16,139 research outputs found
Intentionally Carbon-Doped AlGaN/GaN HEMTs:Necessity for Vertical Leakage Paths
No full textDynamic ON-resistance (RON) in heavily carbon doped AlGaN/GaN high electron mobility transistors is shown to be associated with the semi-insulating carbon-doped buffer region. Using transient substrate bias, differences in RON dispersion between transistors fabricated on nominally identical epilayer structures were found to be due to the band-to-band leakage resistance between the buffer and the 2DEG. Contrary to normal expectations, suppression of dynamic RON dispersion in these devices requires a high density of active defects to increase reverse leakage current through the depletion region allowing the floating weakly p-type buffer to remain in equilibrium with the 2DEG
InGaN/GaN quantum wells grown on polar and nonpolar GaN substrates
No full textNonpolar (m-plane or a-plane) gallium nitride (GaN) is predicted to be a potential substrate material to improve luminous efficiencies of nitride-based quantum wells (QWs). Numerical calculations indicated that the spontaneous emission rate in a single In0.15Ga0.85N/GaN QW could be improved by ~2.2 times if the polarization-induced internal field was avoided by epitaxial deposition on nonpolar substrates.
A challenge for nonpolar GaN is the limited size (less than 10×10 mm2) of substrates, which was addressed by expansion during the regrowth by Hydride Vapor Phase Epitaxy (HVPE). Subsurface damage in GaN substrates were reduced by annealing with NH3 and N2 at 950 ºC for 60 minutes. It was additionally found that the variation of m-plane QWs’ emission properties was significantly increased when the substrate miscut toward a-axis was increased from 0º to 0.1º.
InGaN/GaN QWs were grown by Metalorganic Chemical Vapor Deposition (MOCVD) on c-plane and m-plane GaN substrates. The QWs were studied by cathodoluminescence spectroscopy with different incident electron beam probe currents (0.1 nA ~ 1000 nA). Lower emission intensities and longer peak wavelengths from c-plane QWs were attributed to the Quantum-confined Stark Effect (QCSE). The emission intensity ratios of m-plane QWs to c-plane QWs decreased from 3.04 at 1 nA to 1.53 at 1000 nA. This was identified as the stronger screening effects of QCSE at higher current densities in c-plane QWs.
To further investigate these effects in a fabricated structure, biased photoluminescence measurements were performed on m-plane InGaN/GaN QWs. The purpose was to detect the possible internal fields induced by the dot-like structure in the InGaN layer through the response of these internal fields under externally applied fields. No energy shifts of the QWs were observed, which was attributed to strong surface leakage currents
Duo dian xie zuo: gan rao jian qing yu gan rao li yong
No full textShen, Siduo.Thesis Ph.D. Chinese University of Hong Kong 2014.Includes bibliographical references (leaves 147-161).Abstracts also in Chinese.Title from PDF title page (viewed on 15 September, 2016).Shen, Siduo = Duo dian xie zuo : gan rao jian qing yu gan rao li yong / Shen, Siduo
Behavioral modeling of GaN-based power amplifiers: impact of electrothermal feedback on the model accuracy and identification
No full textIn this article, we discuss the accuracy of behavioral models in simulating the intermodulation distortion (IMD) of microwave GaN-based high-power amplifiers in the presence of strong electrothermal (ET) feedback. Exploiting an accurate self-consistent ET model derived from measurements and thermal finite-element method simulations, we show that behavioral models are able to yield accurate results, provided that the model identification is carried out with signals with wide bandwidth and large dynamics
Remote temperature mapping of high-power InGaN/GaN MQW flip-chip design LEDs
No full textWe report on the study of heat 2D-distribution in InGaN LEDs with the stress made on local device overheating and
temperature gradients inside the structure. The MQW InGaN/GaN/sapphire blue LEDs are designed as bottom emitting
devices where light escapes the structure through the transparent GaN current spreading layer and sapphire substrate, whereas the LED structure with high-reflectivity Ni/Ag p-contact is bonded to the thermally conductive Si submount by a flip-chip method. The measurements are performed with an IR microscope operating in a time-resolved mode (3-5 μm spectral range, <20 μm spatial and 10 μs temporal resolution), while scanning a heat emission map through a transparent sapphire substrate. We show how current crowding (which is difficult to avoid) causes a local hot region near the n-contact pads and affects the performance of the device at a high injection level
Sulfolobus solfataricus
No full textSTIV - infected Sulfolobus solfataricus, Sulfolobus turreted icosahedral virus, Taxonomy ID 269145, Sulfolobus solfataricus, thermophile, pyramid, intrapyramidal body, virus infection<strong>Tilt Series Date:</strong> 2010-01-04</p>
<strong>Data Taken By:</strong> Lu Gan</p>
<strong>Species / Specimen:</strong> Sulfolobus solfataricus</p>
<strong>Strain:</strong> 2-1-12</p>
<strong>Tilt Series Settings:</strong> Single Axis, tilt range: (-60.0°, 60.0°), step: 1°, constant angular increment, dosage: 180.0 eV/Ų, defocus: None μm, magnification: 18000x. </p>
<strong>Acquisition Software:</strong> Leginon</p>
<strong>Upload Method:</strong> pipeline</p>
<strong>Processing Software Used:</strong> Raptor</p>
<strong>Collaborators and Roles:</strong> Prepared sample: Chi-yu FuDesigned experiments: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. JohnsonCollected data: Chi-yu Fu, Lu GanAnalyzed data: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. Johnson</p>
<strong>Purification / Growth Conditions / Treatment:</strong> S. solfataricus strain 2-2-12 cultures were infected with STIV as previously described (Ortmann et al., 2006). Sulfolobus were grown up from glycerol stock in media 182 (pH 3.5), 80°C and passage once. The cultures were passed second time to media 182 (pH 2.5) and infected with STIV at MOI ~22 at OD 650 nm ~0.4. At 22–32 hr postinfection, cells were concentrated ~20 fold by centrifugation.</p>
<strong>Sample Preparation:</strong> Equal volume of cells were mixed with BSA-treated 10 nm gold colloidal beads and applied to plasma cleaned Quantifoil holey carbon films. The grids were plunge-frozen in liquid ethane using a Vitrobot (FEI Inc.) and stored in liquid nitrogen.</p>Files available via S3 at https://renc.osn.xsede.org/ini210004tommorrell/tomography_archive/lga2010-01-04-8</p>8.mrc, Tilt Series (Pixel Size 1.26 nm), 1.0 GB
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8_part122_4.rec, Reconstruction (Pixel Size 2.52 nm), 629.1 MB
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Sulfolobus solfataricus
No full textSTIV - infected Sulfolobus solfataricus, Sulfolobus turreted icosahedral virus, Taxonomy ID 269145, Sulfolobus solfataricus, thermophile, pyramid, intrapyramidal body, virus infection<strong>Tilt Series Date:</strong> 2010-01-04</p>
<strong>Data Taken By:</strong> Lu Gan</p>
<strong>Species / Specimen:</strong> Sulfolobus solfataricus</p>
<strong>Strain:</strong> 2-1-12</p>
<strong>Tilt Series Settings:</strong> Single Axis, tilt range: (-60.0°, 60.0°), step: 1°, constant angular increment, dosage: 180.0 eV/Ų, defocus: None μm, magnification: 18000x. </p>
<strong>Acquisition Software:</strong> Leginon</p>
<strong>Upload Method:</strong> pipeline</p>
<strong>Processing Software Used:</strong> Raptor</p>
<strong>Collaborators and Roles:</strong> Prepared sample: Chi-yu FuDesigned experiments: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. JohnsonCollected data: Chi-yu Fu, Lu GanAnalyzed data: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. Johnson</p>
<strong>Purification / Growth Conditions / Treatment:</strong> S. solfataricus strain 2-2-12 cultures were infected with STIV as previously described (Ortmann et al., 2006). Sulfolobus were grown up from glycerol stock in media 182 (pH 3.5), 80°C and passage once. The cultures were passed second time to media 182 (pH 2.5) and infected with STIV at MOI ~22 at OD 650 nm ~0.4. At 22–32 hr postinfection, cells were concentrated ~20 fold by centrifugation.</p>
<strong>Sample Preparation:</strong> Equal volume of cells were mixed with BSA-treated 10 nm gold colloidal beads and applied to plasma cleaned Quantifoil holey carbon films. The grids were plunge-frozen in liquid ethane using a Vitrobot (FEI Inc.) and stored in liquid nitrogen.</p>Files available via S3 at https://renc.osn.xsede.org/ini210004tommorrell/tomography_archive/lga2010-01-04-38</p>39.mrc, Tilt Series (Pixel Size 1.26 nm), 1.0 GB
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39_part122_8.rec, Reconstruction (Pixel Size 2.52 nm), 629.1 MB
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Sulfolobus solfataricus
No full textSTIV - infected Sulfolobus solfataricus, Sulfolobus turreted icosahedral virus, Taxonomy ID 269145, Sulfolobus solfataricus, thermophile, pyramid, intrapyramidal body, virus infection<strong>Tilt Series Date:</strong> 2010-01-04</p>
<strong>Data Taken By:</strong> Lu Gan</p>
<strong>Species / Specimen:</strong> Sulfolobus solfataricus</p>
<strong>Strain:</strong> 2-1-12</p>
<strong>Tilt Series Settings:</strong> Single Axis, tilt range: (-60.0°, 60.0°), step: 1°, constant angular increment, dosage: 180.0 eV/Ų, defocus: None μm, magnification: 18000x. </p>
<strong>Acquisition Software:</strong> Leginon</p>
<strong>Upload Method:</strong> pipeline</p>
<strong>Processing Software Used:</strong> Raptor</p>
<strong>Collaborators and Roles:</strong> Prepared sample: Chi-yu FuDesigned experiments: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. JohnsonCollected data: Chi-yu Fu, Lu GanAnalyzed data: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. Johnson</p>
<strong>Purification / Growth Conditions / Treatment:</strong> S. solfataricus strain 2-2-12 cultures were infected with STIV as previously described (Ortmann et al., 2006). Sulfolobus were grown up from glycerol stock in media 182 (pH 3.5), 80°C and passage once. The cultures were passed second time to media 182 (pH 2.5) and infected with STIV at MOI ~22 at OD 650 nm ~0.4. At 22–32 hr postinfection, cells were concentrated ~20 fold by centrifugation.</p>
<strong>Sample Preparation:</strong> Equal volume of cells were mixed with BSA-treated 10 nm gold colloidal beads and applied to plasma cleaned Quantifoil holey carbon films. The grids were plunge-frozen in liquid ethane using a Vitrobot (FEI Inc.) and stored in liquid nitrogen.</p>Files available via S3 at https://renc.osn.xsede.org/ini210004tommorrell/tomography_archive/lga2010-01-04-36</p>37.mrc, Tilt Series (Pixel Size 1.26 nm), 1.0 GB
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37_part122_9.rec, Reconstruction (Pixel Size 2.52 nm), 629.1 MB
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Sulfolobus solfataricus
No full textSTIV - infected Sulfolobus solfataricus, Sulfolobus turreted icosahedral virus, Taxonomy ID 269145, Sulfolobus solfataricus, thermophile, pyramid, intrapyramidal body, virus infection<strong>Tilt Series Date:</strong> 2010-01-04</p>
<strong>Data Taken By:</strong> Lu Gan</p>
<strong>Species / Specimen:</strong> Sulfolobus solfataricus</p>
<strong>Strain:</strong> 2-1-12</p>
<strong>Tilt Series Settings:</strong> Single Axis, tilt range: (-60.0°, 60.0°), step: 1°, constant angular increment, dosage: 180.0 eV/Ų, defocus: None μm, magnification: 18000x. </p>
<strong>Acquisition Software:</strong> Leginon</p>
<strong>Upload Method:</strong> pipeline</p>
<strong>Processing Software Used:</strong> Raptor</p>
<strong>Collaborators and Roles:</strong> Prepared sample: Chi-yu FuDesigned experiments: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. JohnsonCollected data: Chi-yu Fu, Lu GanAnalyzed data: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. Johnson</p>
<strong>Purification / Growth Conditions / Treatment:</strong> S. solfataricus strain 2-2-12 cultures were infected with STIV as previously described (Ortmann et al., 2006). Sulfolobus were grown up from glycerol stock in media 182 (pH 3.5), 80°C and passage once. The cultures were passed second time to media 182 (pH 2.5) and infected with STIV at MOI ~22 at OD 650 nm ~0.4. At 22–32 hr postinfection, cells were concentrated ~20 fold by centrifugation.</p>
<strong>Sample Preparation:</strong> Equal volume of cells were mixed with BSA-treated 10 nm gold colloidal beads and applied to plasma cleaned Quantifoil holey carbon films. The grids were plunge-frozen in liquid ethane using a Vitrobot (FEI Inc.) and stored in liquid nitrogen.</p>Files available via S3 at https://renc.osn.xsede.org/ini210004tommorrell/tomography_archive/lga2010-01-04-56</p>55.mrc, Tilt Series (Pixel Size 1.26 nm), 1.0 GB
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55_full.rec, Reconstruction (Pixel Size 2.52 nm), 629.1 MB
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Sulfolobus solfataricus
No full textSTIV - infected Sulfolobus solfataricus, Sulfolobus turreted icosahedral virus, Taxonomy ID 269145, Sulfolobus solfataricus, thermophile, pyramid, intrapyramidal body, virus infection<strong>Tilt Series Date:</strong> 2010-01-04</p>
<strong>Data Taken By:</strong> Lu Gan</p>
<strong>Species / Specimen:</strong> Sulfolobus solfataricus</p>
<strong>Strain:</strong> 2-1-12</p>
<strong>Tilt Series Settings:</strong> Single Axis, tilt range: (-60.0°, 60.0°), step: 1°, constant angular increment, dosage: 180.0 eV/Ų, defocus: None μm, magnification: 18000x. </p>
<strong>Acquisition Software:</strong> Leginon</p>
<strong>Upload Method:</strong> pipeline</p>
<strong>Processing Software Used:</strong> Raptor</p>
<strong>Collaborators and Roles:</strong> Prepared sample: Chi-yu FuDesigned experiments: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. JohnsonCollected data: Chi-yu Fu, Lu GanAnalyzed data: Chi-yu Fu, Kang Wang, Lu Gan, Jason Lanman, Reza Khayat, Mark J. Young, Grant J. Jensen, Peter C. Doerschuk, John E. Johnson</p>
<strong>Purification / Growth Conditions / Treatment:</strong> S. solfataricus strain 2-2-12 cultures were infected with STIV as previously described (Ortmann et al., 2006). Sulfolobus were grown up from glycerol stock in media 182 (pH 3.5), 80°C and passage once. The cultures were passed second time to media 182 (pH 2.5) and infected with STIV at MOI ~22 at OD 650 nm ~0.4. At 22–32 hr postinfection, cells were concentrated ~20 fold by centrifugation.</p>
<strong>Sample Preparation:</strong> Equal volume of cells were mixed with BSA-treated 10 nm gold colloidal beads and applied to plasma cleaned Quantifoil holey carbon films. The grids were plunge-frozen in liquid ethane using a Vitrobot (FEI Inc.) and stored in liquid nitrogen.</p>Files available via S3 at https://renc.osn.xsede.org/ini210004tommorrell/tomography_archive/lga2010-01-04-67</p>66.mrc, Tilt Series (Pixel Size 1.26 nm), 1.0 GB
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66_full.rec, Reconstruction (Pixel Size 2.52 nm), 629.1 MB
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