New York: Imagine how thin a light 'bulb' could be? Well, it could be just one atom thick!
Using graphene - an atomically thin and perfectly crystalline form of carbon - as a filament, scientists have demonstrated for the first time an on-chip visible light source.
They attached small strips of graphene to metal electrodes, suspended the strips above the substrate, and passed current through the filaments to cause them to heat up.
The visible light from atomically thin graphene is so intense that it is visible even to the naked eye, without any additional magnification, said researchers.
"We have created what is essentially the world's thinnest light bulb," said a study co-author professor James Hone from Columbia University.
"This new type of 'broadband' light emitter can be integrated into chips and will pave the way towards the realisation of atomically thin, flexible and transparent displays and graphene-based on chip optical communications."
Creating light in small structures on the surface of a chip is crucial for developing fully integrated 'photonic' circuits that do with light what is now done with electric currents in semiconductor integrated circuits.
Researchers have developed many approaches to do this, but have not yet been able to put the oldest and simplest artificial light source - the incandescent light bulb - onto a chip.
This is primarily because light bulb filaments must be extremely hot - thousands of degrees Celsius - in order to glow in the visible range and micro-scale metal wires cannot withstand such temperatures.
By measuring the spectrum of the light emitted from the graphene, the team was able to show that the graphene was reaching temperatures of above 2500 degrees Celsius, hot enough to glow brightly.
"Edison originally used carbon as a filament for his light bulb and here we are going back to the same element, but using it in its pure form, graphene, and at its ultimate size limit - one atom thick," a co-lead author professor Yun Daniel Park from Seoul National University said.
The study was published on Nature Nanotechnology's website.