B. V. Shanabrook

United States Naval Research Laboratory

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B. R. Bennett

Virginia Tech

E. R. Glaser

United States Naval Research Laboratory

D. S. Katzer

United States Naval Research Laboratory

W. J. Moore

Schiller International University

L. J. Whitman

United States Naval Research Laboratory

D. Gammon

United States Naval Research Laboratory

M. J. Yang

Huainan Normal University

James Waterman

Stony Brook University

R. Magno

United States Naval Research Laboratory

P. M. Thibado

University of Arkansas at Fayetteville

Cooperative Institutions

United States Naval Research Laboratory

126

K Lab (United States)

Naval Research Laboratory Electronics Science and Technology Division

United States Navy

University of Maryland, College Park

University of California, Santa Barbara

University at Buffalo, State University of New York

Optical Sciences (United States)

Georgia Institute of Technology

University of Michigan–Ann Arbor

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Phonons in self-assembled (In,Ga,Al)Sb quantum dots

Applied Physics Letters (1996)

B. R. Bennett B. V. Shanabrook R. Magno

Quantum dots of InSb, GaSb, and AlSb were grown on GaAs substrates by molecular beam epitaxy and characterized by atomic force microscopy and Raman spectroscopy. There is a clear correlation between the observation of quantum dots by atomic force microscopy and a phonon mode at an energy a few wavenumbers below the longitudinal optic phonon energy for thick (In,Ga,Al)Sb layers. In the case of nominally AlSb quantum dots, a two-mode behavior is observed and attributed to the segregation of Ga into the AlSb during growth.

10.1063/1.116111

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Citations (57)

Raman scattering in highly disordered amorphous phosphorus

Physical review. B, Condensed matter (1983)

R. J. Pomian J. S. Lannin B. V. Shanabrook

Raman scattering measurements are presented on amorphous phosphorus ($a\ensuremath{-}\mathrm{P}$) films deposited by rf and dc sputtering under conditions that enhance structural disorder. This includes rf sputtering at increased substrate bias as well as dc sputtering employing in situ measurements on surfaces at 80 K. In addition, the influence of annealing on the Raman spectra has been studied. The experimental results indicate that substantial changes in the Raman spectra occur relative to more ordered rf sputtered $a\ensuremath{-}\mathrm{P}$ films prepared at high pressure. These changes, which are most noticeable in low-temperature dc sputtered films, are interpreted in terms of modifications of both intermediate- as well as short-range order. The results indicate that modifications of intermediate-range order are primarily manifest by changes in the Raman coupling parameters, whereas the most disordered films indicate broadening of the phonon density of states as well. The influence of changes in short-range order on the polarized Raman spectra is related to dynamical correlation effects.

10.1103/physrevb.27.4887

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Accurate determination of effective quantum well thickness: Infrared absorption by transverse-optical phonons

Applied Physics Letters (1992)

M. J. Yang R. J. Wagner B. V. Shanabrook W. J. Moore James Waterman

We have studied far infrared transmission spectra of various AlSb/InAs/AlSb single quantum wells, where the well width ranges from 60 to 200 Å. Because the quantum well is thin, the far infrared absorption due to transverse-optical phonons is not saturated. We obtained excellent fitting to the transmission spectra by taking into account the complex dielectric functions with a transfer matrix formalism. The thickness of InAs quantum wells can be determined with monolayer resolution. High-resolution transmission electron microscopy shows clear lattice images in a region away from the AlSb/InAs interfaces. The thickness of the pure nonintermixed InAs region is in excellent agreement with our far infrared absorption results. Phonon absorption can therefore provide a nondestructive method to effectively determine the number of pure InAs monolayers, in spite of interdiffusion occurring at the interface.

10.1063/1.107844

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Citations (11)

Conditions and Limitations of Using Low-Temperature Photoluminescence to Determine Residual Nitrogen Levels in Semi-Insulating SiC Substrates

Materials science forum (2006)

E. R. Glaser B. V. Shanabrook W. E. Carlos Hun Jae Chung Saurav Nigam

We have employed low-temperature photoluminescence to estimate the total residual N concentration in semi-insulating (SI) SiC substrates where all N shallow donors are compensated in the dark. The ratio of the nitrogen-bound exciton line (Qo) to the free excitonic emission (I77) as a function of excitation power density (Pexc) was tracked for several SI 4H-SiC samples with varying residual N concentration (~ 7x1014 – 5.2x1016 cm-3). Most notably, a linear relationship was found between Qo/I77 and [N] for [N] < 1x1016 cm-3 while a sub-linear behavior was observed for samples with higher N levels. This technique should be particularly valuable to map [N] where the levels are close to or below the present SIMS detection limit of ~ 5-7 x 1014 cm-3. Results obtained for a limited number of low n-type and SI 6H-SiC substrates are also presented.

Liquid nitrogen

10.4028/www.scientific.net/msf.527-529.613

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Raman scattering study of the intermixing of AlAs monolayers in GaAs grown by molecular-beam epitaxy

Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures Processing Measurement and Phenomena (1994)

D. S. Katzer B. V. Shanabrook D. Gammon

In this article we present results from a Raman scattering study of AlAs monolayers in GaAs grown by molecular beam epitaxy. A recent model for the LO phonons in AlxGa1−xAs developed by Molinari et al. [Appl. Surf. Sci. 56–58, 617 (1992); Phys. Rev. B 45, 4280 (1992)] gives excellent qualitative agreement with our measurements. We show that intermixing between AlAs and GaAs is reduced through the use of low substrate temperatures and migration-enhanced epitaxy. We show the utility of the LO phonon model for obtaining quantitative information about the Al concentration in a monolayer. We also discuss the utility of using Raman scattering to help determine the optimum growth conditions to minimize intermixing of GaAs/AlAs interfaces and for mapping Al flux variations across a sample.

10.1116/1.587086

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Optical Spectroscopy of Single GaAs Quantum Dots

D. Gammon Steven W. Brown T. A. Kennedy E. S. Snow B. V. Shanabrook

We discuss a number of experiments involving optical spectroscopy of excitons localized by interface fluctuations in narrow GaAs quantum wells. Monolayer-high steps at the interface lead to lateral confinement that in some cases can be described by a quantum dot (Qdot) potential. We focus on Qdots that are 3 - 5 nm thick, as determined by the quantum well thickness, and an order of magnitude larger in the lateral dimensions, as determined by the sizes of the monolayer-high islands at the interfaces [1].

10.1364/cps.1997.csuc.1

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Controlled n-type doping of antimonide/arsenide heterostructures using GaTe

International Conference on Molecular Bean Epitaxy (2003)

B. R. Bennett R. Magno K. Ikossi N. A. Papanicolaou J. B. Boos

The authors used stoichiometric GaTe in Riber 32P and 21T systems. After outgassing at 425/spl deg/C, they obtained higher-than-expected carrier concentrations: 10/sup 18//cm/sup 3/ at T/sub GaTe/=350/spl deg/C. Following additional outgassing at 500/spl deg/C, the carrier densities were at lower levels and reproducible. This is consistent with the evaporation of elemental Te or Ga/sub 2/Te/sub 3/ during the initial growth and outgassing. Similar densities were observed for GaAs, AlSb, and GaSb. The growth temperatures for the GaAs layers were 550-600/spl deg/C, compared to 500/spl deg/C and 450/spl deg/C for AlSb and GaSb, respectively. Undoped GaAs layers grown after the use of GaTe exhibited a p-type background of 10/sup 14//cm/sup 3/, indicating negligible Te contamination due to a memory effect.

Antimonide

Outgassing

Stoichiometry

10.1109/mbe.2002.1037820

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Citations (1)

Excitons in Semiconductor Doping Superlattices

Springer eBooks (1985)

F. J. Crowne T. L. Reinecke B. V. Shanabrook

10.1007/978-1-4615-7682-2_79

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