A. V. Silva

A. V. Silva
A-to-Be · Research & Innovation

PhD in Physics Engineering
Research Engineer

About

27
Publications
7,637
Reads
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203
Citations
Additional affiliations
April 2016 - present
INESC Microsistemas e Nanotecnologias
Position
  • PostDoc Position
Description
  • Magnetoresistive devices for sensing and high frequency applications. Micro and nanometric silicon wet etch. Micromagnetic and magnetotransport modelling and Micro and nanofabrication of IC technology.
January 2011 - March 2016
INESC Microsistemas e Nanotecnologias
Position
  • PhD
Description
  • Design nanofabrication and characterization of magnetic tunnel junction pillar devices for sensing and RF oscillator applications, supported by micromagnetic and spin magneto-transport finite element simulations
November 2009 - July 2010
Delft University of Technology
Position
  • Internship
Description
  • Development of FleSS: a Matlab based GUI for modeling elastic deformation on multilayer thin-film structures, due to residual stresses and/or applied external bending. Work embedded in SCoDiS, under supervision of Prof. ir. Ronald Dekker.

Publications

Publications (27)
Article
Full-text available
Well-ordered tilted silicon nanobelt arrays have been fabricated over a large area (≥2.5 cm(2)) by metal assisted chemical etching of pre-patterned silicon, which demonstrated markedly enhanced solar hydrogen evolution performance, compared with planar silicon of the same type and previously reported silicon nanowires prepared in a similar way.
Article
Full-text available
Ultrasensitive magnetic field sensors envisaged for applications on biomedical imaging require the detection of low-intensity and low-frequency signals. Therefore linear magnetic sensors with enhanced sensitivity, low noise levels and improved field detection at low operating frequencies are necessary. Suitable devices can be designed using magneto...
Article
The ability to detect the magnetic fields that surround us has promoted vast technological advances in sensing techniques. Among those, magnetoresistive sensors display an unpaired spatial resolution. Here, we successfully control the linear range of nanometric sensors using an interfacial exchange bias sensing layer coupling. An effective matching...
Article
The ability to fabricate MgO magnetic tunnel junction nanopillars with low RA and high TMR opens the door to new devices such as magnetic memories or nano-oscillators. Here, we address the dynamic behavior of a CoFeB/MgO/CoFeB MTJ with a synthetic antiferromagnetic pinned layer as a potential candidate for spin transfer torque (STT) driven applicat...
Article
Full-text available
Spintronic nanodevices are consolidating a highly reputed position in advanced manufacturing industry, not only due to progresses in magnetic hard disk sensors, but also the memory market. The ability to integrate magnetic thin films on large area wafers and subsequent nanofabrication into functional devices is key for such success. This work descr...
Article
The emergence of augmented reality, robotics and point-of-care biosensors has pushed forward the frontiers of compliant sensors with mechanical resilience and capability of being arbitrarily shaped upon demand. Here, we report exchange-biased spin valve structures directly fabricated on 25μm thick commercial polymeric substrates. Linear electrical...
Article
Full-text available
One of the critical issues in spintronics-based technologies is to increase the data storage density. Current strategy is based on shrinking the devices size down to tens of nanometers, or several nanometers, which is reaching its limit. A new proposal is to use multi-level cells (MLCs) to store more than two bits in each cell. In this work, the mu...
Article
Full-text available
We present the fabrication process and characterization of a tunnel magnetoresistance sensor based monolithic device assembled in a Wheatstone bridge architecture, capable of measuring magnetic field in both planar sensitive directions simultaneously. This process is simplified in comparison with other fabrication strategies, as it does not require...
Poster
Nanometric magnetic tunnel junctions (MTJs) for memory devices based on the spin transfer torque (STT) effect require simultaneously low critical current and high thermal stability. Perpendicular magnetic anisotropy (PMA) materials such as CoFeB/MgO interfaces fulfill these requirements in theory when compared to in plane (IMA) materials[1]. Howeve...
Article
Full-text available
Perpendicular magnetic tunnel junctions (p-MTJs) have been explored for spin transfer torque magnetic random access memories (STT-MRAMs). The current-induced switching (CIS) of the p-MTJs requires a relatively high current density (J), hereby, very thin insulating barriers are required, consequently increasing the risk of non-tunneling conduction m...
Article
Full-text available
Perpendicular magnetic tunnel junctions (p-MTJs) attract great interest because of their excellent performance in spin-transfer-torque magnetic random access memories (STT-MRAMs). The annealing process is critical to achieve the required structural and magnetic properties, therefore obtaining high perpendicular tunneling magnetoresistance (p-TMR) a...
Article
Optically detectable labels and probes are commonly used in bioapplications. Together with the miniaturization of analytical platforms based on microfluidic technology, with tuneable properties, they yield unparalleled opportunities towards faster, cheaper and more efficient biomolecule analysis. This work describes the preparation and testing of u...
Poster
Perpendicular magnetic tunnel junction (p-MTJ) arises great interest because of its excellent performance in spin-transfer-torque magnetic random access memory (STT-MRAM). The annealing process is critical to achieve the required structural and magnetic properties, therefore obtaining high perpendicular tunneling magnetoresistance (p-TMR) and lower...
Article
In-vivo experiments to detect the neuronal magnetic field require high sensitivity magnetoresistive sensors incorporated in micro-machined silicon probes which do not damage the organic tissues and enhance the sensors proximity to the signal sources. When in touch with the tissues, the probe experiences a mechanical stress induced by an unavoidable...
Article
Mapping the brain's activity can be done either with non-invasive techniques (e.g. magnetic resonance, electro/magnetoencephalography), or by studies performed in-vivo/vitro at the cell level usually using small-sized electrodes (10 μm) to measure local potentials. Probing locally the neuronal magnetic fields created by the synaptic currents can be...
Article
Highly sensitive nanosensors with high spatial resolution provide the necessary features for high-accuracy imaging of isolated magnetic nanoparticles or mapping of magnetic fields. Here, we fabricated nanosensor devices based on MgO-magnetic tunnel junctions with soft pinned sensing layer. The exchange interaction at the free-layer is tuned to yiel...
Conference Paper
Magnetic tunnel junctions with exchange biased sensing-layer provide a promising solution for nanoscale sensors with improved spatial resolution [1]. In order to design optimized sensors a complete micromagnetic model for a double exchange MTJ stack with coupled magneto-transport was established.
Article
Highly sensitive nanosensors with high spatial resolution provide the necessary features for high accuracy imaging of isolated magnetic nanoparticles. In this work, we report the fabrication and characterization of MgO-barrier magnetic tunnel junction nanosensors, with two exchange-pinned electrodes. The perpendicular magnetization configuration fo...
Article
The switching field dependence on the size of nanometric magnetic tunnel junctions was studied. CoFe/Ru/CoFeB/MgO/CoFeB nano-pillars were fabricated down to 150x300 nm^2 and characterized, revealing a squared transfer curve with a sharp transition between magnetic states. A micromagnetic finite element tool was then used to simulate the magnetic be...
Article
This work compares the performance of spin valve sensors comprising magnetic flux concentrators (MFCs) composed of Co93Zr3Nb4 (CZN) or (Co70Fe30)80B20-based synthetic-antiferromagnet (SAF) multilayer stacks. In addition, the influence of a tapered MFC tip is also studied. When compared to CZN films, SAFs have the disadvantage of lower magnetic susc...
Conference Paper
Full-text available
A thorough study of exposure parameters for electron beam lithography using AR7520 negative tone electron beam resist is here presented. We optimized the beam voltage, apertures diameter and resist thickness in order to achieve the smaller dimensions possible for each resist thicknesses. Monte Carlo simulations of the electrons scattering process c...
Conference Paper
Full-text available
In this paper we present the so-called FleSS (Flexible StressStrain): a Matlab based Graphical User Interface (GUI) that provides the tools for a rapid and easy modeling and monitoring of the elastic deformation of multilayer structures due to residual stresses and applied external bending. Depending on the geometry of the device to be modeled, the...

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Projects

Projects (3)
Project
Development of nanometric sensing devices based on magnetic tunnel junctions or spinvalves, with optimized sensitivity and controlled field detection levels. Implementation of fabrication methodologies based on electron beam lithography.
Project
Micromagnetic and magnetotransport modelling. Micro and nanometric silicon wet etch, embedded in micro and nanofabrication of IC technology. Research aiming radio frequency generation for CMOS RF oscillators, using spin transfer torque based magnetic nano-oscillators and aiming magnetoresistive nano-sensors with high sensitivity and high special resolution for low magnetic fields detection.