Dr. Xianfeng Ni Profile

Dr. Xianfeng Ni

Post-Doctural Researcher at Virginia Commonwealth Univ

SPIE Involvement:

Author

Publications (28)

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 | 4 March 2011 Paper

Effect of substrate offcut on AlGaN/GaN HFET structures on bulk GaN substrates

J. Leach, N. Biswas, T. Paskova, E. Preble, K. Evans, M. Wu, X. Ni, X. Li, Ü. Özgür, H. Morkoç

Proceedings Volume 7939, 79390E (2011) https://doi.org/10.1117/12.875755

KEYWORDS: Gallium nitride, Heterojunctions, Aluminum, Resistance, Semiconducting wafers, Sapphire, Crystals, Polishing, Epitaxy, X-ray diffraction

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Proceedings Article | 4 March 2011 Paper

Optimization of ZnO:Ga properties for application as a transparent conducting oxide in InGaN-based light-emitting diodes

H. Y. Liu, X. Li, S. Liu, X. Ni, V. Avrutin, N. Izyumskaya, Ü. Özgür, A. Yankovich, A. Kvit, P. Voyles, M. Reshchikov, H. Morkoç

Proceedings Volume 7939, 79392E (2011) https://doi.org/10.1117/12.875515

KEYWORDS: Light emitting diodes, Oxygen, Surface roughness, Gallium nitride, Indium gallium nitride, Transmission electron microscopy, Electrodes, 3D metrology, External quantum efficiency, Transparent conducting oxide

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Proceedings Article | 4 March 2011 Paper

Deep inductively coupled plasma etching of ELO-GaN grown with high fill factor

Haiyong Gao, Jaesoong Lee, Xianfeng Ni, Jacob Leach, Ümit Özgür, Hadis Morkoç

Proceedings Volume 7939, 793920 (2011) https://doi.org/10.1117/12.876870

KEYWORDS: Etching, Gallium nitride, Scanning electron microscopy, Epitaxial lateral overgrowth, Dielectrics, Plasma etching, Silica, Metalorganic chemical vapor deposition, Atomic force microscopy, Nickel

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Proceedings Article | 3 March 2011 Paper

Photoluminescence of Mg-doped m-plane GaN grown by MOCVD on bulk GaN substrates

Bo Monemar, Plamen Paskov, Galia Pozina, Carl Hemmingsson, Peder Bergman, David Lindgren, Lars Samuelson, Xianfeng Ni, Hadis Morkoç, Tanya Paskova, Zhaoxia Bi, Jonas Ohlsson

Proceedings Volume 7939, 793907 (2011) https://doi.org/10.1117/12.874687

KEYWORDS: Gallium nitride, Magnesium, Metalorganic chemical vapor deposition, Doping, Excitons, Phonons, Luminescence, Acoustics, Quantum wells, Nanowires

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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 | 18 March 2010 Paper

Efficiency retention at high current injection levels in m-plane InGaN light emitting diodes

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

Proceedings Volume 7602, 76021R (2010) https://doi.org/10.1117/12.843752

KEYWORDS: Light emitting diodes, External quantum efficiency, Gallium nitride, Electroluminescence, Quantum wells, Polarization, Indium gallium nitride, Sapphire, Internal quantum efficiency, Polarizers

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Proceedings Article | 17 March 2010 Paper

InGaN light-emitting diodes with highly transparent ZnO:Ga electrodes

H. Y. Liu, X. Li, X. Ni, V. Avrutin, N. Izyumskaya, Ü. Özgür, H. Morkoç

Proceedings Volume 7602, 76020I (2010) https://doi.org/10.1117/12.853327

KEYWORDS: Light emitting diodes, Electrodes, Annealing, Gallium nitride, External quantum efficiency, Indium gallium nitride, Electroluminescence, Electrons, Zinc oxide, Transparency

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Proceedings Article | 17 March 2010 Paper

Measurements of gate lag in high-quality nearly lattice matched InAlN/AlN/GaN HFET structures

J. Leach, M. Wu, X. Ni, X. Li, Ü. Özgür, H. Morkoç

Proceedings Volume 7602, 76020O (2010) https://doi.org/10.1117/12.843700

KEYWORDS: Gallium nitride, Field effect transistors, Polarization, Binary data, Sapphire, Heterojunctions, Aluminum nitride, Indium nitride, Interfaces, Solids

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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 | 11 March 2010 Paper

On carrier spillover in c- and m-plane InGaN light-emitting diodes

J. Lee, X. Li, X. Ni, Ü. Özgür, H. Morkoç, T. Paskova, G. Mulholland, K. Evans

Proceedings Volume 7602, 760224 (2010) https://doi.org/10.1117/12.845806

KEYWORDS: Light emitting diodes, Electron beam lithography, Gallium nitride, External quantum efficiency, Polarization, Quantum wells, Indium gallium nitride, Internal quantum efficiency, Electroluminescence, Quantum efficiency

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Proceedings Article | 19 February 2009 Paper

GaN-based vertical cavities on highly reflective and crack-free nitride distributed Bragg reflectors

X. Ni, R. Shimada, T. Kang, J. Leach, Ü. Özgür, H. Morkoç

Proceedings Volume 7216, 72162F (2009) https://doi.org/10.1117/12.807902

KEYWORDS: Reflectivity, Gallium nitride, Semiconducting wafers, Distributed Bragg reflectors, Vertical cavity surface emitting lasers, Aluminum nitride, Silica, Scanning electron microscopy, Aluminum, Photomasks

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Proceedings Article | 16 February 2009 Paper

Investigation of vertical current-voltage characteristics of Al(Ga)N/GaN RTD-like heterostructures

J. Lee, Q. Fan, X. Ni, U. Ozgur, V. Litvinov, H. Morkoç

Proceedings Volume 7216, 72160S (2009) https://doi.org/10.1117/12.809435

KEYWORDS: Gallium nitride, Aluminum nitride, Heterojunctions, Doping, Resistance, Epitaxial lateral overgrowth, Quantum wells, Metalorganic chemical vapor deposition, Reactive ion etching, Polarization

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Proceedings Article | 16 February 2009 Paper

Reduction of efficiency droop in InGaN-based blue LEDs

X. Ni, X. Li, J. Xie, Q. Fan, R. Shimada, Ü. Özgür, H. Morkoç

Proceedings Volume 7216, 72161W (2009) https://doi.org/10.1117/12.809877

KEYWORDS: External quantum efficiency, Light emitting diodes, Electroluminescence, Quantum efficiency, Indium gallium nitride, Quantum wells, Doping, Gallium, Blue light emitting diodes, Luminous efficiency

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Proceedings Article | 28 February 2008 Paper

Epitaxial lateral overgrowth of (11¯00) m-plane GaN on m-plane 6H-SiC by metalorganic chemical vapor deposition

X. Ni, Ü. Özgür, S. Chevtchenko, J. Nie, H. Morkoç, R. Devaty, W. Choyke

Proceedings Volume 6894, 689420 (2008) https://doi.org/10.1117/12.763848

KEYWORDS: Gallium nitride, Epitaxial lateral overgrowth, Silicon carbide, Metalorganic chemical vapor deposition, Scanning electron microscopy, Atomic force microscopy, Luminescence, Aluminum nitride, X-ray diffraction, Polarization

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Proceedings Article | 15 February 2008 Paper

AlGaN/SiC heterojunction bipolar transistor

Ya. Alivov, Q. Fan, X. Ni, S. Chevtchenko, I. Bhat, H. Morkoç

Proceedings Volume 6894, 68941W (2008) https://doi.org/10.1117/12.763143

KEYWORDS: Heterojunctions, Transistors, Silicon carbide, Gallium nitride, Aluminum, Metalorganic chemical vapor deposition, Diodes, Doping, Gallium, Electrical engineering

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Proceedings Article | 15 February 2008 Paper

AlxIn1-xN/GaN heterostructure field effect transistors

J. Xie, X. Ni, M. Wu, J. Leach, Ü. Özgür, H. Morkoç

Proceedings Volume 6894, 68941R (2008) https://doi.org/10.1117/12.771297

KEYWORDS: Aluminum nitride, Gallium nitride, Heterojunctions, Aluminum, Indium, Field effect transistors, Polarization, Metalorganic chemical vapor deposition, Temperature metrology, Scattering

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Proceedings Article | 15 February 2008 Paper

Comparative study of deep levels in GaN grown on different templates

J. Nie, S. Chevtchenko, J. Xie, X. Ni, H. Morkoç

Proceedings Volume 6894, 689424 (2008) https://doi.org/10.1117/12.767834

KEYWORDS: Gallium nitride, Epitaxial lateral overgrowth, Spectroscopy, Capacitance, Sapphire, Temperature metrology, Metalorganic chemical vapor deposition, Diodes, Active optics, Thermography

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Proceedings Article | 15 February 2008 Paper

Evolution of surface morphology of polar and nonpolar GaN thin films during photoelectrochemical etching

J. Leach, Ü. Özgür, X. Ni, J. Xie, H. Morkoç

Proceedings Volume 6894, 689425 (2008) https://doi.org/10.1117/12.762383

KEYWORDS: Etching, Gallium nitride, Epitaxial lateral overgrowth, Scanning electron microscopy, Thin films, Nanostructures, Transmission electron microscopy, Ions, Oxides, Active optics

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Proceedings Article | 15 February 2008 Paper

Optical properties of polar, nonpolar, and semipolar InGaN/GaN multiple quantum wells on sapphire

X. Ni, R. Shimada, J. Leach, J. Xie, Ü. Özgür, H. Morkoç

Proceedings Volume 6894, 689428 (2008) https://doi.org/10.1117/12.763260

KEYWORDS: Gallium nitride, Quantum wells, Epitaxial lateral overgrowth, Polarization, Sapphire, Optical properties, Quantum efficiency, Metalorganic chemical vapor deposition, Luminescence, Scanning electron microscopy

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The polarization fields in the c-axis-oriented hexagonal GaN system cause spatial separation of electrons and holes in quantum wells, reducing the quantum efficiency, and resulting in a red shift of the emission as well as a blue shift with increasing injected carrier density. In this paper, we report on the growth and optical characterization of InGaN/GaN multiple quantum wells (MQWs) on nonpolar (112¯0) a- and polar (0001) c-planes, as well as two semipolar planes, (112¯2) and (11¯01) of GaN. There are two kinds of a-plane used in this study. One of the (112¯0) a-planes was obtained on (11¯00) m-plane sapphire substrates during the epitaxial lateral overgrowth (ELO) of (112¯2) oriented semipolar GaN films, while the other one was planar a-plane GaN which was grown on (11¯01) r-plane sapphire substrates. The semipolar (112¯2) and (11¯01) planes were obtained as sidewall facets during the ELO of c-plane GaN with the mask stripes aligned along the GaN m-axis and a-axis, respectively. InGaN/GaN multiple quantum wells (MQWs) with a nominal well thickness of 4 nm and a barrier thickness of 8 nm were grown on these five GaN samples by metalorganic chemical vapor deposition. Excitation power dependent photoluminescence (PL) measurements were carried out on these quantum well structures to study the effect of polarization-induced electric field on the band-edge emission. The quantum-well emission energy from the two a-plane MQWs showed zero shift, compared to a 74 meV blue shift for the c-plane MQWs when the excitation power was increased from 1.3 mW to 37.0 mW. The semipolar (112¯2) showed a blue shift of 35 meV with increased excitation power, suggesting reduced polarization compared to that of c-plane. No quantum-well emission could be observed for the MQWs on (11¯01) semipolar planes. The shift in the quantum-well emission energy was attributed to the change of the screening effect of photon-generated carriers in the quantum wells at different excitation powers. For exact notation please see manuscript