Category: NEWS

Abstract:

The family of 2D and layered materials has been expanding rapidly for more than a decade. Within this large family of hundreds of materials, black phosphorus and its isoelectronic group IV monochalcogenides have a unique place. These puckered materials have distinctive crystalline symmetries and exhibit various exciting properties, such as high carrier mobility , strong infrared responsivity , widely tunable bandgap, in-plane anisotropy and spontaneous electric polarization. Here, we review their basic properties, highlight new electronic and photonic device concepts and novel physical phenomena and discuss future directions.

Key Points:

• The crystalline symmetries of layered black phosphorus and its isoelectronic group IV monochalcogenides play a very important role in the determination of their physical properties.
• Black phosphorus is likely to be the layered semiconductor material with the highest carrier mobility at room temperature, making it promising for high-performance electronic applications.
• Black phosphorus, arsenic phosphorus and other group V alloys may find applications in mid-infrared photonics as alternative material systems owing to their layered nature and moderate bandgap.
• Monolayer group IV monochalcogenides have a broken inversion symmetry and spontaneous in-plane electric polarization. They present a great platform for the exploration of piezoelectricity, ferroelectricity, ferroelasticity and multiferroics.
• In black phosphorus and other group V alloys, the interplay between the crystal symmetry and spin–orbit coupling may lead to the realization of rich topological states.
• Wafer-scale synthesis of this group of materials remains challenging. Future research may leverage the phase transition induced by pressure, temperature or high-intensity light.

Read the full article here: https://www.nature.com/articles/s42254-019-0043-5
For those without a subscription, a read online version is also available at https://rdcu.be/bvAWB

CA2DM researchers transformed recovered carbon black (rCB), a very economical and abundance source of material, into dazzling multicolour fluorescence and visual display, by way of a scanning focused laser treatment. This laser-initiated process is both straightforward and versatile, catering to both micro- and macro-scopic patterning with the sample in ambient or helium environment.

The observed phenomenon is attributed to both chemical and structural induced colouration of rCB powder. Chemically, carbon infusion of oxidised metal occurs when photothermal reaction takes place in ambient. After laser modification with the sample in helium environment, the powder not only fluoresces due to sulphur impurities, control annealing of these powders results in formation of periodic arrangements of carbon nanoparticles.

The periodicity of these arrangement falls within the range of visible wavelength, hence contributing to the visually observable rainbow coloured rCB flakes. The patterned sample is also transferrable using PDMS stamps. This in turn broadens the application of this material in flexible electronic devices/displays.

Photocurrent measurements show most significant enhancement under yellow light illumination. Furthermore, in the presence of an applied potential, the fluorescence detected from the sample can easily be switched off. All in all, they present a simple process to add multiple functionalities to a material that is both inexpensive and sustainable.”

https://link.springer.com/article/10.1007/s12274-018-2239-x

Figure 1: (Left) The lattice mismatch between the monolayer graphene (black) on multilayer black phosphorous (blue) generates PMF on the graphene layer. (Right) The spatial distribution and intensity of the PMF can be tailored by changing the rotation angle between the graphene and black phosphorous. (Image: NUS)

NUS researchers have discovered a simple and effective method to produce a large area pseudo-magnetic field (PMF) on graphene, and demonstrated how it can be tuned with desired spatial distribution and intensity for data storage and logic applications (“Tailoring sample-wide pseudo-magnetic fields on a graphene-black phosphorus heterostructure“).

The field of electronics focuses on how to control and exploit the properties of electrons. To study or modify the properties of these electrons at the quantum regime, a magnetic field has to be applied. Continue Reading

New discovery published in Science explains what happens during the phase transition in Dirac materials, paving the way for engineering advanced electronics that perform significantly faster

Shaffique Adam, who holds joint appointments in Centre for Advanced 2D Materials and the Department of Physics at the National University of Singapore, is the lead author for a recent work that describes a model for electron interaction in Dirac materials, a class of materials that includes graphene and topological insulators, solving a 65-year-old open theoretical problem in the process. The discovery will help scientists better understand electron interaction in new materials, paving the way for developing advanced electronics such as faster processors. The work was published in the peer-reviewed academic journal Science on 10 August 2018.

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Graphene’s usefulness on Earth has already been established in the last decade. It is now an opportune time to expand its prospects for use in space applications – an area touted as being the most challenging to modern technology – and shift the paradigm of materials science. Space is the final frontier for graphene research, and I believe this is the first time that graphene has entered the stratosphere,”
– Professor Antonio Castro Neto

On 30 June 2018, the spacecraft was launched over the Mojave Desert in the United States. CA2DM has teamed up with US-based aerospace company Boreal Space to test the properties of graphene after it has been launched into the stratosphere. The results could provide insights into how graphene could be used for space and satellite technologies.

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