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Search Publications by: Babak Nikoobakht (Fed)

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Displaying 1 - 25 of 28

Long Range and Collective Impact of Au Surface Adatoms on Nanofin Growth

November 3, 2023
Author(s)
Babak Nikoobakht, Aaron Johnston-Peck, Jerry Tersoff
In the Au-catalyzed vapor-liquid-solid (VLS) growth of semiconductor nanowires, individual Au nanodroplets can result in single nanowires per site. However, growth of single nanofins per site using the same process becomes unpredictable. Our results show

Impact of fin aspect ratio on enhancement of external quantum efficiency in single AlGaN fin light-emitting diodes pixels

June 26, 2023
Author(s)
Babak Nikoobakht, Yuqin Zong, Okan Koksal, Amit Agrawal, Christopher B. Montgomery, Jacob Leach, Michael Shur
Previously, we showed within a sub-micron fin shape heterojunction, as current density increases, the non-radiative Auger recombination saturates mediated by the extension of the depletion region into the fin, resulting in a droop-free behavior. In this

ZnO fin optical cavities

June 16, 2022
Author(s)
Babak Nikoobakht, Amit Agrawal, Scott A. Wight, Jonathan Lee, Michael Shur
Nanostructured semiconductors have shown great promise toward miniaturization of electrically driven semiconductor lasers. Previously, we reported on an electrically driven sub-micron size ZnO-GaN fin LED architecture that at high current densities showed

High-brightness lasing at submicrometer enabled by droop-free fin light-emitting diodes (LEDs)

August 14, 2020
Author(s)
Robin P. Hansen, Amit K. Agrawal, Michael Shur, Jerry Tersoff, Babak Nikoobakht, Yuqin Zong
"Efficiency droop," i.e., a decline in brightness of light-emitting diodes (LEDs) at high electrical currents, limits the performance of all commercial LEDs and has limited the output power of submicrometer LEDs and lasers to nanowatts. We present a fin p

Defect Evolution of Ion-Exposed Single-Wall Carbon Nanotubes

January 3, 2019
Author(s)
Jana Kalbacova, Elias J. Garratt, Raul D. Rodriguez, Angela R. Hight Walker, Kevin A. Twedt, Jeffrey Fagan, Teresa I. Madeira, Jabez J. McClelland, Babak Nikoobakht, Dietrich R. Zahn
A systematic evaluation of defects is essential to understand and engineer device properties and applications. Raman spectroscopy is employed for the characterization of carbon nanomaterials in particular to quantitatively evaluate defects from the

Observation and Impact of a "Surface Skin Effect" on Lateral Growth of Nanocrystals

June 3, 2017
Author(s)
Babak Nikoobakht, Elias J. Garratt, Paola Prete, Nico Lovergine
We investigate the impact of a quasi-crystalline two (2D) dimensional surface on the lateral epitaxy of one-dimensional (1D) nanocrystals. The quasi-2D surface was formed by locally conditioning a crystalline lattice at- and below-surface using a low dose

Separation, Sizing, and Quantitation of Engineered Nanoparticles in an Organism Model Using Inductively Coupled Plasma Mass Spectrometry and Image Analysis

December 16, 2016
Author(s)
Monique E. Johnson, Shannon Hanna, Antonio R. Montoro Bustos, Christopher M. Sims, Lindsay C. Elliott, Babak Nikoobakht, John T. Elliott, Richard D. Holbrook, Keana C. Scott, Karen E. Murphy, Elijah J. Petersen, Lee L. Yu, Bryant C. Nelson, Akshay Lingayat, Adrian C. Johnston
For environmental studies assessing uptake of orally ingested engineered nanoparticles (ENPs), a key step in ensuring accurate quantification of ingested ENPs is efficient separation of the organism from ENPs that are either nonspecifically adsorbed to the

Surface-directed Nanoepitaxy on a Surface with an Irregular Lattice

January 8, 2016
Author(s)
Elias J. Garratt, Babak Nikoobakht
Understanding and developing metrics on how nanocrystals respond to local external surface stimuli at their interfaces during growth or operation is a key step in advancing scalable and deterministic approaches for fabricating functional one- and two

Vapor-Liquid-Solid Etch of Semiconductor Surface Channels by Running Gold Nanodroplets

November 24, 2015
Author(s)
Babak Nikoobakht, Andrew A. Herzing, Shinichiro Muramoto, Jerry Tersoff
We show that Au nanoparticles spontaneously move across the (001) surface of InP, InAs, and GaP when heated in the presence of water vapor. As they move, the particles etch crystallographically aligned grooves into the surface. We show that this process is

Structural and Optical Properties of Disc-in-Wire InGaN/GaN LEDs

February 6, 2015
Author(s)
Scott A. Wight, Babak Nikoobakht
This study aims to examine the role of the microstructure and optical properties of InGaN/GaN nanowire LED structures on Si (111) having different nanowire densities. Cathodoluminescence measurements show that all samples exhibit broad emission around the

Where is the required lattice match in horizontal growth of nanowires?

March 12, 2013
Author(s)
Babak Nikoobakht
The surface-directed growth of nanowires (NWs) has been demonstrated for a number of semiconductors and is anticipated to be applicable to a wider group of materials. However, the epitaxial relationship between NWs and their underlying surface has not been

Growth of Planar Arrays of One-dimensional p-n Heterojunctions

September 15, 2010
Author(s)
Babak Nikoobakht, Andrew A. Herzing
We report a general method for /in-situ/ formation and hierarchical assembly of nanowire-based semiconductor heterojunctions that are electrically addressable. Heterojunctions are formed by lateral epitaxial growth of nanowires/nanowalls on a semiconductor

Towards Industrial Scale Fabrication of Nanowire-Based Devices

April 11, 2007
Author(s)
Babak Nikoobakht
The key requirements for mass fabrication of nanodevices are directed positioning and alignment of nanoparticles (e.g., nanowires) with known registries on a large scale. Here, these issues are addressed in a high throughput and scalable approach for

Growth habits and defects in ZnO nanowires grown on GaN/sapphire substrates

August 31, 2005
Author(s)
Igor Levin, Albert Davydov, Babak Nikoobakht, Norman Sanford, Pavel Mogilevsky
Growth habits and defects in epitaxial ZnO nanowires grown from Au catalyst on (00.1) GaN/sapphire substrate using the vapor-liquid-solid (VLS) technique were studied using electron microscopy and x-ray diffraction. The results revealed presence of both

Growth Habits and Defects in ZnO Nanowires Grown on GaN/Sapphire Substrates

August 31, 2005
Author(s)
Igor Levin, Albert Davydov, Babak Nikoobakht, Norman A. Sanford, Pavel Mogilevsky
Growth habits and defects in epitaxial ZnO nanowires grown from Au catalyst on (0001) GaN/sapphire substrate using Vapor-Liquid-Solid (VLS) technique were studied using electron microscopy and X-ray diffraction. The results revealed presence of both