1
|
Saab R, Assali S, Angelides M, Idler J. Surviving Postpartum Group A Streptococcus Sepsis Complicated by Multiorgan System Failure: A Complex Case Presentation. Cureus 2024; 16:e56167. [PMID: 38618427 PMCID: PMC11015903 DOI: 10.7759/cureus.56167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2024] [Indexed: 04/16/2024] Open
Abstract
Postpartum group A streptococcal (GAS) sepsis is a rare obstetric complication with severe clinical implications and high morbidity and mortality, presenting diagnostic and management challenges. This report analyzes a complex case of postpartum GAS sepsis, highlighting the importance of understanding the pathophysiology and clinical trajectories of this often fatal pathogen. A comprehensive analysis was conducted on a patient with postpartum GAS sepsis. Literature review and case comparisons informed the study's context. Medical history, clinical presentation, diagnostic procedures, interventions, and outcomes were reviewed and documented. The patient presented on postpartum day 5 with abdominal pain and vaginal bleeding. Her condition rapidly deteriorated, requiring aggressive interventions and systemic support. Blood cultures confirmed GAS bacteremia. She developed toxic shock syndrome, cardiomyopathy with acute cardiac failure, and seizures secondary to subdural empyema. Multidisciplinary care facilitated eventual clinical recovery. Obstacles in achieving treatment balance were evident, underscoring the systemic nature of GAS infection and the significance of interdisciplinary collaboration. This case underscores the complex pathophysiology of postpartum GAS sepsis and the importance of prompt treatment initiation, aggressive intervention, and a multidisciplinary approach to management. The study contributes to the understanding of disease progression and clinical management in severe peripartum infections, reaffirming the need for further research to improve outcomes.
Collapse
Affiliation(s)
- Rim Saab
- Obstetrics and Gynecology, Drexel University College of Medicine, Philadelphia, USA
| | - Sarah Assali
- General Surgery, Allegheny Health Network, Pittsburgh, USA
| | - Mary Angelides
- Obstetrics and Gynecology, Allegheny Health Network, Pittsburgh, USA
| | - Jay Idler
- Obstetrics and Gynecology, Allegheny Health Network, Pittsburgh, USA
| |
Collapse
|
2
|
Hetrick M, Assali S, Knoell O, Eid G. Hernia Management in a Bariatric Patient Population: A Summary of Treatment Recommendations at a High-Volume Bariatric Center. J Am Coll Surg 2020. [DOI: 10.1016/j.jamcollsurg.2020.08.181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
3
|
Hetrick M, Assali S, Falls S, Eid G. Operative Hiatal Hernias in a Bariatric Patient Population: A Comparison of Intraoperative Findings and Preoperative Esophagogastroduodenoscopy. J Am Coll Surg 2020. [DOI: 10.1016/j.jamcollsurg.2020.08.188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
4
|
Assali S, Lähnemann J, Vu TTT, Jöns KD, Gagliano L, Verheijen MA, Akopian N, Bakkers EPAM, Haverkort JEM. Crystal Phase Quantum Well Emission with Digital Control. Nano Lett 2017; 17:6062-6068. [PMID: 28892396 PMCID: PMC5642001 DOI: 10.1021/acs.nanolett.7b02489] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/06/2017] [Indexed: 05/31/2023]
Abstract
One of the major challenges in the growth of quantum well and quantum dot heterostructures is the realization of atomically sharp interfaces. Nanowires provide a new opportunity to engineer the band structure as they facilitate the controlled switching of the crystal structure between the zinc-blende (ZB) and wurtzite (WZ) phases. Such a crystal phase switching results in the formation of crystal phase quantum wells (CPQWs) and quantum dots (CPQDs). For GaP CPQWs, the inherent electric fields due to the discontinuity of the spontaneous polarization at the WZ/ZB junctions lead to the confinement of both types of charge carriers at the opposite interfaces of the WZ/ZB/WZ structure. This confinement leads to a novel type of transition across a ZB flat plate barrier. Here, we show digital tuning of the visible emission of WZ/ZB/WZ CPQWs in a GaP nanowire by changing the thickness of the ZB barrier. The energy spacing between the sharp emission lines is uniform and is defined by the addition of single ZB monolayers. The controlled growth of identical quantum wells with atomically flat interfaces at predefined positions featuring digitally tunable discrete emission energies may provide a new route to further advance entangled photons in solid state quantum systems.
Collapse
Affiliation(s)
- S. Assali
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
| | - J. Lähnemann
- Paul-Drude-Institut
für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - T. T. T. Vu
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
| | - K. D. Jöns
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA, Delft, The Netherlands
| | - L. Gagliano
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
| | - M. A. Verheijen
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
- Philips
Innovation Services Eindhoven, High Tech Campus 11, 5656 AE, Eindhoven, The
Netherlands
| | - N. Akopian
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA, Delft, The Netherlands
| | - E. P. A. M. Bakkers
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA, Delft, The Netherlands
| | - J. E. M. Haverkort
- Department
of Applied Physics, Eindhoven University
of Technology, 5600 MB, Eindhoven, The Netherlands
| |
Collapse
|
5
|
Assali S, Dijkstra A, Li A, Koelling S, Verheijen MA, Gagliano L, von den Driesch N, Buca D, Koenraad PM, Haverkort JEM, Bakkers EPAM. Growth and Optical Properties of Direct Band Gap Ge/Ge 0.87Sn 0.13 Core/Shell Nanowire Arrays. Nano Lett 2017; 17:1538-1544. [PMID: 28165747 DOI: 10.1021/acs.nanolett.6b04627] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Group IV semiconductor optoelectronic devices are now possible by using strain-free direct band gap GeSn alloys grown on a Ge/Si virtual substrate with Sn contents above 9%. Here, we demonstrate the growth of Ge/GeSn core/shell nanowire arrays with Sn incorporation up to 13% and without the formation of Sn clusters. The nanowire geometry promotes strain relaxation in the Ge0.87Sn0.13 shell and limits the formation of structural defects. This results in room-temperature photoluminescence centered at 0.465 eV and enhanced absorption above 98%. Therefore, direct band gap GeSn grown in a nanowire geometry holds promise as a low-cost and high-efficiency material for photodetectors operating in the short-wave infrared and thermal imaging devices.
Collapse
Affiliation(s)
- S Assali
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - A Dijkstra
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - A Li
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
- Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology , Pingleyuan 100, Beijing 100024, P. R. China
| | - S Koelling
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - M A Verheijen
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Philips Innovation Laboratories Eindhoven , High Tech Campus 11, 5656AE Eindhoven, The Netherlands
| | - L Gagliano
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - N von den Driesch
- Peter Gruenberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Juelich, 52428 Juelich, Germany
| | - D Buca
- Peter Gruenberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Juelich, 52428 Juelich, Germany
| | - P M Koenraad
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - J E M Haverkort
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - E P A M Bakkers
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| |
Collapse
|
6
|
Koelling S, Li A, Cavalli A, Assali S, Car D, Gazibegovic S, Bakkers EPAM, Koenraad PM. Atom-by-Atom Analysis of Semiconductor Nanowires with Parts Per Million Sensitivity. Nano Lett 2017; 17:599-605. [PMID: 28002677 DOI: 10.1021/acs.nanolett.6b03109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The functionality of semiconductor devices is determined by the incorporation of dopants at concentrations down to the parts per million (ppm) level and below. Optimization of intentional and unintentional impurity doping relies on methods to detect and map the level of impurities. Detecting such low concentrations of impurities in nanostructures is however challenging to date as on the one hand methods used for macroscopic samples cannot be applied due to the inherent small volumes or faceted surfaces and on the other hand conventional microscopic analysis techniques are not sufficiently sensitive. Here, we show that we can detect and map impurities at the ppm level in semiconductor nanowires using atom probe tomography. We develop a method applicable to a wide variety of nanowires relevant for electronic and optical devices. We expect that it will contribute significantly to the further optimization of the synthesis of nanowires, nanostructures and devices based on these structures.
Collapse
Affiliation(s)
- S Koelling
- Photonics and Semiconductor Nanophysics, Eindhoven University of Technology , Eindhoven, 5600 MB, The Netherlands
| | - A Li
- Photonics and Semiconductor Nanophysics, Eindhoven University of Technology , Eindhoven, 5600 MB, The Netherlands
- Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology , Beijing, 100024, China
| | - A Cavalli
- Photonics and Semiconductor Nanophysics, Eindhoven University of Technology , Eindhoven, 5600 MB, The Netherlands
| | - S Assali
- Photonics and Semiconductor Nanophysics, Eindhoven University of Technology , Eindhoven, 5600 MB, The Netherlands
| | - D Car
- Photonics and Semiconductor Nanophysics, Eindhoven University of Technology , Eindhoven, 5600 MB, The Netherlands
- Quantum Transport Group, Kavli Institute , Delft, 2628 CJ, The Netherlands
| | - S Gazibegovic
- Photonics and Semiconductor Nanophysics, Eindhoven University of Technology , Eindhoven, 5600 MB, The Netherlands
- Quantum Transport Group, Kavli Institute , Delft, 2628 CJ, The Netherlands
| | - E P A M Bakkers
- Photonics and Semiconductor Nanophysics, Eindhoven University of Technology , Eindhoven, 5600 MB, The Netherlands
- Quantum Transport Group, Kavli Institute , Delft, 2628 CJ, The Netherlands
| | - P M Koenraad
- Photonics and Semiconductor Nanophysics, Eindhoven University of Technology , Eindhoven, 5600 MB, The Netherlands
| |
Collapse
|
7
|
Gagliano L, Belabbes A, Albani M, Assali S, Verheijen MA, Miglio L, Bechstedt F, Haverkort JEM, Bakkers EPAM. Pseudodirect to Direct Compositional Crossover in Wurtzite GaP/In xGa 1-xP Core-Shell Nanowires. Nano Lett 2016; 16:7930-7936. [PMID: 27960532 DOI: 10.1021/acs.nanolett.6b04242] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Thanks to their uniqueness, nanowires allow the realization of novel semiconductor crystal structures with yet unexplored properties, which can be key to overcome current technological limits. Here we develop the growth of wurtzite GaP/InxGa1-xP core-shell nanowires with tunable indium concentration and optical emission in the visible region from 590 nm (2.1 eV) to 760 nm (1.6 eV). We demonstrate a pseudodirect (Γ8c-Γ9v) to direct (Γ7c-Γ9v) transition crossover through experimental and theoretical approach. Time resolved and temperature dependent photoluminescence measurements were used, which led to the observation of a steep change in carrier lifetime and temperature dependence by respectively one and 3 orders of magnitude in the range 0.28 ± 0.04 ≤ x ≤ 0.41 ± 0.04. Our work reveals the electronic properties of wurtzite InxGa1-xP.
Collapse
Affiliation(s)
- L Gagliano
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - A Belabbes
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universitat , Max-Wien-Platz 1, D-07743 Jena, Germany
| | - M Albani
- L-NESS and Department of Materials Science, University of Milano Bicocca , 20125, Milano, Italy
| | - S Assali
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - M A Verheijen
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Philips Innovation Laboratories Eindhoven , High Tech Campus 11, 5656AE Eindhoven, The Netherlands
| | - L Miglio
- L-NESS and Department of Materials Science, University of Milano Bicocca , 20125, Milano, Italy
| | - F Bechstedt
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universitat , Max-Wien-Platz 1, D-07743 Jena, Germany
| | - J E M Haverkort
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
| | - E P A M Bakkers
- Department of Applied Physics, Eindhoven University of Technology , 5600 MB Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| |
Collapse
|
8
|
Greil J, Assali S, Isono Y, Belabbes A, Bechstedt F, Valega Mackenzie FO, Silov AY, Bakkers EPAM, Haverkort JEM. Optical Properties of Strained Wurtzite Gallium Phosphide Nanowires. Nano Lett 2016; 16:3703-3709. [PMID: 27175743 PMCID: PMC4901362 DOI: 10.1021/acs.nanolett.6b01038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/29/2016] [Indexed: 06/01/2023]
Abstract
Wurtzite gallium phosphide (WZ GaP) has been predicted to exhibit a direct bandgap in the green spectral range. Optical transitions, however, are only weakly allowed by the symmetry of the bands. While efficient luminescence has been experimentally shown, the nature of the transitions is not yet clear. Here we apply tensile strain up to 6% and investigate the evolution of the photoluminescence (PL) spectrum of WZ GaP nanowires (NWs). The pressure and polarization dependence of the emission together with a theoretical analysis of strain effects is employed to establish the nature and symmetry of the transitions. We identify the emission lines to be related to localized states with significant admixture of Γ7c symmetry and not exclusively related to the Γ8c conduction band minimum (CBM). The results emphasize the importance of strongly bound state-related emission in the pseudodirect semiconductor WZ GaP and contribute significantly to the understanding of the optoelectronic properties of this novel material.
Collapse
Affiliation(s)
- J. Greil
- Department of Applied
Physics, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - S. Assali
- Department of Applied
Physics, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - Y. Isono
- Department
of Mechanical Engineering, Kobe University, Kobe 657-8501, Japan
| | - A. Belabbes
- Institut für Festkörpertheorie
und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena, Germany
- King Abdullah University of Science & Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - F. Bechstedt
- Institut für Festkörpertheorie
und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena, Germany
| | | | - A. Yu. Silov
- Department of Applied
Physics, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - E. P. A. M. Bakkers
- Department of Applied
Physics, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA, Delft, The Netherlands
| | - J. E. M. Haverkort
- Department of Applied
Physics, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| |
Collapse
|
9
|
Bravo-Nuevo A, Brandli AA, Gerhart J, Nichols J, Pitts M, Sutera CK, Assali S, Scheinfeld V, Prendergast GC, Stone J, George-Weinstein M. Neuroprotective effect of Myo/Nog cells in the stressed retina. Exp Eye Res 2015; 146:22-25. [PMID: 26688580 DOI: 10.1016/j.exer.2015.11.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 10/23/2015] [Accepted: 11/29/2015] [Indexed: 01/15/2023]
Abstract
Myo/Nog cells are essential for eye development in the chick embryo and respond to injury in adult tissues. These cells express mRNA for the skeletal muscle specific transcription factor MyoD, the bone morphogenetic protein (BMP) inhibitor Noggin and the cell surface protein recognized by the G8 monoclonal antibody (mAb). In this study, we determined that Myo/Nog cells are present in low numbers in the retina of the mouse eye. G8-positive Myo/Nog cells were distinguished from neuronal, Müller and microglial cells that were identified with antibodies to calretinin, Chx10, glial fibrillary acidic protein and ionized calcium binding adaptor molecule 1, respectively. In the neonatal retina, the number of Myo/Nog cells increased in parallel with cell death induced by transient exposure to hyperoxia. In this model of retinopathy of prematurity, depletion of Myo/Nog cells by intravitreal injection of the G8 mAb and complement increased cell death. These findings demonstrate that Myo/Nog cells are a distinct population of cells, not previously described in the retina, which increases in response to retinal damage and mitigate hypoxia-induced cell death.
Collapse
Affiliation(s)
| | - Alice A Brandli
- Bosch Institute and Discipline of Physiology University of Sydney, NSW, Australia
| | | | | | - Meghan Pitts
- Lankenau Institute for Medical Research, Wynnewood, PA, USA
| | | | - Sarah Assali
- Lankenau Institute for Medical Research, Wynnewood, PA, USA
| | | | | | - Jonathan Stone
- Bosch Institute and Discipline of Physiology University of Sydney, NSW, Australia
| | | |
Collapse
|
10
|
Assali S, Gagliano L, Oliveira DS, Verheijen MA, Plissard SR, Feiner LF, Bakkers EPAM. Exploring Crystal Phase Switching in GaP Nanowires. Nano Lett 2015; 15:8062-8069. [PMID: 26539748 DOI: 10.1021/acs.nanolett.5b03484] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The growth of wurtzite/zincblende (WZ and ZB, respectively) superstructures opens new avenues for band structure engineering and holds the promise of digitally controlling the energy spectrum of quantum confined systems. Here, we study growth kinetics of pure and thus defect-free WZ/ZB homostructures in GaP nanowires with the aim to obtain monolayer control of the ZB and WZ segment lengths. We find that the Ga concentration and the supersaturation in the catalyst particle are the key parameters determining growth kinetics. These parameters can be tuned by the gallium partial pressure and the temperature. The formation of WZ and ZB can be understood with a model based on nucleation either at the triple phase line for the WZ phase or in the center of the solid-liquid interface for the ZB phase. Furthermore, the observed delay/offset time needed to induce WZ and ZB growth after growth of the other phase can be explained within this framework.
Collapse
Affiliation(s)
- S Assali
- Department of Applied Physics Eindhoven, University of Technology , 5600 MB Eindhoven, The Netherlands
| | - L Gagliano
- Department of Applied Physics Eindhoven, University of Technology , 5600 MB Eindhoven, The Netherlands
| | - D S Oliveira
- Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas, UNICAMP , 13083-859 Campinas, São Paulo, Brazil
| | - M A Verheijen
- Department of Applied Physics Eindhoven, University of Technology , 5600 MB Eindhoven, The Netherlands
- Philips Innovation Services Eindhoven , High Tech Campus 11, 5656AE Eindhoven, The Netherlands
| | - S R Plissard
- CNRS-Laboratoire d'Analyse et d'Architecture des Systèmes (LAAS), Université de Toulouse , 7 avenue du colonel Roche, F-31400 Toulouse, France
| | - L F Feiner
- Department of Applied Physics Eindhoven, University of Technology , 5600 MB Eindhoven, The Netherlands
| | - E P A M Bakkers
- Department of Applied Physics Eindhoven, University of Technology , 5600 MB Eindhoven, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
| |
Collapse
|
11
|
Conesa-Boj S, Hauge HIT, Verheijen MA, Assali S, Li A, Bakkers EPAM, Fontcuberta i Morral A. Cracking the Si Shell Growth in Hexagonal GaP-Si Core-Shell Nanowires. Nano Lett 2015; 15:2974-2979. [PMID: 25922878 DOI: 10.1021/nl504813e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Semiconductor nanowires have increased the palette of possible heterostructures thanks to their more effective strain relaxation. Among these, core-shell heterostructures are much more sensitive to strain than axial ones. It is now accepted that the formation of misfit dislocations depends both on the lattice mismatch and relative dimensions of the core and the shell. Here, we show for the first time the existence of a new kind of defect in core-shell nanowires: cracks. These defects do not originate from a lattice mismatch (we demonstrate their appearance in an essentially zero-mismatch system) but from the thermal history during the growth of the nanowires. Crack defects lead to the development of secondary defects, such as type-I1 stacking faults and Frank-type dislocations. These results provide crucial information with important implications for the optimized synthesis of nanowire-based core-shell heterostructures.
Collapse
Affiliation(s)
- S Conesa-Boj
- †École Polytechnique Fédérale de Lausanne (EPFL), Laboratoire des Matériaux Semiconducteurs (LMSC), 1015 Lausanne, Switzerland
| | - H I T Hauge
- ‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - M A Verheijen
- ‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- §Philips Innovation Services Eindhoven, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands
| | - S Assali
- ‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - A Li
- ‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - E P A M Bakkers
- ‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- ∥Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - A Fontcuberta i Morral
- †École Polytechnique Fédérale de Lausanne (EPFL), Laboratoire des Matériaux Semiconducteurs (LMSC), 1015 Lausanne, Switzerland
| |
Collapse
|
12
|
Assali S, Zardo I, Plissard S, Kriegner D, Verheijen MA, Bauer G, Meijerink A, Belabbes A, Bechstedt F, Haverkort JEM, Bakkers EPAM. Direct band gap wurtzite gallium phosphide nanowires. Nano Lett 2013; 13:1559-63. [PMID: 23464761 PMCID: PMC3624814 DOI: 10.1021/nl304723c] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/20/2013] [Indexed: 05/27/2023]
Abstract
The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555-690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality.
Collapse
Affiliation(s)
- S. Assali
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
| | - I. Zardo
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
| | - S. Plissard
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
| | - D. Kriegner
- Institute
of Semiconductor and
Solid State Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - M. A. Verheijen
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
- Philips Innovation
Services Eindhoven, High Tech Campus 11, 5656AE Eindhoven,
The Netherlands
| | - G. Bauer
- Institute
of Semiconductor and
Solid State Physics, Johannes Kepler University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - A. Meijerink
- Debye Institute, Utrecht University, Princetonplein 1, 3500TA Utrecht,
The Netherlands
| | - A. Belabbes
- Institut
für Festkörpertheorie
und −optik, Friedrich Schiller Universität, 07743 Jena, Germany
| | - F. Bechstedt
- Institut
für Festkörpertheorie
und −optik, Friedrich Schiller Universität, 07743 Jena, Germany
| | - J. E. M. Haverkort
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
| | - E. P. A. M. Bakkers
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven,
The Netherlands
- Kavli
Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The
Netherlands
| |
Collapse
|
13
|
Standing AJ, Assali S, Haverkort JEM, Bakkers EPAM. High yield transfer of ordered nanowire arrays into transparent flexible polymer films. Nanotechnology 2012; 23:495305. [PMID: 23154816 DOI: 10.1088/0957-4484/23/49/495305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The factors affecting transfer of nanowire arrays from their substrates into flexible PDMS films have been systematically investigated. Experiments were carried out on gallium phosphide nanowires with a standard length of 10 μm with varying pitch (0.2-1.5 μm). The important factors were found to be penetration of the PDMS within the nanowire arrays and the strength/rigidity of the PDMS film. The PDMS penetration between wires in the arrays is affected by both the viscosity of the PDMS solution and the presence of air pockets trapped within nanowire arrays, particularly at small pitches. Dilution with hexane and curing in a vacuum desiccator solve the wire penetration problem, and an increase in cure/base ratio increases the rigidity and strength of the PDMS. The procedures for preparation and deposition of the PDMS solution are optimized and a high yield, up to 95%, of wire transfer across a range of nanowire pitches has been obtained.
Collapse
Affiliation(s)
- A J Standing
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
| | | | | | | |
Collapse
|