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Displaying 76 - 100 of 161

Operational analysis of a quantum dot, optically gated, field-effect transistor as a single-photon detector

July 1, 2007
Author(s)
Eric Gansen, Mary A. Rowe, Marion Greene, Danna Rosenberg, Todd E. Harvey, Mark Su, Robert Hadfield, Sae Woo Nam, Richard Mirin
We report on the operation of a novel single-photon detector, where a layer of self-assembled quantum dots (QDs) is used as an optically addressable floating gate in a GaAs/Al0.2Ga0.8As Δ}-doped field-effect transistor. Photogenerated holes charge the QDs

Photon-number-resolving capabilities of a semiconductor quantum dot, optically gated, field-effect transistor

May 6, 2007
Author(s)
Eric Gansen, Mary A. Rowe, Marion Greene, Danna Rosenberg, Todd E. Harvey, Mark Su, Robert Hadfield, Sae Woo Nam, Richard Mirin
We demonstrate the photon-number-resolving capabilities of a novel quantum dot, optically gated, field-effect transistor cooled to 4 K. Peaks are observed in the detector's response to highly attenuated laser pulses in accordance with Poisson statistics.

Single-photon detection using a quantum dot optically gated field-effect transistor with high internal quantum efficiency

December 19, 2006
Author(s)
Mary A. Rowe, Eric Gansen, Marion Greene, Danna Rosenberg, Robert Hadfield, Todd E. Harvey, Sae Woo Nam, Mark Su, Richard Mirin
We investigate the operation of a quantum dot, optically gated, field-effect transistor as a photon detector. The detector exhibits time-gated, single-shot, single-photon sensitivity, a linear response, and an internal quantum efficiency of up to [68±18] %

Nucleation conditions for catalyst-free GaN nanowires

December 8, 2006
Author(s)
Kristine A. Bertness, Alexana Roshko, Lorelle Mansfield, Todd E. Harvey, Norman Sanford
We have examined the initial steps for catalyst-free growth of GaN using molecular beam epitaxy on Si (111) substrates using AlN buffer layers. These wires form spontaneously under high N-to-Ga ratios for a growth temperature range of about 810 to 830 °C

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

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

Cavity ring-down spectroscopy of semiconductor quantum dots

May 16, 2004
Author(s)
Joseph J. Berry, Todd E. Harvey, Richard Mirin, A Marian, Jun Ye
We employ cavity ringdown to perform absorption experiments of InGaAs/GaAs QDs. Integrating an AlAs/GaAs DBR incorporating InGaAs QD?s into a Fabry-Perot cavity, we demonstrate this approach and its potentials for sensitive measurements on semiconductor

Photoluminescence from an Nd3+ doped AlGaAs semiconductor structure

May 16, 2004
Author(s)
Kirk Ullmann, Mark Su, Kevin L. Silverman, Joseph J. Berry, Todd E. Harvey, Richard Mirin
We report room temperature photoluminescence from a Nd3+ doped AlGaAs semiconductor. Oxidation of the AlGaAs greatly improves the luminescence efficiency of the Nd3+ ions.

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

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

Accuracy of AlGaAs Rates and Composition Determination Using RHEED Oscillations

September 1, 2002
Author(s)
Todd E. Harvey, Kristine A. Bertness, Chih-Ming Wang, Jolene Splett
Reflection high-energy electron diffraction (RHEED) oscillations are widely used in molecular beam epitaxy (MBE) as a technique to calibrate material growth rates. The growth rates are used to predict the composition of the following growth run. For many