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Thomas Schäpers - One of the best experts on this subject based on the ideXlab platform.
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anisotropic phase coherence in gaas inas core Shell Nanowires
Nanotechnology, 2017Co-Authors: Fabian Haas, Mihail Ion Lepsa, Torsten Rieger, Detlev Grützmacher, Patrick Zellekens, Tobias Wenz, N Demarina, Hans Luth, Thomas SchäpersAbstract:Low-temperature transport in Nanowires is accompanied by phase-coherent effects, which are observed as modulation of the conductance in an external magnetic field. In the GaAs/InAs core/Shell Nanowires investigated here, these are h/e flux periodic oscillations in a magnetic field aligned parallel to the nanowire axis and aperiodic universal conductance fluctuations in a field aligned perpendicularly to the nanowire axis. Both electron interference effects are used to analyse the phase coherence of the system. Temperature-dependent measurements are carried out, in order to derive the phase coherence lengths in the cross-sectional plane as well as along the nanowire sidewalls. It is found that these values show a strong anisotropy, which can be explained by the crystal structure of the GaAs/InAs core/Shell nanowire. For Nanowires with a radius as low as 45 nm, flux periodic oscillations were observed up to a temperature of 55 K.
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nanoimprint and selective area movpe for growth of gaas inas core Shell Nanowires
Nanotechnology, 2013Co-Authors: Fabian Haas, Torsten Rieger, Thomas Schäpers, Detlev Grützmacher, Hans Luth, K Sladek, A Winden, M Von Der Ahe, Thomas E Weirich, H HardtdegenAbstract:We report on the technology and growth optimization of GaAs/InAs core/Shell Nanowires. The GaAs nanowire cores were grown selectively by metal organic vapor phase epitaxy (SA-MOVPE) on SiO2 masked GaAs templates. These were structured by a complete thermal nanoimprint lithography process, which is presented in detail. The influence of the subsequent InAs Shell growth temperature on the Shell morphology and crystal structure was investigated by scanning and transmission electron microscopy in order to obtain the desired homogeneous and uniform InAs overgrowth. At the optimal growth temperature, the InAs Shell adopted the morphology and crystal structure of the underlying GaAs core and was perfectly uniform.
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molecular beam epitaxy growth of gaas inas core Shell Nanowires and fabrication of inas nanotubes
Nano Letters, 2012Co-Authors: Torsten Rieger, Thomas Schäpers, Detlev Grützmacher, M Luysberg, Mihail Ion LepsaAbstract:We present results about the growth of GaAs/InAs core–Shell Nanowires (NWs) using molecular beam epitaxy. The core is grown via the Ga droplet-assisted growth mechanism. For a homogeneous growth of...
Torsten Rieger - One of the best experts on this subject based on the ideXlab platform.
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anisotropic phase coherence in gaas inas core Shell Nanowires
Nanotechnology, 2017Co-Authors: Fabian Haas, Mihail Ion Lepsa, Torsten Rieger, Detlev Grützmacher, Patrick Zellekens, Tobias Wenz, N Demarina, Hans Luth, Thomas SchäpersAbstract:Low-temperature transport in Nanowires is accompanied by phase-coherent effects, which are observed as modulation of the conductance in an external magnetic field. In the GaAs/InAs core/Shell Nanowires investigated here, these are h/e flux periodic oscillations in a magnetic field aligned parallel to the nanowire axis and aperiodic universal conductance fluctuations in a field aligned perpendicularly to the nanowire axis. Both electron interference effects are used to analyse the phase coherence of the system. Temperature-dependent measurements are carried out, in order to derive the phase coherence lengths in the cross-sectional plane as well as along the nanowire sidewalls. It is found that these values show a strong anisotropy, which can be explained by the crystal structure of the GaAs/InAs core/Shell nanowire. For Nanowires with a radius as low as 45 nm, flux periodic oscillations were observed up to a temperature of 55 K.
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misfit dislocation free inas gasb core Shell Nanowires grown by molecular beam epitaxy
Nanoscale, 2015Co-Authors: Torsten Rieger, Detlev Grützmacher, Mihail Ion LepsaAbstract:In this report, we present the growth and structural analyses of broken gap InAs/GaSb core–Shell Nanowires by molecular beam epitaxy using an Au-free approach. Depending on the Shell growth temperature, two distinct growth regimes for the GaSb Shells are identified resulting in conformal or tapered Shells. Morphological analyses reveal a dodecagonal nanowire cross-section after GaSb Shell growth. Detailed transmission electron microscope investigations from different zone axes confirm that the small lattice mismatch of 0.6% allows the deposition of 40 nm thick GaSb Shells free of misfit dislocations. Additionally, an abrupt interface from InAs to GaSb is found. These Nanowires are suitable for future devices such as TFETs.
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nanoimprint and selective area movpe for growth of gaas inas core Shell Nanowires
Nanotechnology, 2013Co-Authors: Fabian Haas, Torsten Rieger, Thomas Schäpers, Detlev Grützmacher, Hans Luth, K Sladek, A Winden, M Von Der Ahe, Thomas E Weirich, H HardtdegenAbstract:We report on the technology and growth optimization of GaAs/InAs core/Shell Nanowires. The GaAs nanowire cores were grown selectively by metal organic vapor phase epitaxy (SA-MOVPE) on SiO2 masked GaAs templates. These were structured by a complete thermal nanoimprint lithography process, which is presented in detail. The influence of the subsequent InAs Shell growth temperature on the Shell morphology and crystal structure was investigated by scanning and transmission electron microscopy in order to obtain the desired homogeneous and uniform InAs overgrowth. At the optimal growth temperature, the InAs Shell adopted the morphology and crystal structure of the underlying GaAs core and was perfectly uniform.
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molecular beam epitaxy growth of gaas inas core Shell Nanowires and fabrication of inas nanotubes
Nano Letters, 2012Co-Authors: Torsten Rieger, Thomas Schäpers, Detlev Grützmacher, M Luysberg, Mihail Ion LepsaAbstract:We present results about the growth of GaAs/InAs core–Shell Nanowires (NWs) using molecular beam epitaxy. The core is grown via the Ga droplet-assisted growth mechanism. For a homogeneous growth of...
Takashi Fukui - One of the best experts on this subject based on the ideXlab platform.
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realization of conductive inas nanotubes based on lattice mismatched inp inas core Shell Nanowires
Applied Physics Letters, 2006Co-Authors: Premila Mohan, Junichi Motohisa, Takashi FukuiAbstract:We report the realization of ordered arrays of single-crystalline InAs nanotubes by a simple pure-eptiaxial approach. The process involved the fabrication of lattice-mismatched InP∕InAs core-Shell Nanowires using selective area metalorganic vapor phase epitaxy on InP (111)A substrates. The subsequent removal of the InP core resulted in vertically aligned InAs nanotubes which were highly uniform with well-defined features and controllable dimensions. Transmission electron microscopy studies confirmed that the nanotubes were single-crystalline with wurtzite crystal structure and temperature-dependent transport measurements revealed that they were conductive without any intentional doping. The realization of such conductive InAs nanotubes opens up new possibilities for both fundamental studies and future device applications.
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fabrication and characterization of freestanding gaas algaas core Shell Nanowires and algaas nanotubes by using selective area metalorganic vapor phase epitaxy
Applied Physics Letters, 2005Co-Authors: J Noborisaka, Junichi Motohisa, Shinjiro Hara, Takashi FukuiAbstract:We fabricated GaAs∕AlGaAs core-Shell Nanowires by using selective-area metalorganic vapor phase epitaxy. First, GaAs Nanowires were selectively grown on partially masked GaAs (111)B substrates; then AlGaAs was grown to form freestanding heterostructured Nanowires. Investigation of nanowire diameter as a function of AlGaAs growth time suggested that the AlGaAs was grown on the sidewalls of the GaAs Nanowires, forming GaAs∕AlGaAs core-Shell structures. Microphotoluminescence measurements of GaAs and GaAs∕AlGaAs core-Shell Nanowires reveal an enhancement of photoluminescence intensity in GaAs∕AlGaAs core-Shell structures. Based on these core-Shell Nanowires, AlGaAs nanotubes were formed by using anisotropic dry etching and wet chemical preferential etching to confirm the formation of a core-Shell structure and to explore a new class of materials.
Detlev Grützmacher - One of the best experts on this subject based on the ideXlab platform.
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anisotropic phase coherence in gaas inas core Shell Nanowires
Nanotechnology, 2017Co-Authors: Fabian Haas, Mihail Ion Lepsa, Torsten Rieger, Detlev Grützmacher, Patrick Zellekens, Tobias Wenz, N Demarina, Hans Luth, Thomas SchäpersAbstract:Low-temperature transport in Nanowires is accompanied by phase-coherent effects, which are observed as modulation of the conductance in an external magnetic field. In the GaAs/InAs core/Shell Nanowires investigated here, these are h/e flux periodic oscillations in a magnetic field aligned parallel to the nanowire axis and aperiodic universal conductance fluctuations in a field aligned perpendicularly to the nanowire axis. Both electron interference effects are used to analyse the phase coherence of the system. Temperature-dependent measurements are carried out, in order to derive the phase coherence lengths in the cross-sectional plane as well as along the nanowire sidewalls. It is found that these values show a strong anisotropy, which can be explained by the crystal structure of the GaAs/InAs core/Shell nanowire. For Nanowires with a radius as low as 45 nm, flux periodic oscillations were observed up to a temperature of 55 K.
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misfit dislocation free inas gasb core Shell Nanowires grown by molecular beam epitaxy
Nanoscale, 2015Co-Authors: Torsten Rieger, Detlev Grützmacher, Mihail Ion LepsaAbstract:In this report, we present the growth and structural analyses of broken gap InAs/GaSb core–Shell Nanowires by molecular beam epitaxy using an Au-free approach. Depending on the Shell growth temperature, two distinct growth regimes for the GaSb Shells are identified resulting in conformal or tapered Shells. Morphological analyses reveal a dodecagonal nanowire cross-section after GaSb Shell growth. Detailed transmission electron microscope investigations from different zone axes confirm that the small lattice mismatch of 0.6% allows the deposition of 40 nm thick GaSb Shells free of misfit dislocations. Additionally, an abrupt interface from InAs to GaSb is found. These Nanowires are suitable for future devices such as TFETs.
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nanoimprint and selective area movpe for growth of gaas inas core Shell Nanowires
Nanotechnology, 2013Co-Authors: Fabian Haas, Torsten Rieger, Thomas Schäpers, Detlev Grützmacher, Hans Luth, K Sladek, A Winden, M Von Der Ahe, Thomas E Weirich, H HardtdegenAbstract:We report on the technology and growth optimization of GaAs/InAs core/Shell Nanowires. The GaAs nanowire cores were grown selectively by metal organic vapor phase epitaxy (SA-MOVPE) on SiO2 masked GaAs templates. These were structured by a complete thermal nanoimprint lithography process, which is presented in detail. The influence of the subsequent InAs Shell growth temperature on the Shell morphology and crystal structure was investigated by scanning and transmission electron microscopy in order to obtain the desired homogeneous and uniform InAs overgrowth. At the optimal growth temperature, the InAs Shell adopted the morphology and crystal structure of the underlying GaAs core and was perfectly uniform.
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molecular beam epitaxy growth of gaas inas core Shell Nanowires and fabrication of inas nanotubes
Nano Letters, 2012Co-Authors: Torsten Rieger, Thomas Schäpers, Detlev Grützmacher, M Luysberg, Mihail Ion LepsaAbstract:We present results about the growth of GaAs/InAs core–Shell Nanowires (NWs) using molecular beam epitaxy. The core is grown via the Ga droplet-assisted growth mechanism. For a homogeneous growth of...
Mihail Ion Lepsa - One of the best experts on this subject based on the ideXlab platform.
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anisotropic phase coherence in gaas inas core Shell Nanowires
Nanotechnology, 2017Co-Authors: Fabian Haas, Mihail Ion Lepsa, Torsten Rieger, Detlev Grützmacher, Patrick Zellekens, Tobias Wenz, N Demarina, Hans Luth, Thomas SchäpersAbstract:Low-temperature transport in Nanowires is accompanied by phase-coherent effects, which are observed as modulation of the conductance in an external magnetic field. In the GaAs/InAs core/Shell Nanowires investigated here, these are h/e flux periodic oscillations in a magnetic field aligned parallel to the nanowire axis and aperiodic universal conductance fluctuations in a field aligned perpendicularly to the nanowire axis. Both electron interference effects are used to analyse the phase coherence of the system. Temperature-dependent measurements are carried out, in order to derive the phase coherence lengths in the cross-sectional plane as well as along the nanowire sidewalls. It is found that these values show a strong anisotropy, which can be explained by the crystal structure of the GaAs/InAs core/Shell nanowire. For Nanowires with a radius as low as 45 nm, flux periodic oscillations were observed up to a temperature of 55 K.
-
misfit dislocation free inas gasb core Shell Nanowires grown by molecular beam epitaxy
Nanoscale, 2015Co-Authors: Torsten Rieger, Detlev Grützmacher, Mihail Ion LepsaAbstract:In this report, we present the growth and structural analyses of broken gap InAs/GaSb core–Shell Nanowires by molecular beam epitaxy using an Au-free approach. Depending on the Shell growth temperature, two distinct growth regimes for the GaSb Shells are identified resulting in conformal or tapered Shells. Morphological analyses reveal a dodecagonal nanowire cross-section after GaSb Shell growth. Detailed transmission electron microscope investigations from different zone axes confirm that the small lattice mismatch of 0.6% allows the deposition of 40 nm thick GaSb Shells free of misfit dislocations. Additionally, an abrupt interface from InAs to GaSb is found. These Nanowires are suitable for future devices such as TFETs.
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molecular beam epitaxy growth of gaas inas core Shell Nanowires and fabrication of inas nanotubes
Nano Letters, 2012Co-Authors: Torsten Rieger, Thomas Schäpers, Detlev Grützmacher, M Luysberg, Mihail Ion LepsaAbstract:We present results about the growth of GaAs/InAs core–Shell Nanowires (NWs) using molecular beam epitaxy. The core is grown via the Ga droplet-assisted growth mechanism. For a homogeneous growth of...