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Search Publications by: Kris A. Bertness (Fed)

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Displaying 126 - 150 of 178

Composition Standards for AlGaAs Epitaxial Layers

April 1, 2006
Author(s)
Kristine A. Bertness, Todd E. Harvey, C. M. Wang, Albert J. Paul, Larry Robins
Standard Reference Materials (SRMs) 2840 to 2843 are semiconductor material artifacts that consist of an epitaxial layer of AlxGa (1-x)As on a GaAs substrate. From the energy at the peak intensity in the photoluminescence (PL) spectrum, the composition of

High-accuracy determination of epitaxial AlGaAs composition with inductively coupled plasma optical emission spectroscopy

March 1, 2006
Author(s)
Kristine A. Bertness, C. M. Wang, Marc L. Salit, Gregory C. Turk, Therese A. Butler, Albert J. Paul, Larry Robins
Inductively coupled plasma optical emission spectroscopy is shown to confirm a recent correlation between photoluminescence (PL) peak energy for AlGaAs epitaxial films and the Al mole fraction x of those films. These two methods also agree within their

Catalyst-Free Growth of GaN Nanowires

January 1, 2006
Author(s)
Kristine A. Bertness, Norman Sanford, Joy Barker, John B. Schlager, Alexana Roshko, Albert Davydov, Igor Levin
We have grown GaN and AlGaN nanowires on Si (111) substrates with gassource molecular beam epitaxy (MBE). No metal catalysts were used. The nanowires displayed a number of interesting materials properties, including room-temperature luminescence intensity

High Degree of Crystalline Perfection in Spontaneously Grown GaN Nanowires

January 1, 2006
Author(s)
Kristine A. Bertness, Alexana Roshko, Albert Davydov, Igor Levin, Mark D. Vaudin, Joy Barker, John B. Schlager, Norman Sanford, Larry Robins
We have grown a variety of isolated GaN nanowires using gas-source molecular beam epitaxy (MBE) and characterized their structural and optical properties. The nanowires have demonstrated a number of promising materials characteristics, including low defect

Spontaneously grown GaN and AlGaN nanowires

January 1, 2006
Author(s)
Kristine A. Bertness, Alexana Roshko, Norman A. Sanford, Joy Barker, Albert Davydov
We have identified crystal growth conditions in gas-source molecular beam epitaxy (MBE) that lead to spontaneous formation of GaN nanowires with high aspect ratio on Si (1 1 1) substrates. The nanowires were oriented along the GaN c-axis and normal to the

GaAs Buffer Layer Morphology and Lateral Distributions of InGaAs Quantum Dots

May 1, 2005
Author(s)
Alexana Roshko, Todd E. Harvey, Susan Y. Lehman, Richard Mirin, Kristine A. Bertness, Brittany Hyland
Atomic force microscopy was used to study the morphology of GaAs buffer layers and the density and height distributions of self-assembled InGaAs quantum dots (QDs) grown on these buffers by molecular beam epitaxy. The surface roughness and terrace size of

Storage Conditions for High-Accuracy Composition Standards of AlGaAs

May 1, 2005
Author(s)
Kristine A. Bertness, Alexana Roshko, S. E. Asher, Craig L. Perkins
AlGaAs epitaxial films were stored under different environmental conditions and the resulting surface oxidation and contamination variations measured using several analytical techniques. Auger depth profiles confirmed that oxidation and carbon

EBSD Measurement of Strains in GaAs due to Oxidation of Buried AlGaAs Layers

February 27, 2004
Author(s)
T Keller, Alexana Roshko, R.H. Geiss, Kristine A. Bertness, T.P. Quinn
We have characterized elastic strain fields associated with the wet-thermal oxidation of buried Al xGa 1-xAs (x 0.98) layers of thickness 80 nm, situated between GaAs layers of thickness 200 nm, on a GaAs substrate. The compressive strains accompanying

Composition Verification of AlGaAs Epitaxial Layers using Inductively Coupled Plasma Optical-Emission Spectroscopy

September 28, 2003
Author(s)
Kristine A. Bertness, Todd E. Harvey, Albert J. Paul, Larry Robins, Gregory C. Turk, Therese A. Butler, Marc L. Salit
We have applied an analytical chemistry method, inductively coupled plasma optical-emission spectroscopy (ICP-OES), to increase the accuracy of composition measurement of AlGaAs epitaxial thin films. ICP-OES results were compared with composition

Electron Backscatter Diffraction for Studies of Localized Deformation

July 1, 2003
Author(s)
Roy H. Geiss, Alexana Roshko, Kristine A. Bertness, R R. Keller
Electron backscatter diffraction (EBSD) was used to study localized deformation in two types ofconstrained-volume materials. We present a study of deformation in narrow aluminum interconnects afterlow frequency, AC cycling at high current density. Joule

High-accuracy determination of the dependence of the photoluminescence emission energy on alloy composition in Al x Ga 1-x As films

April 1, 2003
Author(s)
Larry Robins, J T. Armstrong, Ryna B. Marinenko, Albert J. Paul, John Pellegrino, Kristine A. Bertness
In an effort to improve the accuracy of photoluminescence (PL) measurements of the Al mole fraction (x) of Al xGa 1-xAs alloys, the PL peak emission energy, E PL,peak, was measured at room temperature for molecular-beam epitaxy-grown Al xGa 1-xAs films

High-Accuracy Determination of the Dependence of the PhotoluminescenceEmission Energy on Alloy Composition in Al x Ga 1-x As Films

April 1, 2003
Author(s)
Lawrence H. Robins, J T. Armstrong, Ryna B. Marinenko, Albert J. Paul, J G. Pellegrino, Kristine A. Bertness
In an effort to improve the accuracy of photoluminescence (PL)spectroscopy as a composition (Al mole fraction) measurement method forthe Al xGa 1-xAs alloy system, the PL peak emission energy,E PL,peak, was measured at room temperature for a set of MBE

Electron Backscatter Diffraction for Studies of Localized Deformation

March 1, 2003
Author(s)
R.H. Geiss, Alexana Roshko, Kristine A. Bertness, T Keller
Electron backscatter diffraction (EBSD) was used to study localized deformation in two types of constrained-volume materials. We present a study of deformation in narrow aluminum interconnects after low frequency, AC cycling at high current density. Joule

Accuracy of AlGaAs Growth Rates and Composition Determination Using RHEED Oscillations

January 1, 2003
Author(s)
Todd E. Harvey, Kristine A. Bertness, Robert K. Hickernell, C. M. Wang, Jolene Splett
We investigate the sources of uncertainty in the measurement of the reflection high-energy electron diffraction (RHEED) intensity oscillations during growth of AlAs, GaAs, and AlGaAs on GaAs substrates, and the resulting effects on predicted growth rates

Biaxial Stress Dependence of the GaAs-Like and AlAs-Like Raman Lines in Al x Ga 1-x As

January 1, 2003
Author(s)
Grady S. White, Albert J. Paul, Kristine A. Bertness, Alexana Roshko
Raman peak shifts of Al xGa 1-xAs have been measured as a function of both x and applied biaxial stress in a backscatter geometry. Within the precision of the Raman measurements, the stress-induced peak shifts of the Raman singlet GaAs-like and AlAs-like

Detection of Trace Water in Phosphine with Cavity Ring-down Spectroscopy

January 1, 2003
Author(s)
Susan Y. Lehman, Kristine A. Bertness, Joseph T. Hodges
Water is a detrimental impurity even at concentrations of 10 nmol/mol or less in source gases for compound semiconductor epitaxial growth. Oxygen complexes from water incorporation cause degraded luminescent efficiency and reduced minority carrier

Effects of noise level in fitting in situ optical reflectance spectroscopy data

January 1, 2003
Author(s)
Chih-chiang Fu, Kristine A. Bertness, C. M. Wang
Curve-fitting of simulated optical reflectance spctroscopy data is used to evaluate the accuracy of parameters derived from the fits of actual data. These simulations show that to determine the index of refraction 'n' to an accuracy of 0.0015