Young Duck Kim, a postdoctoral research scientist in James Hone’s group at Columbia University School of Engineering heading the team of scientists from Columbia, Seoul National University, and Korea Research Institute of Standards and Science reported that for the first time ever they have successfully demonstrated an on-chip visible light source by using graphene as a filament. Graphene is atomically thin and a perfect crystalline form of carbon. Scientists attached small strips of graphene to metal electrodes. Then they suspended the strips above the substrate and passed current through the graphene filaments which resulted in heating up of the filaments. Researchers said that this heating then resulted into formation of visible light from the atomically thin graphene and this light is so intense that it was visible to naked eyes even without the need of additional magnification. James Hone, a professor from Columbia University and a co-author in the study said: “We have created what is essentially the world’s thinnest light bulb.” He added: “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.”
Researchers explained that in case of the incandescent light bulb the filament is made to reach very high temperatures, which is almost some thousands of degrees Celsius and due to this extreme heat the filaments start glowing in the visible range. On the other hand, it is difficult for the micro scale metal wires to even withstand such high temperatures. This is one of the basic reasons as to why though many researchers tried to develop methods to put the incandescent light bulb on to a chip; however were not able to achieve success. Incandescent light bulb, is one of the oldest and simplest source of artificial light. The spectrum of light emitting from graphene filament was measured by the researchers and it showed that the filament was reaching a temperature above 2500 degrees Celsius which was quite hot and enough for the filament to produce a visible glow. Developing light on the surface of a chip and in a layer which is only a atom thick, is a promising step for the development of fully integrated ‘photonic’ circuits in future. Researchers believe that these photonic circuits will use light instead of electric currents in semiconductor integrated circuits. Yun Daniel Park, a co-lead author professor from Seoul National University said: “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.”
