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- Keyword
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- DOPED GAN; VACANCIES; FILMS (1)
- ELECTRON (1)
- ETCHED GALLIUM NITRIDE; YELLOW LUMINESCENCE; POROUS SILICON; DEFECTS (1)
- GALLIUM; NITRIDE (1)
- ION-SCATTERING SPECTROSCOPY; FACE ALGAN/GAN HETEROSTRUCTURES; 2-DIMENSIONAL ELECTRON GASES; VAPOR-PHASE-EPITAXY; WURTZITE GAN; LATTICE POLARITY; SINGLE-CRYSTALS; GAN(0001) FILM; SAPPHIRE; POLARIZATION (1)
Articles 1 - 9 of 9
Full-Text Articles in Engineering
Giant Photoresistivity And Optically Controlled Switching In Self-Assembled Nanowires, N. Kouklin, L. Menon, A. Z. Wong, D. W. Thompson, J. A. Woollam, P. F. Williams, Supriyo Bandyopadhyay
Giant Photoresistivity And Optically Controlled Switching In Self-Assembled Nanowires, N. Kouklin, L. Menon, A. Z. Wong, D. W. Thompson, J. A. Woollam, P. F. Williams, Supriyo Bandyopadhyay
Electrical and Computer Engineering Publications
We report the observation of giant photoresistivity in electrochemically self-assembledCdS and ZnSenanowireselectrodeposited in a porous alumina film. The resistance of these nanowires increases by one to two orders of magnitude when exposed to infrared radiation, possibly because of real-space transfer of electrons from the nanowires into the surrounding alumina by photon absorption. This phenomenon has potential applications in “normally on” infrared photodetectors and optically controlled switches.
Systematic Measurement Of Alxga1−Xn Refractive Indices, Ü. Özgür, Grady Webb-Wood, Henry O. Everitt, Feng Yun, Hadis Morkoç
Systematic Measurement Of Alxga1−Xn Refractive Indices, Ü. Özgür, Grady Webb-Wood, Henry O. Everitt, Feng Yun, Hadis Morkoç
Electrical and Computer Engineering Publications
Dispersion of the ordinary and extraordinary indices of refraction have been measured systematically for wurtzitic AlxGa1−xNepitaxial layers with 0.0⩽x⩽1.0 throughout the visible wavelength region. The dispersion, measured by a prism coupling waveguide technique, is found to be well described by a Sellmeier relation. Discrepancies among previous measurements of refractive indexdispersion, as a consequence of different growth conditions and corresponding band gap bowing parameter, are reconciled when the Sellmeier relation is parameterized not by x but by band gapenergy.
Photoluminescence Of Gan Grown By Molecular-Beam Epitaxy On A Freestanding Gan Template, Michael A. Reshchikov, D. Huang, F. Yun, L. He, Hadis Morkoç, D. C. Reynolds, S. S. Park, K. Y. Lee
Photoluminescence Of Gan Grown By Molecular-Beam Epitaxy On A Freestanding Gan Template, Michael A. Reshchikov, D. Huang, F. Yun, L. He, Hadis Morkoç, D. C. Reynolds, S. S. Park, K. Y. Lee
Electrical and Computer Engineering Publications
Photoluminescence(PL) studies were performed on a 1.5-μm-thick GaN layer grown by molecular-beam epitaxy on a freestanding GaN template that in turn was grown by hydride vapor-phase epitaxy.PL spectra from both the epilayer and the substrate contain a plethora of sharp peaks related to excitonic transitions. We identified the main peaks in the PL spectrum. Taking advantage of the observation of donor bound exciton peaks and their associated two-electron satellites, we have determined the binding energies of two distinct shallow donors (28.8 and 32.6 meV), which are attributed to Si and O, respectively.
Dependence Of Gan Polarity On The Parameters Of The Buffer Layer Grown By Molecular Beam Epitaxy, D. Huang, P. Visconti, K. M. Jones, Michael A. Reshchikov, F. Yun, A. A. Baski, T. King, Hadis Morkoç
Dependence Of Gan Polarity On The Parameters Of The Buffer Layer Grown By Molecular Beam Epitaxy, D. Huang, P. Visconti, K. M. Jones, Michael A. Reshchikov, F. Yun, A. A. Baski, T. King, Hadis Morkoç
Electrical and Computer Engineering Publications
The polarity of GaNfilmsgrown using GaN and AlNbuffer layers on sapphire substrates by molecular beam epitaxy were investigated by atomic force microscopy, hot wet chemical etching, and reflection high-energy electron diffraction. We found that the GaNfilmsgrown on high temperature AlN (>890 °C) and GaN (770–900 °C) buffer layers invariably show Ga and N polarity, respectively. However, the filmsgrown using low temperature (∼500 °C) buffer layers, either GaN or AlN, could have either Ga or N polarity, depending on the growth rate of the buffer layer.
Yellow And Green Luminescence In A Freestanding Gan Template, Michael A. Reshchikov, Hadis Morkoç, S. S. Park, K. Y. Lee
Yellow And Green Luminescence In A Freestanding Gan Template, Michael A. Reshchikov, Hadis Morkoç, S. S. Park, K. Y. Lee
Electrical and Computer Engineering Publications
We have studied a broad photoluminescence band in high-mobility freestanding 200-μm-thick GaN template prepared by hydride vapor-phase epitaxy. Variable-excitation intensity and energy experiments showed two defect-related bands: a yellow luminescence (YL) band at about 2.15 eV and a green luminescence (GL) band at about 2.43 eV. In contrast to epitaxial GaN samples prepared by both vapor-phase and molecular-beam epitaxy, the YL in the sample studied is weak and can be easily saturated. However, the GL is dominant. We attribute the GL to isolated defects involving galliumvacancies and the YL to the same defect, but bound to dislocations, or possibly to …
Transient Photoluminescence Of Defect Transitions In Freestanding Gan, Michael A. Reshchikov, Hadis Morkoç, S. S. Park, K. Y. Lee
Transient Photoluminescence Of Defect Transitions In Freestanding Gan, Michael A. Reshchikov, Hadis Morkoç, S. S. Park, K. Y. Lee
Electrical and Computer Engineering Publications
Deep level defects responsible for the 2.4 eV photoluminescence (PL) band in a freestanding GaN template were studied by transient photoluminescence. A nonexponential decay of PL intensity observed at low temperature is attributed to a donor–acceptor pair recombination involving a shallow donor and a deep acceptor. At room temperature, a single-exponential PL decay with a lifetime of 30 μs was observed at the high-energy side of the band, whereas the second component with a lifetime of about 750 μs was detected at the low-energy side of the band. The PL decay and transformation of the PL spectrum at room temperature …
Characterization Of Free-Standing Hydride Vapor Phase Epitaxy Gan, J. Jasinski, W. Sider, Z. Lilental-Weber, P. Visconti, K. M. Jones, Michael A. Reshchikov, F. Yun, Hadis Morkoç, S. S. Park, K. Y. Lee
Characterization Of Free-Standing Hydride Vapor Phase Epitaxy Gan, J. Jasinski, W. Sider, Z. Lilental-Weber, P. Visconti, K. M. Jones, Michael A. Reshchikov, F. Yun, Hadis Morkoç, S. S. Park, K. Y. Lee
Electrical and Computer Engineering Publications
A free-standing GaN template grown by hydride vapor phase epitaxy has been characterized by transmission electron microscopy(TEM). The TEM investigation was augmented by x-ray diffraction, defect delineation etching process followed by imaging with atomic force microscopy and variable temperature photoluminescence. The density of dislocations near the N face was determined to be, in order, 3±1×107, 4±1×107, and about 1×107 cm−2 by cross-sectional TEM, plan-view TEM, and a defect revealing etch, respectively. The same methods on the Ga face revealed the defect concentration to be, in order, less than 1×107 cm−2 by plan-view TEM, less than 5×106 cm−2 by cross-sectional TEM, …
Deep Centers In A Free-Standing Gan Layer, Z.-Q. Fang, D. C. Look, P. Visconti, D.-F. Wang, C.-Z. Lu, F. Yun, Hadis Morkoç, S. S. Park, K. Y. Lee
Deep Centers In A Free-Standing Gan Layer, Z.-Q. Fang, D. C. Look, P. Visconti, D.-F. Wang, C.-Z. Lu, F. Yun, Hadis Morkoç, S. S. Park, K. Y. Lee
Electrical and Computer Engineering Publications
Schottky barrierdiodes, on both Ga and N faces of a ∼300-μm-thick free-standing GaN layer, grown by hydride vapor phase epitaxy(HVPE) on Al2O3 followed by laser separation, were studied by capacitance–voltage and deep level transient spectroscopy(DLTS) measurements. From a 1/C2 vs V analysis, the barrier heights of Ni/Au Schottky contacts were determined to be different for the two polar faces: 1.27 eV for the Ga face, and 0.75 eV for the N face. In addition to the four common DLTS traps observed previously in other epitaxial GaN including HVPE-grown GaN a new trap B′ with activation energyET=0.53 eV was found in …
Blue Photoluminescence Activated By Surface States In Gan Grown By Molecular Beam Epitaxy, Michael A. Reshchikov, P. Visconti, Hadis Morkoç
Blue Photoluminescence Activated By Surface States In Gan Grown By Molecular Beam Epitaxy, Michael A. Reshchikov, P. Visconti, Hadis Morkoç
Electrical and Computer Engineering Publications
We have studied the broad blue band, which emerges in the photoluminescence(PL)spectrum of c-plane GaN layers after etching in hot H3PO4 and subsequent exposure to air. This band exhibited a 100 meV blueshift with increasing excitation intensity and a thermal quenching with activation energies of 12 and 100 meV. These observations led us to suggest that surface states may be formed on etchedsurfaces and cause bandbending, which leads to a shift in transition energy with excitation. The blue PL is related to transitions from the shallow donors filled with nonequilibrium electrons to the surface states, which capture the photogenerated …