Scientists have demonstrated -- for the first time -- an on-chip visible light source using graphene, an atomically thin and perfectly crystalline form of carbon, as a filament. They attached small strips of graphene to metal electrodes, suspended the strips above the substrate, and passed a current through the filaments to cause them to heat up.

The study, 'Bright visible light emission from graphene,' is published in the Advance Online Publication (AOP) on Nature Nanotechnology's website on June 15.

'We've created what is essentially the world's thinnest light bulb,' says Hone, Wang Fon-Jen Professor of Mechanical Engineering at Columbia Engineering and co-author of the study. 'This new type of 'broadband' light emitter can be integrated into chips and will pave the way towards the realization 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.