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Displaying 26 - 43 of 43

Fabrication and Analysis of GaN Nanorods grown by MBE

January 1, 2005
Author(s)
Norman Sanford, Larry Robins, Matthew H. Gray, J E. Van Nostrand, C Stutz, R Cortez, Albert Davydov, Alexander J. Shapiro, Igor Levin, Alexana Roshko
GaN nanorods were grown on c-plane sapphire substrates under N-rich conditions by plasma-assisted molecular-beam epitaxy. Scanning electron microsopy revealed densely packed nanorods of hexagonal cross section with diameters ranging from roughly 40 to 100

Nitrogen-Activated Bowing of Dilute In y Ga 1-y As 1- x N x Based on Photoreflectance Studies

December 1, 2003
Author(s)
M M. Fahmi, A Kahn, J A. Griffin, G L. Harris, Larry Robins, Anthony G. Birdwell, Youn S. Kang, D J. Smith, T Steiner, S N. Mohammad
The dependence of the fundamental band gap and higher-lying critical-point energies of dilute-nitrogen Ga 1-yIn yAs 1-xN x epilayers on nitrogen mole fraction (x), for x less than or equal to} 0.0125, and temperature, from 20 K to 295 K, was investigated

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

Refractive Index Study of Al x Ga 1-x N Films Grown on Sapphire Substrates

September 1, 2003
Author(s)
Norman Sanford, Larry Robins, Albert Davydov, Alexander J. Shapiro, Denis V. Tsvetkov, Vladimir A. Dmitriev, Stacia Keller, Umesh Mishra, Steven P. DenBaars
A prism coupling method was used to measure the ordinary (italic}n o) and extraordinary (italic}n e) refractive indices of Al xGa 1-xN films, grown by hydride vapor phase epitaxy (HVPE) and metalorganic chemical vapor deposition (MOCVD) on sapphire, at

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

Measurements of the Refractive Indices of MOCVD and HVPE Grown AlGAN Films Using Prism-Coupling Techniques Correlated With Spectroscopic Reflection/Transmission Analysis

January 1, 2003
Author(s)
Norman Sanford, Larry Robins, Albert Davydov, Alexander J. Shapiro, Denis V. Tsvetkov, Vladimir A. Dmitriev, Stacia Keller, Umesh Mishra, Steven P. DenBaars
Waveguide prism-coupling methods were used to measure the ordinary and extraordinary refractive indices of Al xGaN films grown on sapphire substrates by HVPE and MOCVD. Several discrete wavelengths ranging from 442 nm to 1064 nm were used and the results

X-ray diffraction, photoluminescence and composition standards of compound semiconductors

January 1, 2003
Author(s)
Alexana Roshko, Kristine A. Bertness, J T. Armstrong, Ryna B. Marinenko, Marc L. Salit, Lawrence H. Robins, Albert J. Paul, R J. Matyi
Work is underway to develop composition standards and standardized assessment procedures for compound semiconductors. An AlGaAs composition standard with less than 2% uncertainty is being developed. The improved accuracy of this standard is being achieved

Composition standards for III-V semiconductor epitaxial films

November 11, 2002
Author(s)
Kristine A. Bertness, Lawrence H. Robins, J T. Armstrong, Ryna B. Marinenko, Albert J. Paul, Marc L. Salit
A program is underway at NIST to establish standard reference materials (SRMs) for the calibration of instruments used to measure the chemical composition of epitaxially grown III-V semiconductor thin films. These SRMs are designed for the calibration of

AlGaAs Composition Measurements from In Situ Optical Reflectance

July 1, 2000
Author(s)
Kristine A. Bertness, J T. Armstrong, Ryna B. Marinenko, Larry Robins, Albert J. Paul, Joseph G. Pellegrino, Paul M. Amirtharaj, Deane Chandler-Horowitz
We measure the composition of AlGaAs layers during epitaxial crystal growth using in situ normal-incidence optical reflectance supported by independent methods of measuring growth rate. The results are compared with conventional ex situ characterization.

A Comparison of Aluminum Nitride Freely Nucleated and Seeded on 6H-Silicon Carbide

January 1, 2000
Author(s)
J H. Edgar, Larry Robins, S E. Coatney, L Liu, J Chaudhuri, K Ignatiev, Z J. Rek
The crystal structure and optical properties of AlN single crystals prepared by the sublimation-recondensation method were analyzed by cathodoluminescence (CL) spectroscopy, Raman spectroscopy, and synchrotron white-beam x-ray topography (SWBXT). Needles