The Experts below are selected from a list of 10767 Experts worldwide ranked by ideXlab platform
Sophie Guillemin - One of the best experts on this subject based on the ideXlab platform.
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identification of Extended Defect and interface related luminescence lines in polycrystalline zno thin films grown by sol gel process
RSC Advances, 2016Co-Authors: Sophie Guillemin, Vincent Consonni, Laetitia Rapenne, E Sarigiannidou, Fabrice Donatini, G BremondAbstract:The luminescence lines related to Extended Defects and interfaces in polycrystalline ZnO thin films grown by sol–gel process are deeply investigated by combining temperature-dependent photoluminescence and cathodoluminescence imaging with high-resolution transmission electron microscopy. A typical broad emission band is shown in the range of 3.316 to 3.333 eV and mainly consists of two distinct contributions. At high energy, a 3.333 eV line is associated with interfaces (i.e., free surfaces and grain boundaries) and predominates for small ZnO nanoparticles owing to their high density. The intensity ratio of the excitonic to interface-related transitions is low in this first configuration and the 3.333 eV line is characterized by an activation energy of 12.0 ± 1.2 meV and a Huang-Rhys factor of 0.54 ± 0.05 at 12 K. At low energy, a 3.316 eV line is attributed to basal plane stacking faults that are mostly of I1-type and prevail for large ZnO nanoparticles. The 3.316 eV line is characterized by an activation energy of 6.7 ± 0.8 meV and a Huang Rhys constant of 0.87 ± 0.03 at 12 K. Basal plane stacking faults are most likely formed as the coalescence process proceeds with the decomposition and crystallization processes during annealing. As shown by low-temperature monochromatic cathodoluminescence imaging, the luminescence corresponding to the 3.316 eV line is, in this second configuration, limited to some specific area (i.e., large nanoparticles), and the relative intensity ratio of the excitonic to interface-related transitions is increased due to the smaller free surface area and density of grain boundaries.
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Extended Defect related photoluminescence line at 3 33 ev in nanostructured zno thin films
Applied Physics Express, 2013Co-Authors: Sophie Guillemin, Vincent Consonni, Bruno Masenelli, G BremondAbstract:The 3.33 eV photoluminescence line is investigated in ZnO thin films deposited by dip coating. These films are oriented along the c-axis and exhibit basal-plane stacking faults and random grain boundaries. It is found that the relative intensity of the free exciton peak to the 3.33 eV line decreases as the nanoparticle size is reduced and that the corresponding Huang–Rhys factor is about 0.5. This reveals that excitons bound to Extended Defects at grain boundaries are involved. Also, post growth annealing strongly affects the photoluminescence spectra. In particular, the 3.31 eV line coming from stacking faults is enhanced at high annealing temperature.
G Bremond - One of the best experts on this subject based on the ideXlab platform.
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identification of Extended Defect and interface related luminescence lines in polycrystalline zno thin films grown by sol gel process
RSC Advances, 2016Co-Authors: Sophie Guillemin, Vincent Consonni, Laetitia Rapenne, E Sarigiannidou, Fabrice Donatini, G BremondAbstract:The luminescence lines related to Extended Defects and interfaces in polycrystalline ZnO thin films grown by sol–gel process are deeply investigated by combining temperature-dependent photoluminescence and cathodoluminescence imaging with high-resolution transmission electron microscopy. A typical broad emission band is shown in the range of 3.316 to 3.333 eV and mainly consists of two distinct contributions. At high energy, a 3.333 eV line is associated with interfaces (i.e., free surfaces and grain boundaries) and predominates for small ZnO nanoparticles owing to their high density. The intensity ratio of the excitonic to interface-related transitions is low in this first configuration and the 3.333 eV line is characterized by an activation energy of 12.0 ± 1.2 meV and a Huang-Rhys factor of 0.54 ± 0.05 at 12 K. At low energy, a 3.316 eV line is attributed to basal plane stacking faults that are mostly of I1-type and prevail for large ZnO nanoparticles. The 3.316 eV line is characterized by an activation energy of 6.7 ± 0.8 meV and a Huang Rhys constant of 0.87 ± 0.03 at 12 K. Basal plane stacking faults are most likely formed as the coalescence process proceeds with the decomposition and crystallization processes during annealing. As shown by low-temperature monochromatic cathodoluminescence imaging, the luminescence corresponding to the 3.316 eV line is, in this second configuration, limited to some specific area (i.e., large nanoparticles), and the relative intensity ratio of the excitonic to interface-related transitions is increased due to the smaller free surface area and density of grain boundaries.
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Extended Defect related photoluminescence line at 3 33 ev in nanostructured zno thin films
Applied Physics Express, 2013Co-Authors: Sophie Guillemin, Vincent Consonni, Bruno Masenelli, G BremondAbstract:The 3.33 eV photoluminescence line is investigated in ZnO thin films deposited by dip coating. These films are oriented along the c-axis and exhibit basal-plane stacking faults and random grain boundaries. It is found that the relative intensity of the free exciton peak to the 3.33 eV line decreases as the nanoparticle size is reduced and that the corresponding Huang–Rhys factor is about 0.5. This reveals that excitons bound to Extended Defects at grain boundaries are involved. Also, post growth annealing strongly affects the photoluminescence spectra. In particular, the 3.31 eV line coming from stacking faults is enhanced at high annealing temperature.
James S. Speck - One of the best experts on this subject based on the ideXlab platform.
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Extended Defect structure of a plane gan produced by sidewall lateral epitaxial overgrowth
Journal of Crystal Growth, 2011Co-Authors: Yanling Hu, P Fini, Stefan Kraemer, James S. SpeckAbstract:Abstract This paper demonstrates the use of Sidewall Lateral Epitaxial Overgrowth (S-LEO) on a -plane GaN thick films on r -plane sapphire by hydride vapor phase epitaxy (HVPE). Comprehensive study of the Extended Defect microstructure of the a -plane GaN films was carried out using cross-sectional and plan-view transmission electron microscopy (TEM). A very low density of primary threading dislocations and a heterogeneous microstructure can be found in the GaN films. In the window region and N-face wing region, the Extended Defects included type I 1 and type I 2 basal stacking faults (BSFs), as well as prismatic stacking faults (PSFs) on a -planes. The density of type I 1 BSFs was in the order of ∼2×10 5 cm −1 , type I 2 BSFs in the order of ∼10 4 cm −1 , and corresponding localized partial dislocation density less than 1.5×10 9 cm −2 . PSFs on a -planes were connected to two neighboring type I 1 BSFs with an estimated density of 3×10 2 cm −1 in the plan-view images. In the Ga-face overgrowth regions, the density of BSFs was lower than 10 4 cm −1 . However, inversion domains bounded by (1 1 0 2), (1 1 0 2), and (1 1 0 0) planes were found in the Ga-face wing regions. The nature of inversion domain boundaries (IDB) on m -planes can be explained by the Auserman-Gehamn model using high-angle annular dark-field TEM images.
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continuous wave operation of ingan gan laser diodes on semipolar 1 12 2 plane gallium nitrides
Applied Physics Express, 2009Co-Authors: Hirokuni Asamizu, Steven P. Denbaars, Makoto Saito, Kenji Fujito, James S. Speck, Shuji NakamuraAbstract:Continuous-wave (CW) operations of semipolar (1 12 2) plane InGaN/GaN laser diodes (LDs) were demonstrated. The LD structures were grown on low Extended Defect density semipolar (1 12 2) GaN bulk substrates, using conventional metal organic chemical vapor deposition (MOCVD) at atmospheric pressure. The threshold current was 54 mA (6.5 kA/cm2) for the CW operation [39 mA (4.6 kA/cm2) for pulsed mode]. Stimulated emission was observed at 405.9 nm with a spectral line-width of 1 nm. These results indicate that semipolar (1 12 2) GaN is a promising orientation for the realization of blue-green and green LDs.
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low Extended Defect density nonpolar m plane gan by sidewall lateral epitaxial overgrowth
Applied Physics Letters, 2008Co-Authors: Mathew C Schmidt, Steven P. Denbaars, Shuji Nakamura, Feng Wu, Melvin Mclaurin, Asako Hirai, James S. SpeckAbstract:Sidewall lateral epitaxial overgrowth (SLEO) is demonstrated by metal organic chemical vapor deposition for nonpolar {11¯00} m-plane GaN films. m-plane GaN films were grown by metal organic chemical vapor deposition on m-plane 6H SiC substrates with an AlN initiation layer. Subsequently, an SiO2 stripe dielectric pattern was formed with 2μm window openings parallel to the [112¯0] a-direction and an 8μm mask and then the m-plane GaN was etched through the window openings to reveal Ga-face (0001) and N-face (0001¯) sidewalls. The SLEO growth was achieved in two growth steps—lateral growth from the sidewalls and subsequent growth through and then over the dielectric mask openings. In comparison to planar m-plane GaN films grown on 6H SiC, the threading dislocation density was reduced from low 1010to3×108cm−2 and the stacking fault density was reduced by one order of magnitude.
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p type conduction in stacking fault free m plane gan
Physica Status Solidi-rapid Research Letters, 2007Co-Authors: Melvin Mclaurin, James S. SpeckAbstract:Transport measurements of p-type m -plane GaN films grown on low Extended-Defect density, free-standing m -plane (100) GaN substrates are presented. No significant anisotropy in in-plane mobility was found for hole concentrations between 2.45 × 1017 and 8.7 × 1018 cm–3. Since faulted, heteroepitaxial m -plane films showed significant anisotropy in electron and hole mobility a microstructural feature with anisotropic distribution (basal plane stacking faults) is discussed as a possible source of anisotropic scattering in non-polar and semi-polar films. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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high power and high external efficiency m plane ingan light emitting diodes
Japanese Journal of Applied Physics, 2007Co-Authors: Mathew C Schmidt, Natalie Fellows, Steven P. Denbaars, Shuji Nakamura, H. Sato, Hisashi Masui, James S. SpeckAbstract:High power and high efficiency nonpolar m-plane (1100) nitride light emitting diodes (LEDs) have been fabricated on low Extended Defect bulk m-plane GaN substrates. The LEDs were grown by metal organic chemical vapor deposition (MOCVD) using conditions similar to that of c-plane device growth. The output power and external quantum efficiency (EQE) of the packaged 300 ×300 µm2 was 23.7 mW and 38.9%, respectively, at 20 mA. The peak wavelength was 407 nm and <1 nm redshift was observed with change in drive current from 1–20 mA. The EQE shows a minimal drop off at higher currents.
Vincent Consonni - One of the best experts on this subject based on the ideXlab platform.
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identification of Extended Defect and interface related luminescence lines in polycrystalline zno thin films grown by sol gel process
RSC Advances, 2016Co-Authors: Sophie Guillemin, Vincent Consonni, Laetitia Rapenne, E Sarigiannidou, Fabrice Donatini, G BremondAbstract:The luminescence lines related to Extended Defects and interfaces in polycrystalline ZnO thin films grown by sol–gel process are deeply investigated by combining temperature-dependent photoluminescence and cathodoluminescence imaging with high-resolution transmission electron microscopy. A typical broad emission band is shown in the range of 3.316 to 3.333 eV and mainly consists of two distinct contributions. At high energy, a 3.333 eV line is associated with interfaces (i.e., free surfaces and grain boundaries) and predominates for small ZnO nanoparticles owing to their high density. The intensity ratio of the excitonic to interface-related transitions is low in this first configuration and the 3.333 eV line is characterized by an activation energy of 12.0 ± 1.2 meV and a Huang-Rhys factor of 0.54 ± 0.05 at 12 K. At low energy, a 3.316 eV line is attributed to basal plane stacking faults that are mostly of I1-type and prevail for large ZnO nanoparticles. The 3.316 eV line is characterized by an activation energy of 6.7 ± 0.8 meV and a Huang Rhys constant of 0.87 ± 0.03 at 12 K. Basal plane stacking faults are most likely formed as the coalescence process proceeds with the decomposition and crystallization processes during annealing. As shown by low-temperature monochromatic cathodoluminescence imaging, the luminescence corresponding to the 3.316 eV line is, in this second configuration, limited to some specific area (i.e., large nanoparticles), and the relative intensity ratio of the excitonic to interface-related transitions is increased due to the smaller free surface area and density of grain boundaries.
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Extended Defect related photoluminescence line at 3 33 ev in nanostructured zno thin films
Applied Physics Express, 2013Co-Authors: Sophie Guillemin, Vincent Consonni, Bruno Masenelli, G BremondAbstract:The 3.33 eV photoluminescence line is investigated in ZnO thin films deposited by dip coating. These films are oriented along the c-axis and exhibit basal-plane stacking faults and random grain boundaries. It is found that the relative intensity of the free exciton peak to the 3.33 eV line decreases as the nanoparticle size is reduced and that the corresponding Huang–Rhys factor is about 0.5. This reveals that excitons bound to Extended Defects at grain boundaries are involved. Also, post growth annealing strongly affects the photoluminescence spectra. In particular, the 3.31 eV line coming from stacking faults is enhanced at high annealing temperature.
Shuji Nakamura - One of the best experts on this subject based on the ideXlab platform.
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continuous wave operation of ingan gan laser diodes on semipolar 1 12 2 plane gallium nitrides
Applied Physics Express, 2009Co-Authors: Hirokuni Asamizu, Steven P. Denbaars, Makoto Saito, Kenji Fujito, James S. Speck, Shuji NakamuraAbstract:Continuous-wave (CW) operations of semipolar (1 12 2) plane InGaN/GaN laser diodes (LDs) were demonstrated. The LD structures were grown on low Extended Defect density semipolar (1 12 2) GaN bulk substrates, using conventional metal organic chemical vapor deposition (MOCVD) at atmospheric pressure. The threshold current was 54 mA (6.5 kA/cm2) for the CW operation [39 mA (4.6 kA/cm2) for pulsed mode]. Stimulated emission was observed at 405.9 nm with a spectral line-width of 1 nm. These results indicate that semipolar (1 12 2) GaN is a promising orientation for the realization of blue-green and green LDs.
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low Extended Defect density nonpolar m plane gan by sidewall lateral epitaxial overgrowth
Applied Physics Letters, 2008Co-Authors: Mathew C Schmidt, Steven P. Denbaars, Shuji Nakamura, Feng Wu, Melvin Mclaurin, Asako Hirai, James S. SpeckAbstract:Sidewall lateral epitaxial overgrowth (SLEO) is demonstrated by metal organic chemical vapor deposition for nonpolar {11¯00} m-plane GaN films. m-plane GaN films were grown by metal organic chemical vapor deposition on m-plane 6H SiC substrates with an AlN initiation layer. Subsequently, an SiO2 stripe dielectric pattern was formed with 2μm window openings parallel to the [112¯0] a-direction and an 8μm mask and then the m-plane GaN was etched through the window openings to reveal Ga-face (0001) and N-face (0001¯) sidewalls. The SLEO growth was achieved in two growth steps—lateral growth from the sidewalls and subsequent growth through and then over the dielectric mask openings. In comparison to planar m-plane GaN films grown on 6H SiC, the threading dislocation density was reduced from low 1010to3×108cm−2 and the stacking fault density was reduced by one order of magnitude.
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high power and high external efficiency m plane ingan light emitting diodes
Japanese Journal of Applied Physics, 2007Co-Authors: Mathew C Schmidt, Natalie Fellows, Steven P. Denbaars, Shuji Nakamura, H. Sato, Hisashi Masui, James S. SpeckAbstract:High power and high efficiency nonpolar m-plane (1100) nitride light emitting diodes (LEDs) have been fabricated on low Extended Defect bulk m-plane GaN substrates. The LEDs were grown by metal organic chemical vapor deposition (MOCVD) using conditions similar to that of c-plane device growth. The output power and external quantum efficiency (EQE) of the packaged 300 ×300 µm2 was 23.7 mW and 38.9%, respectively, at 20 mA. The peak wavelength was 407 nm and <1 nm redshift was observed with change in drive current from 1–20 mA. The EQE shows a minimal drop off at higher currents.
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High Brightness Blue InGaN/GaN Light Emitting Diode on Nonpolar m -plane Bulk GaN Substrate
Japanese Journal of Applied Physics, 2007Co-Authors: K Iso, Hirohiko Hirasawa, Natalie Fellows, Hisashi Yamada, Steven P. Denbaars, Makoto Saito, Kenji Fujito, James S. Speck, Shuji NakamuraAbstract:Improved nonpolar m-plane (1-1100) light emitting diode (LED) with a thick InGaN active layer of 8 nm and a thick GaN barrier layer of 37.5 nm for multi-quantum-well (MQW) structure have been fabricated on low Extended Defect bulk m-plane GaN substrates using metal organic chemical vapor deposition (MOCVD). The peak wavelength of the electroluminescence (EL) emission from the packaged LED was 468 nm. The output power and external quantum efficiency (EQE) were 8.9 mW and 16.8%, respectively, at a DC driving current of 20 mA.
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Recent Performance of Nonpolar/Semipolar GaN-based Blue LEDs/LDs
LEOS 2007 - IEEE Lasers and Electro-Optics Society Annual Meeting Conference Proceedings, 2007Co-Authors: Shuji Nakamura, Daniel Feezell, Steven P. Denbaars, Makoto Saito, James S. Speck, M. C. Schmidt, R. M. Farrell, D. A. Cohen, H. Sato, H. AsamizuAbstract:Violet InGaN/GaN light emitting diodes (LEDs) was fabricated on semipolar GaN bulk substrates. The output power and external quantum efficiency at a driving current of 20 mA were measured. The first nonpolar m-plane nitride laser diodes (LDs) were realized on low Extended Defect bulk m-plane GaN substrates.
