Dr. Alison A. Baski Profile

Dr. Alison A. Baski

Associate Professor/Physics at Virginia Commonwealth Univ

SPIE Involvement:

Author

Proceedings Article | 28 February 2012 Paper

Temperature dependent behavior of the SPV for n-type GaN

J. McNamara, M. Foussekis, H. Liu, H. Morkoç, M. Reshchikov, A. Baski

Proceedings Volume 8262, 826213 (2012) https://doi.org/10.1117/12.910289

KEYWORDS: Gallium nitride, Temperature metrology, Oxygen, Electrons, Ultraviolet radiation, Adsorption, Statistical modeling, Data modeling, Interfaces, Vapor phase epitaxy

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Proceedings Article | 4 March 2011 Paper

Kelvin probe measurements of p-type GaN

M. Foussekis, X. Ni, H. Morkoç, M. Reshchikov, A. Baski

Proceedings Volume 7939, 79390A (2011) https://doi.org/10.1117/12.876166

KEYWORDS: Gallium nitride, Metalorganic chemical vapor deposition, Photons, Oxygen, Ultraviolet radiation, Statistical analysis, Adsorption, Vapor phase epitaxy, Chemical vapor deposition, Interfaces

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Proceedings Article | 20 March 2010 Paper

Effect of UV exposure on the surface charge behavior for GaN

M. Foussekis, J. Ferguson, X. Ni, H. Morkoç, M. Reshchikov, A. Baski

Proceedings Volume 7602, 76020Y (2010) https://doi.org/10.1117/12.843864

KEYWORDS: Ultraviolet radiation, Oxides, Gallium nitride, Oxygen, Atomic force microscopy, Gallium, Photoemission spectroscopy, Scanning probe microscopy, Microscopy, Data acquisition

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Proceedings Article | 17 March 2010 Paper

Non-polar m-plane GaN on patterned Si(112) substrates by metalorganic chemical vapor deposition

X. Ni, M. Wu, J. Lee, X. Li, A. Baski, Ü. Özgür, H. Morkoç

Proceedings Volume 7602, 760220 (2010) https://doi.org/10.1117/12.845652

KEYWORDS: Gallium nitride, Silicon, Metalorganic chemical vapor deposition, Indium gallium nitride, Silica, Light emitting diodes, Internal quantum efficiency, Scanning electron microscopy, Etching, Atomic force microscopy

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Proceedings Article | 12 March 2010 Paper

Internal quantum efficiency of m-plane InGaN on Si and GaN

J. Lee, X. Ni, M. Wu, X. Li, R. Shimada, Ü. Özgür, A. Baski, H. Morkoç, T. Paskova, G. Mulholland, K. Evans

Proceedings Volume 7602, 76021N (2010) https://doi.org/10.1117/12.843727

KEYWORDS: Light emitting diodes, Indium gallium nitride, Silicon, Gallium nitride, Sapphire, Polarization, Internal quantum efficiency, Quantum wells, Optical matrix switches, Optical components

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Proceedings Article | 16 February 2009 Paper

Effect of ambient on electrical and optical properties of GaN

M. Reshchikov, M. Foussekis, A. Baski, H. Morkoç

Proceedings Volume 7216, 721614 (2009) https://doi.org/10.1117/12.812258

KEYWORDS: Gallium nitride, Ultraviolet radiation, Electrons, Luminescence, Oxygen, Sapphire, Optical properties, Switching, Adsorption, Scanning probe microscopy

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Proceedings Article | 15 February 2008 Paper

Investigation of charge trapping at the oxide/semiconductor interface for MBE-grown GaN films

J. Moore, M. Reshchikov, J. Ortiz, J. Xie, H. Morkoç, A. Baski

Proceedings Volume 6894, 68940B (2008) https://doi.org/10.1117/12.768041

KEYWORDS: Gallium nitride, Electrons, Interfaces, Ultraviolet radiation, Oxides, Metalorganic chemical vapor deposition, Atomic force microscopy, Microscopy, Semiconductors, Gallium

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Proceedings Article | 20 February 2007 Paper

Carrier relaxation and stimulated emission in ZnO nanorods grown by catalyst-assisted vapor transport on various substrates

V. Avrutin, Ü. Özgür, N. Izyumskaya, S. Chevtchenko, J. Leach, J. Moore, A. Baski, C. Litton, H. Everitt, K. Tsen, M. Abouzaid, P. Ruterana, H. Morkoç

Proceedings Volume 6474, 64741M (2007) https://doi.org/10.1117/12.708835

KEYWORDS: Zinc oxide, Silicon, Near field scanning optical microscopy, Atomic force microscopy, Luminescence, Transmission electron microscopy, Gallium nitride, Raman spectroscopy, Nanostructures, Nanorods

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Proceedings Article | 8 February 2007 Paper

AFM and CAFM studies of ELO GaN films

V. Kasliwal, J. Moore, X. Ni, H. Morkoç, A. Baski

Proceedings Volume 6473, 647308 (2007) https://doi.org/10.1117/12.706773

KEYWORDS: Epitaxial lateral overgrowth, Gallium nitride, Atomic force microscopy, Metalorganic chemical vapor deposition, Data acquisition, Gallium, Near field scanning optical microscopy, Oxides, Silicon, Oxidation

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Proceedings Article | 7 February 2007 Paper

Two-step epitaxial lateral overgrowth of a-plane GaN by MOCVD

X. Ni, Ü. Özgür, H. Morkoç, A. Baski, Z. Liliental-Weber, H. Everitt

Proceedings Volume 6473, 647303 (2007) https://doi.org/10.1117/12.706826

KEYWORDS: Gallium nitride, Epitaxial lateral overgrowth, Metalorganic chemical vapor deposition, Transmission electron microscopy, Luminescence, Atomic force microscopy, Near field scanning optical microscopy, Picosecond phenomena, Scanning electron microscopy, Excitons

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We report on growth and characterization of epitaxial lateral overgrown (ELO) (11₂^-0) a-plane GaN by metalorganic chemical vapor deposition (MOCVD). The ELO samples were grown using a SiO₂ striped mask pattern consisting of 4 &mgr;m wide open windows and 10 &mgr;m or 20 &mgr;m wide SiO₂ stripes. Different growth rates in Ga- and N-wings along with the wing tilt create a major obstacle for achieving a fully coalesced flat surface in ELO-GaN. To address this problem we have employed a two-step growth method that is able to provide a high height to width aspect ratio in the first growth step followed by enhanced lateral growth in the second step by controlling the growth temperature. Depending on the growth conditions, lateral growth rate of the wings with Ga-polarity were from 2 to 5 times larger than that of the N-polarity wings. We investigated the effects of growth parameters on wing tilt, which was observed to be ~0.25° from the Kikuchi lines using large angle convergent beam electron diffraction (LACBED) and accompanied by some twist (0.09°) between the two opposite wings. Transmission electron microscopy (TEM) results showed that the threading dislocation density in the resulting fully coalesced overgrown GaN was reduced from 4.2×10¹⁰ cm^-2 in the window area to 1.0×10⁸ cm^-2 in the wing area, and that the wing areas contained relatively high density of basal stacking faults, 1.2×10⁴ cm^-1. The recombination of carriers/excitons localized at stacking faults was evident in far-field near bandedge photoluminescence (PL) measured at 10 K. Moreover, atomic force microscopy (AFM) measurements revealed two orders of magnitude higher density of surface pits in window than in wing regions, which could be decorating dislocation termination on surface. Time-resolved PL measurements for the a-plane ELO-GaN samples revealed biexponential decays. The recombination times were significantly increased ( &tgr;₁ =80 ps and &tgr;₂ =250 ps) compared to the standard a-plane epitaxial layers (<45 ps), and ratio of the slow decaying component magnitude to the fast decaying one was more than 1.5, showing considerable reduction of nonradiative centers by lateral overgrowth. In addition, room temperature near-field optical microscopy studies revealed the improved optical quality in the wing regions of the overgrown GaN. As revealed from far-field PL, the band edge luminescence at room temperature was more than two orders of magnitude weaker than the yellow luminescence. Therefore, the overall spectrally integrated near field PL was collected, and its intensity was noticeably stronger in the wing areas with both Ga and N polarity. The much weaker emission at the windows and meeting fronts of the two opposite wings were consistent with the observations of high density of dislocations in the window regions and new defects originating at the meeting boundaries from TEM.

Proceedings Article | 3 March 2006 Paper

Conductive atomic force microscopy study of MBE GaN films

J. C. Moore, K. Cooper, J. Xie, H. Morko, A. Baski

Proceedings Volume 6121, 61210J (2006) https://doi.org/10.1117/12.658045

KEYWORDS: Atomic force microscopy, Gallium nitride, Metalorganic chemical vapor deposition, Data acquisition, Gallium, Data modeling, Molecular beam epitaxy, Nitrogen, Amplifiers, Physics

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Showing 5 of 11 publications

Conference Committee Involvement (5)

Gallium Nitride Materials and Devices VI

24 January 2011 | San Francisco, California, United States

Gallium Nitride Materials and Devices V

25 January 2010 | San Francisco, California, United States

Gallium Nitride Materials and Devices IV

26 January 2009 | San Jose, California, United States

Gallium Nitride Materials and Devices III

21 January 2008 | San Jose, California, United States

Gallium Nitride Materials and Devices II

22 January 2007 | San Jose, California, United States

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