10 research outputs found
Doping incorporation paths in catalyst-free Be-doped GaAs nanowires
The incorporation paths of Be in GaAs nanowires grown by the Ga-assisted
method in molecular beam epitaxy has been investigated by electrical
measurements of nanowires with different doping profiles. We find that Be atoms
incorporate preferentially via the nanowire side facets, while the
incorporation path through the Ga droplet is negligible. We also demonstrate
that Be can diffuse into the volume of the nanowire giving an alternative
incorporation path. This work is an important step towards controlled doping of
nanowires and will serve as a help for designing future devices based on
nanowires.Comment: 4 pages, 4 figure
Effects of buffer composition and dilution on nanowire field-effect biosensors
Nanowire-based field-effect transistors (FETs) can be used as ultra-sensitive and label-free biosensors for detecting protein-protein interactions. A way to increase the performance of such sensors is to dilute the sensing buffer drastically. However, we show here that this can have an important effect on the function of the proteins. Moreover, it is demonstrated that this dilution significantly affects the pH stability of the sensing buffer, which consequently impacts the charge of the protein and thus the response and signal-to-noise ratio in the sensing experiments. Three model systems are investigated experimentally to illustrate the impact on ligand-protein and protein-protein interactions. Simulations are performed to illustrate the effect on the performance of the sensors. Combining various parameters, the current study provides a means for evaluating and selecting the most appropriate buffer composition for bioFET measurements. © 2013 IOP Publishing Ltd
Semiconductor-Ferromagnetic Insulator-Superconductor Nanowires:Stray Field and Exchange Field
Nanowires can serve as flexible substrates for hybrid epitaxial growth on
selected facets, allowing for design of heterostructures with complex material
combinations and geometries. In this work we report on hybrid epitaxy of
semiconductor - ferromagnetic insulator - superconductor (InAs/EuS/Al) nanowire
heterostructures. We study the crystal growth and complex epitaxial matching of
wurtzite InAs / rock-salt EuS interfaces as well as rock-salt EuS /
face-centered cubic Al interfaces. Because of the magnetic anisotropy
originating from the nanowire shape, the magnetic structure of the EuS phase
are easily tuned into single magnetic domains. This effect efficiently ejects
the stray field lines along the nanowires. With tunnel spectroscopy
measurements of the density of states, we show the material has a hard induced
superconducting gap, and magnetic hysteretic evolution which indicates that the
magnetic exchange fields are not negligible. These hybrid nanowires fulfil key
material requirements for serving as a platform for spin-based quantum
applications, such as scalable topological quantum computing.Comment: 15 pages, 5 figure
Semiconductor-ferromagnetic insulator-superconductor nanowires : stray field and exchange field
Altres ajuts: ICN2 is funded by the CERCA Programme/Generalitat de Catalunya. Part of the present work has been performed in the framework of Universitat Autònoma de Barcelona Materials Science PhD program. Part of the HAADF-STEM microscopy was conducted in the Laboratorio de Microscopias Avanzadas at Instituto de Nanociencia de Aragon-Universidad de Zaragoza. ICN2 acknowledge support from CSIC Research Platform on Quantum Technologies PTI-001.Nanowires can serve as flexible substrates for hybrid epitaxial growth on selected facets, allowing for the design of heterostructures with complex material combinations and geometries. In this work we report on hybrid epitaxy of freestanding vapor-liquid-solid grown and in-plane selective area grown semiconductor-ferromagnetic insulator-superconductor (InAs/EuS/Al) nanowire heterostructures. We study the crystal growth and complex epitaxial matching of wurtzite and zinc-blende InAs/rock-salt EuS interfaces as well as rock-salt EuS/face-centered cubic Al interfaces. Because of the magnetic anisotropy originating from the nanowire shape, the magnetic structure of the EuS phase is easily tuned into single magnetic domains. This effect efficiently ejects the stray field lines along the nanowires. With tunnel spectroscopy measurements of the density of states, we show that the material has a hard induced superconducting gap, and magnetic hysteretic evolution which indicates that the magnetic exchange fields are not negligible. These hybrid nanowires fulfill key material requirements for serving as a platform for spin-based quantum applications, such as scalable topological quantum computing
Proceedings of the International Conference on Frontiers in Desalination, Energy, Environment and Material Sciences for Sustainable Development
This proceeding contains articles on the various ideas of the academic community presented at the International Conference on Frontiers in Desalination, Energy, Environment and Material Sciences for Sustainable Development (FEEMSSD-2023) & Annual Congress of InDA (InDACON-2023) jointly organized by the Madan Mohan Malaviya University of Technology Gorakhpur, KIPM-College of Engineering and Technology Gida Gorakhpur, and Indian Desalination Association, India on 16th-17th March 2023. FEEMSSD-2023 & InDACON-2023 focuses on addressing issues and concerns related to sustainability in all domains of Energy, Environment, Desalination, and Material Science and attempts to present the research and innovative outputs in a global platform. The conference aims to bring together leading academicians, researchers, technocrats, practitioners, and students to exchange and share their experiences and research outputs in Energy, Environment, Desalination, and Material Science.
Conference Title: International Conference on Frontiers in Desalination, Energy, Environment and Material Sciences for Sustainable Development & Annual Congress of InDAConference Acronyms: FEEMSSD-2023 & InDACON-2023Conference Date: 16th-17th March 2023Conference Location: Madan Mohan Malaviya University of Technology, GorakhpurConference Organizers: Madan Mohan Malaviya University of Technology Gorakhpur, KIPM-College of Engineering and Technology Gida Gorakhpur, and Indian Desalination Association, Indi
InAs-Al Hybrid Devices Passing the Topological Gap Protocol
We present measurements and simulations of semiconductor-superconductor
heterostructure devices that are consistent with the observation of topological
superconductivity and Majorana zero modes. The devices are fabricated from
high-mobility two-dimensional electron gases in which quasi-one-dimensional
wires are defined by electrostatic gates. These devices enable measurements of
local and non-local transport properties and have been optimized via extensive
simulations for robustness against non-uniformity and disorder. Our main result
is that several devices, fabricated according to the design's engineering
specifications, have passed the topological gap protocol defined in Pikulin
{\it et al.}\ [arXiv:2103.12217]. This protocol is a stringent test composed of
a sequence of three-terminal local and non-local transport measurements
performed while varying the magnetic field, semiconductor electron density, and
junction transparencies. Passing the protocol indicates a high probability of
detection of a topological phase hosting Majorana zero modes. Our experimental
results are consistent with a quantum phase transition into a topological
superconducting phase that extends over several hundred millitesla in magnetic
field and several millivolts in gate voltage, corresponding to approximately
one hundred micro-electron-volts in Zeeman energy and chemical potential in the
semiconducting wire. These regions feature a closing and re-opening of the bulk
gap, with simultaneous zero-bias conductance peaks at {\it both} ends of the
devices that withstand changes in the junction transparencies. The measured
maximum topological gaps in our devices are 20-eV. This demonstration
is a prerequisite for experiments involving fusion and braiding of Majorana
zero modes.Comment: Fixed typos. Fig. 3 is now readable by Adobe Reade