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H2020Individual fellowship2015–2017

2DSi · Magnetic Sensors based on Two-Dimensional Materials/Si

Horizon 2020 — Marie Skłodowska-Curie Actions

Duration
2015-08-03 → 2017-08-02
EU contribution
€195,455
Participants
1
Scheme
MSCA-IF-EF-ST

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Results in brief

Magnetic Sensors based on Two-Dimensional Materials/Si

Due to severe shortage of accessible clean water, the world is looking at alternate technologies/mechanisms by which efficient separation of ions and molecules at the smallest length scale can be realized. The importance of membranes with good ion/water separation capabilities is ever increasing. Reducing the size of capillaries/channels to match the hydrated size of the ions is one of the approaches. Graphene oxide (GO), the oxidized graphite has been widely explored for this purpose; however swelling of capillaries when immersed in water makes it not very useful. The swelling is due to the incorporation of 2 to 3 layers of water molecules inside interlayer spaces in GO provided by oxidized and un-oxidized regions of GO. As a result, the size of the capillaries increases from 0.8 to 1.3 nm when immersed in water, which is much larger than the size of salt ions in water, making it harder to filter out ions. One of the first problems addressed in this project was to devise methods that either completely elliminates or minimize swelling. Further, we challenged ourselves to tune the size of the capillaries so that the ions can be stopped from passing through essentially permitting only water to pass through. The aim was to expose graphene oxide to different humidity conditions and then mechanically glue the GO under these conditions so that filling of water layers can be adjusted. Controlling the capillary/channel dimensions in a flexible and controllable way is still a dream as the demonstrated nanochannels are made using nanotubes, nanopores or graphene oxide, which lack the scalability required for large scale nanofluidic applications. To remove this bottleneck, we have taken lessons from the recent discovery of graphene which was produced by peeling monolayers from graphite crystals. To create scalable nanofluidic channels, we have aimed to utilize the mechanical peeling capability of van der Waals crystals and lithographic techniques. The aim is to fabricate atomically thin fluidic channels so as to have these membranes either performing desalination or isolate individual ions from a mixture of ions, for example, industrial waste.

Data: CORDIS, © European Union

Project objective

Magnetoresistance sensors based on the change in electrical resistance upon an external magnetic field are widely used in day to day applications. The magnetic sensor industry sells billions of dollars worth of sensors every year and there is an ever-growing demand for magnetic sensors with high sensitivity, small size, low power consumption and low cost with compatibility with existing electronic systems. The project aims to develop a new class of highly sensitive magnetoresistance sensors based on doped Si and two dimensional (2D) layered materials, with a focus on single layer graphene and single layer WS2 which could be easily extended to other low dimensional layered materials. This plan will utilize the advantages of tunnelling through SiO2, gate tunability of 2D materials and the geometry of Si to obtain highly sensitive magnetic sensors from Si, which is very unique and novel. The large magnetoresistance observed in graphene by the applicant's group (Gopinadhan et al. Phys. Rev. B 88, 195429 (2013)) can be utilized to get an additional positive change in total resistance per unit applied magnetic field for higher sensitivity. Si can be integrated monolithically, in contrast, 2D layered materials such as graphene possess excellent electrical, thermal and mechanical properties. Its high mobility of carriers are very attractive for high speed applications. The interface between Si and 2D materials are little explored, however there is an enormous technological interest for applications such as graphene-based transparent electrodes in Si solar cells, high speed non-volatile flash memory, microwave switches, voltage controlled diodes, logic devices etc. Furthermore, most of the existing magnetic sensors are electron based and the possibility of both n and p type magnetic sensors due to the electric field tunability of 2D materials may provide new applications such as magnetic sensor and diode (p-n junction) in one active device.

Original text from CORDIS.

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Data: CORDIS, © European Union