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Search Publications by: Norman A. Sanford (Fed)

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Displaying 101 - 125 of 161

A Brighter Future From Gallium Nitride Nanowires

October 1, 2006
Author(s)
Kristine A. Bertness, Norman Sanford, Albert Davydov
How might nitride semiconductor nanowires change the future of computing? In the spirit of this special issue on how science fiction might become working technology, we offer some speculations and explain the science behind them. This article focuses on

Molecular Beam Epitaxial Growth of High-Quality GaN Nanocolumns

January 5, 2006
Author(s)
J E. Van Nostrand, J. E. Averett, R Cortez, J. Boeckl, C Stutz, Norman Sanford, Albert Davydov, M M. Maska
Vertically oriented gallium nitride GaN nanocolumns (NCs) approximately 90±10 nm wide and 0.75 microns tall were grown by plasma-assisted molecular beam epitaxy on Al_(2)O_(3)(0001) and Si(111). The dense packing of the NCs gives them the appearance of a

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

Molecular Beam Epitaxial Growth of High-Quality GaN Nanocolumns

January 1, 2006
Author(s)
J E. Van Nostrand, K L. Averett, R Cortez, J Boecki, C E. Stutz, Norman Sanford, Albert Davydov, J D. Albrecht
Vertically oriented GaN nanocolumns (NCs) approximately 90+10 nm wide and 0.75 microns tall were grown byt plasma-assisted molecular beam epitaxy on Al_(2)O_(3)(0001) and Si(111). The dense packing of the NCs gives them the appearance of a continuous film

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

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

Measurement of Second Order Susceptibilities of GaN and AlGaN

March 1, 2005
Author(s)
Norman Sanford, Albert Davydov, Denis V. Tsvetkov, Vladimir A. Dmitriev, Stacia Keller, Umesh Mishra, Steven P. DenBaars, S S. Park, J H. Han
Rotational Maker fringes, scaled with respect to χ 11 (2) of crystalline quartz, were used to determine the nonlinear optical coefficients χ 31 (2) and χ 33 (2) for samples of thin Al xGa 1-xN films and a bulk free-standing GaN platelet. The Al xGa 1-xN

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

Refractive index and birefringence of InGaN films grown by MOCVD

January 1, 2005
Author(s)
Norman Sanford, Anneli Munkholm, Mike A. Krames, Alexander J. Shapiro, Igor Levin, Albert Davydov, Safak Sayan, L Wielunski, T E. Madey
The refractive index and birefringence of InxGa1'xN films grown on GaN layers were measured by prism coupling used in conjunction with multilayer optical waveguide analysis. Samples with x = 0.036, 0.049, 0.060, and 0.066 were examined at the separate

Passively Mode-locked Glass Waveguide Laser with 14 fs Timing Jitter

December 1, 2003
Author(s)
John B. Schlager, Berton Callicoatt, Richard Mirin, Norman Sanford, David J. Jones, Jun Ye
Ultra-low jitter pulse trains are produced from a passively mode-locked erbium/ytterbium co-doped planar waveguide laser using high-bandwidth feedback control acting on the physical cavity length and optical pump power. Synchronization of a 750 MHz

Compact Solid-State Waveguide Lasers

September 1, 2003
Author(s)
Berton Callicoatt, John B. Schlager, Robert K. Hickernell, Richard Mirin, Norman Sanford
DBR and mode-locked Er/Yb waveguide lasers offer single-frequency and ultralow jitter performance.

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

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

Mode-Locked and Single-Frequency Er/Yb Co-Doped Waveguide Lasers

January 1, 2003
Author(s)
John B. Schlager, Berton Callicoatt, Richard Mirin, Norman Sanford
Erbium/ytterbium co-doped planar waveguide lasers are fabricated for low-jitter mode-locked operation and single-frequency operation at 1.54 υm. The passively mode-locked lasers produce picosecond pulses at fundamental repetition rates up to 1 GHz with

Passively Mode-Locked Waveguide Laser with Low Residual Jitter

September 1, 2002
Author(s)
John B. Schlager, Berton Callicoatt, Richard Mirin, Norman Sanford
Picosecond pulses at 1.53 υm with low residual jitter are generated from a passively mode-locked erbium/ytterbium co-doped planar waveguide laser in an extended cavity configuration. The round-trip frequency of the laser cavity is actively referenced to

Passive and Active Characterization of Hybrid Glass Substrates for Telecommunication Applications

January 1, 2002
Author(s)
Joseph S. Hayden, Robert D. Simpson, Samuel D. Conzone, Robert K. Hickernell, Berton Callicoatt, Alexana Roshko, Norman Sanford
Phosphate glasses have become increasingly popular for planar waveguide devices owing in part to the development of a number of different commercial compositions with a wide range of optical, physical, chemical and laser properties. In addition, the recent

Uniformity Studies of Congruent LiNbO 3 by Means of Maker Fringe Analysis

January 1, 2002
Author(s)
Norman Sanford, J A. Aust
Nonlinear optical analysis was used to map the uniformity of LiNbO 3 wafers in terms of birefringence, composition, thickness and strain. Birefringence variations are directly related to variations in the composition of the material. The typical variation