A revolutionary new transistor has been designed for medical imaging and security screening which has been developed by Graphene researchers at the Universities of Manchester and Nottingham (UoM and UoN)
Publishing in Nature Communications the researchers reported a new graphene based transistor with bistable characteristics, which means that the device can rapidly switch between two electronic states. The devices postulated are in great demand as emitters of electromagnetic waves in the high frequency range between Radio Detection and Ranging (RADAR) and Infrared (IR), which is relevant for applications such as security systems-to-medical imaging.
Bistability is a common effect and has a seesaw outcome with two equivalent states and small perturbations that can subsequently trigger switching. The way in which charge carrying electrons in Graphene transistors move makes the switching very fast - trillions of switches/second.
As described by many since its isolation is that Graphene is the world's thinnest, strongest and most conductive material, which has potential to revolutionise a number of applications from smartphones, ultrafast broadband to drug delivery and/or computer chips.
The device consists of two layers of Graphene separated by an insulating layer of Boron nitride (BN) just a few atomic layers thick. The electron clouds in each Graphene layer can be tuned by the application of a small voltage. Therefore, this induces the electrons into a state where they can move at high speed between the layers.
The insulating layer separating the two Graphene sheets is ultra thin and electrons are able to move through this barrier by a phenomenon called 'quantum tunnelling'. Such a process induces a rapid motion of electrical charge which leads to the emission of high frequency electromagnetic waves.
Therefore, it is claimed that the new transistors exhibit the signature of a quantum seesaw which is called a negative differential conductance whereby the same electrical current flows at two different applied voltages. The researchers wish to learn how to optimise the transistor as a detector and/or emitter.
One researcher, Professor Laurence Eaves, has stated - "In addition to its potential in medical imaging and security screening, the Graphene devices could also be integrated on a chip and conventional, or other Graphene based, electronic components to provide new architectures and functionality."
"For more than 40 years, technology has led to ever smaller transistors; a tour de force of engineering that has provided us with today's state-of-the-art silicon chips which contain billions of transistors. Scientists are searching for an alternative to silicon based technology, which is likely to hit the buffers in a few years' time, and Graphene may be an answer."
As, also, stated by Dr Liam Britnell, first author from the UoM - "Graphene research is relatively mature but multi-layered devices made of different atomically-thin materials such as Graphene were first reported only a year ago. This architecture can bring many more surprises." Original article available here
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