Penetration of cell membranes with this 'nano… more
Date: January 30, 2007
Creator: Chen, Xing; Kis, Andras; Zettl, Alex & Bertozzi, Carolyn R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Adaptive Projection Subspace Dimension for the Thick-Restart Lanczos Method

Description: The Thick-Restart Lanczos (TRLan) method is an effective method for solving large-scale Hermitian eigenvalue problems. However, its performance strongly depends on the dimension of the projection subspace. In this paper, we propose an objective function to quantify the effectiveness of a chosen subspace dimension, and then introduce an adaptive scheme to dynamically adjust the dimension at each restart. An open-source software package, nu-TRLan, which implements the TRLan method with this adapt… more
Date: October 1, 2008
Creator: Yamazaki, Ichitaro; Bai, Zhaojun; Simon, Horst; Wang, Lin-Wang & Wu, K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The use of bulk states to accelerate the band edge statecalculation of a semiconductor quantum dot

Description: We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number… more
Date: May 10, 2006
Creator: Vomel, Christof; Tomov, Stanimire Z.; Wang, Lin-Wang; Marques,Osni A. & Dongarra, Jack J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Neutron and Gamma-Ray Detectors Based on Quantum Dots

Description: Through this funded project, our research group at the Oak Ridge National Laboratory has pioneered and been successful in preparing and evaluating the performance of prototypes of neutron, alpha, and gamma-ray detectors based on various types of nanoparticles. These include organic fluors [2,5-diphenyloxazole (PPO) and 1,4-bis-2-(5-phenyloxazolyl)-benzene (POPOP)]-doped polystyrene and polyvinyltoluene nanoparticles, highly crystalline inorganic ZnS-capped CdSe, ZnS, three-component CdSxSe1-x, … more
Date: June 1, 2000
Creator: Dai, S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Synthesis of cadmium telluride quantum wires and the similarity of their band gaps to those of equidiameter cadmium telluride quantum dots

Description: High-quality colloidal CdTe quantum wires having purposefully controlled diameters in the range of 5-11 nm are grown by the solution-liquid-solid (SLS) method, using Bi-nanoparticle catalysts, cadmium octadecylphosphonate and trioctylphosphine telluride as precursors, and a TOPO solvent. The wires adopt the wurtzite structure, and grow along the [002] direction (parallel to the c axis). The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to… more
Date: July 11, 2008
Creator: Wang, Lin-Wang; Sun, Jianwei; Wang, Lin-Wang & Buhro, William E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Metal-induced assembly of a semiconductor-island lattice: Getruncated pyramids on Au-patterned Si

Description: We report the two-dimensional alignment of semiconductor islands using rudimentary metal patterning to control nucleation and growth. In the Ge on Si system, a square array of sub-micron Au dots on the Si (001) surface induces the assembly of deposited Ge adatoms into an extensive island lattice. Remarkably, these highly ordered Ge islands form between the patterned Au dots and are characterized by a unique truncated pyramidal shape. A model based on patterned diffusion barriers explains the ob… more
Date: August 28, 2005
Creator: Robinson, J. T.; Liddle, J. A.; Minor, A.; Radmilovic, V.; Yi, D. O.; Greaney, P. A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Final LDRD report : infrared detection and power generation using self-assembled quantum dots.

Description: Alternative solutions are desired for mid-wavelength and long-wavelength infrared radiation detection and imaging arrays. We have investigated quantum dot infrared photodetectors (QDIPs) as a possible solution for long-wavelength infrared (8 to 12 {mu}m) radiation sensing. This document provides a summary for work done under the LDRD 'Infrared Detection and Power Generation Using Self-Assembled Quantum Dots'. Under this LDRD, we have developed QDIP sensors and made efforts to improve these devi… more
Date: February 1, 2008
Creator: Cederberg, Jeffrey George; Ellis, Robert & Shaner, Eric Arthur
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting

Description: We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet… more
Date: March 31, 2007
Creator: Nurmikko, Arto V. & Han, Jung
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A Linear Scaling Three Dimensional Fragment Method for Large ScaleElectronic Structure Calculations

Description: We present a novel linear scaling ab initio total energyelectronic structure calculation method, which is simple to implement,easily to parallelize, and produces essentially thesame results as thedirect ab initio method, while it could be thousands of times faster.Using this method, we have studied the dipole moments of CdSe quantumdots, and found both significant bulk and surface contributions. The bulkdipole contribution cannot simply be estimated from the bulk spontaneouspolarization value b… more
Date: July 26, 2007
Creator: Wang, Lin-Wang; Zhao, Zhengji & Meza, Juan
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Toxicological studies of semiconductor quantum dots on immune cells.

Description: Nanoengineered materials hold a vast promise of enabling revolutionary technologies, but also pose an emerging and potentially serious threat to human and environmental health. While there is increasing knowledge concerning the risks posed by engineered nanomaterials, significant inconsistencies exist within the current data based on the high degree of variability in the materials (e.g., synthesis method, coatings, etc) and biological test systems (e.g., cell lines, whole organism, etc). In thi… more
Date: November 1, 2008
Creator: Ricken, James Bryce; Rios, Lynette; Poschet, Jens Fredrich; Bachand, Marlene; Bachand, George David; Greene, Adrienne Celeste et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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In vivo collection of rare proteins using kinesin-based "nano-harvesters".

Description: In this project, we have developed a novel platform for capturing, transport, and separating target analytes using the work harnessed from biomolecular transport systems. Nanoharvesters were constructed by co-organizing kinesin motor proteins and antibodies on a nanocrystal quantum dot (nQD) scaffold. Attachment of kinesin and antibodies to the nQD was achieved through biotin-streptavidin non-covalent bonds. Assembly of the nanoharvesters was characterized using a modified enzyme-linked immunos… more
Date: November 1, 2008
Creator: Bachand, Marlene; Bachand, George David; Greene, Adrienne Celeste & Carroll-Portillo, Amanda
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Semiconductor Quantum Rods as Single Molecule FluorescentBiological Labels

Description: In recent years, semiconductor quantum dots have beenapplied with great advantage in a wide range of biological imagingapplications. The continuing developments in the synthesis of nanoscalematerials and specifically in the area of colloidal semiconductornanocrystals have created an opportunity to generate a next generation ofbiological labels with complementary or in some cases enhanced propertiescompared to colloidal quantum dots. In this paper, we report thedevelopment of rod shaped semicond… more
Date: May 29, 2006
Creator: Fu, Aihua; Gu, Weiwei; Boussert, Benjamine; Koski, Kristie; Gerion, Daniele; Manna, Liberato et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Examination of the local structure in composite and low dimensional semiconductor by X-ray Absorption Spectroscopy

Description: X-ray absorption methods have been successfully used to obtain quantitative information about local atomic composition of two different materials. X-ray Absorption Near Edge Structure analysis and X-Ray Photoelectron Spectroscopy allowed us to determine seven chemical compounds and their concentrations in c-BN composite. Use of Extended X-ray Absorption Fine Structure in combination with Transmission Electron Microscopy enabled us to determine the composition and size of buried Ge quantum dots.… more
Date: September 25, 2006
Creator: Lawniczak-Jablonska, K.; Demchenko, I. N.; Piskorska, E.; Wolska, A.; Talik, E.; Zakharov, D. N. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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LDRD final report on Bloch Oscillations in two-dimensional nanostructure arrays for high frequency applications.

Description: We have investigated the physics of Bloch oscillations (BO) of electrons, engineered in high mobility quantum wells patterned into lateral periodic arrays of nanostructures, i.e. two-dimensional (2D) quantum dot superlattices (QDSLs). A BO occurs when an electron moves out of the Brillouin zone (BZ) in response to a DC electric field, passing back into the BZ on the opposite side. This results in quantum oscillations of the electron--i.e., a high frequency AC current in response to a DC voltage… more
Date: September 1, 2008
Creator: Lyo, Sungkwun Kenneth; Pan, Wei; Reno, John Louis; Wendt, Joel Robert & Barton, Daniel Lee
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Formation of Nanopore-Arrays by Plasma-based Thin FilmDeposition

Description: The ability to fabricate membranes with arrays of apertures only a few nanometers in diameter are important to many fields of research, including ion beam lithography, DNA sequencing, single ion implantations, and single molecule studies. Because even the state-of-the-art lithography tools are limited in their ability to produce nanoscale features, alternative methods of fabricating single pores of nanometer scale have been developed, using ion-beam sculpting and focused-ion-beam assisted depos… more
Date: March 18, 2005
Creator: Ji, Qing; Chen, Y.; Jiang, Ximan; Ji, Lili & Leung, K. N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Spectroscopic properties of colloidal indium phosphide quantum wires

Description: Colloidal InP quantum wires are grown by the solution-liquid-solid (SLS) method, and passivated with the traditional quantum dots surfactants 1-hexadecylamine and tri-n-octylphosphine oxide. The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to other experimental results for InP quantum dots and wires, and to the predictions of theory. The photoluminescence behavior of the wires is also investigated. Efforts to enhance photoluminescence ef… more
Date: July 11, 2008
Creator: Wang, Lin-Wang; Wang, Fudong; Yu, Heng; Li, Jingbo; Hang, Qingling; Zemlyanov, Dmitry et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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National Renewable Energy Laboratory 2004 Research Review

Description: In-depth articles on several NREL technologies and advances, including: aligning quantum dots and related nanoscience and nanotechnology research; using NREL's Advanced Automotive Manikin (ADAM) to help test and design ancillary automotive systems; and harvesting ocean wind to generate electricity with deep-water wind turbines. Also covered are NREL news, research updates, and awards and honors received by the Laboratory.
Date: March 1, 2005
Item Type: Refine your search to only Text
Partner: UNT Libraries Government Documents Department
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Concurrent Multiscale Simulation at Finite Temperature: Coarse-Grained Molecular Dynamics

Description: With the advent of nanotechnology, predictive simulations of nanoscale systems have become in great demand. In some cases nanoscale systems can be simulated directly at the level of atoms. The atomistic techniques used range from models based on a quantum mechanical treatment of the electronic bonds to those based on more empirical descriptions of the interatomic forces. In many cases, however, even nanoscale systems are too big for a purely atomistic approach, typically because the nanoscale d… more
Date: January 22, 2004
Creator: Rudd, R E
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Quantum Dot Light Enhancement Substrate for OLED Solid-State Lighting

Description: With DOE Award No. DE-EE00000628, QD Vision developed and demonstrated a cost-competitive solution for increasing the light extraction efficiency of OLEDs with efficient and stable color rendering index (CRI) for solid state lighting (SSL). Solution processable quantum dot (QD) films were integrated into OLED ITO-glass substrates to generate tunable white emission from blue emitting OLED) devices as well as outcouple light from the ITO film. This QD light-enhancement substrate (QD-LED) technolo… more
Date: January 21, 2011
Creator: Perkins, James; Stevenson, Matthew; Mahan, Gagan; Coe-Sullivan, Seth & Kazlas, Peter
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Quantum Dots Promise to Significantly Boost Solar Cell Efficiencies (Fact Sheet)

Description: In the search for a third generation of solar-cell technologies, a leading candidate is the use of 'quantum dots' -- tiny spheres of semiconductor material measuring only about 2-10 billionths of a meter in diameter. Quantum dots have the potential to dramatically increase the efficiency of converting sunlight into energy -- perhaps even doubling it in some devices -- because of their ability to generate more than one bound electron-hole pair, or exciton, per incoming photon. NREL has produced … more
Date: August 1, 2013
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Biomolecular interactions and responses of human epithelial and macrophage cells to engineered nanomaterials.

Description: Engineered nanomaterials (ENMs) are increasingly being used in commercial products, particularly in the biomedical, cosmetic, and clothing industries. For example, pants and shirts are routinely manufactured with silver nanoparticles to render them 'wrinkle-free.' Despite the growing applications, the associated environmental health and safety (EHS) impacts are completely unknown. The significance of this problem became pervasive within the general public when Prince Charles authored an article… more
Date: December 1, 2011
Creator: Kotula, Paul Gabriel; Brozik, Susan Marie; Achyuthan, Komandoor E.; Greene, Adrienne Celeste; Timlin, Jerilyn Ann; Bachand, George David et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Transport and deposition of functionalized CdTe nanoparticles in saturated porous media

Description: Comprehensive understanding of the transport and deposition of engineered nanoparticles (NPs) in subsurface is required to assess their potential negative impact on the environment. We studied the deposition behavior of functionalized quantum dot (QD) NPs (CdTe) in different types of sands (Accusand, ultrapure quartz, and iron-coated sand) at various solution ionic strengths (IS). The observed transport behavior in ultrapure quartz and iron-coated sand was consistent with conventional colloid d… more
Date: October 15, 2010
Creator: Torkzaban, S.; Wan, J.; Kim, Y.; Mulvihill, M. & Tokunaga, T. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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